ata: libata-scsi: fix ata_dsm_trim_pages() kernel-docgrafted

make htmldocs fails with:

  Documentation/driver-api/libata:604: ./drivers/ata/libata-scsi.c:2301:
  ERROR: Unexpected indentation. [docutils]

The Return: section of ata_dsm_trim_pages() ends its first sentence with
a colon and continues with an indented bullet list. reStructuredText
requires a blank line before an indented block, so docutils chokes on
the list.

Simply adding the missing blank line does not work either: Return: is a
kernel-doc "special section", which is terminated by the first blank
line, so the bullet list would end up in the Description section,
detached from the sentence introducing it.

Spell the two bounds out as prose instead, so that the Return: section
stays self-contained. Documentation-only change.

Fixes: e64e6b5dc867 ("ata: libata-scsi: scale DSM TRIM payload by MAX PAGES PER DSM COMMAND")
Reported-by: Thomas Huth <thuth@redhat.com>
Closes: https://lore.kernel.org/linux-ide/b0a0b8e8-cc4f-4c7b-8bc5-fee0712d405a@redhat.com/
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20260916130031.29990-2-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>

7 files changed, 4729 insertions, 0 deletions

diff --git a/drivers/most/Kconfig b/drivers/most/Kconfig
new file mode 100644
index 000000000..69c9e728b
--- /dev/null
+++ b/drivers/most/Kconfig
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0
+menuconfig MOST
+	tristate "MOST (Media Oriented Systems Transport) support"
+	depends on HAS_DMA && CONFIGFS_FS
+	default n
+	help
+	  Say Y here if you want to enable MOST support.
+	  This driver needs at least one additional component to enable the
+	  desired access from userspace (e.g. character devices) and one that
+	  matches the network controller's hardware interface (e.g. USB).
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_core.
+
+	  If in doubt, say N here.
+
+if MOST
+config MOST_USB_HDM
+	tristate "USB"
+	depends on USB
+	help
+	  Say Y here if you want to connect via USB to network transceiver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_usb.
+
+config MOST_CDEV
+	tristate "Cdev"
+
+	help
+	  Say Y here if you want to commumicate via character devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_cdev.
+
+config MOST_SND
+	tristate "Sound"
+	depends on SND
+	select SND_PCM
+	help
+	  Say Y here if you want to commumicate via ALSA/sound devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_sound.
+endif
diff --git a/drivers/most/Makefile b/drivers/most/Makefile
new file mode 100644
index 000000000..60db6cd37
--- /dev/null
+++ b/drivers/most/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_MOST) += most_core.o
+most_core-y :=	core.o \
+		configfs.o
+
+obj-$(CONFIG_MOST_USB_HDM) += most_usb.o
+obj-$(CONFIG_MOST_CDEV) += most_cdev.o
+obj-$(CONFIG_MOST_SND) += most_snd.o
diff --git a/drivers/most/configfs.c b/drivers/most/configfs.c
new file mode 100644
index 000000000..8f5158d95
--- /dev/null
+++ b/drivers/most/configfs.c
@@ -0,0 +1,724 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * configfs.c - Implementation of configfs interface to the driver stack
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/configfs.h>
+#include <linux/most.h>
+
+#define MAX_STRING_SIZE 80
+
+struct mdev_link {
+	struct config_item item;
+	struct list_head list;
+	bool create_link;
+	bool destroy_link;
+	u16 num_buffers;
+	u16 buffer_size;
+	u16 subbuffer_size;
+	u16 packets_per_xact;
+	u16 dbr_size;
+	char datatype[MAX_STRING_SIZE];
+	char direction[MAX_STRING_SIZE];
+	char name[MAX_STRING_SIZE];
+	char device[MAX_STRING_SIZE];
+	char channel[MAX_STRING_SIZE];
+	char comp[MAX_STRING_SIZE];
+	char comp_params[MAX_STRING_SIZE];
+};
+
+static struct list_head mdev_link_list;
+
+static int set_cfg_buffer_size(struct mdev_link *link)
+{
+	return most_set_cfg_buffer_size(link->device, link->channel,
+					link->buffer_size);
+}
+
+static int set_cfg_subbuffer_size(struct mdev_link *link)
+{
+	return most_set_cfg_subbuffer_size(link->device, link->channel,
+					   link->subbuffer_size);
+}
+
+static int set_cfg_dbr_size(struct mdev_link *link)
+{
+	return most_set_cfg_dbr_size(link->device, link->channel,
+				     link->dbr_size);
+}
+
+static int set_cfg_num_buffers(struct mdev_link *link)
+{
+	return most_set_cfg_num_buffers(link->device, link->channel,
+					link->num_buffers);
+}
+
+static int set_cfg_packets_xact(struct mdev_link *link)
+{
+	return most_set_cfg_packets_xact(link->device, link->channel,
+					 link->packets_per_xact);
+}
+
+static int set_cfg_direction(struct mdev_link *link)
+{
+	return most_set_cfg_direction(link->device, link->channel,
+				      link->direction);
+}
+
+static int set_cfg_datatype(struct mdev_link *link)
+{
+	return most_set_cfg_datatype(link->device, link->channel,
+				     link->datatype);
+}
+
+static int (*set_config_val[])(struct mdev_link *link) = {
+	set_cfg_buffer_size,
+	set_cfg_subbuffer_size,
+	set_cfg_dbr_size,
+	set_cfg_num_buffers,
+	set_cfg_packets_xact,
+	set_cfg_direction,
+	set_cfg_datatype,
+};
+
+static struct mdev_link *to_mdev_link(struct config_item *item)
+{
+	return container_of(item, struct mdev_link, item);
+}
+
+static int set_config_and_add_link(struct mdev_link *mdev_link)
+{
+	int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(set_config_val); i++) {
+		ret = set_config_val[i](mdev_link);
+		if (ret < 0 && ret != -ENODEV) {
+			pr_err("Config failed\n");
+			return ret;
+		}
+	}
+
+	return most_add_link(mdev_link->device, mdev_link->channel,
+			     mdev_link->comp, mdev_link->name,
+			     mdev_link->comp_params);
+}
+
+static ssize_t mdev_link_create_link_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	bool tmp;
+	int ret;
+
+	ret = kstrtobool(page, &tmp);
+	if (ret)
+		return ret;
+	if (!tmp)
+		return count;
+	ret = set_config_and_add_link(mdev_link);
+	if (ret && ret != -ENODEV)
+		return ret;
+	list_add_tail(&mdev_link->list, &mdev_link_list);
+	mdev_link->create_link = tmp;
+	mdev_link->destroy_link = false;
+
+	return count;
+}
+
+static ssize_t mdev_link_destroy_link_store(struct config_item *item,
+					    const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	bool tmp;
+	int ret;
+
+	ret = kstrtobool(page, &tmp);
+	if (ret)
+		return ret;
+	if (!tmp)
+		return count;
+
+	ret = most_remove_link(mdev_link->device, mdev_link->channel,
+			       mdev_link->comp);
+	if (ret)
+		return ret;
+	if (!list_empty(&mdev_link_list))
+		list_del(&mdev_link->list);
+
+	mdev_link->destroy_link = tmp;
+
+	return count;
+}
+
+static ssize_t mdev_link_direction_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->direction);
+}
+
+static ssize_t mdev_link_direction_store(struct config_item *item,
+					 const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	if (!sysfs_streq(page, "dir_rx") && !sysfs_streq(page, "rx") &&
+	    !sysfs_streq(page, "dir_tx") && !sysfs_streq(page, "tx"))
+		return -EINVAL;
+	strcpy(mdev_link->direction, page);
+	strim(mdev_link->direction);
+	return count;
+}
+
+static ssize_t mdev_link_datatype_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->datatype);
+}
+
+static ssize_t mdev_link_datatype_store(struct config_item *item,
+					const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	if (!sysfs_streq(page, "control") && !sysfs_streq(page, "async") &&
+	    !sysfs_streq(page, "sync") && !sysfs_streq(page, "isoc") &&
+	    !sysfs_streq(page, "isoc_avp"))
+		return -EINVAL;
+	strcpy(mdev_link->datatype, page);
+	strim(mdev_link->datatype);
+	return count;
+}
+
+static ssize_t mdev_link_device_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->device);
+}
+
+static ssize_t mdev_link_device_store(struct config_item *item,
+				      const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->device, page, sizeof(mdev_link->device));
+	strim(mdev_link->device);
+	return count;
+}
+
+static ssize_t mdev_link_channel_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->channel);
+}
+
+static ssize_t mdev_link_channel_store(struct config_item *item,
+				       const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->channel, page, sizeof(mdev_link->channel));
+	strim(mdev_link->channel);
+	return count;
+}
+
+static ssize_t mdev_link_comp_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->comp);
+}
+
+static ssize_t mdev_link_comp_store(struct config_item *item,
+				    const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->comp, page, sizeof(mdev_link->comp));
+	strim(mdev_link->comp);
+	return count;
+}
+
+static ssize_t mdev_link_comp_params_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n",
+			to_mdev_link(item)->comp_params);
+}
+
+static ssize_t mdev_link_comp_params_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->comp_params, page, sizeof(mdev_link->comp_params));
+	strim(mdev_link->comp_params);
+	return count;
+}
+
+static ssize_t mdev_link_num_buffers_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->num_buffers);
+}
+
+static ssize_t mdev_link_num_buffers_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->num_buffers);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_buffer_size_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->buffer_size);
+}
+
+static ssize_t mdev_link_buffer_size_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->buffer_size);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_subbuffer_size_show(struct config_item *item,
+					     char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->subbuffer_size);
+}
+
+static ssize_t mdev_link_subbuffer_size_store(struct config_item *item,
+					      const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->subbuffer_size);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_packets_per_xact_show(struct config_item *item,
+					       char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->packets_per_xact);
+}
+
+static ssize_t mdev_link_packets_per_xact_store(struct config_item *item,
+						const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->packets_per_xact);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_dbr_size_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n", to_mdev_link(item)->dbr_size);
+}
+
+static ssize_t mdev_link_dbr_size_store(struct config_item *item,
+					const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->dbr_size);
+	if (ret)
+		return ret;
+	return count;
+}
+
+CONFIGFS_ATTR_WO(mdev_link_, create_link);
+CONFIGFS_ATTR_WO(mdev_link_, destroy_link);
+CONFIGFS_ATTR(mdev_link_, device);
+CONFIGFS_ATTR(mdev_link_, channel);
+CONFIGFS_ATTR(mdev_link_, comp);
+CONFIGFS_ATTR(mdev_link_, comp_params);
+CONFIGFS_ATTR(mdev_link_, num_buffers);
+CONFIGFS_ATTR(mdev_link_, buffer_size);
+CONFIGFS_ATTR(mdev_link_, subbuffer_size);
+CONFIGFS_ATTR(mdev_link_, packets_per_xact);
+CONFIGFS_ATTR(mdev_link_, datatype);
+CONFIGFS_ATTR(mdev_link_, direction);
+CONFIGFS_ATTR(mdev_link_, dbr_size);
+
+static struct configfs_attribute *mdev_link_attrs[] = {
+	&mdev_link_attr_create_link,
+	&mdev_link_attr_destroy_link,
+	&mdev_link_attr_device,
+	&mdev_link_attr_channel,
+	&mdev_link_attr_comp,
+	&mdev_link_attr_comp_params,
+	&mdev_link_attr_num_buffers,
+	&mdev_link_attr_buffer_size,
+	&mdev_link_attr_subbuffer_size,
+	&mdev_link_attr_packets_per_xact,
+	&mdev_link_attr_datatype,
+	&mdev_link_attr_direction,
+	&mdev_link_attr_dbr_size,
+	NULL,
+};
+
+static void mdev_link_release(struct config_item *item)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	if (mdev_link->destroy_link)
+		goto free_item;
+
+	ret = most_remove_link(mdev_link->device, mdev_link->channel,
+			       mdev_link->comp);
+	if (ret) {
+		pr_err("Removing link failed.\n");
+		goto free_item;
+	}
+
+	if (!list_empty(&mdev_link_list))
+		list_del(&mdev_link->list);
+
+free_item:
+	kfree(to_mdev_link(item));
+}
+
+static struct configfs_item_operations mdev_link_item_ops = {
+	.release		= mdev_link_release,
+};
+
+static const struct config_item_type mdev_link_type = {
+	.ct_item_ops	= &mdev_link_item_ops,
+	.ct_attrs	= mdev_link_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+struct most_common {
+	struct config_group group;
+	struct module *mod;
+	struct configfs_subsystem subsys;
+};
+
+static struct most_common *to_most_common(struct configfs_subsystem *subsys)
+{
+	return container_of(subsys, struct most_common, subsys);
+}
+
+static struct config_item *most_common_make_item(struct config_group *group,
+						 const char *name)
+{
+	struct mdev_link *mdev_link;
+	struct most_common *mc = to_most_common(group->cg_subsys);
+
+	mdev_link = kzalloc_obj(*mdev_link);
+	if (!mdev_link)
+		return ERR_PTR(-ENOMEM);
+
+	if (!try_module_get(mc->mod)) {
+		kfree(mdev_link);
+		return ERR_PTR(-ENOLCK);
+	}
+	config_item_init_type_name(&mdev_link->item, name,
+				   &mdev_link_type);
+
+	if (!strcmp(group->cg_item.ci_namebuf, "most_cdev"))
+		strcpy(mdev_link->comp, "cdev");
+	else if (!strcmp(group->cg_item.ci_namebuf, "most_net"))
+		strcpy(mdev_link->comp, "net");
+	else if (!strcmp(group->cg_item.ci_namebuf, "most_video"))
+		strcpy(mdev_link->comp, "video");
+	strcpy(mdev_link->name, name);
+	return &mdev_link->item;
+}
+
+static void most_common_release(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	kfree(to_most_common(group->cg_subsys));
+}
+
+static struct configfs_item_operations most_common_item_ops = {
+	.release	= most_common_release,
+};
+
+static void most_common_disconnect(struct config_group *group,
+				   struct config_item *item)
+{
+	struct most_common *mc = to_most_common(group->cg_subsys);
+
+	module_put(mc->mod);
+}
+
+static struct configfs_group_operations most_common_group_ops = {
+	.make_item	= most_common_make_item,
+	.disconnect_notify = most_common_disconnect,
+};
+
+static const struct config_item_type most_common_type = {
+	.ct_item_ops	= &most_common_item_ops,
+	.ct_group_ops	= &most_common_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct most_common most_cdev = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_cdev",
+				.ci_type = &most_common_type,
+			},
+		},
+	},
+};
+
+static struct most_common most_net = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_net",
+				.ci_type = &most_common_type,
+			},
+		},
+	},
+};
+
+static struct most_common most_video = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_video",
+				.ci_type = &most_common_type,
+			},
+		},
+	},
+};
+
+struct most_snd_grp {
+	struct config_group group;
+	bool create_card;
+	struct list_head list;
+};
+
+static struct most_snd_grp *to_most_snd_grp(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct most_snd_grp, group);
+}
+
+static struct config_item *most_snd_grp_make_item(struct config_group *group,
+						  const char *name)
+{
+	struct mdev_link *mdev_link;
+
+	mdev_link = kzalloc_obj(*mdev_link);
+	if (!mdev_link)
+		return ERR_PTR(-ENOMEM);
+
+	config_item_init_type_name(&mdev_link->item, name, &mdev_link_type);
+	mdev_link->create_link = false;
+	strcpy(mdev_link->name, name);
+	strcpy(mdev_link->comp, "sound");
+	return &mdev_link->item;
+}
+
+static ssize_t most_snd_grp_create_card_store(struct config_item *item,
+					      const char *page, size_t count)
+{
+	struct most_snd_grp *snd_grp = to_most_snd_grp(item);
+	int ret;
+	bool tmp;
+
+	ret = kstrtobool(page, &tmp);
+	if (ret)
+		return ret;
+	if (tmp) {
+		ret = most_cfg_complete("sound");
+		if (ret)
+			return ret;
+	}
+	snd_grp->create_card = tmp;
+	return count;
+}
+
+CONFIGFS_ATTR_WO(most_snd_grp_, create_card);
+
+static struct configfs_attribute *most_snd_grp_attrs[] = {
+	&most_snd_grp_attr_create_card,
+	NULL,
+};
+
+static void most_snd_grp_release(struct config_item *item)
+{
+	struct most_snd_grp *group = to_most_snd_grp(item);
+
+	list_del(&group->list);
+	kfree(group);
+}
+
+static struct configfs_item_operations most_snd_grp_item_ops = {
+	.release	= most_snd_grp_release,
+};
+
+static struct configfs_group_operations most_snd_grp_group_ops = {
+	.make_item	= most_snd_grp_make_item,
+};
+
+static const struct config_item_type most_snd_grp_type = {
+	.ct_item_ops	= &most_snd_grp_item_ops,
+	.ct_group_ops	= &most_snd_grp_group_ops,
+	.ct_attrs	= most_snd_grp_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+struct most_sound {
+	struct configfs_subsystem subsys;
+	struct list_head soundcard_list;
+	struct module *mod;
+};
+
+static struct config_group *most_sound_make_group(struct config_group *group,
+						  const char *name)
+{
+	struct most_snd_grp *most;
+	struct most_sound *ms = container_of(group->cg_subsys,
+					     struct most_sound, subsys);
+
+	list_for_each_entry(most, &ms->soundcard_list, list) {
+		if (!most->create_card) {
+			pr_info("adapter configuration still in progress.\n");
+			return ERR_PTR(-EPROTO);
+		}
+	}
+	if (!try_module_get(ms->mod))
+		return ERR_PTR(-ENOLCK);
+	most = kzalloc_obj(*most);
+	if (!most) {
+		module_put(ms->mod);
+		return ERR_PTR(-ENOMEM);
+	}
+	config_group_init_type_name(&most->group, name, &most_snd_grp_type);
+	list_add_tail(&most->list, &ms->soundcard_list);
+	return &most->group;
+}
+
+static void most_sound_disconnect(struct config_group *group,
+				  struct config_item *item)
+{
+	struct most_sound *ms = container_of(group->cg_subsys,
+					     struct most_sound, subsys);
+	module_put(ms->mod);
+}
+
+static struct configfs_group_operations most_sound_group_ops = {
+	.make_group	= most_sound_make_group,
+	.disconnect_notify = most_sound_disconnect,
+};
+
+static const struct config_item_type most_sound_type = {
+	.ct_group_ops	= &most_sound_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct most_sound most_sound_subsys = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_sound",
+				.ci_type = &most_sound_type,
+			},
+		},
+	},
+};
+
+int most_register_configfs_subsys(struct most_component *c)
+{
+	int ret;
+
+	if (!strcmp(c->name, "cdev")) {
+		most_cdev.mod = c->mod;
+		ret = configfs_register_subsystem(&most_cdev.subsys);
+	} else if (!strcmp(c->name, "net")) {
+		most_net.mod = c->mod;
+		ret = configfs_register_subsystem(&most_net.subsys);
+	} else if (!strcmp(c->name, "video")) {
+		most_video.mod = c->mod;
+		ret = configfs_register_subsystem(&most_video.subsys);
+	} else if (!strcmp(c->name, "sound")) {
+		most_sound_subsys.mod = c->mod;
+		ret = configfs_register_subsystem(&most_sound_subsys.subsys);
+	} else {
+		return -ENODEV;
+	}
+
+	if (ret) {
+		pr_err("Error %d while registering subsystem %s\n",
+		       ret, c->name);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(most_register_configfs_subsys);
+
+void most_interface_register_notify(const char *mdev)
+{
+	bool register_snd_card = false;
+	struct mdev_link *mdev_link;
+
+	list_for_each_entry(mdev_link, &mdev_link_list, list) {
+		if (!strcmp(mdev_link->device, mdev)) {
+			set_config_and_add_link(mdev_link);
+			if (!strcmp(mdev_link->comp, "sound"))
+				register_snd_card = true;
+		}
+	}
+	if (register_snd_card)
+		most_cfg_complete("sound");
+}
+
+void most_deregister_configfs_subsys(struct most_component *c)
+{
+	if (!strcmp(c->name, "cdev"))
+		configfs_unregister_subsystem(&most_cdev.subsys);
+	else if (!strcmp(c->name, "net"))
+		configfs_unregister_subsystem(&most_net.subsys);
+	else if (!strcmp(c->name, "video"))
+		configfs_unregister_subsystem(&most_video.subsys);
+	else if (!strcmp(c->name, "sound"))
+		configfs_unregister_subsystem(&most_sound_subsys.subsys);
+}
+EXPORT_SYMBOL_GPL(most_deregister_configfs_subsys);
+
+int __init configfs_init(void)
+{
+	config_group_init(&most_cdev.subsys.su_group);
+	mutex_init(&most_cdev.subsys.su_mutex);
+
+	config_group_init(&most_net.subsys.su_group);
+	mutex_init(&most_net.subsys.su_mutex);
+
+	config_group_init(&most_video.subsys.su_group);
+	mutex_init(&most_video.subsys.su_mutex);
+
+	config_group_init(&most_sound_subsys.subsys.su_group);
+	mutex_init(&most_sound_subsys.subsys.su_mutex);
+
+	INIT_LIST_HEAD(&most_sound_subsys.soundcard_list);
+	INIT_LIST_HEAD(&mdev_link_list);
+
+	return 0;
+}
diff --git a/drivers/most/core.c b/drivers/most/core.c
new file mode 100644
index 000000000..c2616da8b
--- /dev/null
+++ b/drivers/most/core.c
@@ -0,0 +1,1497 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * core.c - Implementation of core module of MOST Linux driver stack
+ *
+ * Copyright (C) 2013-2020 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/poll.h>
+#include <linux/wait.h>
+#include <linux/kobject.h>
+#include <linux/mutex.h>
+#include <linux/completion.h>
+#include <linux/sysfs.h>
+#include <linux/kthread.h>
+#include <linux/dma-mapping.h>
+#include <linux/idr.h>
+#include <linux/most.h>
+
+#define MAX_CHANNELS	64
+#define STRING_SIZE	80
+
+static struct ida mdev_id;
+static int dummy_num_buffers;
+static struct list_head comp_list;
+
+struct pipe {
+	struct most_component *comp;
+	int refs;
+	int num_buffers;
+};
+
+struct most_channel {
+	struct device dev;
+	struct completion cleanup;
+	atomic_t mbo_ref;
+	atomic_t mbo_nq_level;
+	u16 channel_id;
+	char name[STRING_SIZE];
+	bool is_poisoned;
+	struct mutex start_mutex; /* channel activation synchronization */
+	struct mutex nq_mutex; /* nq thread synchronization */
+	int is_starving;
+	struct most_interface *iface;
+	struct most_channel_config cfg;
+	bool keep_mbo;
+	bool enqueue_halt;
+	struct list_head fifo;
+	spinlock_t fifo_lock; /* fifo access synchronization */
+	struct list_head halt_fifo;
+	struct list_head list;
+	struct pipe pipe0;
+	struct pipe pipe1;
+	struct list_head trash_fifo;
+	struct task_struct *hdm_enqueue_task;
+	wait_queue_head_t hdm_fifo_wq;
+
+};
+
+#define to_channel(d) container_of(d, struct most_channel, dev)
+
+struct interface_private {
+	int dev_id;
+	char name[STRING_SIZE];
+	struct most_channel *channel[MAX_CHANNELS];
+	struct list_head channel_list;
+};
+
+static const struct {
+	int most_ch_data_type;
+	const char *name;
+} ch_data_type[] = {
+	{ MOST_CH_CONTROL, "control" },
+	{ MOST_CH_ASYNC, "async" },
+	{ MOST_CH_SYNC, "sync" },
+	{ MOST_CH_ISOC, "isoc"},
+	{ MOST_CH_ISOC, "isoc_avp"},
+};
+
+/**
+ * list_pop_mbo - retrieves the first MBO of the list and removes it
+ * @ptr: the list head to grab the MBO from.
+ */
+#define list_pop_mbo(ptr)						\
+({									\
+	struct mbo *_mbo = list_first_entry(ptr, struct mbo, list);	\
+	list_del(&_mbo->list);						\
+	_mbo;								\
+})
+
+/**
+ * most_free_mbo_coherent - free an MBO and its coherent buffer
+ * @mbo: most buffer
+ */
+static void most_free_mbo_coherent(struct mbo *mbo)
+{
+	struct most_channel *c = mbo->context;
+	u16 const coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
+
+	if (c->iface->dma_free)
+		c->iface->dma_free(mbo, coherent_buf_size);
+	else
+		kfree(mbo->virt_address);
+	kfree(mbo);
+	if (atomic_sub_and_test(1, &c->mbo_ref))
+		complete(&c->cleanup);
+}
+
+/**
+ * flush_channel_fifos - clear the channel fifos
+ * @c: pointer to channel object
+ */
+static void flush_channel_fifos(struct most_channel *c)
+{
+	unsigned long flags, hf_flags;
+	struct mbo *mbo, *tmp;
+
+	if (list_empty(&c->fifo) && list_empty(&c->halt_fifo))
+		return;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_for_each_entry_safe(mbo, tmp, &c->fifo, list) {
+		list_del(&mbo->list);
+		spin_unlock_irqrestore(&c->fifo_lock, flags);
+		most_free_mbo_coherent(mbo);
+		spin_lock_irqsave(&c->fifo_lock, flags);
+	}
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+
+	spin_lock_irqsave(&c->fifo_lock, hf_flags);
+	list_for_each_entry_safe(mbo, tmp, &c->halt_fifo, list) {
+		list_del(&mbo->list);
+		spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
+		most_free_mbo_coherent(mbo);
+		spin_lock_irqsave(&c->fifo_lock, hf_flags);
+	}
+	spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
+
+	if (unlikely((!list_empty(&c->fifo) || !list_empty(&c->halt_fifo))))
+		dev_warn(&c->dev, "Channel or trash fifo not empty\n");
+}
+
+/**
+ * flush_trash_fifo - clear the trash fifo
+ * @c: pointer to channel object
+ */
+static int flush_trash_fifo(struct most_channel *c)
+{
+	struct mbo *mbo, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_for_each_entry_safe(mbo, tmp, &c->trash_fifo, list) {
+		list_del(&mbo->list);
+		spin_unlock_irqrestore(&c->fifo_lock, flags);
+		most_free_mbo_coherent(mbo);
+		spin_lock_irqsave(&c->fifo_lock, flags);
+	}
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+	return 0;
+}
+
+static ssize_t available_directions_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	strcpy(buf, "");
+	if (c->iface->channel_vector[i].direction & MOST_CH_RX)
+		strcat(buf, "rx ");
+	if (c->iface->channel_vector[i].direction & MOST_CH_TX)
+		strcat(buf, "tx ");
+	strcat(buf, "\n");
+	return strlen(buf);
+}
+
+static ssize_t available_datatypes_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	strcpy(buf, "");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_CONTROL)
+		strcat(buf, "control ");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_ASYNC)
+		strcat(buf, "async ");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_SYNC)
+		strcat(buf, "sync ");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_ISOC)
+		strcat(buf, "isoc ");
+	strcat(buf, "\n");
+	return strlen(buf);
+}
+
+static ssize_t number_of_packet_buffers_show(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].num_buffers_packet);
+}
+
+static ssize_t number_of_stream_buffers_show(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].num_buffers_streaming);
+}
+
+static ssize_t size_of_packet_buffer_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].buffer_size_packet);
+}
+
+static ssize_t size_of_stream_buffer_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].buffer_size_streaming);
+}
+
+static ssize_t channel_starving_show(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->is_starving);
+}
+
+static ssize_t set_number_of_buffers_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.num_buffers);
+}
+
+static ssize_t set_buffer_size_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.buffer_size);
+}
+
+static ssize_t set_direction_show(struct device *dev,
+				  struct device_attribute *attr,
+				  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	if (c->cfg.direction & MOST_CH_TX)
+		return snprintf(buf, PAGE_SIZE, "tx\n");
+	else if (c->cfg.direction & MOST_CH_RX)
+		return snprintf(buf, PAGE_SIZE, "rx\n");
+	return snprintf(buf, PAGE_SIZE, "unconfigured\n");
+}
+
+static ssize_t set_datatype_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	int i;
+	struct most_channel *c = to_channel(dev);
+
+	for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
+		if (c->cfg.data_type & ch_data_type[i].most_ch_data_type)
+			return snprintf(buf, PAGE_SIZE, "%s",
+					ch_data_type[i].name);
+	}
+	return snprintf(buf, PAGE_SIZE, "unconfigured\n");
+}
+
+static ssize_t set_subbuffer_size_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.subbuffer_size);
+}
+
+static ssize_t set_packets_per_xact_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.packets_per_xact);
+}
+
+static ssize_t set_dbr_size_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.dbr_size);
+}
+
+#define to_dev_attr(a) container_of(a, struct device_attribute, attr)
+static umode_t channel_attr_is_visible(struct kobject *kobj,
+				       struct attribute *attr, int index)
+{
+	struct device_attribute *dev_attr = to_dev_attr(attr);
+	struct device *dev = kobj_to_dev(kobj);
+	struct most_channel *c = to_channel(dev);
+
+	if (!strcmp(dev_attr->attr.name, "set_dbr_size") &&
+	    (c->iface->interface != ITYPE_MEDIALB_DIM2))
+		return 0;
+	if (!strcmp(dev_attr->attr.name, "set_packets_per_xact") &&
+	    (c->iface->interface != ITYPE_USB))
+		return 0;
+
+	return attr->mode;
+}
+
+#define DEV_ATTR(_name)  (&dev_attr_##_name.attr)
+
+static DEVICE_ATTR_RO(available_directions);
+static DEVICE_ATTR_RO(available_datatypes);
+static DEVICE_ATTR_RO(number_of_packet_buffers);
+static DEVICE_ATTR_RO(number_of_stream_buffers);
+static DEVICE_ATTR_RO(size_of_stream_buffer);
+static DEVICE_ATTR_RO(size_of_packet_buffer);
+static DEVICE_ATTR_RO(channel_starving);
+static DEVICE_ATTR_RO(set_buffer_size);
+static DEVICE_ATTR_RO(set_number_of_buffers);
+static DEVICE_ATTR_RO(set_direction);
+static DEVICE_ATTR_RO(set_datatype);
+static DEVICE_ATTR_RO(set_subbuffer_size);
+static DEVICE_ATTR_RO(set_packets_per_xact);
+static DEVICE_ATTR_RO(set_dbr_size);
+
+static struct attribute *channel_attrs[] = {
+	DEV_ATTR(available_directions),
+	DEV_ATTR(available_datatypes),
+	DEV_ATTR(number_of_packet_buffers),
+	DEV_ATTR(number_of_stream_buffers),
+	DEV_ATTR(size_of_stream_buffer),
+	DEV_ATTR(size_of_packet_buffer),
+	DEV_ATTR(channel_starving),
+	DEV_ATTR(set_buffer_size),
+	DEV_ATTR(set_number_of_buffers),
+	DEV_ATTR(set_direction),
+	DEV_ATTR(set_datatype),
+	DEV_ATTR(set_subbuffer_size),
+	DEV_ATTR(set_packets_per_xact),
+	DEV_ATTR(set_dbr_size),
+	NULL,
+};
+
+static const struct attribute_group channel_attr_group = {
+	.attrs = channel_attrs,
+	.is_visible = channel_attr_is_visible,
+};
+
+static const struct attribute_group *channel_attr_groups[] = {
+	&channel_attr_group,
+	NULL,
+};
+
+static ssize_t description_show(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct most_interface *iface = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", iface->description);
+}
+
+static ssize_t interface_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct most_interface *iface = dev_get_drvdata(dev);
+
+	switch (iface->interface) {
+	case ITYPE_LOOPBACK:
+		return snprintf(buf, PAGE_SIZE, "loopback\n");
+	case ITYPE_I2C:
+		return snprintf(buf, PAGE_SIZE, "i2c\n");
+	case ITYPE_I2S:
+		return snprintf(buf, PAGE_SIZE, "i2s\n");
+	case ITYPE_TSI:
+		return snprintf(buf, PAGE_SIZE, "tsi\n");
+	case ITYPE_HBI:
+		return snprintf(buf, PAGE_SIZE, "hbi\n");
+	case ITYPE_MEDIALB_DIM:
+		return snprintf(buf, PAGE_SIZE, "mlb_dim\n");
+	case ITYPE_MEDIALB_DIM2:
+		return snprintf(buf, PAGE_SIZE, "mlb_dim2\n");
+	case ITYPE_USB:
+		return snprintf(buf, PAGE_SIZE, "usb\n");
+	case ITYPE_PCIE:
+		return snprintf(buf, PAGE_SIZE, "pcie\n");
+	}
+	return snprintf(buf, PAGE_SIZE, "unknown\n");
+}
+
+static DEVICE_ATTR_RO(description);
+static DEVICE_ATTR_RO(interface);
+
+static struct attribute *interface_attrs[] = {
+	DEV_ATTR(description),
+	DEV_ATTR(interface),
+	NULL,
+};
+
+static const struct attribute_group interface_attr_group = {
+	.attrs = interface_attrs,
+};
+
+static const struct attribute_group *interface_attr_groups[] = {
+	&interface_attr_group,
+	NULL,
+};
+
+static struct most_component *match_component(char *name)
+{
+	struct most_component *comp;
+
+	list_for_each_entry(comp, &comp_list, list) {
+		if (!strcmp(comp->name, name))
+			return comp;
+	}
+	return NULL;
+}
+
+struct show_links_data {
+	int offs;
+	char *buf;
+};
+
+static int print_links(struct device *dev, void *data)
+{
+	struct show_links_data *d = data;
+	int offs = d->offs;
+	char *buf = d->buf;
+	struct most_channel *c;
+	struct most_interface *iface = dev_get_drvdata(dev);
+
+	list_for_each_entry(c, &iface->p->channel_list, list) {
+		if (c->pipe0.comp) {
+			offs += scnprintf(buf + offs,
+					 PAGE_SIZE - offs,
+					 "%s:%s:%s\n",
+					 c->pipe0.comp->name,
+					 dev_name(iface->dev),
+					 dev_name(&c->dev));
+		}
+		if (c->pipe1.comp) {
+			offs += scnprintf(buf + offs,
+					 PAGE_SIZE - offs,
+					 "%s:%s:%s\n",
+					 c->pipe1.comp->name,
+					 dev_name(iface->dev),
+					 dev_name(&c->dev));
+		}
+	}
+	d->offs = offs;
+	return 0;
+}
+
+static int most_match(struct device *dev, const struct device_driver *drv)
+{
+	if (!strcmp(dev_name(dev), "most"))
+		return 0;
+	else
+		return 1;
+}
+
+static const struct bus_type mostbus = {
+	.name = "most",
+	.match = most_match,
+};
+
+static ssize_t links_show(struct device_driver *drv, char *buf)
+{
+	struct show_links_data d = { .buf = buf };
+
+	bus_for_each_dev(&mostbus, NULL, &d, print_links);
+	return d.offs;
+}
+
+static ssize_t components_show(struct device_driver *drv, char *buf)
+{
+	struct most_component *comp;
+	int offs = 0;
+
+	list_for_each_entry(comp, &comp_list, list) {
+		offs += scnprintf(buf + offs, PAGE_SIZE - offs, "%s\n",
+				 comp->name);
+	}
+	return offs;
+}
+
+/**
+ * get_channel - get pointer to channel
+ * @mdev: name of the device interface
+ * @mdev_ch: name of channel
+ */
+static struct most_channel *get_channel(char *mdev, char *mdev_ch)
+{
+	struct device *dev = NULL;
+	struct most_interface *iface;
+	struct most_channel *c, *tmp;
+
+	dev = bus_find_device_by_name(&mostbus, NULL, mdev);
+	if (!dev)
+		return NULL;
+	iface = dev_get_drvdata(dev);
+	put_device(dev);
+	list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
+		if (!strcmp(dev_name(&c->dev), mdev_ch))
+			return c;
+	}
+	return NULL;
+}
+
+static
+inline int link_channel_to_component(struct most_channel *c,
+				     struct most_component *comp,
+				     char *name,
+				     char *comp_param)
+{
+	int ret;
+	struct most_component **comp_ptr;
+
+	if (!c->pipe0.comp)
+		comp_ptr = &c->pipe0.comp;
+	else if (!c->pipe1.comp)
+		comp_ptr = &c->pipe1.comp;
+	else
+		return -ENOSPC;
+
+	*comp_ptr = comp;
+	ret = comp->probe_channel(c->iface, c->channel_id, &c->cfg, name,
+				  comp_param);
+	if (ret) {
+		*comp_ptr = NULL;
+		return ret;
+	}
+	return 0;
+}
+
+int most_set_cfg_buffer_size(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.buffer_size = val;
+	return 0;
+}
+
+int most_set_cfg_subbuffer_size(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.subbuffer_size = val;
+	return 0;
+}
+
+int most_set_cfg_dbr_size(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.dbr_size = val;
+	return 0;
+}
+
+int most_set_cfg_num_buffers(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.num_buffers = val;
+	return 0;
+}
+
+int most_set_cfg_datatype(char *mdev, char *mdev_ch, char *buf)
+{
+	int i;
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
+		if (!strcmp(buf, ch_data_type[i].name)) {
+			c->cfg.data_type = ch_data_type[i].most_ch_data_type;
+			break;
+		}
+	}
+
+	if (i == ARRAY_SIZE(ch_data_type))
+		dev_warn(&c->dev, "Invalid attribute settings\n");
+	return 0;
+}
+
+int most_set_cfg_direction(char *mdev, char *mdev_ch, char *buf)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	if (!strcmp(buf, "dir_rx")) {
+		c->cfg.direction = MOST_CH_RX;
+	} else if (!strcmp(buf, "rx")) {
+		c->cfg.direction = MOST_CH_RX;
+	} else if (!strcmp(buf, "dir_tx")) {
+		c->cfg.direction = MOST_CH_TX;
+	} else if (!strcmp(buf, "tx")) {
+		c->cfg.direction = MOST_CH_TX;
+	} else {
+		dev_err(&c->dev, "Invalid direction\n");
+		return -ENODATA;
+	}
+	return 0;
+}
+
+int most_set_cfg_packets_xact(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.packets_per_xact = val;
+	return 0;
+}
+
+int most_cfg_complete(char *comp_name)
+{
+	struct most_component *comp;
+
+	comp = match_component(comp_name);
+	if (!comp)
+		return -ENODEV;
+
+	return comp->cfg_complete();
+}
+
+int most_add_link(char *mdev, char *mdev_ch, char *comp_name, char *link_name,
+		  char *comp_param)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+	struct most_component *comp = match_component(comp_name);
+
+	if (!c || !comp)
+		return -ENODEV;
+
+	return link_channel_to_component(c, comp, link_name, comp_param);
+}
+
+int most_remove_link(char *mdev, char *mdev_ch, char *comp_name)
+{
+	struct most_channel *c;
+	struct most_component *comp;
+
+	comp = match_component(comp_name);
+	if (!comp)
+		return -ENODEV;
+	c = get_channel(mdev, mdev_ch);
+	if (!c)
+		return -ENODEV;
+
+	if (comp->disconnect_channel(c->iface, c->channel_id))
+		return -EIO;
+	if (c->pipe0.comp == comp)
+		c->pipe0.comp = NULL;
+	if (c->pipe1.comp == comp)
+		c->pipe1.comp = NULL;
+	return 0;
+}
+
+#define DRV_ATTR(_name)  (&driver_attr_##_name.attr)
+
+static DRIVER_ATTR_RO(links);
+static DRIVER_ATTR_RO(components);
+
+static struct attribute *mc_attrs[] = {
+	DRV_ATTR(links),
+	DRV_ATTR(components),
+	NULL,
+};
+
+static const struct attribute_group mc_attr_group = {
+	.attrs = mc_attrs,
+};
+
+static const struct attribute_group *mc_attr_groups[] = {
+	&mc_attr_group,
+	NULL,
+};
+
+static struct device_driver mostbus_driver = {
+	.name = "most_core",
+	.bus = &mostbus,
+	.groups = mc_attr_groups,
+};
+
+static inline void trash_mbo(struct mbo *mbo)
+{
+	unsigned long flags;
+	struct most_channel *c = mbo->context;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_add(&mbo->list, &c->trash_fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+}
+
+static bool hdm_mbo_ready(struct most_channel *c)
+{
+	bool empty;
+
+	if (c->enqueue_halt)
+		return false;
+
+	spin_lock_irq(&c->fifo_lock);
+	empty = list_empty(&c->halt_fifo);
+	spin_unlock_irq(&c->fifo_lock);
+
+	return !empty;
+}
+
+static void nq_hdm_mbo(struct mbo *mbo)
+{
+	unsigned long flags;
+	struct most_channel *c = mbo->context;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_add_tail(&mbo->list, &c->halt_fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+	wake_up_interruptible(&c->hdm_fifo_wq);
+}
+
+static int hdm_enqueue_thread(void *data)
+{
+	struct most_channel *c = data;
+	struct mbo *mbo;
+	int ret;
+	typeof(c->iface->enqueue) enqueue = c->iface->enqueue;
+
+	while (likely(!kthread_should_stop())) {
+		wait_event_interruptible(c->hdm_fifo_wq,
+					 hdm_mbo_ready(c) ||
+					 kthread_should_stop());
+
+		mutex_lock(&c->nq_mutex);
+		spin_lock_irq(&c->fifo_lock);
+		if (unlikely(c->enqueue_halt || list_empty(&c->halt_fifo))) {
+			spin_unlock_irq(&c->fifo_lock);
+			mutex_unlock(&c->nq_mutex);
+			continue;
+		}
+
+		mbo = list_pop_mbo(&c->halt_fifo);
+		spin_unlock_irq(&c->fifo_lock);
+
+		if (c->cfg.direction == MOST_CH_RX)
+			mbo->buffer_length = c->cfg.buffer_size;
+
+		ret = enqueue(mbo->ifp, mbo->hdm_channel_id, mbo);
+		mutex_unlock(&c->nq_mutex);
+
+		if (unlikely(ret)) {
+			dev_err(&c->dev, "Buffer enqueue failed\n");
+			nq_hdm_mbo(mbo);
+			c->hdm_enqueue_task = NULL;
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
+static int run_enqueue_thread(struct most_channel *c, int channel_id)
+{
+	struct task_struct *task =
+		kthread_run(hdm_enqueue_thread, c, "hdm_fifo_%d",
+			    channel_id);
+
+	if (IS_ERR(task))
+		return PTR_ERR(task);
+
+	c->hdm_enqueue_task = task;
+	return 0;
+}
+
+/**
+ * arm_mbo - recycle MBO for further usage
+ * @mbo: most buffer
+ *
+ * This puts an MBO back to the list to have it ready for up coming
+ * tx transactions.
+ *
+ * In case the MBO belongs to a channel that recently has been
+ * poisoned, the MBO is scheduled to be trashed.
+ * Calls the completion handler of an attached component.
+ */
+static void arm_mbo(struct mbo *mbo)
+{
+	unsigned long flags;
+	struct most_channel *c;
+
+	c = mbo->context;
+
+	if (c->is_poisoned) {
+		trash_mbo(mbo);
+		return;
+	}
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	++*mbo->num_buffers_ptr;
+	list_add_tail(&mbo->list, &c->fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+
+	if (c->pipe0.refs && c->pipe0.comp->tx_completion)
+		c->pipe0.comp->tx_completion(c->iface, c->channel_id);
+
+	if (c->pipe1.refs && c->pipe1.comp->tx_completion)
+		c->pipe1.comp->tx_completion(c->iface, c->channel_id);
+}
+
+/**
+ * arm_mbo_chain - helper function that arms an MBO chain for the HDM
+ * @c: pointer to interface channel
+ * @dir: direction of the channel
+ * @compl: pointer to completion function
+ *
+ * This allocates buffer objects including the containing DMA coherent
+ * buffer and puts them in the fifo.
+ * Buffers of Rx channels are put in the kthread fifo, hence immediately
+ * submitted to the HDM.
+ *
+ * Returns the number of allocated and enqueued MBOs.
+ */
+static int arm_mbo_chain(struct most_channel *c, int dir,
+			 void (*compl)(struct mbo *))
+{
+	unsigned int i;
+	struct mbo *mbo;
+	unsigned long flags;
+	u32 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
+
+	atomic_set(&c->mbo_nq_level, 0);
+
+	for (i = 0; i < c->cfg.num_buffers; i++) {
+		mbo = kzalloc_obj(*mbo);
+		if (!mbo)
+			goto flush_fifos;
+
+		mbo->context = c;
+		mbo->ifp = c->iface;
+		mbo->hdm_channel_id = c->channel_id;
+		if (c->iface->dma_alloc) {
+			mbo->virt_address =
+				c->iface->dma_alloc(mbo, coherent_buf_size);
+		} else {
+			mbo->virt_address =
+				kzalloc(coherent_buf_size, GFP_KERNEL);
+		}
+		if (!mbo->virt_address)
+			goto release_mbo;
+
+		mbo->complete = compl;
+		mbo->num_buffers_ptr = &dummy_num_buffers;
+		if (dir == MOST_CH_RX) {
+			nq_hdm_mbo(mbo);
+			atomic_inc(&c->mbo_nq_level);
+		} else {
+			spin_lock_irqsave(&c->fifo_lock, flags);
+			list_add_tail(&mbo->list, &c->fifo);
+			spin_unlock_irqrestore(&c->fifo_lock, flags);
+		}
+	}
+	return c->cfg.num_buffers;
+
+release_mbo:
+	kfree(mbo);
+
+flush_fifos:
+	flush_channel_fifos(c);
+	return 0;
+}
+
+/**
+ * most_submit_mbo - submits an MBO to fifo
+ * @mbo: most buffer
+ */
+void most_submit_mbo(struct mbo *mbo)
+{
+	if (WARN_ONCE(!mbo || !mbo->context,
+		      "Bad buffer or missing channel reference\n"))
+		return;
+
+	nq_hdm_mbo(mbo);
+}
+EXPORT_SYMBOL_GPL(most_submit_mbo);
+
+/**
+ * most_write_completion - write completion handler
+ * @mbo: most buffer
+ *
+ * This recycles the MBO for further usage. In case the channel has been
+ * poisoned, the MBO is scheduled to be trashed.
+ */
+static void most_write_completion(struct mbo *mbo)
+{
+	struct most_channel *c;
+
+	c = mbo->context;
+	if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE)))
+		trash_mbo(mbo);
+	else
+		arm_mbo(mbo);
+}
+
+int channel_has_mbo(struct most_interface *iface, int id,
+		    struct most_component *comp)
+{
+	struct most_channel *c = iface->p->channel[id];
+	unsigned long flags;
+	int empty;
+
+	if (unlikely(!c))
+		return -EINVAL;
+
+	if (c->pipe0.refs && c->pipe1.refs &&
+	    ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
+	     (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
+		return 0;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	empty = list_empty(&c->fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+	return !empty;
+}
+EXPORT_SYMBOL_GPL(channel_has_mbo);
+
+/**
+ * most_get_mbo - get pointer to an MBO of pool
+ * @iface: pointer to interface instance
+ * @id: channel ID
+ * @comp: driver component
+ *
+ * This attempts to get a free buffer out of the channel fifo.
+ * Returns a pointer to MBO on success or NULL otherwise.
+ */
+struct mbo *most_get_mbo(struct most_interface *iface, int id,
+			 struct most_component *comp)
+{
+	struct mbo *mbo;
+	struct most_channel *c;
+	unsigned long flags;
+	int *num_buffers_ptr;
+
+	c = iface->p->channel[id];
+	if (unlikely(!c))
+		return NULL;
+
+	if (c->pipe0.refs && c->pipe1.refs &&
+	    ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
+	     (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
+		return NULL;
+
+	if (comp == c->pipe0.comp)
+		num_buffers_ptr = &c->pipe0.num_buffers;
+	else if (comp == c->pipe1.comp)
+		num_buffers_ptr = &c->pipe1.num_buffers;
+	else
+		num_buffers_ptr = &dummy_num_buffers;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	if (list_empty(&c->fifo)) {
+		spin_unlock_irqrestore(&c->fifo_lock, flags);
+		return NULL;
+	}
+	mbo = list_pop_mbo(&c->fifo);
+	--*num_buffers_ptr;
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+
+	mbo->num_buffers_ptr = num_buffers_ptr;
+	mbo->buffer_length = c->cfg.buffer_size;
+	return mbo;
+}
+EXPORT_SYMBOL_GPL(most_get_mbo);
+
+/**
+ * most_put_mbo - return buffer to pool
+ * @mbo: most buffer
+ */
+void most_put_mbo(struct mbo *mbo)
+{
+	struct most_channel *c = mbo->context;
+
+	if (c->cfg.direction == MOST_CH_TX) {
+		arm_mbo(mbo);
+		return;
+	}
+	nq_hdm_mbo(mbo);
+	atomic_inc(&c->mbo_nq_level);
+}
+EXPORT_SYMBOL_GPL(most_put_mbo);
+
+/**
+ * most_read_completion - read completion handler
+ * @mbo: most buffer
+ *
+ * This function is called by the HDM when data has been received from the
+ * hardware and copied to the buffer of the MBO.
+ *
+ * In case the channel has been poisoned it puts the buffer in the trash queue.
+ * Otherwise, it passes the buffer to an component for further processing.
+ */
+static void most_read_completion(struct mbo *mbo)
+{
+	struct most_channel *c = mbo->context;
+
+	if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE))) {
+		trash_mbo(mbo);
+		return;
+	}
+
+	if (mbo->status == MBO_E_INVAL) {
+		nq_hdm_mbo(mbo);
+		atomic_inc(&c->mbo_nq_level);
+		return;
+	}
+
+	if (atomic_sub_and_test(1, &c->mbo_nq_level))
+		c->is_starving = 1;
+
+	if (c->pipe0.refs && c->pipe0.comp->rx_completion &&
+	    c->pipe0.comp->rx_completion(mbo) == 0)
+		return;
+
+	if (c->pipe1.refs && c->pipe1.comp->rx_completion &&
+	    c->pipe1.comp->rx_completion(mbo) == 0)
+		return;
+
+	most_put_mbo(mbo);
+}
+
+/**
+ * most_start_channel - prepares a channel for communication
+ * @iface: pointer to interface instance
+ * @id: channel ID
+ * @comp: driver component
+ *
+ * This prepares the channel for usage. Cross-checks whether the
+ * channel's been properly configured.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+int most_start_channel(struct most_interface *iface, int id,
+		       struct most_component *comp)
+{
+	int num_buffer;
+	int ret;
+	struct most_channel *c = iface->p->channel[id];
+
+	if (unlikely(!c))
+		return -EINVAL;
+
+	mutex_lock(&c->start_mutex);
+	if (c->pipe0.refs + c->pipe1.refs > 0)
+		goto out; /* already started by another component */
+
+	if (!try_module_get(iface->mod)) {
+		dev_err(&c->dev, "Failed to acquire HDM lock\n");
+		mutex_unlock(&c->start_mutex);
+		return -ENOLCK;
+	}
+
+	c->cfg.extra_len = 0;
+	if (c->iface->configure(c->iface, c->channel_id, &c->cfg)) {
+		dev_err(&c->dev, "Channel configuration failed. Go check settings...\n");
+		ret = -EINVAL;
+		goto err_put_module;
+	}
+
+	init_waitqueue_head(&c->hdm_fifo_wq);
+
+	if (c->cfg.direction == MOST_CH_RX)
+		num_buffer = arm_mbo_chain(c, c->cfg.direction,
+					   most_read_completion);
+	else
+		num_buffer = arm_mbo_chain(c, c->cfg.direction,
+					   most_write_completion);
+	if (unlikely(!num_buffer)) {
+		ret = -ENOMEM;
+		goto err_put_module;
+	}
+
+	ret = run_enqueue_thread(c, id);
+	if (ret)
+		goto err_put_module;
+
+	c->is_starving = 0;
+	c->pipe0.num_buffers = c->cfg.num_buffers / 2;
+	c->pipe1.num_buffers = c->cfg.num_buffers - c->pipe0.num_buffers;
+	atomic_set(&c->mbo_ref, num_buffer);
+
+out:
+	if (comp == c->pipe0.comp)
+		c->pipe0.refs++;
+	if (comp == c->pipe1.comp)
+		c->pipe1.refs++;
+	mutex_unlock(&c->start_mutex);
+	return 0;
+
+err_put_module:
+	module_put(iface->mod);
+	mutex_unlock(&c->start_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(most_start_channel);
+
+/**
+ * most_stop_channel - stops a running channel
+ * @iface: pointer to interface instance
+ * @id: channel ID
+ * @comp: driver component
+ */
+int most_stop_channel(struct most_interface *iface, int id,
+		      struct most_component *comp)
+{
+	struct most_channel *c;
+
+	if (unlikely((!iface) || (id >= iface->num_channels) || (id < 0))) {
+		pr_err("Bad interface or index out of range\n");
+		return -EINVAL;
+	}
+	c = iface->p->channel[id];
+	if (unlikely(!c))
+		return -EINVAL;
+
+	mutex_lock(&c->start_mutex);
+	if (c->pipe0.refs + c->pipe1.refs >= 2)
+		goto out;
+
+	if (c->hdm_enqueue_task)
+		kthread_stop(c->hdm_enqueue_task);
+	c->hdm_enqueue_task = NULL;
+
+	if (iface->mod)
+		module_put(iface->mod);
+
+	c->is_poisoned = true;
+	if (c->iface->poison_channel(c->iface, c->channel_id)) {
+		dev_err(&c->dev, "Failed to stop channel %d of interface %s\n", c->channel_id,
+			c->iface->description);
+		mutex_unlock(&c->start_mutex);
+		return -EAGAIN;
+	}
+	flush_trash_fifo(c);
+	flush_channel_fifos(c);
+
+#ifdef CMPL_INTERRUPTIBLE
+	if (wait_for_completion_interruptible(&c->cleanup)) {
+		dev_err(&c->dev, "Interrupted while cleaning up channel %d\n", c->channel_id);
+		mutex_unlock(&c->start_mutex);
+		return -EINTR;
+	}
+#else
+	wait_for_completion(&c->cleanup);
+#endif
+	c->is_poisoned = false;
+
+out:
+	if (comp == c->pipe0.comp)
+		c->pipe0.refs--;
+	if (comp == c->pipe1.comp)
+		c->pipe1.refs--;
+	mutex_unlock(&c->start_mutex);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(most_stop_channel);
+
+/**
+ * most_register_component - registers a driver component with the core
+ * @comp: driver component
+ */
+int most_register_component(struct most_component *comp)
+{
+	if (!comp) {
+		pr_err("Bad component\n");
+		return -EINVAL;
+	}
+	list_add_tail(&comp->list, &comp_list);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(most_register_component);
+
+static int disconnect_channels(struct device *dev, void *data)
+{
+	struct most_interface *iface;
+	struct most_channel *c, *tmp;
+	struct most_component *comp = data;
+
+	iface = dev_get_drvdata(dev);
+	list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
+		if (c->pipe0.comp == comp || c->pipe1.comp == comp)
+			comp->disconnect_channel(c->iface, c->channel_id);
+		if (c->pipe0.comp == comp)
+			c->pipe0.comp = NULL;
+		if (c->pipe1.comp == comp)
+			c->pipe1.comp = NULL;
+	}
+	return 0;
+}
+
+/**
+ * most_deregister_component - deregisters a driver component with the core
+ * @comp: driver component
+ */
+int most_deregister_component(struct most_component *comp)
+{
+	if (!comp) {
+		pr_err("Bad component\n");
+		return -EINVAL;
+	}
+
+	bus_for_each_dev(&mostbus, NULL, comp, disconnect_channels);
+	list_del(&comp->list);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(most_deregister_component);
+
+static void release_channel(struct device *dev)
+{
+	struct most_channel *c = to_channel(dev);
+
+	kfree(c);
+}
+
+/**
+ * most_register_interface - registers an interface with core
+ * @iface: device interface
+ *
+ * Allocates and initializes a new interface instance and all of its channels.
+ * Returns a pointer to kobject or an error pointer.
+ */
+int most_register_interface(struct most_interface *iface)
+{
+	unsigned int i;
+	int id;
+	struct most_channel *c;
+
+	if (!iface)
+		return -EINVAL;
+
+	device_initialize(iface->dev);
+
+	if (!iface->enqueue || !iface->configure || !iface->poison_channel ||
+	    (iface->num_channels > MAX_CHANNELS)) {
+		put_device(iface->dev);
+		return -EINVAL;
+	}
+
+	id = ida_alloc(&mdev_id, GFP_KERNEL);
+	if (id < 0) {
+		dev_err(iface->dev, "Failed to allocate device ID\n");
+		put_device(iface->dev);
+		return id;
+	}
+
+	iface->p = kzalloc_obj(*iface->p);
+	if (!iface->p) {
+		ida_free(&mdev_id, id);
+		put_device(iface->dev);
+		return -ENOMEM;
+	}
+
+	INIT_LIST_HEAD(&iface->p->channel_list);
+	iface->p->dev_id = id;
+	strscpy(iface->p->name, iface->description, sizeof(iface->p->name));
+	iface->dev->bus = &mostbus;
+	iface->dev->groups = interface_attr_groups;
+	dev_set_drvdata(iface->dev, iface);
+	if (device_add(iface->dev)) {
+		dev_err(iface->dev, "Failed to register interface device\n");
+		kfree(iface->p);
+		put_device(iface->dev);
+		ida_free(&mdev_id, id);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < iface->num_channels; i++) {
+		const char *name_suffix = iface->channel_vector[i].name_suffix;
+
+		c = kzalloc_obj(*c);
+		if (!c)
+			goto err_free_resources;
+		if (!name_suffix)
+			snprintf(c->name, STRING_SIZE, "ch%d", i);
+		else
+			snprintf(c->name, STRING_SIZE, "%s", name_suffix);
+		c->dev.init_name = c->name;
+		c->dev.parent = iface->dev;
+		c->dev.groups = channel_attr_groups;
+		c->dev.release = release_channel;
+		iface->p->channel[i] = c;
+		c->is_starving = 0;
+		c->iface = iface;
+		c->channel_id = i;
+		c->keep_mbo = false;
+		c->enqueue_halt = false;
+		c->is_poisoned = false;
+		c->cfg.direction = 0;
+		c->cfg.data_type = 0;
+		c->cfg.num_buffers = 0;
+		c->cfg.buffer_size = 0;
+		c->cfg.subbuffer_size = 0;
+		c->cfg.packets_per_xact = 0;
+		spin_lock_init(&c->fifo_lock);
+		INIT_LIST_HEAD(&c->fifo);
+		INIT_LIST_HEAD(&c->trash_fifo);
+		INIT_LIST_HEAD(&c->halt_fifo);
+		init_completion(&c->cleanup);
+		atomic_set(&c->mbo_ref, 0);
+		mutex_init(&c->start_mutex);
+		mutex_init(&c->nq_mutex);
+		list_add_tail(&c->list, &iface->p->channel_list);
+		if (device_register(&c->dev)) {
+			dev_err(&c->dev, "Failed to register channel device\n");
+			goto err_free_most_channel;
+		}
+	}
+	most_interface_register_notify(iface->description);
+	return 0;
+
+err_free_most_channel:
+	put_device(&c->dev);
+
+err_free_resources:
+	while (i > 0) {
+		c = iface->p->channel[--i];
+		device_unregister(&c->dev);
+	}
+	kfree(iface->p);
+	device_unregister(iface->dev);
+	ida_free(&mdev_id, id);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(most_register_interface);
+
+/**
+ * most_deregister_interface - deregisters an interface with core
+ * @iface: device interface
+ *
+ * Before removing an interface instance from the list, all running
+ * channels are stopped and poisoned.
+ */
+void most_deregister_interface(struct most_interface *iface)
+{
+	int i;
+	struct most_channel *c;
+
+	for (i = 0; i < iface->num_channels; i++) {
+		c = iface->p->channel[i];
+		if (c->pipe0.comp)
+			c->pipe0.comp->disconnect_channel(c->iface,
+							c->channel_id);
+		if (c->pipe1.comp)
+			c->pipe1.comp->disconnect_channel(c->iface,
+							c->channel_id);
+		c->pipe0.comp = NULL;
+		c->pipe1.comp = NULL;
+		list_del(&c->list);
+		device_unregister(&c->dev);
+	}
+
+	ida_free(&mdev_id, iface->p->dev_id);
+	kfree(iface->p);
+	device_unregister(iface->dev);
+}
+EXPORT_SYMBOL_GPL(most_deregister_interface);
+
+/**
+ * most_stop_enqueue - prevents core from enqueueing MBOs
+ * @iface: pointer to interface
+ * @id: channel id
+ *
+ * This is called by an HDM that _cannot_ attend to its duties and
+ * is imminent to get run over by the core. The core is not going to
+ * enqueue any further packets unless the flagging HDM calls
+ * most_resume enqueue().
+ */
+void most_stop_enqueue(struct most_interface *iface, int id)
+{
+	struct most_channel *c = iface->p->channel[id];
+
+	if (!c)
+		return;
+
+	mutex_lock(&c->nq_mutex);
+	c->enqueue_halt = true;
+	mutex_unlock(&c->nq_mutex);
+}
+EXPORT_SYMBOL_GPL(most_stop_enqueue);
+
+/**
+ * most_resume_enqueue - allow core to enqueue MBOs again
+ * @iface: pointer to interface
+ * @id: channel id
+ *
+ * This clears the enqueue halt flag and enqueues all MBOs currently
+ * sitting in the wait fifo.
+ */
+void most_resume_enqueue(struct most_interface *iface, int id)
+{
+	struct most_channel *c = iface->p->channel[id];
+
+	if (!c)
+		return;
+
+	mutex_lock(&c->nq_mutex);
+	c->enqueue_halt = false;
+	mutex_unlock(&c->nq_mutex);
+
+	wake_up_interruptible(&c->hdm_fifo_wq);
+}
+EXPORT_SYMBOL_GPL(most_resume_enqueue);
+
+static int __init most_init(void)
+{
+	int err;
+
+	INIT_LIST_HEAD(&comp_list);
+	ida_init(&mdev_id);
+
+	err = bus_register(&mostbus);
+	if (err) {
+		pr_err("Failed to register most bus\n");
+		return err;
+	}
+	err = driver_register(&mostbus_driver);
+	if (err) {
+		pr_err("Failed to register core driver\n");
+		goto err_unregister_bus;
+	}
+	configfs_init();
+	return 0;
+
+err_unregister_bus:
+	bus_unregister(&mostbus);
+	return err;
+}
+
+static void __exit most_exit(void)
+{
+	driver_unregister(&mostbus_driver);
+	bus_unregister(&mostbus);
+	ida_destroy(&mdev_id);
+}
+
+subsys_initcall(most_init);
+module_exit(most_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_DESCRIPTION("Core module of stacked MOST Linux driver");
diff --git a/drivers/most/most_cdev.c b/drivers/most/most_cdev.c
new file mode 100644
index 000000000..5df508d8d
--- /dev/null
+++ b/drivers/most/most_cdev.c
@@ -0,0 +1,546 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cdev.c - Character device component for Mostcore
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/poll.h>
+#include <linux/kfifo.h>
+#include <linux/uaccess.h>
+#include <linux/idr.h>
+#include <linux/most.h>
+
+#define CHRDEV_REGION_SIZE 50
+
+static const struct class most_cdev_class = {
+	.name		= "most_cdev"
+};
+
+static struct cdev_component {
+	dev_t devno;
+	struct ida minor_id;
+	unsigned int major;
+	struct most_component cc;
+} comp;
+
+struct comp_channel {
+	wait_queue_head_t wq;
+	spinlock_t unlink;	/* synchronization lock to unlink channels */
+	struct cdev cdev;
+	struct device *dev;
+	struct mutex io_mutex;
+	struct most_interface *iface;
+	struct most_channel_config *cfg;
+	unsigned int channel_id;
+	dev_t devno;
+	size_t mbo_offs;
+	DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
+	int access_ref;
+	struct list_head list;
+};
+
+#define to_channel(d) container_of(d, struct comp_channel, cdev)
+static LIST_HEAD(channel_list);
+static DEFINE_SPINLOCK(ch_list_lock);
+
+static inline bool ch_has_mbo(struct comp_channel *c)
+{
+	return channel_has_mbo(c->iface, c->channel_id, &comp.cc) > 0;
+}
+
+static inline struct mbo *ch_get_mbo(struct comp_channel *c, struct mbo **mbo)
+{
+	if (!kfifo_peek(&c->fifo, mbo)) {
+		*mbo = most_get_mbo(c->iface, c->channel_id, &comp.cc);
+		if (*mbo)
+			kfifo_in(&c->fifo, mbo, 1);
+	}
+	return *mbo;
+}
+
+static struct comp_channel *get_channel(struct most_interface *iface, int id)
+{
+	struct comp_channel *c, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ch_list_lock, flags);
+	list_for_each_entry_safe(c, tmp, &channel_list, list) {
+		if ((c->iface == iface) && (c->channel_id == id)) {
+			spin_unlock_irqrestore(&ch_list_lock, flags);
+			return c;
+		}
+	}
+	spin_unlock_irqrestore(&ch_list_lock, flags);
+	return NULL;
+}
+
+static void stop_channel(struct comp_channel *c)
+{
+	struct mbo *mbo;
+
+	while (kfifo_out((struct kfifo *)&c->fifo, &mbo, 1))
+		most_put_mbo(mbo);
+	most_stop_channel(c->iface, c->channel_id, &comp.cc);
+}
+
+static void destroy_cdev(struct comp_channel *c)
+{
+	unsigned long flags;
+
+	device_destroy(&most_cdev_class, c->devno);
+	cdev_del(&c->cdev);
+	spin_lock_irqsave(&ch_list_lock, flags);
+	list_del(&c->list);
+	spin_unlock_irqrestore(&ch_list_lock, flags);
+}
+
+static void destroy_channel(struct comp_channel *c)
+{
+	ida_free(&comp.minor_id, MINOR(c->devno));
+	kfifo_free(&c->fifo);
+	kfree(c);
+}
+
+/**
+ * comp_open - implements the syscall to open the device
+ * @inode: inode pointer
+ * @filp: file pointer
+ *
+ * This stores the channel pointer in the private data field of
+ * the file structure and activates the channel within the core.
+ */
+static int comp_open(struct inode *inode, struct file *filp)
+{
+	struct comp_channel *c;
+	int ret;
+
+	c = to_channel(inode->i_cdev);
+	filp->private_data = c;
+
+	if (((c->cfg->direction == MOST_CH_RX) &&
+	     ((filp->f_flags & O_ACCMODE) != O_RDONLY)) ||
+	     ((c->cfg->direction == MOST_CH_TX) &&
+		((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
+		return -EACCES;
+	}
+
+	mutex_lock(&c->io_mutex);
+	if (!c->dev) {
+		mutex_unlock(&c->io_mutex);
+		return -ENODEV;
+	}
+
+	if (c->access_ref) {
+		mutex_unlock(&c->io_mutex);
+		return -EBUSY;
+	}
+
+	c->mbo_offs = 0;
+	ret = most_start_channel(c->iface, c->channel_id, &comp.cc);
+	if (!ret)
+		c->access_ref = 1;
+	mutex_unlock(&c->io_mutex);
+	return ret;
+}
+
+/**
+ * comp_close - implements the syscall to close the device
+ * @inode: inode pointer
+ * @filp: file pointer
+ *
+ * This stops the channel within the core.
+ */
+static int comp_close(struct inode *inode, struct file *filp)
+{
+	struct comp_channel *c = to_channel(inode->i_cdev);
+
+	mutex_lock(&c->io_mutex);
+	spin_lock(&c->unlink);
+	c->access_ref = 0;
+	spin_unlock(&c->unlink);
+	if (c->dev) {
+		stop_channel(c);
+		mutex_unlock(&c->io_mutex);
+	} else {
+		mutex_unlock(&c->io_mutex);
+		destroy_channel(c);
+	}
+	return 0;
+}
+
+/**
+ * comp_write - implements the syscall to write to the device
+ * @filp: file pointer
+ * @buf: pointer to user buffer
+ * @count: number of bytes to write
+ * @offset: offset from where to start writing
+ */
+static ssize_t comp_write(struct file *filp, const char __user *buf,
+			  size_t count, loff_t *offset)
+{
+	int ret;
+	size_t to_copy, left;
+	struct mbo *mbo = NULL;
+	struct comp_channel *c = filp->private_data;
+
+	mutex_lock(&c->io_mutex);
+	while (c->dev && !ch_get_mbo(c, &mbo)) {
+		mutex_unlock(&c->io_mutex);
+
+		if ((filp->f_flags & O_NONBLOCK))
+			return -EAGAIN;
+		if (wait_event_interruptible(c->wq, ch_has_mbo(c) || !c->dev))
+			return -ERESTARTSYS;
+		mutex_lock(&c->io_mutex);
+	}
+
+	if (unlikely(!c->dev)) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+
+	to_copy = min(count, c->cfg->buffer_size - c->mbo_offs);
+	left = copy_from_user(mbo->virt_address + c->mbo_offs, buf, to_copy);
+	if (left == to_copy) {
+		ret = -EFAULT;
+		goto unlock;
+	}
+
+	c->mbo_offs += to_copy - left;
+	if (c->mbo_offs >= c->cfg->buffer_size ||
+	    c->cfg->data_type == MOST_CH_CONTROL ||
+	    c->cfg->data_type == MOST_CH_ASYNC) {
+		kfifo_skip(&c->fifo);
+		mbo->buffer_length = c->mbo_offs;
+		c->mbo_offs = 0;
+		most_submit_mbo(mbo);
+	}
+
+	ret = to_copy - left;
+unlock:
+	mutex_unlock(&c->io_mutex);
+	return ret;
+}
+
+/**
+ * comp_read - implements the syscall to read from the device
+ * @filp: file pointer
+ * @buf: pointer to user buffer
+ * @count: number of bytes to read
+ * @offset: offset from where to start reading
+ */
+static ssize_t
+comp_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
+{
+	size_t to_copy, not_copied, copied;
+	struct mbo *mbo = NULL;
+	struct comp_channel *c = filp->private_data;
+
+	mutex_lock(&c->io_mutex);
+	while (c->dev && !kfifo_peek(&c->fifo, &mbo)) {
+		mutex_unlock(&c->io_mutex);
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+		if (wait_event_interruptible(c->wq,
+					     (!kfifo_is_empty(&c->fifo) ||
+					      (!c->dev))))
+			return -ERESTARTSYS;
+		mutex_lock(&c->io_mutex);
+	}
+
+	/* make sure we don't submit to gone devices */
+	if (unlikely(!c->dev)) {
+		mutex_unlock(&c->io_mutex);
+		return -ENODEV;
+	}
+
+	to_copy = min_t(size_t,
+			count,
+			mbo->processed_length - c->mbo_offs);
+
+	not_copied = copy_to_user(buf,
+				  mbo->virt_address + c->mbo_offs,
+				  to_copy);
+
+	copied = to_copy - not_copied;
+
+	c->mbo_offs += copied;
+	if (c->mbo_offs >= mbo->processed_length) {
+		kfifo_skip(&c->fifo);
+		most_put_mbo(mbo);
+		c->mbo_offs = 0;
+	}
+	mutex_unlock(&c->io_mutex);
+	return copied;
+}
+
+static __poll_t comp_poll(struct file *filp, poll_table *wait)
+{
+	struct comp_channel *c = filp->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(filp, &c->wq, wait);
+
+	mutex_lock(&c->io_mutex);
+	if (c->cfg->direction == MOST_CH_RX) {
+		if (!c->dev || !kfifo_is_empty(&c->fifo))
+			mask |= EPOLLIN | EPOLLRDNORM;
+	} else {
+		if (!c->dev || !kfifo_is_empty(&c->fifo) || ch_has_mbo(c))
+			mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+	mutex_unlock(&c->io_mutex);
+	return mask;
+}
+
+/*
+ * Initialization of struct file_operations
+ */
+static const struct file_operations channel_fops = {
+	.owner = THIS_MODULE,
+	.read = comp_read,
+	.write = comp_write,
+	.open = comp_open,
+	.release = comp_close,
+	.poll = comp_poll,
+};
+
+/**
+ * comp_disconnect_channel - disconnect a channel
+ * @iface: pointer to interface instance
+ * @channel_id: channel index
+ *
+ * This frees allocated memory and removes the cdev that represents this
+ * channel in user space.
+ */
+static int comp_disconnect_channel(struct most_interface *iface, int channel_id)
+{
+	struct comp_channel *c;
+
+	c = get_channel(iface, channel_id);
+	if (!c)
+		return -EINVAL;
+
+	mutex_lock(&c->io_mutex);
+	spin_lock(&c->unlink);
+	c->dev = NULL;
+	spin_unlock(&c->unlink);
+	destroy_cdev(c);
+	if (c->access_ref) {
+		stop_channel(c);
+		wake_up_interruptible(&c->wq);
+		mutex_unlock(&c->io_mutex);
+	} else {
+		mutex_unlock(&c->io_mutex);
+		destroy_channel(c);
+	}
+	return 0;
+}
+
+/**
+ * comp_rx_completion - completion handler for rx channels
+ * @mbo: pointer to buffer object that has completed
+ *
+ * This searches for the channel linked to this MBO and stores it in the local
+ * fifo buffer.
+ */
+static int comp_rx_completion(struct mbo *mbo)
+{
+	struct comp_channel *c;
+
+	if (!mbo)
+		return -EINVAL;
+
+	c = get_channel(mbo->ifp, mbo->hdm_channel_id);
+	if (!c)
+		return -EINVAL;
+
+	spin_lock(&c->unlink);
+	if (!c->access_ref || !c->dev) {
+		spin_unlock(&c->unlink);
+		return -ENODEV;
+	}
+	kfifo_in(&c->fifo, &mbo, 1);
+	spin_unlock(&c->unlink);
+#ifdef DEBUG_MESG
+	if (kfifo_is_full(&c->fifo))
+		dev_warn(c->dev, "Fifo is full\n");
+#endif
+	wake_up_interruptible(&c->wq);
+	return 0;
+}
+
+/**
+ * comp_tx_completion - completion handler for tx channels
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ *
+ * This wakes sleeping processes in the wait-queue.
+ */
+static int comp_tx_completion(struct most_interface *iface, int channel_id)
+{
+	struct comp_channel *c;
+
+	c = get_channel(iface, channel_id);
+	if (!c)
+		return -EINVAL;
+
+	if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
+		dev_warn(c->dev, "Channel ID out of range\n");
+		return -EINVAL;
+	}
+
+	wake_up_interruptible(&c->wq);
+	return 0;
+}
+
+/**
+ * comp_probe - probe function of the driver module
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ * @cfg: pointer to actual channel configuration
+ * @name: name of the device to be created
+ * @args: pointer to array of component parameters (from configfs)
+ *
+ * This allocates a channel object and creates the device node in /dev
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int comp_probe(struct most_interface *iface, int channel_id,
+		      struct most_channel_config *cfg, char *name, char *args)
+{
+	struct comp_channel *c;
+	unsigned long cl_flags;
+	int retval;
+	int current_minor;
+
+	if (!cfg || !name)
+		return -EINVAL;
+
+	c = get_channel(iface, channel_id);
+	if (c)
+		return -EEXIST;
+
+	current_minor = ida_alloc(&comp.minor_id, GFP_KERNEL);
+	if (current_minor < 0)
+		return current_minor;
+
+	c = kzalloc_obj(*c);
+	if (!c) {
+		retval = -ENOMEM;
+		goto err_remove_ida;
+	}
+
+	c->devno = MKDEV(comp.major, current_minor);
+	cdev_init(&c->cdev, &channel_fops);
+	c->cdev.owner = THIS_MODULE;
+	retval = cdev_add(&c->cdev, c->devno, 1);
+	if (retval < 0)
+		goto err_free_c;
+	c->iface = iface;
+	c->cfg = cfg;
+	c->channel_id = channel_id;
+	c->access_ref = 0;
+	spin_lock_init(&c->unlink);
+	INIT_KFIFO(c->fifo);
+	retval = kfifo_alloc(&c->fifo, cfg->num_buffers, GFP_KERNEL);
+	if (retval)
+		goto err_del_cdev_and_free_channel;
+	init_waitqueue_head(&c->wq);
+	mutex_init(&c->io_mutex);
+	spin_lock_irqsave(&ch_list_lock, cl_flags);
+	list_add_tail(&c->list, &channel_list);
+	spin_unlock_irqrestore(&ch_list_lock, cl_flags);
+	c->dev = device_create(&most_cdev_class, NULL, c->devno, NULL, "%s", name);
+
+	if (IS_ERR(c->dev)) {
+		retval = PTR_ERR(c->dev);
+		goto err_free_kfifo_and_del_list;
+	}
+	kobject_uevent(&c->dev->kobj, KOBJ_ADD);
+	return 0;
+
+err_free_kfifo_and_del_list:
+	kfifo_free(&c->fifo);
+	list_del(&c->list);
+err_del_cdev_and_free_channel:
+	cdev_del(&c->cdev);
+err_free_c:
+	kfree(c);
+err_remove_ida:
+	ida_free(&comp.minor_id, current_minor);
+	return retval;
+}
+
+static struct cdev_component comp = {
+	.cc = {
+		.mod = THIS_MODULE,
+		.name = "cdev",
+		.probe_channel = comp_probe,
+		.disconnect_channel = comp_disconnect_channel,
+		.rx_completion = comp_rx_completion,
+		.tx_completion = comp_tx_completion,
+	},
+};
+
+
+static int __init most_cdev_init(void)
+{
+	int err;
+
+	err = class_register(&most_cdev_class);
+	if (err)
+		return err;
+
+	ida_init(&comp.minor_id);
+
+	err = alloc_chrdev_region(&comp.devno, 0, CHRDEV_REGION_SIZE, "cdev");
+	if (err < 0)
+		goto dest_ida;
+	comp.major = MAJOR(comp.devno);
+	err = most_register_component(&comp.cc);
+	if (err)
+		goto free_cdev;
+	err = most_register_configfs_subsys(&comp.cc);
+	if (err)
+		goto deregister_comp;
+	return 0;
+
+deregister_comp:
+	most_deregister_component(&comp.cc);
+free_cdev:
+	unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE);
+dest_ida:
+	ida_destroy(&comp.minor_id);
+	class_unregister(&most_cdev_class);
+	return err;
+}
+
+static void __exit most_cdev_exit(void)
+{
+	struct comp_channel *c, *tmp;
+
+	most_deregister_configfs_subsys(&comp.cc);
+	most_deregister_component(&comp.cc);
+
+	list_for_each_entry_safe(c, tmp, &channel_list, list) {
+		destroy_cdev(c);
+		destroy_channel(c);
+	}
+	unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE);
+	ida_destroy(&comp.minor_id);
+	class_unregister(&most_cdev_class);
+}
+
+module_init(most_cdev_init);
+module_exit(most_cdev_exit);
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("character device component for mostcore");
diff --git a/drivers/most/most_snd.c b/drivers/most/most_snd.c
new file mode 100644
index 000000000..68b9e6c64
--- /dev/null
+++ b/drivers/most/most_snd.c
@@ -0,0 +1,747 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sound.c - Sound component for Mostcore
+ *
+ * Copyright (C) 2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <linux/sched.h>
+#include <linux/kthread.h>
+#include <linux/most.h>
+
+#define DRIVER_NAME "sound"
+#define STRING_SIZE	80
+
+static struct most_component comp;
+
+/**
+ * struct channel - private structure to keep channel specific data
+ * @substream: stores the substream structure
+ * @pcm_hardware: low-level hardware description
+ * @iface: interface for which the channel belongs to
+ * @cfg: channel configuration
+ * @card: registered sound card
+ * @list: list for private use
+ * @id: channel index
+ * @period_pos: current period position (ring buffer)
+ * @buffer_pos: current buffer position (ring buffer)
+ * @is_stream_running: identifies whether a stream is running or not
+ * @opened: set when the stream is opened
+ * @playback_task: playback thread
+ * @playback_waitq: waitq used by playback thread
+ * @copy_fn: copy function for PCM-specific format and width
+ */
+struct channel {
+	struct snd_pcm_substream *substream;
+	struct snd_pcm_hardware pcm_hardware;
+	struct most_interface *iface;
+	struct most_channel_config *cfg;
+	struct snd_card *card;
+	struct list_head list;
+	int id;
+	unsigned int period_pos;
+	unsigned int buffer_pos;
+	bool is_stream_running;
+	struct task_struct *playback_task;
+	wait_queue_head_t playback_waitq;
+	void (*copy_fn)(void *alsa, void *most, unsigned int bytes);
+};
+
+struct sound_adapter {
+	struct list_head dev_list;
+	struct most_interface *iface;
+	struct snd_card *card;
+	struct list_head list;
+	bool registered;
+	int pcm_dev_idx;
+};
+
+static struct list_head adpt_list;
+
+#define MOST_PCM_INFO (SNDRV_PCM_INFO_MMAP | \
+		       SNDRV_PCM_INFO_MMAP_VALID | \
+		       SNDRV_PCM_INFO_BATCH | \
+		       SNDRV_PCM_INFO_INTERLEAVED | \
+		       SNDRV_PCM_INFO_BLOCK_TRANSFER)
+
+static void swap_copy16(u16 *dest, const u16 *source, unsigned int bytes)
+{
+	unsigned int i = 0;
+
+	while (i < (bytes / 2)) {
+		dest[i] = swab16(source[i]);
+		i++;
+	}
+}
+
+static void swap_copy24(u8 *dest, const u8 *source, unsigned int bytes)
+{
+	unsigned int i = 0;
+
+	if (bytes < 2)
+		return;
+	while (i < bytes - 2) {
+		dest[i] = source[i + 2];
+		dest[i + 1] = source[i + 1];
+		dest[i + 2] = source[i];
+		i += 3;
+	}
+}
+
+static void swap_copy32(u32 *dest, const u32 *source, unsigned int bytes)
+{
+	unsigned int i = 0;
+
+	while (i < bytes / 4) {
+		dest[i] = swab32(source[i]);
+		i++;
+	}
+}
+
+static void alsa_to_most_memcpy(void *alsa, void *most, unsigned int bytes)
+{
+	memcpy(most, alsa, bytes);
+}
+
+static void alsa_to_most_copy16(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy16(most, alsa, bytes);
+}
+
+static void alsa_to_most_copy24(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy24(most, alsa, bytes);
+}
+
+static void alsa_to_most_copy32(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy32(most, alsa, bytes);
+}
+
+static void most_to_alsa_memcpy(void *alsa, void *most, unsigned int bytes)
+{
+	memcpy(alsa, most, bytes);
+}
+
+static void most_to_alsa_copy16(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy16(alsa, most, bytes);
+}
+
+static void most_to_alsa_copy24(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy24(alsa, most, bytes);
+}
+
+static void most_to_alsa_copy32(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy32(alsa, most, bytes);
+}
+
+/**
+ * get_channel - get pointer to channel
+ * @iface: interface structure
+ * @channel_id: channel ID
+ *
+ * This traverses the channel list and returns the channel matching the
+ * ID and interface.
+ *
+ * Returns pointer to channel on success or NULL otherwise.
+ */
+static struct channel *get_channel(struct most_interface *iface,
+				   int channel_id)
+{
+	struct sound_adapter *adpt = iface->priv;
+	struct channel *channel;
+
+	list_for_each_entry(channel, &adpt->dev_list, list) {
+		if ((channel->iface == iface) && (channel->id == channel_id))
+			return channel;
+	}
+	return NULL;
+}
+
+/**
+ * copy_data - implements data copying function
+ * @channel: channel
+ * @mbo: MBO from core
+ *
+ * Copy data from/to ring buffer to/from MBO and update the buffer position
+ */
+static bool copy_data(struct channel *channel, struct mbo *mbo)
+{
+	struct snd_pcm_runtime *const runtime = channel->substream->runtime;
+	unsigned int const frame_bytes = channel->cfg->subbuffer_size;
+	unsigned int const buffer_size = runtime->buffer_size;
+	unsigned int frames;
+	unsigned int fr0;
+
+	if (channel->cfg->direction & MOST_CH_RX)
+		frames = mbo->processed_length / frame_bytes;
+	else
+		frames = mbo->buffer_length / frame_bytes;
+	fr0 = min(buffer_size - channel->buffer_pos, frames);
+
+	channel->copy_fn(runtime->dma_area + channel->buffer_pos * frame_bytes,
+			 mbo->virt_address,
+			 fr0 * frame_bytes);
+
+	if (frames > fr0) {
+		/* wrap around at end of ring buffer */
+		channel->copy_fn(runtime->dma_area,
+				 mbo->virt_address + fr0 * frame_bytes,
+				 (frames - fr0) * frame_bytes);
+	}
+
+	channel->buffer_pos += frames;
+	if (channel->buffer_pos >= buffer_size)
+		channel->buffer_pos -= buffer_size;
+	channel->period_pos += frames;
+	if (channel->period_pos >= runtime->period_size) {
+		channel->period_pos -= runtime->period_size;
+		return true;
+	}
+	return false;
+}
+
+/**
+ * playback_thread - function implements the playback thread
+ * @data: private data
+ *
+ * Thread which does the playback functionality in a loop. It waits for a free
+ * MBO from mostcore for a particular channel and copy the data from ring buffer
+ * to MBO. Submit the MBO back to mostcore, after copying the data.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int playback_thread(void *data)
+{
+	struct channel *const channel = data;
+
+	while (!kthread_should_stop()) {
+		struct mbo *mbo = NULL;
+		bool period_elapsed = false;
+
+		wait_event_interruptible(
+			channel->playback_waitq,
+			kthread_should_stop() ||
+			(channel->is_stream_running &&
+			 (mbo = most_get_mbo(channel->iface, channel->id,
+					     &comp))));
+		if (!mbo)
+			continue;
+
+		if (channel->is_stream_running)
+			period_elapsed = copy_data(channel, mbo);
+		else
+			memset(mbo->virt_address, 0, mbo->buffer_length);
+
+		most_submit_mbo(mbo);
+		if (period_elapsed)
+			snd_pcm_period_elapsed(channel->substream);
+	}
+	return 0;
+}
+
+/**
+ * pcm_open - implements open callback function for PCM middle layer
+ * @substream: pointer to ALSA PCM substream
+ *
+ * This is called when a PCM substream is opened. At least, the function should
+ * initialize the runtime->hw record.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_open(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct most_channel_config *cfg = channel->cfg;
+	int ret;
+
+	channel->substream = substream;
+
+	if (cfg->direction == MOST_CH_TX) {
+		channel->playback_task = kthread_run(playback_thread, channel,
+						     "most_audio_playback");
+		if (IS_ERR(channel->playback_task)) {
+			pr_err("Couldn't start thread\n");
+			return PTR_ERR(channel->playback_task);
+		}
+	}
+
+	ret = most_start_channel(channel->iface, channel->id, &comp);
+	if (ret) {
+		pr_err("most_start_channel() failed!\n");
+		if (cfg->direction == MOST_CH_TX)
+			kthread_stop(channel->playback_task);
+		return ret;
+	}
+
+	runtime->hw = channel->pcm_hardware;
+	return 0;
+}
+
+/**
+ * pcm_close - implements close callback function for PCM middle layer
+ * @substream: sub-stream pointer
+ *
+ * Obviously, this is called when a PCM substream is closed. Any private
+ * instance for a PCM substream allocated in the open callback will be
+ * released here.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_close(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+
+	if (channel->cfg->direction == MOST_CH_TX)
+		kthread_stop(channel->playback_task);
+	most_stop_channel(channel->iface, channel->id, &comp);
+	return 0;
+}
+
+/**
+ * pcm_prepare - implements prepare callback function for PCM middle layer
+ * @substream: substream pointer
+ *
+ * This callback is called when the PCM is "prepared". Format rate, sample rate,
+ * etc., can be set here. This callback can be called many times at each setup.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct most_channel_config *cfg = channel->cfg;
+	int width = snd_pcm_format_physical_width(runtime->format);
+
+	channel->copy_fn = NULL;
+
+	if (cfg->direction == MOST_CH_TX) {
+		if (snd_pcm_format_big_endian(runtime->format) || width == 8)
+			channel->copy_fn = alsa_to_most_memcpy;
+		else if (width == 16)
+			channel->copy_fn = alsa_to_most_copy16;
+		else if (width == 24)
+			channel->copy_fn = alsa_to_most_copy24;
+		else if (width == 32)
+			channel->copy_fn = alsa_to_most_copy32;
+	} else {
+		if (snd_pcm_format_big_endian(runtime->format) || width == 8)
+			channel->copy_fn = most_to_alsa_memcpy;
+		else if (width == 16)
+			channel->copy_fn = most_to_alsa_copy16;
+		else if (width == 24)
+			channel->copy_fn = most_to_alsa_copy24;
+		else if (width == 32)
+			channel->copy_fn = most_to_alsa_copy32;
+	}
+
+	if (!channel->copy_fn)
+		return -EINVAL;
+	channel->period_pos = 0;
+	channel->buffer_pos = 0;
+	return 0;
+}
+
+/**
+ * pcm_trigger - implements trigger callback function for PCM middle layer
+ * @substream: substream pointer
+ * @cmd: action to perform
+ *
+ * This is called when the PCM is started, stopped or paused. The action will be
+ * specified in the second argument, SNDRV_PCM_TRIGGER_XXX
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	struct channel *channel = substream->private_data;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+		channel->is_stream_running = true;
+		wake_up_interruptible(&channel->playback_waitq);
+		return 0;
+
+	case SNDRV_PCM_TRIGGER_STOP:
+		channel->is_stream_running = false;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/**
+ * pcm_pointer - implements pointer callback function for PCM middle layer
+ * @substream: substream pointer
+ *
+ * This callback is called when the PCM middle layer inquires the current
+ * hardware position on the buffer. The position must be returned in frames,
+ * ranging from 0 to buffer_size-1.
+ */
+static snd_pcm_uframes_t pcm_pointer(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+
+	return channel->buffer_pos;
+}
+
+/*
+ * Initialization of struct snd_pcm_ops
+ */
+static const struct snd_pcm_ops pcm_ops = {
+	.open       = pcm_open,
+	.close      = pcm_close,
+	.prepare    = pcm_prepare,
+	.trigger    = pcm_trigger,
+	.pointer    = pcm_pointer,
+};
+
+static int split_arg_list(char *buf, u16 *ch_num, char **sample_res)
+{
+	char *num;
+	int ret;
+
+	num = strsep(&buf, "x");
+	if (!num)
+		goto err;
+	ret = kstrtou16(num, 0, ch_num);
+	if (ret)
+		goto err;
+	*sample_res = strsep(&buf, ".\n");
+	if (!*sample_res)
+		goto err;
+	return 0;
+
+err:
+	pr_err("Bad PCM format\n");
+	return -EINVAL;
+}
+
+static const struct sample_resolution_info {
+	const char *sample_res;
+	int bytes;
+	u64 formats;
+} sinfo[] = {
+	{ "8", 1, SNDRV_PCM_FMTBIT_S8 },
+	{ "16", 2, SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE },
+	{ "24", 3, SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE },
+	{ "32", 4, SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE },
+};
+
+static int audio_set_hw_params(struct snd_pcm_hardware *pcm_hw,
+			       u16 ch_num, char *sample_res,
+			       struct most_channel_config *cfg)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(sinfo); i++) {
+		if (!strcmp(sample_res, sinfo[i].sample_res))
+			goto found;
+	}
+	pr_err("Unsupported PCM format\n");
+	return -EINVAL;
+
+found:
+	if (!ch_num) {
+		pr_err("Bad number of channels\n");
+		return -EINVAL;
+	}
+
+	if (cfg->subbuffer_size != ch_num * sinfo[i].bytes) {
+		pr_err("Audio resolution doesn't fit subbuffer size\n");
+		return -EINVAL;
+	}
+
+	pcm_hw->info = MOST_PCM_INFO;
+	pcm_hw->rates = SNDRV_PCM_RATE_48000;
+	pcm_hw->rate_min = 48000;
+	pcm_hw->rate_max = 48000;
+	pcm_hw->buffer_bytes_max = cfg->num_buffers * cfg->buffer_size;
+	pcm_hw->period_bytes_min = cfg->buffer_size;
+	pcm_hw->period_bytes_max = cfg->buffer_size;
+	pcm_hw->periods_min = 1;
+	pcm_hw->periods_max = cfg->num_buffers;
+	pcm_hw->channels_min = ch_num;
+	pcm_hw->channels_max = ch_num;
+	pcm_hw->formats = sinfo[i].formats;
+	return 0;
+}
+
+static void release_adapter(struct sound_adapter *adpt)
+{
+	struct channel *channel, *tmp;
+
+	list_for_each_entry_safe(channel, tmp, &adpt->dev_list, list) {
+		list_del(&channel->list);
+		kfree(channel);
+	}
+	if (adpt->card)
+		snd_card_free(adpt->card);
+	list_del(&adpt->list);
+	kfree(adpt);
+}
+
+/**
+ * audio_probe_channel - probe function of the driver module
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ * @cfg: pointer to actual channel configuration
+ * @device_name: name of the device to be created in /dev
+ * @arg_list: string that provides the desired audio resolution
+ *
+ * Creates sound card, pcm device, sets pcm ops and registers sound card.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_probe_channel(struct most_interface *iface, int channel_id,
+			       struct most_channel_config *cfg,
+			       char *device_name, char *arg_list)
+{
+	struct channel *channel;
+	struct sound_adapter *adpt;
+	struct snd_pcm *pcm;
+	int playback_count = 0;
+	int capture_count = 0;
+	int ret;
+	int direction;
+	u16 ch_num;
+	char *sample_res;
+	char arg_list_cpy[STRING_SIZE];
+
+	if (cfg->data_type != MOST_CH_SYNC) {
+		pr_err("Incompatible channel type\n");
+		return -EINVAL;
+	}
+	strscpy(arg_list_cpy, arg_list, STRING_SIZE);
+	ret = split_arg_list(arg_list_cpy, &ch_num, &sample_res);
+	if (ret < 0)
+		return ret;
+
+	list_for_each_entry(adpt, &adpt_list, list) {
+		if (adpt->iface != iface)
+			continue;
+		if (adpt->registered)
+			return -ENOSPC;
+		adpt->pcm_dev_idx++;
+		goto skip_adpt_alloc;
+	}
+	adpt = kzalloc_obj(*adpt);
+	if (!adpt)
+		return -ENOMEM;
+
+	adpt->iface = iface;
+	INIT_LIST_HEAD(&adpt->dev_list);
+	iface->priv = adpt;
+	list_add_tail(&adpt->list, &adpt_list);
+	ret = snd_card_new(iface->driver_dev, -1, "INIC", THIS_MODULE,
+			   sizeof(*channel), &adpt->card);
+	if (ret < 0)
+		goto err_free_adpt;
+	snprintf(adpt->card->driver, sizeof(adpt->card->driver),
+		 "%s", DRIVER_NAME);
+	snprintf(adpt->card->shortname, sizeof(adpt->card->shortname),
+		 "Microchip INIC");
+	snprintf(adpt->card->longname, sizeof(adpt->card->longname),
+		 "%s at %s", adpt->card->shortname, iface->description);
+skip_adpt_alloc:
+	if (get_channel(iface, channel_id)) {
+		pr_err("channel (%s:%d) is already linked\n",
+		       iface->description, channel_id);
+		return -EEXIST;
+	}
+
+	if (cfg->direction == MOST_CH_TX) {
+		playback_count = 1;
+		direction = SNDRV_PCM_STREAM_PLAYBACK;
+	} else {
+		capture_count = 1;
+		direction = SNDRV_PCM_STREAM_CAPTURE;
+	}
+	channel = kzalloc_obj(*channel);
+	if (!channel) {
+		ret = -ENOMEM;
+		goto err_free_adpt;
+	}
+	channel->card = adpt->card;
+	channel->cfg = cfg;
+	channel->iface = iface;
+	channel->id = channel_id;
+	init_waitqueue_head(&channel->playback_waitq);
+	list_add_tail(&channel->list, &adpt->dev_list);
+
+	ret = audio_set_hw_params(&channel->pcm_hardware, ch_num, sample_res,
+				  cfg);
+	if (ret)
+		goto err_free_adpt;
+
+	ret = snd_pcm_new(adpt->card, device_name, adpt->pcm_dev_idx,
+			  playback_count, capture_count, &pcm);
+
+	if (ret < 0)
+		goto err_free_adpt;
+
+	pcm->private_data = channel;
+	strscpy(pcm->name, device_name, sizeof(pcm->name));
+	snd_pcm_set_ops(pcm, direction, &pcm_ops);
+	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
+	return 0;
+
+err_free_adpt:
+	release_adapter(adpt);
+	return ret;
+}
+
+static int audio_create_sound_card(void)
+{
+	int ret;
+	struct sound_adapter *adpt;
+
+	list_for_each_entry(adpt, &adpt_list, list) {
+		if (!adpt->registered)
+			goto adpt_alloc;
+	}
+	return -ENODEV;
+adpt_alloc:
+	ret = snd_card_register(adpt->card);
+	if (ret < 0) {
+		release_adapter(adpt);
+		return ret;
+	}
+	adpt->registered = true;
+	return 0;
+}
+
+/**
+ * audio_disconnect_channel - function to disconnect a channel
+ * @iface: pointer to interface instance
+ * @channel_id: channel index
+ *
+ * This frees allocated memory and removes the sound card from ALSA
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_disconnect_channel(struct most_interface *iface,
+				    int channel_id)
+{
+	struct channel *channel;
+	struct sound_adapter *adpt = iface->priv;
+
+	channel = get_channel(iface, channel_id);
+	if (!channel)
+		return -EINVAL;
+
+	list_del(&channel->list);
+
+	kfree(channel);
+	if (list_empty(&adpt->dev_list))
+		release_adapter(adpt);
+	return 0;
+}
+
+/**
+ * audio_rx_completion - completion handler for rx channels
+ * @mbo: pointer to buffer object that has completed
+ *
+ * This searches for the channel this MBO belongs to and copy the data from MBO
+ * to ring buffer
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_rx_completion(struct mbo *mbo)
+{
+	struct channel *channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
+	bool period_elapsed = false;
+
+	if (!channel)
+		return -EINVAL;
+	if (channel->is_stream_running)
+		period_elapsed = copy_data(channel, mbo);
+	most_put_mbo(mbo);
+	if (period_elapsed)
+		snd_pcm_period_elapsed(channel->substream);
+	return 0;
+}
+
+/**
+ * audio_tx_completion - completion handler for tx channels
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ *
+ * This searches the channel that belongs to this combination of interface
+ * pointer and channel ID and wakes a process sitting in the wait queue of
+ * this channel.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_tx_completion(struct most_interface *iface, int channel_id)
+{
+	struct channel *channel = get_channel(iface, channel_id);
+
+	if (!channel)
+		return -EINVAL;
+
+	wake_up_interruptible(&channel->playback_waitq);
+	return 0;
+}
+
+/*
+ * Initialization of the struct most_component
+ */
+static struct most_component comp = {
+	.mod = THIS_MODULE,
+	.name = DRIVER_NAME,
+	.probe_channel = audio_probe_channel,
+	.disconnect_channel = audio_disconnect_channel,
+	.rx_completion = audio_rx_completion,
+	.tx_completion = audio_tx_completion,
+	.cfg_complete = audio_create_sound_card,
+};
+
+static int __init audio_init(void)
+{
+	int ret;
+
+	INIT_LIST_HEAD(&adpt_list);
+
+	ret = most_register_component(&comp);
+	if (ret) {
+		pr_err("Failed to register %s\n", comp.name);
+		return ret;
+	}
+	ret = most_register_configfs_subsys(&comp);
+	if (ret) {
+		pr_err("Failed to register %s configfs subsys\n", comp.name);
+		most_deregister_component(&comp);
+	}
+	return ret;
+}
+
+static void __exit audio_exit(void)
+{
+	most_deregister_configfs_subsys(&comp);
+	most_deregister_component(&comp);
+}
+
+module_init(audio_init);
+module_exit(audio_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_DESCRIPTION("Sound Component Module for Mostcore");
diff --git a/drivers/most/most_usb.c b/drivers/most/most_usb.c
new file mode 100644
index 000000000..6437733af
--- /dev/null
+++ b/drivers/most/most_usb.c
@@ -0,0 +1,1162 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * usb.c - Hardware dependent module for USB
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/usb.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/sysfs.h>
+#include <linux/dma-mapping.h>
+#include <linux/etherdevice.h>
+#include <linux/uaccess.h>
+#include <linux/most.h>
+
+#define USB_MTU			512
+#define NO_ISOCHRONOUS_URB	0
+#define AV_PACKETS_PER_XACT	2
+#define BUF_CHAIN_SIZE		0xFFFF
+#define MAX_NUM_ENDPOINTS	30
+#define MAX_SUFFIX_LEN		10
+#define MAX_STRING_LEN		80
+#define MAX_BUF_SIZE		0xFFFF
+
+#define USB_VENDOR_ID_SMSC	0x0424  /* VID: SMSC */
+#define USB_DEV_ID_BRDG		0xC001  /* PID: USB Bridge */
+#define USB_DEV_ID_OS81118	0xCF18  /* PID: USB OS81118 */
+#define USB_DEV_ID_OS81119	0xCF19  /* PID: USB OS81119 */
+#define USB_DEV_ID_OS81210	0xCF30  /* PID: USB OS81210 */
+/* DRCI Addresses */
+#define DRCI_REG_NI_STATE	0x0100
+#define DRCI_REG_PACKET_BW	0x0101
+#define DRCI_REG_NODE_ADDR	0x0102
+#define DRCI_REG_NODE_POS	0x0103
+#define DRCI_REG_MEP_FILTER	0x0140
+#define DRCI_REG_HASH_TBL0	0x0141
+#define DRCI_REG_HASH_TBL1	0x0142
+#define DRCI_REG_HASH_TBL2	0x0143
+#define DRCI_REG_HASH_TBL3	0x0144
+#define DRCI_REG_HW_ADDR_HI	0x0145
+#define DRCI_REG_HW_ADDR_MI	0x0146
+#define DRCI_REG_HW_ADDR_LO	0x0147
+#define DRCI_REG_BASE		0x1100
+#define DRCI_COMMAND		0x02
+#define DRCI_READ_REQ		0xA0
+#define DRCI_WRITE_REQ		0xA1
+
+/**
+ * struct most_dci_obj - Direct Communication Interface
+ * @kobj:position in sysfs
+ * @usb_device: pointer to the usb device
+ * @reg_addr: register address for arbitrary DCI access
+ */
+struct most_dci_obj {
+	struct device dev;
+	struct usb_device *usb_device;
+	u16 reg_addr;
+};
+
+#define to_dci_obj(p) container_of(p, struct most_dci_obj, dev)
+
+struct most_dev;
+
+struct clear_hold_work {
+	struct work_struct ws;
+	struct most_dev *mdev;
+	unsigned int channel;
+	int pipe;
+};
+
+#define to_clear_hold_work(w) container_of(w, struct clear_hold_work, ws)
+
+/**
+ * struct most_dev - holds all usb interface specific stuff
+ * @usb_device: pointer to usb device
+ * @iface: hardware interface
+ * @cap: channel capabilities
+ * @conf: channel configuration
+ * @dci: direct communication interface of hardware
+ * @ep_address: endpoint address table
+ * @description: device description
+ * @suffix: suffix for channel name
+ * @channel_lock: synchronize channel access
+ * @padding_active: indicates channel uses padding
+ * @is_channel_healthy: health status table of each channel
+ * @busy_urbs: list of anchored items
+ * @io_mutex: synchronize I/O with disconnect
+ * @link_stat_timer: timer for link status reports
+ * @poll_work_obj: work for polling link status
+ */
+struct most_dev {
+	struct device dev;
+	struct usb_device *usb_device;
+	struct most_interface iface;
+	struct most_channel_capability *cap;
+	struct most_channel_config *conf;
+	struct most_dci_obj *dci;
+	u8 *ep_address;
+	char description[MAX_STRING_LEN];
+	char suffix[MAX_NUM_ENDPOINTS][MAX_SUFFIX_LEN];
+	spinlock_t channel_lock[MAX_NUM_ENDPOINTS]; /* sync channel access */
+	bool padding_active[MAX_NUM_ENDPOINTS];
+	bool is_channel_healthy[MAX_NUM_ENDPOINTS];
+	struct clear_hold_work clear_work[MAX_NUM_ENDPOINTS];
+	struct usb_anchor *busy_urbs;
+	struct mutex io_mutex;
+	struct timer_list link_stat_timer;
+	struct work_struct poll_work_obj;
+	void (*on_netinfo)(struct most_interface *most_iface,
+			   unsigned char link_state, unsigned char *addrs);
+};
+
+#define to_mdev(d) container_of(d, struct most_dev, iface)
+#define to_mdev_from_dev(d) container_of(d, struct most_dev, dev)
+#define to_mdev_from_work(w) container_of(w, struct most_dev, poll_work_obj)
+
+static void wq_clear_halt(struct work_struct *wq_obj);
+static void wq_netinfo(struct work_struct *wq_obj);
+
+/**
+ * drci_rd_reg - read a DCI register
+ * @dev: usb device
+ * @reg: register address
+ * @buf: buffer to store data
+ *
+ * This is reads data from INIC's direct register communication interface
+ */
+static inline int drci_rd_reg(struct usb_device *dev, u16 reg, u16 *buf)
+{
+	int retval;
+	__le16 *dma_buf;
+	u8 req_type = USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
+
+	dma_buf = kzalloc_obj(*dma_buf);
+	if (!dma_buf)
+		return -ENOMEM;
+
+	retval = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+				 DRCI_READ_REQ, req_type,
+				 0x0000,
+				 reg, dma_buf, sizeof(*dma_buf),
+				 USB_CTRL_GET_TIMEOUT);
+	*buf = le16_to_cpu(*dma_buf);
+	kfree(dma_buf);
+
+	if (retval < 0)
+		return retval;
+	return 0;
+}
+
+/**
+ * drci_wr_reg - write a DCI register
+ * @dev: usb device
+ * @reg: register address
+ * @data: data to write
+ *
+ * This is writes data to INIC's direct register communication interface
+ */
+static inline int drci_wr_reg(struct usb_device *dev, u16 reg, u16 data)
+{
+	return usb_control_msg(dev,
+			       usb_sndctrlpipe(dev, 0),
+			       DRCI_WRITE_REQ,
+			       USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			       data,
+			       reg,
+			       NULL,
+			       0,
+			       USB_CTRL_SET_TIMEOUT);
+}
+
+static inline int start_sync_ep(struct usb_device *usb_dev, u16 ep)
+{
+	return drci_wr_reg(usb_dev, DRCI_REG_BASE + DRCI_COMMAND + ep * 16, 1);
+}
+
+/**
+ * get_stream_frame_size - calculate frame size of current configuration
+ * @dev: device structure
+ * @cfg: channel configuration
+ */
+static unsigned int get_stream_frame_size(struct device *dev,
+					  struct most_channel_config *cfg)
+{
+	unsigned int frame_size;
+	unsigned int sub_size = cfg->subbuffer_size;
+
+	if (!sub_size) {
+		dev_warn(dev, "Misconfig: Subbuffer size zero.\n");
+		return 0;
+	}
+	switch (cfg->data_type) {
+	case MOST_CH_ISOC:
+		frame_size = AV_PACKETS_PER_XACT * sub_size;
+		break;
+	case MOST_CH_SYNC:
+		if (cfg->packets_per_xact == 0) {
+			dev_warn(dev, "Misconfig: Packets per XACT zero\n");
+			frame_size = 0;
+		} else if (cfg->packets_per_xact == 0xFF) {
+			frame_size = (USB_MTU / sub_size) * sub_size;
+		} else {
+			frame_size = cfg->packets_per_xact * sub_size;
+		}
+		break;
+	default:
+		dev_warn(dev, "Query frame size of non-streaming channel\n");
+		frame_size = 0;
+		break;
+	}
+	return frame_size;
+}
+
+/**
+ * hdm_poison_channel - mark buffers of this channel as invalid
+ * @iface: pointer to the interface
+ * @channel: channel ID
+ *
+ * This unlinks all URBs submitted to the HCD,
+ * calls the associated completion function of the core and removes
+ * them from the list.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int hdm_poison_channel(struct most_interface *iface, int channel)
+{
+	struct most_dev *mdev = to_mdev(iface);
+	unsigned long flags;
+	spinlock_t *lock; /* temp. lock */
+
+	if (channel < 0 || channel >= iface->num_channels) {
+		dev_warn(&mdev->usb_device->dev, "Channel ID out of range.\n");
+		return -ECHRNG;
+	}
+
+	lock = mdev->channel_lock + channel;
+	spin_lock_irqsave(lock, flags);
+	mdev->is_channel_healthy[channel] = false;
+	spin_unlock_irqrestore(lock, flags);
+
+	cancel_work_sync(&mdev->clear_work[channel].ws);
+
+	mutex_lock(&mdev->io_mutex);
+	usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
+	if (mdev->padding_active[channel])
+		mdev->padding_active[channel] = false;
+
+	if (mdev->conf[channel].data_type == MOST_CH_ASYNC) {
+		timer_delete_sync(&mdev->link_stat_timer);
+		cancel_work_sync(&mdev->poll_work_obj);
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+/**
+ * hdm_add_padding - add padding bytes
+ * @mdev: most device
+ * @channel: channel ID
+ * @mbo: buffer object
+ *
+ * This inserts the INIC hardware specific padding bytes into a streaming
+ * channel's buffer
+ */
+static int hdm_add_padding(struct most_dev *mdev, int channel, struct mbo *mbo)
+{
+	struct most_channel_config *conf = &mdev->conf[channel];
+	unsigned int frame_size = get_stream_frame_size(&mdev->dev, conf);
+	unsigned int j, num_frames;
+
+	if (!frame_size)
+		return -EINVAL;
+	num_frames = mbo->buffer_length / frame_size;
+
+	if (num_frames < 1) {
+		dev_err(&mdev->usb_device->dev,
+			"Missed minimal transfer unit.\n");
+		return -EINVAL;
+	}
+
+	for (j = num_frames - 1; j > 0; j--)
+		memmove(mbo->virt_address + j * USB_MTU,
+			mbo->virt_address + j * frame_size,
+			frame_size);
+	mbo->buffer_length = num_frames * USB_MTU;
+	return 0;
+}
+
+/**
+ * hdm_remove_padding - remove padding bytes
+ * @mdev: most device
+ * @channel: channel ID
+ * @mbo: buffer object
+ *
+ * This takes the INIC hardware specific padding bytes off a streaming
+ * channel's buffer.
+ */
+static int hdm_remove_padding(struct most_dev *mdev, int channel,
+			      struct mbo *mbo)
+{
+	struct most_channel_config *const conf = &mdev->conf[channel];
+	unsigned int frame_size = get_stream_frame_size(&mdev->dev, conf);
+	unsigned int j, num_frames;
+
+	if (!frame_size)
+		return -EINVAL;
+	num_frames = mbo->processed_length / USB_MTU;
+
+	for (j = 1; j < num_frames; j++)
+		memmove(mbo->virt_address + frame_size * j,
+			mbo->virt_address + USB_MTU * j,
+			frame_size);
+
+	mbo->processed_length = frame_size * num_frames;
+	return 0;
+}
+
+/**
+ * hdm_write_completion - completion function for submitted Tx URBs
+ * @urb: the URB that has been completed
+ *
+ * This checks the status of the completed URB. In case the URB has been
+ * unlinked before, it is immediately freed. On any other error the MBO
+ * transfer flag is set. On success it frees allocated resources and calls
+ * the completion function.
+ *
+ * Context: interrupt!
+ */
+static void hdm_write_completion(struct urb *urb)
+{
+	struct mbo *mbo = urb->context;
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+	unsigned int channel = mbo->hdm_channel_id;
+	spinlock_t *lock = mdev->channel_lock + channel;
+	unsigned long flags;
+
+	spin_lock_irqsave(lock, flags);
+
+	mbo->processed_length = 0;
+	mbo->status = MBO_E_INVAL;
+	if (likely(mdev->is_channel_healthy[channel])) {
+		switch (urb->status) {
+		case 0:
+		case -ESHUTDOWN:
+			mbo->processed_length = urb->actual_length;
+			mbo->status = MBO_SUCCESS;
+			break;
+		case -EPIPE:
+			dev_warn(&mdev->usb_device->dev,
+				 "Broken pipe on ep%02x\n",
+				 mdev->ep_address[channel]);
+			mdev->is_channel_healthy[channel] = false;
+			mdev->clear_work[channel].pipe = urb->pipe;
+			schedule_work(&mdev->clear_work[channel].ws);
+			break;
+		case -ENODEV:
+		case -EPROTO:
+			mbo->status = MBO_E_CLOSE;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(lock, flags);
+
+	if (likely(mbo->complete))
+		mbo->complete(mbo);
+	usb_free_urb(urb);
+}
+
+/**
+ * hdm_read_completion - completion function for submitted Rx URBs
+ * @urb: the URB that has been completed
+ *
+ * This checks the status of the completed URB. In case the URB has been
+ * unlinked before it is immediately freed. On any other error the MBO transfer
+ * flag is set. On success it frees allocated resources, removes
+ * padding bytes -if necessary- and calls the completion function.
+ *
+ * Context: interrupt!
+ */
+static void hdm_read_completion(struct urb *urb)
+{
+	struct mbo *mbo = urb->context;
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+	unsigned int channel = mbo->hdm_channel_id;
+	struct device *dev = &mdev->usb_device->dev;
+	spinlock_t *lock = mdev->channel_lock + channel;
+	unsigned long flags;
+
+	spin_lock_irqsave(lock, flags);
+
+	mbo->processed_length = 0;
+	mbo->status = MBO_E_INVAL;
+	if (likely(mdev->is_channel_healthy[channel])) {
+		switch (urb->status) {
+		case 0:
+		case -ESHUTDOWN:
+			mbo->processed_length = urb->actual_length;
+			mbo->status = MBO_SUCCESS;
+			if (mdev->padding_active[channel] &&
+			    hdm_remove_padding(mdev, channel, mbo)) {
+				mbo->processed_length = 0;
+				mbo->status = MBO_E_INVAL;
+			}
+			break;
+		case -EPIPE:
+			dev_warn(dev, "Broken pipe on ep%02x\n",
+				 mdev->ep_address[channel]);
+			mdev->is_channel_healthy[channel] = false;
+			mdev->clear_work[channel].pipe = urb->pipe;
+			schedule_work(&mdev->clear_work[channel].ws);
+			break;
+		case -ENODEV:
+		case -EPROTO:
+			mbo->status = MBO_E_CLOSE;
+			break;
+		case -EOVERFLOW:
+			dev_warn(dev, "Babble on ep%02x\n",
+				 mdev->ep_address[channel]);
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(lock, flags);
+
+	if (likely(mbo->complete))
+		mbo->complete(mbo);
+	usb_free_urb(urb);
+}
+
+/**
+ * hdm_enqueue - receive a buffer to be used for data transfer
+ * @iface: interface to enqueue to
+ * @channel: ID of the channel
+ * @mbo: pointer to the buffer object
+ *
+ * This allocates a new URB and fills it according to the channel
+ * that is being used for transmission of data. Before the URB is
+ * submitted it is stored in the private anchor list.
+ *
+ * Returns 0 on success. On any error the URB is freed and a error code
+ * is returned.
+ *
+ * Context: Could in _some_ cases be interrupt!
+ */
+static int hdm_enqueue(struct most_interface *iface, int channel,
+		       struct mbo *mbo)
+{
+	struct most_dev *mdev = to_mdev(iface);
+	struct most_channel_config *conf;
+	int retval = 0;
+	struct urb *urb;
+	unsigned long length;
+	void *virt_address;
+
+	if (!mbo)
+		return -EINVAL;
+	if (iface->num_channels <= channel || channel < 0)
+		return -ECHRNG;
+
+	urb = usb_alloc_urb(NO_ISOCHRONOUS_URB, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
+
+	conf = &mdev->conf[channel];
+
+	mutex_lock(&mdev->io_mutex);
+	if (!mdev->usb_device) {
+		retval = -ENODEV;
+		goto err_free_urb;
+	}
+
+	if ((conf->direction & MOST_CH_TX) && mdev->padding_active[channel] &&
+	    hdm_add_padding(mdev, channel, mbo)) {
+		retval = -EINVAL;
+		goto err_free_urb;
+	}
+
+	urb->transfer_dma = mbo->bus_address;
+	virt_address = mbo->virt_address;
+	length = mbo->buffer_length;
+
+	if (conf->direction & MOST_CH_TX) {
+		usb_fill_bulk_urb(urb, mdev->usb_device,
+				  usb_sndbulkpipe(mdev->usb_device,
+						  mdev->ep_address[channel]),
+				  virt_address,
+				  length,
+				  hdm_write_completion,
+				  mbo);
+		if (conf->data_type != MOST_CH_ISOC &&
+		    conf->data_type != MOST_CH_SYNC)
+			urb->transfer_flags |= URB_ZERO_PACKET;
+	} else {
+		usb_fill_bulk_urb(urb, mdev->usb_device,
+				  usb_rcvbulkpipe(mdev->usb_device,
+						  mdev->ep_address[channel]),
+				  virt_address,
+				  length + conf->extra_len,
+				  hdm_read_completion,
+				  mbo);
+	}
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+	usb_anchor_urb(urb, &mdev->busy_urbs[channel]);
+
+	retval = usb_submit_urb(urb, GFP_KERNEL);
+	if (retval) {
+		dev_err(&mdev->usb_device->dev,
+			"URB submit failed with error %d.\n", retval);
+		goto err_unanchor_urb;
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+
+err_unanchor_urb:
+	usb_unanchor_urb(urb);
+err_free_urb:
+	usb_free_urb(urb);
+	mutex_unlock(&mdev->io_mutex);
+	return retval;
+}
+
+static void *hdm_dma_alloc(struct mbo *mbo, u32 size)
+{
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+
+	return usb_alloc_coherent(mdev->usb_device, size, GFP_KERNEL,
+				  &mbo->bus_address);
+}
+
+static void hdm_dma_free(struct mbo *mbo, u32 size)
+{
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+
+	usb_free_coherent(mdev->usb_device, size, mbo->virt_address,
+			  mbo->bus_address);
+}
+
+/**
+ * hdm_configure_channel - receive channel configuration from core
+ * @iface: interface
+ * @channel: channel ID
+ * @conf: structure that holds the configuration information
+ *
+ * The attached network interface controller (NIC) supports a padding mode
+ * to avoid short packets on USB, hence increasing the performance due to a
+ * lower interrupt load. This mode is default for synchronous data and can
+ * be switched on for isochronous data. In case padding is active the
+ * driver needs to know the frame size of the payload in order to calculate
+ * the number of bytes it needs to pad when transmitting or to cut off when
+ * receiving data.
+ *
+ */
+static int hdm_configure_channel(struct most_interface *iface, int channel,
+				 struct most_channel_config *conf)
+{
+	unsigned int num_frames;
+	unsigned int frame_size;
+	struct most_dev *mdev = to_mdev(iface);
+	struct device *dev = &mdev->usb_device->dev;
+
+	if (!conf) {
+		dev_err(dev, "Bad config pointer.\n");
+		return -EINVAL;
+	}
+	if (channel < 0 || channel >= iface->num_channels) {
+		dev_err(dev, "Channel ID out of range.\n");
+		return -EINVAL;
+	}
+
+	mdev->is_channel_healthy[channel] = true;
+	mdev->clear_work[channel].channel = channel;
+	mdev->clear_work[channel].mdev = mdev;
+	INIT_WORK(&mdev->clear_work[channel].ws, wq_clear_halt);
+
+	if (!conf->num_buffers || !conf->buffer_size) {
+		dev_err(dev, "Misconfig: buffer size or #buffers zero.\n");
+		return -EINVAL;
+	}
+
+	if (conf->data_type != MOST_CH_SYNC &&
+	    !(conf->data_type == MOST_CH_ISOC &&
+	      conf->packets_per_xact != 0xFF)) {
+		mdev->padding_active[channel] = false;
+		/*
+		 * Since the NIC's padding mode is not going to be
+		 * used, we can skip the frame size calculations and
+		 * move directly on to exit.
+		 */
+		goto exit;
+	}
+
+	mdev->padding_active[channel] = true;
+
+	frame_size = get_stream_frame_size(&mdev->dev, conf);
+	if (frame_size == 0 || frame_size > USB_MTU) {
+		dev_warn(dev, "Misconfig: frame size wrong\n");
+		return -EINVAL;
+	}
+
+	num_frames = conf->buffer_size / frame_size;
+
+	if (conf->buffer_size % frame_size) {
+		u16 old_size = conf->buffer_size;
+
+		conf->buffer_size = num_frames * frame_size;
+		dev_warn(dev, "%s: fixed buffer size (%d -> %d)\n",
+			 mdev->suffix[channel], old_size, conf->buffer_size);
+	}
+
+	/* calculate extra length to comply w/ HW padding */
+	conf->extra_len = num_frames * (USB_MTU - frame_size);
+
+exit:
+	mdev->conf[channel] = *conf;
+	if (conf->data_type == MOST_CH_ASYNC) {
+		u16 ep = mdev->ep_address[channel];
+
+		if (start_sync_ep(mdev->usb_device, ep) < 0)
+			dev_warn(dev, "sync for ep%02x failed", ep);
+	}
+	return 0;
+}
+
+/**
+ * hdm_request_netinfo - request network information
+ * @iface: pointer to interface
+ * @channel: channel ID
+ *
+ * This is used as trigger to set up the link status timer that
+ * polls for the NI state of the INIC every 2 seconds.
+ *
+ */
+static void hdm_request_netinfo(struct most_interface *iface, int channel,
+				void (*on_netinfo)(struct most_interface *,
+						   unsigned char,
+						   unsigned char *))
+{
+	struct most_dev *mdev = to_mdev(iface);
+
+	mdev->on_netinfo = on_netinfo;
+	if (!on_netinfo)
+		return;
+
+	mdev->link_stat_timer.expires = jiffies + HZ;
+	mod_timer(&mdev->link_stat_timer, mdev->link_stat_timer.expires);
+}
+
+/**
+ * link_stat_timer_handler - schedule work obtaining mac address and link status
+ * @t: pointer to timer_list which holds a pointer to the USB device instance
+ *
+ * The handler runs in interrupt context. That's why we need to defer the
+ * tasks to a work queue.
+ */
+static void link_stat_timer_handler(struct timer_list *t)
+{
+	struct most_dev *mdev = timer_container_of(mdev, t, link_stat_timer);
+
+	schedule_work(&mdev->poll_work_obj);
+	mdev->link_stat_timer.expires = jiffies + (2 * HZ);
+	add_timer(&mdev->link_stat_timer);
+}
+
+/**
+ * wq_netinfo - work queue function to deliver latest networking information
+ * @wq_obj: object that holds data for our deferred work to do
+ *
+ * This retrieves the network interface status of the USB INIC
+ */
+static void wq_netinfo(struct work_struct *wq_obj)
+{
+	struct most_dev *mdev = to_mdev_from_work(wq_obj);
+	struct usb_device *usb_device = mdev->usb_device;
+	struct device *dev = &usb_device->dev;
+	u16 hi, mi, lo, link;
+	u8 hw_addr[6];
+
+	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_HI, &hi)) {
+		dev_err(dev, "Vendor request 'hw_addr_hi' failed\n");
+		return;
+	}
+
+	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_MI, &mi)) {
+		dev_err(dev, "Vendor request 'hw_addr_mid' failed\n");
+		return;
+	}
+
+	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_LO, &lo)) {
+		dev_err(dev, "Vendor request 'hw_addr_low' failed\n");
+		return;
+	}
+
+	if (drci_rd_reg(usb_device, DRCI_REG_NI_STATE, &link)) {
+		dev_err(dev, "Vendor request 'link status' failed\n");
+		return;
+	}
+
+	hw_addr[0] = hi >> 8;
+	hw_addr[1] = hi;
+	hw_addr[2] = mi >> 8;
+	hw_addr[3] = mi;
+	hw_addr[4] = lo >> 8;
+	hw_addr[5] = lo;
+
+	if (mdev->on_netinfo)
+		mdev->on_netinfo(&mdev->iface, link, hw_addr);
+}
+
+/**
+ * wq_clear_halt - work queue function
+ * @wq_obj: work_struct object to execute
+ *
+ * This sends a clear_halt to the given USB pipe.
+ */
+static void wq_clear_halt(struct work_struct *wq_obj)
+{
+	struct clear_hold_work *clear_work = to_clear_hold_work(wq_obj);
+	struct most_dev *mdev = clear_work->mdev;
+	unsigned int channel = clear_work->channel;
+	int pipe = clear_work->pipe;
+	int snd_pipe;
+	int peer;
+
+	mutex_lock(&mdev->io_mutex);
+	most_stop_enqueue(&mdev->iface, channel);
+	usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
+	if (usb_clear_halt(mdev->usb_device, pipe))
+		dev_warn(&mdev->usb_device->dev, "Failed to reset endpoint.\n");
+
+	/* If the functional Stall condition has been set on an
+	 * asynchronous rx channel, we need to clear the tx channel
+	 * too, since the hardware runs its clean-up sequence on both
+	 * channels, as they are physically one on the network.
+	 *
+	 * The USB interface that exposes the asynchronous channels
+	 * contains always two endpoints, and two only.
+	 */
+	if (mdev->conf[channel].data_type == MOST_CH_ASYNC &&
+	    mdev->conf[channel].direction == MOST_CH_RX) {
+		if (channel == 0)
+			peer = 1;
+		else
+			peer = 0;
+		snd_pipe = usb_sndbulkpipe(mdev->usb_device,
+					   mdev->ep_address[peer]);
+		usb_clear_halt(mdev->usb_device, snd_pipe);
+	}
+	mdev->is_channel_healthy[channel] = true;
+	most_resume_enqueue(&mdev->iface, channel);
+	mutex_unlock(&mdev->io_mutex);
+}
+
+/*
+ * hdm_usb_fops - file operation table for USB driver
+ */
+static const struct file_operations hdm_usb_fops = {
+	.owner = THIS_MODULE,
+};
+
+/*
+ * usb_device_id - ID table for HCD device probing
+ */
+static const struct usb_device_id usbid[] = {
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_BRDG), },
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81118), },
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81119), },
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81210), },
+	{ } /* Terminating entry */
+};
+
+struct regs {
+	const char *name;
+	u16 reg;
+};
+
+static const struct regs ro_regs[] = {
+	{ "ni_state", DRCI_REG_NI_STATE },
+	{ "packet_bandwidth", DRCI_REG_PACKET_BW },
+	{ "node_address", DRCI_REG_NODE_ADDR },
+	{ "node_position", DRCI_REG_NODE_POS },
+};
+
+static const struct regs rw_regs[] = {
+	{ "mep_filter", DRCI_REG_MEP_FILTER },
+	{ "mep_hash0", DRCI_REG_HASH_TBL0 },
+	{ "mep_hash1", DRCI_REG_HASH_TBL1 },
+	{ "mep_hash2", DRCI_REG_HASH_TBL2 },
+	{ "mep_hash3", DRCI_REG_HASH_TBL3 },
+	{ "mep_eui48_hi", DRCI_REG_HW_ADDR_HI },
+	{ "mep_eui48_mi", DRCI_REG_HW_ADDR_MI },
+	{ "mep_eui48_lo", DRCI_REG_HW_ADDR_LO },
+};
+
+static int get_stat_reg_addr(const struct regs *regs, int size,
+			     const char *name, u16 *reg_addr)
+{
+	int i;
+
+	for (i = 0; i < size; i++) {
+		if (sysfs_streq(name, regs[i].name)) {
+			*reg_addr = regs[i].reg;
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+
+#define get_static_reg_addr(regs, name, reg_addr) \
+	get_stat_reg_addr(regs, ARRAY_SIZE(regs), name, reg_addr)
+
+static ssize_t value_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	const char *name = attr->attr.name;
+	struct most_dci_obj *dci_obj = to_dci_obj(dev);
+	u16 val;
+	u16 reg_addr;
+	int err;
+
+	if (sysfs_streq(name, "arb_address"))
+		return sysfs_emit(buf, "%04x\n", dci_obj->reg_addr);
+
+	if (sysfs_streq(name, "arb_value"))
+		reg_addr = dci_obj->reg_addr;
+	else if (get_static_reg_addr(ro_regs, name, &reg_addr) &&
+		 get_static_reg_addr(rw_regs, name, &reg_addr))
+		return -EINVAL;
+
+	err = drci_rd_reg(dci_obj->usb_device, reg_addr, &val);
+	if (err < 0)
+		return err;
+
+	return sysfs_emit(buf, "%04x\n", val);
+}
+
+static ssize_t value_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	u16 val;
+	u16 reg_addr;
+	const char *name = attr->attr.name;
+	struct most_dci_obj *dci_obj = to_dci_obj(dev);
+	struct usb_device *usb_dev = dci_obj->usb_device;
+	int err;
+
+	err = kstrtou16(buf, 16, &val);
+	if (err)
+		return err;
+
+	if (sysfs_streq(name, "arb_address")) {
+		dci_obj->reg_addr = val;
+		return count;
+	}
+
+	if (sysfs_streq(name, "arb_value"))
+		err = drci_wr_reg(usb_dev, dci_obj->reg_addr, val);
+	else if (sysfs_streq(name, "sync_ep"))
+		err = start_sync_ep(usb_dev, val);
+	else if (!get_static_reg_addr(rw_regs, name, &reg_addr))
+		err = drci_wr_reg(usb_dev, reg_addr, val);
+	else
+		return -EINVAL;
+
+	if (err < 0)
+		return err;
+
+	return count;
+}
+
+static DEVICE_ATTR(ni_state, 0444, value_show, NULL);
+static DEVICE_ATTR(packet_bandwidth, 0444, value_show, NULL);
+static DEVICE_ATTR(node_address, 0444, value_show, NULL);
+static DEVICE_ATTR(node_position, 0444, value_show, NULL);
+static DEVICE_ATTR(sync_ep, 0200, NULL, value_store);
+static DEVICE_ATTR(mep_filter, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash0, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash1, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash2, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash3, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_hi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_mi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_lo, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_address, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_value, 0644, value_show, value_store);
+
+static struct attribute *dci_attrs[] = {
+	&dev_attr_ni_state.attr,
+	&dev_attr_packet_bandwidth.attr,
+	&dev_attr_node_address.attr,
+	&dev_attr_node_position.attr,
+	&dev_attr_sync_ep.attr,
+	&dev_attr_mep_filter.attr,
+	&dev_attr_mep_hash0.attr,
+	&dev_attr_mep_hash1.attr,
+	&dev_attr_mep_hash2.attr,
+	&dev_attr_mep_hash3.attr,
+	&dev_attr_mep_eui48_hi.attr,
+	&dev_attr_mep_eui48_mi.attr,
+	&dev_attr_mep_eui48_lo.attr,
+	&dev_attr_arb_address.attr,
+	&dev_attr_arb_value.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(dci);
+
+static void release_dci(struct device *dev)
+{
+	struct most_dci_obj *dci = to_dci_obj(dev);
+
+	put_device(dev->parent);
+	kfree(dci);
+}
+
+static void release_mdev(struct device *dev)
+{
+	struct most_dev *mdev = to_mdev_from_dev(dev);
+
+	kfree(mdev->busy_urbs);
+	kfree(mdev->cap);
+	kfree(mdev->conf);
+	kfree(mdev->ep_address);
+	kfree(mdev);
+}
+/**
+ * hdm_probe - probe function of USB device driver
+ * @interface: Interface of the attached USB device
+ * @id: Pointer to the USB ID table.
+ *
+ * This allocates and initializes the device instance, adds the new
+ * entry to the internal list, scans the USB descriptors and registers
+ * the interface with the core.
+ * Additionally, the DCI objects are created and the hardware is sync'd.
+ *
+ * Return 0 on success. In case of an error a negative number is returned.
+ */
+static int
+hdm_probe(struct usb_interface *interface, const struct usb_device_id *id)
+{
+	struct usb_host_interface *usb_iface_desc = interface->cur_altsetting;
+	struct usb_device *usb_dev = interface_to_usbdev(interface);
+	struct device *dev = &usb_dev->dev;
+	struct most_dev *mdev;
+	unsigned int i;
+	unsigned int num_endpoints;
+	struct most_channel_capability *tmp_cap;
+	struct usb_endpoint_descriptor *ep_desc;
+	int ret = -ENOMEM;
+
+	mdev = kzalloc_obj(*mdev);
+	if (!mdev)
+		return -ENOMEM;
+
+	usb_set_intfdata(interface, mdev);
+	num_endpoints = usb_iface_desc->desc.bNumEndpoints;
+	if (num_endpoints > MAX_NUM_ENDPOINTS) {
+		kfree(mdev);
+		return -EINVAL;
+	}
+	mutex_init(&mdev->io_mutex);
+	INIT_WORK(&mdev->poll_work_obj, wq_netinfo);
+	timer_setup(&mdev->link_stat_timer, link_stat_timer_handler, 0);
+
+	mdev->usb_device = usb_dev;
+	mdev->link_stat_timer.expires = jiffies + (2 * HZ);
+
+	mdev->iface.mod = hdm_usb_fops.owner;
+	mdev->iface.dev = &mdev->dev;
+	mdev->iface.driver_dev = &interface->dev;
+	mdev->iface.interface = ITYPE_USB;
+	mdev->iface.configure = hdm_configure_channel;
+	mdev->iface.request_netinfo = hdm_request_netinfo;
+	mdev->iface.enqueue = hdm_enqueue;
+	mdev->iface.poison_channel = hdm_poison_channel;
+	mdev->iface.dma_alloc = hdm_dma_alloc;
+	mdev->iface.dma_free = hdm_dma_free;
+	mdev->iface.description = mdev->description;
+	mdev->iface.num_channels = num_endpoints;
+
+	snprintf(mdev->description, sizeof(mdev->description),
+		 "%d-%s:%d.%d",
+		 usb_dev->bus->busnum,
+		 usb_dev->devpath,
+		 usb_dev->config->desc.bConfigurationValue,
+		 usb_iface_desc->desc.bInterfaceNumber);
+
+	mdev->dev.init_name = mdev->description;
+	mdev->dev.parent = &interface->dev;
+	mdev->dev.release = release_mdev;
+	mdev->conf = kzalloc_objs(*mdev->conf, num_endpoints);
+	if (!mdev->conf)
+		goto err_free_mdev;
+
+	mdev->cap = kzalloc_objs(*mdev->cap, num_endpoints);
+	if (!mdev->cap)
+		goto err_free_conf;
+
+	mdev->iface.channel_vector = mdev->cap;
+	mdev->ep_address = kzalloc_objs(*mdev->ep_address, num_endpoints);
+	if (!mdev->ep_address)
+		goto err_free_cap;
+
+	mdev->busy_urbs = kzalloc_objs(*mdev->busy_urbs, num_endpoints);
+	if (!mdev->busy_urbs)
+		goto err_free_ep_address;
+
+	tmp_cap = mdev->cap;
+	for (i = 0; i < num_endpoints; i++) {
+		ep_desc = &usb_iface_desc->endpoint[i].desc;
+		mdev->ep_address[i] = ep_desc->bEndpointAddress;
+		mdev->padding_active[i] = false;
+		mdev->is_channel_healthy[i] = true;
+
+		snprintf(&mdev->suffix[i][0], MAX_SUFFIX_LEN, "ep%02x",
+			 mdev->ep_address[i]);
+
+		tmp_cap->name_suffix = &mdev->suffix[i][0];
+		tmp_cap->buffer_size_packet = MAX_BUF_SIZE;
+		tmp_cap->buffer_size_streaming = MAX_BUF_SIZE;
+		tmp_cap->num_buffers_packet = BUF_CHAIN_SIZE;
+		tmp_cap->num_buffers_streaming = BUF_CHAIN_SIZE;
+		tmp_cap->data_type = MOST_CH_CONTROL | MOST_CH_ASYNC |
+				     MOST_CH_ISOC | MOST_CH_SYNC;
+		if (usb_endpoint_dir_in(ep_desc))
+			tmp_cap->direction = MOST_CH_RX;
+		else
+			tmp_cap->direction = MOST_CH_TX;
+		tmp_cap++;
+		init_usb_anchor(&mdev->busy_urbs[i]);
+		spin_lock_init(&mdev->channel_lock[i]);
+	}
+	dev_dbg(dev, "claimed gadget: Vendor=%4.4x ProdID=%4.4x Bus=%02x Device=%02x\n",
+		le16_to_cpu(usb_dev->descriptor.idVendor),
+		le16_to_cpu(usb_dev->descriptor.idProduct),
+		usb_dev->bus->busnum,
+		usb_dev->devnum);
+
+	dev_dbg(dev, "device path: /sys/bus/usb/devices/%d-%s:%d.%d\n",
+		usb_dev->bus->busnum,
+		usb_dev->devpath,
+		usb_dev->config->desc.bConfigurationValue,
+		usb_iface_desc->desc.bInterfaceNumber);
+
+	ret = most_register_interface(&mdev->iface);
+	if (ret)
+		return ret;
+
+	mutex_lock(&mdev->io_mutex);
+	if (le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81118 ||
+	    le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81119 ||
+	    le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81210) {
+		mdev->dci = kzalloc_obj(*mdev->dci);
+		if (!mdev->dci) {
+			mutex_unlock(&mdev->io_mutex);
+			most_deregister_interface(&mdev->iface);
+			return -ENOMEM;
+		}
+
+		mdev->dci->dev.init_name = "dci";
+		mdev->dci->dev.parent = get_device(mdev->iface.dev);
+		mdev->dci->dev.groups = dci_groups;
+		mdev->dci->dev.release = release_dci;
+		if (device_register(&mdev->dci->dev)) {
+			mutex_unlock(&mdev->io_mutex);
+			put_device(&mdev->dci->dev);
+			most_deregister_interface(&mdev->iface);
+			return -ENOMEM;
+		}
+		mdev->dci->usb_device = mdev->usb_device;
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+
+err_free_ep_address:
+	kfree(mdev->ep_address);
+err_free_cap:
+	kfree(mdev->cap);
+err_free_conf:
+	kfree(mdev->conf);
+err_free_mdev:
+	kfree(mdev);
+	return ret;
+}
+
+/**
+ * hdm_disconnect - disconnect function of USB device driver
+ * @interface: Interface of the attached USB device
+ *
+ * This deregisters the interface with the core, removes the kernel timer
+ * and frees resources.
+ *
+ * Context: hub kernel thread
+ */
+static void hdm_disconnect(struct usb_interface *interface)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+
+	mutex_lock(&mdev->io_mutex);
+	usb_set_intfdata(interface, NULL);
+	mdev->usb_device = NULL;
+	mutex_unlock(&mdev->io_mutex);
+
+	timer_delete_sync(&mdev->link_stat_timer);
+	cancel_work_sync(&mdev->poll_work_obj);
+
+	if (mdev->dci)
+		device_unregister(&mdev->dci->dev);
+	most_deregister_interface(&mdev->iface);
+}
+
+static int hdm_suspend(struct usb_interface *interface, pm_message_t message)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+	int i;
+
+	mutex_lock(&mdev->io_mutex);
+	for (i = 0; i < mdev->iface.num_channels; i++) {
+		most_stop_enqueue(&mdev->iface, i);
+		usb_kill_anchored_urbs(&mdev->busy_urbs[i]);
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+static int hdm_resume(struct usb_interface *interface)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+	int i;
+
+	mutex_lock(&mdev->io_mutex);
+	for (i = 0; i < mdev->iface.num_channels; i++)
+		most_resume_enqueue(&mdev->iface, i);
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+static struct usb_driver hdm_usb = {
+	.name = "hdm_usb",
+	.id_table = usbid,
+	.probe = hdm_probe,
+	.disconnect = hdm_disconnect,
+	.resume = hdm_resume,
+	.suspend = hdm_suspend,
+};
+
+module_usb_driver(hdm_usb);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_DESCRIPTION("HDM_4_USB");