Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1645 insertions, 0 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
new file mode 100644
index 000000000..6ffd8bd82
--- /dev/null
+++ b/drivers/dma/dmaengine.c
@@ -0,0 +1,1645 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
+ */
+
+/*
+ * This code implements the DMA subsystem. It provides a HW-neutral interface
+ * for other kernel code to use asynchronous memory copy capabilities,
+ * if present, and allows different HW DMA drivers to register as providing
+ * this capability.
+ *
+ * Due to the fact we are accelerating what is already a relatively fast
+ * operation, the code goes to great lengths to avoid additional overhead,
+ * such as locking.
+ *
+ * LOCKING:
+ *
+ * The subsystem keeps a global list of dma_device structs it is protected by a
+ * mutex, dma_list_mutex.
+ *
+ * A subsystem can get access to a channel by calling dmaengine_get() followed
+ * by dma_find_channel(), or if it has need for an exclusive channel it can call
+ * dma_request_channel().  Once a channel is allocated a reference is taken
+ * against its corresponding driver to disable removal.
+ *
+ * Each device has a channels list, which runs unlocked but is never modified
+ * once the device is registered, it's just setup by the driver.
+ *
+ * See Documentation/driver-api/dmaengine for more details
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/acpi_dma.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/hardirq.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/mempool.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/numa.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+#include <linux/percpu.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "dmaengine.h"
+
+static DEFINE_MUTEX(dma_list_mutex);
+static DEFINE_IDA(dma_ida);
+static LIST_HEAD(dma_device_list);
+static long dmaengine_ref_count;
+
+/* --- debugfs implementation --- */
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+
+static struct dentry *rootdir;
+
+static void dmaengine_debug_register(struct dma_device *dma_dev)
+{
+	dma_dev->dbg_dev_root = debugfs_create_dir(dev_name(dma_dev->dev),
+						   rootdir);
+	if (IS_ERR(dma_dev->dbg_dev_root))
+		dma_dev->dbg_dev_root = NULL;
+}
+
+static void dmaengine_debug_unregister(struct dma_device *dma_dev)
+{
+	debugfs_remove_recursive(dma_dev->dbg_dev_root);
+	dma_dev->dbg_dev_root = NULL;
+}
+
+static void dmaengine_dbg_summary_show(struct seq_file *s,
+				       struct dma_device *dma_dev)
+{
+	struct dma_chan *chan;
+
+	list_for_each_entry(chan, &dma_dev->channels, device_node) {
+		if (chan->client_count) {
+			seq_printf(s, " %-13s| %s", dma_chan_name(chan),
+				   chan->dbg_client_name ?: "in-use");
+
+			if (chan->router)
+				seq_printf(s, " (via router: %s)\n",
+					dev_name(chan->router->dev));
+			else
+				seq_puts(s, "\n");
+		}
+	}
+}
+
+static int dmaengine_summary_show(struct seq_file *s, void *data)
+{
+	struct dma_device *dma_dev = NULL;
+
+	mutex_lock(&dma_list_mutex);
+	list_for_each_entry(dma_dev, &dma_device_list, global_node) {
+		seq_printf(s, "dma%d (%s): number of channels: %u\n",
+			   dma_dev->dev_id, dev_name(dma_dev->dev),
+			   dma_dev->chancnt);
+
+		if (dma_dev->dbg_summary_show)
+			dma_dev->dbg_summary_show(s, dma_dev);
+		else
+			dmaengine_dbg_summary_show(s, dma_dev);
+
+		if (!list_is_last(&dma_dev->global_node, &dma_device_list))
+			seq_puts(s, "\n");
+	}
+	mutex_unlock(&dma_list_mutex);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(dmaengine_summary);
+
+static void __init dmaengine_debugfs_init(void)
+{
+	rootdir = debugfs_create_dir("dmaengine", NULL);
+
+	/* /sys/kernel/debug/dmaengine/summary */
+	debugfs_create_file("summary", 0444, rootdir, NULL,
+			    &dmaengine_summary_fops);
+}
+#else
+static inline void dmaengine_debugfs_init(void) { }
+static inline int dmaengine_debug_register(struct dma_device *dma_dev)
+{
+	return 0;
+}
+
+static inline void dmaengine_debug_unregister(struct dma_device *dma_dev) { }
+#endif	/* DEBUG_FS */
+
+/* --- sysfs implementation --- */
+
+#define DMA_SLAVE_NAME	"slave"
+
+/**
+ * dev_to_dma_chan - convert a device pointer to its sysfs container object
+ * @dev:	device node
+ *
+ * Must be called under dma_list_mutex.
+ */
+static struct dma_chan *dev_to_dma_chan(struct device *dev)
+{
+	struct dma_chan_dev *chan_dev;
+
+	chan_dev = container_of(dev, typeof(*chan_dev), device);
+	return chan_dev->chan;
+}
+
+static ssize_t memcpy_count_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct dma_chan *chan;
+	unsigned long count = 0;
+	int i;
+	int err;
+
+	mutex_lock(&dma_list_mutex);
+	chan = dev_to_dma_chan(dev);
+	if (chan) {
+		for_each_possible_cpu(i)
+			count += per_cpu_ptr(chan->local, i)->memcpy_count;
+		err = sysfs_emit(buf, "%lu\n", count);
+	} else
+		err = -ENODEV;
+	mutex_unlock(&dma_list_mutex);
+
+	return err;
+}
+static DEVICE_ATTR_RO(memcpy_count);
+
+static ssize_t bytes_transferred_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct dma_chan *chan;
+	unsigned long count = 0;
+	int i;
+	int err;
+
+	mutex_lock(&dma_list_mutex);
+	chan = dev_to_dma_chan(dev);
+	if (chan) {
+		for_each_possible_cpu(i)
+			count += per_cpu_ptr(chan->local, i)->bytes_transferred;
+		err = sysfs_emit(buf, "%lu\n", count);
+	} else
+		err = -ENODEV;
+	mutex_unlock(&dma_list_mutex);
+
+	return err;
+}
+static DEVICE_ATTR_RO(bytes_transferred);
+
+static ssize_t in_use_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct dma_chan *chan;
+	int err;
+
+	mutex_lock(&dma_list_mutex);
+	chan = dev_to_dma_chan(dev);
+	if (chan)
+		err = sysfs_emit(buf, "%d\n", chan->client_count);
+	else
+		err = -ENODEV;
+	mutex_unlock(&dma_list_mutex);
+
+	return err;
+}
+static DEVICE_ATTR_RO(in_use);
+
+static struct attribute *dma_dev_attrs[] = {
+	&dev_attr_memcpy_count.attr,
+	&dev_attr_bytes_transferred.attr,
+	&dev_attr_in_use.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(dma_dev);
+
+static void chan_dev_release(struct device *dev)
+{
+	struct dma_chan_dev *chan_dev;
+
+	chan_dev = container_of(dev, typeof(*chan_dev), device);
+	kfree(chan_dev);
+}
+
+static struct class dma_devclass = {
+	.name		= "dma",
+	.dev_groups	= dma_dev_groups,
+	.dev_release	= chan_dev_release,
+};
+
+/* --- client and device registration --- */
+
+/* enable iteration over all operation types */
+static dma_cap_mask_t dma_cap_mask_all;
+
+/**
+ * struct dma_chan_tbl_ent - tracks channel allocations per core/operation
+ * @chan:	associated channel for this entry
+ */
+struct dma_chan_tbl_ent {
+	struct dma_chan *chan;
+};
+
+/* percpu lookup table for memory-to-memory offload providers */
+static struct dma_chan_tbl_ent __percpu *channel_table[DMA_TX_TYPE_END];
+
+static int __init dma_channel_table_init(void)
+{
+	enum dma_transaction_type cap;
+	int err = 0;
+
+	bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
+
+	/* 'interrupt', 'private', and 'slave' are channel capabilities,
+	 * but are not associated with an operation so they do not need
+	 * an entry in the channel_table
+	 */
+	clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
+	clear_bit(DMA_PRIVATE, dma_cap_mask_all.bits);
+	clear_bit(DMA_SLAVE, dma_cap_mask_all.bits);
+
+	for_each_dma_cap_mask(cap, dma_cap_mask_all) {
+		channel_table[cap] = alloc_percpu(struct dma_chan_tbl_ent);
+		if (!channel_table[cap]) {
+			err = -ENOMEM;
+			break;
+		}
+	}
+
+	if (err) {
+		pr_err("dmaengine dma_channel_table_init failure: %d\n", err);
+		for_each_dma_cap_mask(cap, dma_cap_mask_all)
+			free_percpu(channel_table[cap]);
+	}
+
+	return err;
+}
+arch_initcall(dma_channel_table_init);
+
+/**
+ * dma_chan_is_local - checks if the channel is in the same NUMA-node as the CPU
+ * @chan:	DMA channel to test
+ * @cpu:	CPU index which the channel should be close to
+ *
+ * Returns true if the channel is in the same NUMA-node as the CPU.
+ */
+static bool dma_chan_is_local(struct dma_chan *chan, int cpu)
+{
+	int node = dev_to_node(chan->device->dev);
+	return node == NUMA_NO_NODE ||
+		cpumask_test_cpu(cpu, cpumask_of_node(node));
+}
+
+/**
+ * min_chan - finds the channel with min count and in the same NUMA-node as the CPU
+ * @cap:	capability to match
+ * @cpu:	CPU index which the channel should be close to
+ *
+ * If some channels are close to the given CPU, the one with the lowest
+ * reference count is returned. Otherwise, CPU is ignored and only the
+ * reference count is taken into account.
+ *
+ * Must be called under dma_list_mutex.
+ */
+static struct dma_chan *min_chan(enum dma_transaction_type cap, int cpu)
+{
+	struct dma_device *device;
+	struct dma_chan *chan;
+	struct dma_chan *min = NULL;
+	struct dma_chan *localmin = NULL;
+
+	list_for_each_entry(device, &dma_device_list, global_node) {
+		if (!dma_has_cap(cap, device->cap_mask) ||
+		    dma_has_cap(DMA_PRIVATE, device->cap_mask))
+			continue;
+		list_for_each_entry(chan, &device->channels, device_node) {
+			if (!chan->client_count)
+				continue;
+			if (!min || chan->table_count < min->table_count)
+				min = chan;
+
+			if (dma_chan_is_local(chan, cpu))
+				if (!localmin ||
+				    chan->table_count < localmin->table_count)
+					localmin = chan;
+		}
+	}
+
+	chan = localmin ? localmin : min;
+
+	if (chan)
+		chan->table_count++;
+
+	return chan;
+}
+
+/**
+ * dma_channel_rebalance - redistribute the available channels
+ *
+ * Optimize for CPU isolation (each CPU gets a dedicated channel for an
+ * operation type) in the SMP case, and operation isolation (avoid
+ * multi-tasking channels) in the non-SMP case.
+ *
+ * Must be called under dma_list_mutex.
+ */
+static void dma_channel_rebalance(void)
+{
+	struct dma_chan *chan;
+	struct dma_device *device;
+	int cpu;
+	int cap;
+
+	/* undo the last distribution */
+	for_each_dma_cap_mask(cap, dma_cap_mask_all)
+		for_each_possible_cpu(cpu)
+			per_cpu_ptr(channel_table[cap], cpu)->chan = NULL;
+
+	list_for_each_entry(device, &dma_device_list, global_node) {
+		if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
+			continue;
+		list_for_each_entry(chan, &device->channels, device_node)
+			chan->table_count = 0;
+	}
+
+	/* don't populate the channel_table if no clients are available */
+	if (!dmaengine_ref_count)
+		return;
+
+	/* redistribute available channels */
+	for_each_dma_cap_mask(cap, dma_cap_mask_all)
+		for_each_online_cpu(cpu) {
+			chan = min_chan(cap, cpu);
+			per_cpu_ptr(channel_table[cap], cpu)->chan = chan;
+		}
+}
+
+static int dma_device_satisfies_mask(struct dma_device *device,
+				     const dma_cap_mask_t *want)
+{
+	dma_cap_mask_t has;
+
+	bitmap_and(has.bits, want->bits, device->cap_mask.bits,
+		DMA_TX_TYPE_END);
+	return bitmap_equal(want->bits, has.bits, DMA_TX_TYPE_END);
+}
+
+static struct module *dma_chan_to_owner(struct dma_chan *chan)
+{
+	return chan->device->owner;
+}
+
+/**
+ * balance_ref_count - catch up the channel reference count
+ * @chan:	channel to balance ->client_count versus dmaengine_ref_count
+ *
+ * Must be called under dma_list_mutex.
+ */
+static void balance_ref_count(struct dma_chan *chan)
+{
+	struct module *owner = dma_chan_to_owner(chan);
+
+	while (chan->client_count < dmaengine_ref_count) {
+		__module_get(owner);
+		chan->client_count++;
+	}
+}
+
+static void dma_device_release(struct kref *ref)
+{
+	struct dma_device *device = container_of(ref, struct dma_device, ref);
+
+	list_del_rcu(&device->global_node);
+	dma_channel_rebalance();
+
+	if (device->device_release)
+		device->device_release(device);
+}
+
+static void dma_device_put(struct dma_device *device)
+{
+	lockdep_assert_held(&dma_list_mutex);
+	kref_put(&device->ref, dma_device_release);
+}
+
+/**
+ * dma_chan_get - try to grab a DMA channel's parent driver module
+ * @chan:	channel to grab
+ *
+ * Must be called under dma_list_mutex.
+ */
+static int dma_chan_get(struct dma_chan *chan)
+{
+	struct module *owner = dma_chan_to_owner(chan);
+	int ret;
+
+	/* The channel is already in use, update client count */
+	if (chan->client_count) {
+		__module_get(owner);
+		chan->client_count++;
+		return 0;
+	}
+
+	if (!try_module_get(owner))
+		return -ENODEV;
+
+	ret = kref_get_unless_zero(&chan->device->ref);
+	if (!ret) {
+		ret = -ENODEV;
+		goto module_put_out;
+	}
+
+	/* allocate upon first client reference */
+	if (chan->device->device_alloc_chan_resources) {
+		ret = chan->device->device_alloc_chan_resources(chan);
+		if (ret < 0)
+			goto err_out;
+	}
+
+	chan->client_count++;
+
+	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
+		balance_ref_count(chan);
+
+	return 0;
+
+err_out:
+	dma_device_put(chan->device);
+module_put_out:
+	module_put(owner);
+	return ret;
+}
+
+/**
+ * dma_chan_put - drop a reference to a DMA channel's parent driver module
+ * @chan:	channel to release
+ *
+ * Must be called under dma_list_mutex.
+ */
+static void dma_chan_put(struct dma_chan *chan)
+{
+	/* This channel is not in use, bail out */
+	if (!chan->client_count)
+		return;
+
+	chan->client_count--;
+
+	/* This channel is not in use anymore, free it */
+	if (!chan->client_count && chan->device->device_free_chan_resources) {
+		/* Make sure all operations have completed */
+		dmaengine_synchronize(chan);
+		chan->device->device_free_chan_resources(chan);
+	}
+
+	/* If the channel is used via a DMA request router, free the mapping */
+	if (chan->router && chan->router->route_free) {
+		chan->router->route_free(chan->router->dev, chan->route_data);
+		chan->router = NULL;
+		chan->route_data = NULL;
+	}
+
+	dma_device_put(chan->device);
+	module_put(dma_chan_to_owner(chan));
+}
+
+enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie)
+{
+	enum dma_status status;
+	unsigned long dma_sync_wait_timeout = jiffies + msecs_to_jiffies(5000);
+
+	dma_async_issue_pending(chan);
+	do {
+		status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
+		if (time_after_eq(jiffies, dma_sync_wait_timeout)) {
+			dev_err(chan->device->dev, "%s: timeout!\n", __func__);
+			return DMA_ERROR;
+		}
+		if (status != DMA_IN_PROGRESS)
+			break;
+		cpu_relax();
+	} while (1);
+
+	return status;
+}
+EXPORT_SYMBOL(dma_sync_wait);
+
+/**
+ * dma_find_channel - find a channel to carry out the operation
+ * @tx_type:	transaction type
+ */
+struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
+{
+	return this_cpu_read(channel_table[tx_type]->chan);
+}
+EXPORT_SYMBOL(dma_find_channel);
+
+/**
+ * dma_issue_pending_all - flush all pending operations across all channels
+ */
+void dma_issue_pending_all(void)
+{
+	struct dma_device *device;
+	struct dma_chan *chan;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(device, &dma_device_list, global_node) {
+		if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
+			continue;
+		list_for_each_entry(chan, &device->channels, device_node)
+			if (chan->client_count)
+				device->device_issue_pending(chan);
+	}
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(dma_issue_pending_all);
+
+int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
+{
+	struct dma_device *device;
+
+	if (!chan || !caps)
+		return -EINVAL;
+
+	device = chan->device;
+
+	/* check if the channel supports slave transactions */
+	if (!(test_bit(DMA_SLAVE, device->cap_mask.bits) ||
+	      test_bit(DMA_CYCLIC, device->cap_mask.bits)))
+		return -ENXIO;
+
+	/*
+	 * Check whether it reports it uses the generic slave
+	 * capabilities, if not, that means it doesn't support any
+	 * kind of slave capabilities reporting.
+	 */
+	if (!device->directions)
+		return -ENXIO;
+
+	caps->src_addr_widths = device->src_addr_widths;
+	caps->dst_addr_widths = device->dst_addr_widths;
+	caps->directions = device->directions;
+	caps->min_burst = device->min_burst;
+	caps->max_burst = device->max_burst;
+	caps->max_sg_burst = device->max_sg_burst;
+	caps->residue_granularity = device->residue_granularity;
+	caps->descriptor_reuse = device->descriptor_reuse;
+	caps->cmd_pause = !!device->device_pause;
+	caps->cmd_resume = !!device->device_resume;
+	caps->cmd_terminate = !!device->device_terminate_all;
+
+	/*
+	 * DMA engine device might be configured with non-uniformly
+	 * distributed slave capabilities per device channels. In this
+	 * case the corresponding driver may provide the device_caps
+	 * callback to override the generic capabilities with
+	 * channel-specific ones.
+	 */
+	if (device->device_caps)
+		device->device_caps(chan, caps);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dma_get_slave_caps);
+
+static struct dma_chan *private_candidate(const dma_cap_mask_t *mask,
+					  struct dma_device *dev,
+					  dma_filter_fn fn, void *fn_param)
+{
+	struct dma_chan *chan;
+
+	if (mask && !dma_device_satisfies_mask(dev, mask)) {
+		dev_dbg(dev->dev, "%s: wrong capabilities\n", __func__);
+		return NULL;
+	}
+	/* devices with multiple channels need special handling as we need to
+	 * ensure that all channels are either private or public.
+	 */
+	if (dev->chancnt > 1 && !dma_has_cap(DMA_PRIVATE, dev->cap_mask))
+		list_for_each_entry(chan, &dev->channels, device_node) {
+			/* some channels are already publicly allocated */
+			if (chan->client_count)
+				return NULL;
+		}
+
+	list_for_each_entry(chan, &dev->channels, device_node) {
+		if (chan->client_count) {
+			dev_dbg(dev->dev, "%s: %s busy\n",
+				 __func__, dma_chan_name(chan));
+			continue;
+		}
+		if (fn && !fn(chan, fn_param)) {
+			dev_dbg(dev->dev, "%s: %s filter said false\n",
+				 __func__, dma_chan_name(chan));
+			continue;
+		}
+		return chan;
+	}
+
+	return NULL;
+}
+
+static struct dma_chan *find_candidate(struct dma_device *device,
+				       const dma_cap_mask_t *mask,
+				       dma_filter_fn fn, void *fn_param)
+{
+	struct dma_chan *chan = private_candidate(mask, device, fn, fn_param);
+	int err;
+
+	if (chan) {
+		/* Found a suitable channel, try to grab, prep, and return it.
+		 * We first set DMA_PRIVATE to disable balance_ref_count as this
+		 * channel will not be published in the general-purpose
+		 * allocator
+		 */
+		dma_cap_set(DMA_PRIVATE, device->cap_mask);
+		device->privatecnt++;
+		err = dma_chan_get(chan);
+
+		if (err) {
+			if (err == -ENODEV) {
+				dev_dbg(device->dev, "%s: %s module removed\n",
+					__func__, dma_chan_name(chan));
+				list_del_rcu(&device->global_node);
+			} else
+				dev_dbg(device->dev,
+					"%s: failed to get %s: (%d)\n",
+					 __func__, dma_chan_name(chan), err);
+
+			if (--device->privatecnt == 0)
+				dma_cap_clear(DMA_PRIVATE, device->cap_mask);
+
+			chan = ERR_PTR(err);
+		}
+	}
+
+	return chan ? chan : ERR_PTR(-EPROBE_DEFER);
+}
+
+/**
+ * dma_get_slave_channel - try to get specific channel exclusively
+ * @chan:	target channel
+ */
+struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
+{
+	/* lock against __dma_request_channel */
+	mutex_lock(&dma_list_mutex);
+
+	if (chan->client_count == 0) {
+		struct dma_device *device = chan->device;
+		int err;
+
+		dma_cap_set(DMA_PRIVATE, device->cap_mask);
+		device->privatecnt++;
+		err = dma_chan_get(chan);
+		if (err) {
+			dev_dbg(chan->device->dev,
+				"%s: failed to get %s: (%d)\n",
+				__func__, dma_chan_name(chan), err);
+			chan = NULL;
+			if (--device->privatecnt == 0)
+				dma_cap_clear(DMA_PRIVATE, device->cap_mask);
+		}
+	} else
+		chan = NULL;
+
+	mutex_unlock(&dma_list_mutex);
+
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(dma_get_slave_channel);
+
+struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
+{
+	dma_cap_mask_t mask;
+	struct dma_chan *chan;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	/* lock against __dma_request_channel */
+	mutex_lock(&dma_list_mutex);
+
+	chan = find_candidate(device, &mask, NULL, NULL);
+
+	mutex_unlock(&dma_list_mutex);
+
+	return IS_ERR(chan) ? NULL : chan;
+}
+EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
+
+/**
+ * __dma_request_channel - try to allocate an exclusive channel
+ * @mask:	capabilities that the channel must satisfy
+ * @fn:		optional callback to disposition available channels
+ * @fn_param:	opaque parameter to pass to dma_filter_fn()
+ * @np:		device node to look for DMA channels
+ *
+ * Returns pointer to appropriate DMA channel on success or NULL.
+ */
+struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
+				       dma_filter_fn fn, void *fn_param,
+				       struct device_node *np)
+{
+	struct dma_device *device, *_d;
+	struct dma_chan *chan = NULL;
+
+	/* Find a channel */
+	mutex_lock(&dma_list_mutex);
+	list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
+		/* Finds a DMA controller with matching device node */
+		if (np && !device_match_of_node(device->dev, np))
+			continue;
+
+		chan = find_candidate(device, mask, fn, fn_param);
+		if (!IS_ERR(chan))
+			break;
+
+		chan = NULL;
+	}
+	mutex_unlock(&dma_list_mutex);
+
+	pr_debug("%s: %s (%s)\n",
+		 __func__,
+		 chan ? "success" : "fail",
+		 chan ? dma_chan_name(chan) : NULL);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(__dma_request_channel);
+
+static const struct dma_slave_map *dma_filter_match(struct dma_device *device,
+						    const char *name,
+						    struct device *dev)
+{
+	int i;
+
+	if (!device->filter.mapcnt)
+		return NULL;
+
+	for (i = 0; i < device->filter.mapcnt; i++) {
+		const struct dma_slave_map *map = &device->filter.map[i];
+
+		if (!strcmp(map->devname, dev_name(dev)) &&
+		    !strcmp(map->slave, name))
+			return map;
+	}
+
+	return NULL;
+}
+
+/**
+ * dma_request_chan - try to allocate an exclusive slave channel
+ * @dev:	pointer to client device structure
+ * @name:	slave channel name
+ *
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
+ */
+struct dma_chan *dma_request_chan(struct device *dev, const char *name)
+{
+	struct fwnode_handle *fwnode;
+	struct dma_device *d, *_d;
+	struct dma_chan *chan = NULL;
+
+	if (WARN_ON(!dev || !name))
+		return ERR_PTR(-EINVAL);
+
+	fwnode = dev_fwnode(dev);
+
+	if (is_of_node(fwnode))
+		chan = of_dma_request_slave_channel(to_of_node(fwnode), name);
+	else if (is_acpi_device_node(fwnode))
+		chan = acpi_dma_request_slave_chan_by_name(dev, name);
+
+	if (PTR_ERR(chan) == -EPROBE_DEFER)
+		return chan;
+
+	if (!IS_ERR_OR_NULL(chan))
+		goto found;
+
+	/* Try to find the channel via the DMA filter map(s) */
+	mutex_lock(&dma_list_mutex);
+	list_for_each_entry_safe(d, _d, &dma_device_list, global_node) {
+		dma_cap_mask_t mask;
+		const struct dma_slave_map *map = dma_filter_match(d, name, dev);
+
+		if (!map)
+			continue;
+
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+
+		chan = find_candidate(d, &mask, d->filter.fn, map->param);
+		if (!IS_ERR(chan))
+			break;
+	}
+	mutex_unlock(&dma_list_mutex);
+
+	if (IS_ERR(chan))
+		return chan;
+	if (!chan)
+		return ERR_PTR(-EPROBE_DEFER);
+
+found:
+#ifdef CONFIG_DEBUG_FS
+	chan->dbg_client_name = kasprintf(GFP_KERNEL, "%s:%s", dev_name(dev), name);
+	/* No functional issue if it fails, users are supposed to test before use */
+#endif
+
+	chan->name = kasprintf(GFP_KERNEL, "dma:%s", name);
+	if (!chan->name)
+		return chan;
+	chan->slave = dev;
+
+	if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj,
+			      DMA_SLAVE_NAME))
+		dev_warn(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
+	if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name))
+		dev_warn(dev, "Cannot create DMA %s symlink\n", chan->name);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(dma_request_chan);
+
+/**
+ * dma_request_chan_by_mask - allocate a channel satisfying certain capabilities
+ * @mask:	capabilities that the channel must satisfy
+ *
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
+ */
+struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
+{
+	struct dma_chan *chan;
+
+	if (!mask)
+		return ERR_PTR(-ENODEV);
+
+	chan = __dma_request_channel(mask, NULL, NULL, NULL);
+	if (!chan) {
+		mutex_lock(&dma_list_mutex);
+		if (list_empty(&dma_device_list))
+			chan = ERR_PTR(-EPROBE_DEFER);
+		else
+			chan = ERR_PTR(-ENODEV);
+		mutex_unlock(&dma_list_mutex);
+	}
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(dma_request_chan_by_mask);
+
+void dma_release_channel(struct dma_chan *chan)
+{
+	mutex_lock(&dma_list_mutex);
+	WARN_ONCE(chan->client_count != 1,
+		  "chan reference count %d != 1\n", chan->client_count);
+	/* drop PRIVATE cap enabled by __dma_request_channel() */
+	if (--chan->device->privatecnt == 0)
+		dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask);
+
+	dma_chan_put(chan);
+
+	if (chan->slave) {
+		sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
+		sysfs_remove_link(&chan->slave->kobj, chan->name);
+		kfree(chan->name);
+		chan->name = NULL;
+		chan->slave = NULL;
+	}
+
+#ifdef CONFIG_DEBUG_FS
+	kfree(chan->dbg_client_name);
+	chan->dbg_client_name = NULL;
+#endif
+	mutex_unlock(&dma_list_mutex);
+}
+EXPORT_SYMBOL_GPL(dma_release_channel);
+
+static void dmaenginem_release_channel(void *chan)
+{
+	dma_release_channel(chan);
+}
+
+/**
+ * devm_dma_request_chan - try to allocate an exclusive slave channel
+ * @dev:	pointer to client device structure
+ * @name:	slave channel name
+ *
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
+ *
+ * The operation is managed and will be undone on driver detach.
+ */
+
+struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name)
+{
+	struct dma_chan *chan;
+	int ret;
+
+	chan = dma_request_chan(dev, name);
+	if (IS_ERR(chan))
+		return chan;
+
+	ret = devm_add_action_or_reset(dev, dmaenginem_release_channel, chan);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(devm_dma_request_chan);
+
+/**
+ * dmaengine_get - register interest in dma_channels
+ */
+void dmaengine_get(void)
+{
+	struct dma_device *device, *_d;
+	struct dma_chan *chan;
+	int err;
+
+	mutex_lock(&dma_list_mutex);
+	dmaengine_ref_count++;
+
+	/* try to grab channels */
+	list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
+		if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
+			continue;
+		list_for_each_entry(chan, &device->channels, device_node) {
+			err = dma_chan_get(chan);
+			if (err == -ENODEV) {
+				/* module removed before we could use it */
+				list_del_rcu(&device->global_node);
+				break;
+			} else if (err)
+				dev_dbg(chan->device->dev,
+					"%s: failed to get %s: (%d)\n",
+					__func__, dma_chan_name(chan), err);
+		}
+	}
+
+	/* if this is the first reference and there were channels
+	 * waiting we need to rebalance to get those channels
+	 * incorporated into the channel table
+	 */
+	if (dmaengine_ref_count == 1)
+		dma_channel_rebalance();
+	mutex_unlock(&dma_list_mutex);
+}
+EXPORT_SYMBOL(dmaengine_get);
+
+/**
+ * dmaengine_put - let DMA drivers be removed when ref_count == 0
+ */
+void dmaengine_put(void)
+{
+	struct dma_device *device, *_d;
+	struct dma_chan *chan;
+
+	mutex_lock(&dma_list_mutex);
+	dmaengine_ref_count--;
+	BUG_ON(dmaengine_ref_count < 0);
+	/* drop channel references */
+	list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
+		if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
+			continue;
+		list_for_each_entry(chan, &device->channels, device_node)
+			dma_chan_put(chan);
+	}
+	mutex_unlock(&dma_list_mutex);
+}
+EXPORT_SYMBOL(dmaengine_put);
+
+static bool device_has_all_tx_types(struct dma_device *device)
+{
+	/* A device that satisfies this test has channels that will never cause
+	 * an async_tx channel switch event as all possible operation types can
+	 * be handled.
+	 */
+	#ifdef CONFIG_ASYNC_TX_DMA
+	if (!dma_has_cap(DMA_INTERRUPT, device->cap_mask))
+		return false;
+	#endif
+
+	#if IS_ENABLED(CONFIG_ASYNC_MEMCPY)
+	if (!dma_has_cap(DMA_MEMCPY, device->cap_mask))
+		return false;
+	#endif
+
+	#if IS_ENABLED(CONFIG_ASYNC_XOR)
+	if (!dma_has_cap(DMA_XOR, device->cap_mask))
+		return false;
+
+	#ifndef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
+	if (!dma_has_cap(DMA_XOR_VAL, device->cap_mask))
+		return false;
+	#endif
+	#endif
+
+	#if IS_ENABLED(CONFIG_ASYNC_PQ)
+	if (!dma_has_cap(DMA_PQ, device->cap_mask))
+		return false;
+
+	#ifndef CONFIG_ASYNC_TX_DISABLE_PQ_VAL_DMA
+	if (!dma_has_cap(DMA_PQ_VAL, device->cap_mask))
+		return false;
+	#endif
+	#endif
+
+	return true;
+}
+
+static int get_dma_id(struct dma_device *device)
+{
+	int rc = ida_alloc(&dma_ida, GFP_KERNEL);
+
+	if (rc < 0)
+		return rc;
+	device->dev_id = rc;
+	return 0;
+}
+
+static int __dma_async_device_channel_register(struct dma_device *device,
+					       struct dma_chan *chan,
+					       const char *name)
+{
+	int rc;
+
+	chan->local = alloc_percpu(typeof(*chan->local));
+	if (!chan->local)
+		return -ENOMEM;
+	chan->dev = kzalloc_obj(*chan->dev);
+	if (!chan->dev) {
+		rc = -ENOMEM;
+		goto err_free_local;
+	}
+
+	/*
+	 * When the chan_id is a negative value, we are dynamically adding
+	 * the channel. Otherwise we are static enumerating.
+	 */
+	chan->chan_id = ida_alloc(&device->chan_ida, GFP_KERNEL);
+	if (chan->chan_id < 0) {
+		pr_err("%s: unable to alloc ida for chan: %d\n",
+		       __func__, chan->chan_id);
+		rc = chan->chan_id;
+		goto err_free_dev;
+	}
+
+	chan->dev->device.class = &dma_devclass;
+	chan->dev->device.parent = device->dev;
+	chan->dev->chan = chan;
+	chan->dev->dev_id = device->dev_id;
+	spin_lock_init(&chan->lock);
+
+	if (!name)
+		dev_set_name(&chan->dev->device, "dma%dchan%d", device->dev_id, chan->chan_id);
+	else
+		dev_set_name(&chan->dev->device, "%s", name);
+	rc = device_register(&chan->dev->device);
+	if (rc)
+		goto err_out_ida;
+	chan->client_count = 0;
+	device->chancnt++;
+
+	return 0;
+
+ err_out_ida:
+	ida_free(&device->chan_ida, chan->chan_id);
+ err_free_dev:
+	kfree(chan->dev);
+ err_free_local:
+	free_percpu(chan->local);
+	chan->local = NULL;
+	return rc;
+}
+
+int dma_async_device_channel_register(struct dma_device *device,
+				      struct dma_chan *chan,
+				      const char *name)
+{
+	int rc;
+
+	rc = __dma_async_device_channel_register(device, chan, name);
+	if (rc < 0)
+		return rc;
+
+	dma_channel_rebalance();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dma_async_device_channel_register);
+
+static void __dma_async_device_channel_unregister(struct dma_device *device,
+						  struct dma_chan *chan)
+{
+	if (chan->local == NULL)
+		return;
+
+	WARN_ONCE(!device->device_release && chan->client_count,
+		  "%s called while %d clients hold a reference\n",
+		  __func__, chan->client_count);
+	mutex_lock(&dma_list_mutex);
+	device->chancnt--;
+	chan->dev->chan = NULL;
+	mutex_unlock(&dma_list_mutex);
+	ida_free(&device->chan_ida, chan->chan_id);
+	device_unregister(&chan->dev->device);
+	free_percpu(chan->local);
+}
+
+void dma_async_device_channel_unregister(struct dma_device *device,
+					 struct dma_chan *chan)
+{
+	__dma_async_device_channel_unregister(device, chan);
+	dma_channel_rebalance();
+}
+EXPORT_SYMBOL_GPL(dma_async_device_channel_unregister);
+
+/**
+ * dma_async_device_register - registers DMA devices found
+ * @device:	pointer to &struct dma_device
+ *
+ * After calling this routine the structure should not be freed except in the
+ * device_release() callback which will be called after
+ * dma_async_device_unregister() is called and no further references are taken.
+ */
+int dma_async_device_register(struct dma_device *device)
+{
+	int rc;
+	struct dma_chan* chan;
+
+	if (!device)
+		return -ENODEV;
+
+	/* validate device routines */
+	if (!device->dev) {
+		pr_err("DMAdevice must have dev\n");
+		return -EIO;
+	}
+
+	device->owner = device->dev->driver->owner;
+
+#define CHECK_CAP(_name, _type)								\
+{											\
+	if (dma_has_cap(_type, device->cap_mask) && !device->device_prep_##_name) {	\
+		dev_err(device->dev,							\
+			"Device claims capability %s, but op is not defined\n",		\
+			__stringify(_type));						\
+		return -EIO;								\
+	}										\
+}
+
+	CHECK_CAP(dma_memcpy,      DMA_MEMCPY);
+	CHECK_CAP(dma_xor,         DMA_XOR);
+	CHECK_CAP(dma_xor_val,     DMA_XOR_VAL);
+	CHECK_CAP(dma_pq,          DMA_PQ);
+	CHECK_CAP(dma_pq_val,      DMA_PQ_VAL);
+	CHECK_CAP(dma_memset,      DMA_MEMSET);
+	CHECK_CAP(dma_interrupt,   DMA_INTERRUPT);
+	CHECK_CAP(dma_cyclic,      DMA_CYCLIC);
+	CHECK_CAP(interleaved_dma, DMA_INTERLEAVE);
+
+#undef CHECK_CAP
+
+	if (!device->device_tx_status) {
+		dev_err(device->dev, "Device tx_status is not defined\n");
+		return -EIO;
+	}
+
+
+	if (!device->device_issue_pending) {
+		dev_err(device->dev, "Device issue_pending is not defined\n");
+		return -EIO;
+	}
+
+	if (!device->device_release)
+		dev_dbg(device->dev,
+			 "WARN: Device release is not defined so it is not safe to unbind this driver while in use\n");
+
+	kref_init(&device->ref);
+
+	/* note: this only matters in the
+	 * CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH=n case
+	 */
+	if (device_has_all_tx_types(device))
+		dma_cap_set(DMA_ASYNC_TX, device->cap_mask);
+
+	rc = get_dma_id(device);
+	if (rc != 0)
+		return rc;
+
+	ida_init(&device->chan_ida);
+
+	/* represent channels in sysfs. Probably want devs too */
+	list_for_each_entry(chan, &device->channels, device_node) {
+		rc = __dma_async_device_channel_register(device, chan, NULL);
+		if (rc < 0)
+			goto err_out;
+	}
+
+	mutex_lock(&dma_list_mutex);
+	/* take references on public channels */
+	if (dmaengine_ref_count && !dma_has_cap(DMA_PRIVATE, device->cap_mask))
+		list_for_each_entry(chan, &device->channels, device_node) {
+			/* if clients are already waiting for channels we need
+			 * to take references on their behalf
+			 */
+			if (dma_chan_get(chan) == -ENODEV) {
+				/* note we can only get here for the first
+				 * channel as the remaining channels are
+				 * guaranteed to get a reference
+				 */
+				rc = -ENODEV;
+				mutex_unlock(&dma_list_mutex);
+				goto err_out;
+			}
+		}
+	list_add_tail_rcu(&device->global_node, &dma_device_list);
+	if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
+		device->privatecnt++;	/* Always private */
+	dma_channel_rebalance();
+	mutex_unlock(&dma_list_mutex);
+
+	dmaengine_debug_register(device);
+
+	return 0;
+
+err_out:
+	/* if we never registered a channel just release the idr */
+	if (!device->chancnt) {
+		ida_free(&dma_ida, device->dev_id);
+		return rc;
+	}
+
+	list_for_each_entry(chan, &device->channels, device_node) {
+		if (chan->local == NULL)
+			continue;
+		mutex_lock(&dma_list_mutex);
+		chan->dev->chan = NULL;
+		mutex_unlock(&dma_list_mutex);
+		device_unregister(&chan->dev->device);
+		free_percpu(chan->local);
+	}
+	return rc;
+}
+EXPORT_SYMBOL(dma_async_device_register);
+
+/**
+ * dma_async_device_unregister - unregister a DMA device
+ * @device:	pointer to &struct dma_device
+ *
+ * This routine is called by dma driver exit routines, dmaengine holds module
+ * references to prevent it being called while channels are in use.
+ */
+void dma_async_device_unregister(struct dma_device *device)
+{
+	struct dma_chan *chan, *n;
+
+	dmaengine_debug_unregister(device);
+
+	list_for_each_entry_safe(chan, n, &device->channels, device_node)
+		__dma_async_device_channel_unregister(device, chan);
+
+	mutex_lock(&dma_list_mutex);
+	/*
+	 * setting DMA_PRIVATE ensures the device being torn down will not
+	 * be used in the channel_table
+	 */
+	dma_cap_set(DMA_PRIVATE, device->cap_mask);
+	dma_channel_rebalance();
+	ida_free(&dma_ida, device->dev_id);
+	dma_device_put(device);
+	mutex_unlock(&dma_list_mutex);
+}
+EXPORT_SYMBOL(dma_async_device_unregister);
+
+static void dmaenginem_async_device_unregister(void *device)
+{
+	dma_async_device_unregister(device);
+}
+
+/**
+ * dmaenginem_async_device_register - registers DMA devices found
+ * @device:	pointer to &struct dma_device
+ *
+ * The operation is managed and will be undone on driver detach.
+ */
+int dmaenginem_async_device_register(struct dma_device *device)
+{
+	int ret;
+
+	ret = dma_async_device_register(device);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(device->dev, dmaenginem_async_device_unregister, device);
+}
+EXPORT_SYMBOL(dmaenginem_async_device_register);
+
+struct dmaengine_unmap_pool {
+	struct kmem_cache *cache;
+	const char *name;
+	mempool_t *pool;
+	size_t size;
+};
+
+#define __UNMAP_POOL(x) { .size = x, .name = "dmaengine-unmap-" __stringify(x) }
+static struct dmaengine_unmap_pool unmap_pool[] = {
+	__UNMAP_POOL(2),
+	#if IS_ENABLED(CONFIG_DMA_ENGINE_RAID)
+	__UNMAP_POOL(16),
+	__UNMAP_POOL(128),
+	__UNMAP_POOL(256),
+	#endif
+};
+
+static struct dmaengine_unmap_pool *__get_unmap_pool(int nr)
+{
+	int order = get_count_order(nr);
+
+	switch (order) {
+	case 0 ... 1:
+		return &unmap_pool[0];
+#if IS_ENABLED(CONFIG_DMA_ENGINE_RAID)
+	case 2 ... 4:
+		return &unmap_pool[1];
+	case 5 ... 7:
+		return &unmap_pool[2];
+	case 8:
+		return &unmap_pool[3];
+#endif
+	default:
+		BUG();
+		return NULL;
+	}
+}
+
+static void dmaengine_unmap(struct kref *kref)
+{
+	struct dmaengine_unmap_data *unmap = container_of(kref, typeof(*unmap), kref);
+	struct device *dev = unmap->dev;
+	int cnt, i;
+
+	cnt = unmap->to_cnt;
+	for (i = 0; i < cnt; i++)
+		dma_unmap_page(dev, unmap->addr[i], unmap->len,
+			       DMA_TO_DEVICE);
+	cnt += unmap->from_cnt;
+	for (; i < cnt; i++)
+		dma_unmap_page(dev, unmap->addr[i], unmap->len,
+			       DMA_FROM_DEVICE);
+	cnt += unmap->bidi_cnt;
+	for (; i < cnt; i++) {
+		if (unmap->addr[i] == 0)
+			continue;
+		dma_unmap_page(dev, unmap->addr[i], unmap->len,
+			       DMA_BIDIRECTIONAL);
+	}
+	cnt = unmap->map_cnt;
+	mempool_free(unmap, __get_unmap_pool(cnt)->pool);
+}
+
+void dmaengine_unmap_put(struct dmaengine_unmap_data *unmap)
+{
+	if (unmap)
+		kref_put(&unmap->kref, dmaengine_unmap);
+}
+EXPORT_SYMBOL_GPL(dmaengine_unmap_put);
+
+static void dmaengine_destroy_unmap_pool(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(unmap_pool); i++) {
+		struct dmaengine_unmap_pool *p = &unmap_pool[i];
+
+		mempool_destroy(p->pool);
+		p->pool = NULL;
+		kmem_cache_destroy(p->cache);
+		p->cache = NULL;
+	}
+}
+
+static int __init dmaengine_init_unmap_pool(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(unmap_pool); i++) {
+		struct dmaengine_unmap_pool *p = &unmap_pool[i];
+		size_t size;
+
+		size = sizeof(struct dmaengine_unmap_data) +
+		       sizeof(dma_addr_t) * p->size;
+
+		p->cache = kmem_cache_create(p->name, size, 0,
+					     SLAB_HWCACHE_ALIGN, NULL);
+		if (!p->cache)
+			break;
+		p->pool = mempool_create_slab_pool(1, p->cache);
+		if (!p->pool)
+			break;
+	}
+
+	if (i == ARRAY_SIZE(unmap_pool))
+		return 0;
+
+	dmaengine_destroy_unmap_pool();
+	return -ENOMEM;
+}
+
+struct dmaengine_unmap_data *
+dmaengine_get_unmap_data(struct device *dev, int nr, gfp_t flags)
+{
+	struct dmaengine_unmap_data *unmap;
+
+	unmap = mempool_alloc(__get_unmap_pool(nr)->pool, flags);
+	if (!unmap)
+		return NULL;
+
+	memset(unmap, 0, sizeof(*unmap));
+	kref_init(&unmap->kref);
+	unmap->dev = dev;
+	unmap->map_cnt = nr;
+
+	return unmap;
+}
+EXPORT_SYMBOL(dmaengine_get_unmap_data);
+
+void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
+	struct dma_chan *chan)
+{
+	tx->chan = chan;
+	#ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
+	spin_lock_init(&tx->lock);
+	#endif
+}
+EXPORT_SYMBOL(dma_async_tx_descriptor_init);
+
+static inline int desc_check_and_set_metadata_mode(
+	struct dma_async_tx_descriptor *desc, enum dma_desc_metadata_mode mode)
+{
+	/* Make sure that the metadata mode is not mixed */
+	if (!desc->desc_metadata_mode) {
+		if (dmaengine_is_metadata_mode_supported(desc->chan, mode))
+			desc->desc_metadata_mode = mode;
+		else
+			return -ENOTSUPP;
+	} else if (desc->desc_metadata_mode != mode) {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int dmaengine_desc_attach_metadata(struct dma_async_tx_descriptor *desc,
+				   void *data, size_t len)
+{
+	int ret;
+
+	if (!desc)
+		return -EINVAL;
+
+	ret = desc_check_and_set_metadata_mode(desc, DESC_METADATA_CLIENT);
+	if (ret)
+		return ret;
+
+	if (!desc->metadata_ops || !desc->metadata_ops->attach)
+		return -ENOTSUPP;
+
+	return desc->metadata_ops->attach(desc, data, len);
+}
+EXPORT_SYMBOL_GPL(dmaengine_desc_attach_metadata);
+
+void *dmaengine_desc_get_metadata_ptr(struct dma_async_tx_descriptor *desc,
+				      size_t *payload_len, size_t *max_len)
+{
+	int ret;
+
+	if (!desc)
+		return ERR_PTR(-EINVAL);
+
+	ret = desc_check_and_set_metadata_mode(desc, DESC_METADATA_ENGINE);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!desc->metadata_ops || !desc->metadata_ops->get_ptr)
+		return ERR_PTR(-ENOTSUPP);
+
+	return desc->metadata_ops->get_ptr(desc, payload_len, max_len);
+}
+EXPORT_SYMBOL_GPL(dmaengine_desc_get_metadata_ptr);
+
+int dmaengine_desc_set_metadata_len(struct dma_async_tx_descriptor *desc,
+				    size_t payload_len)
+{
+	int ret;
+
+	if (!desc)
+		return -EINVAL;
+
+	ret = desc_check_and_set_metadata_mode(desc, DESC_METADATA_ENGINE);
+	if (ret)
+		return ret;
+
+	if (!desc->metadata_ops || !desc->metadata_ops->set_len)
+		return -ENOTSUPP;
+
+	return desc->metadata_ops->set_len(desc, payload_len);
+}
+EXPORT_SYMBOL_GPL(dmaengine_desc_set_metadata_len);
+
+/**
+ * dma_wait_for_async_tx - spin wait for a transaction to complete
+ * @tx:		in-flight transaction to wait on
+ */
+enum dma_status
+dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
+{
+	unsigned long dma_sync_wait_timeout = jiffies + msecs_to_jiffies(5000);
+
+	if (!tx)
+		return DMA_COMPLETE;
+
+	while (tx->cookie == -EBUSY) {
+		if (time_after_eq(jiffies, dma_sync_wait_timeout)) {
+			dev_err(tx->chan->device->dev,
+				"%s timeout waiting for descriptor submission\n",
+				__func__);
+			return DMA_ERROR;
+		}
+		cpu_relax();
+	}
+	return dma_sync_wait(tx->chan, tx->cookie);
+}
+EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);
+
+/**
+ * dma_run_dependencies - process dependent operations on the target channel
+ * @tx:		transaction with dependencies
+ *
+ * Helper routine for DMA drivers to process (start) dependent operations
+ * on their target channel.
+ */
+void dma_run_dependencies(struct dma_async_tx_descriptor *tx)
+{
+	struct dma_async_tx_descriptor *dep = txd_next(tx);
+	struct dma_async_tx_descriptor *dep_next;
+	struct dma_chan *chan;
+
+	if (!dep)
+		return;
+
+	/* we'll submit tx->next now, so clear the link */
+	txd_clear_next(tx);
+	chan = dep->chan;
+
+	/* keep submitting up until a channel switch is detected
+	 * in that case we will be called again as a result of
+	 * processing the interrupt from async_tx_channel_switch
+	 */
+	for (; dep; dep = dep_next) {
+		txd_lock(dep);
+		txd_clear_parent(dep);
+		dep_next = txd_next(dep);
+		if (dep_next && dep_next->chan == chan)
+			txd_clear_next(dep); /* ->next will be submitted */
+		else
+			dep_next = NULL; /* submit current dep and terminate */
+		txd_unlock(dep);
+
+		dep->tx_submit(dep);
+	}
+
+	chan->device->device_issue_pending(chan);
+}
+EXPORT_SYMBOL_GPL(dma_run_dependencies);
+
+static int __init dma_bus_init(void)
+{
+	int err = dmaengine_init_unmap_pool();
+
+	if (err)
+		return err;
+
+	err = class_register(&dma_devclass);
+	if (!err)
+		dmaengine_debugfs_init();
+
+	return err;
+}
+arch_initcall(dma_bus_init);