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
  ...

2 files changed, 892 insertions, 0 deletions

diff --git a/drivers/sh/maple/Makefile b/drivers/sh/maple/Makefile
new file mode 100644
index 000000000..c3a80910c
--- /dev/null
+++ b/drivers/sh/maple/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# Makefile for Maple Bus
+
+obj-$(CONFIG_MAPLE) := maple.o
diff --git a/drivers/sh/maple/maple.c b/drivers/sh/maple/maple.c
new file mode 100644
index 000000000..5585f220e
--- /dev/null
+++ b/drivers/sh/maple/maple.c
@@ -0,0 +1,888 @@
+/*
+ * Core maple bus functionality
+ *
+ *  Copyright (C) 2007 - 2009 Adrian McMenamin
+ *  Copyright (C) 2001 - 2008 Paul Mundt
+ *  Copyright (C) 2000 - 2001 YAEGASHI Takeshi
+ *  Copyright (C) 2001 M. R. Brown
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/maple.h>
+#include <linux/dma-mapping.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <asm/cacheflush.h>
+#include <asm/dma.h>
+#include <asm/io.h>
+#include <mach/dma.h>
+#include <mach/sysasic.h>
+
+MODULE_AUTHOR("Adrian McMenamin <adrian@mcmen.demon.co.uk>");
+MODULE_DESCRIPTION("Maple bus driver for Dreamcast");
+MODULE_LICENSE("GPL v2");
+
+static void maple_dma_handler(struct work_struct *work);
+static void maple_vblank_handler(struct work_struct *work);
+
+static DECLARE_WORK(maple_dma_process, maple_dma_handler);
+static DECLARE_WORK(maple_vblank_process, maple_vblank_handler);
+
+static LIST_HEAD(maple_waitq);
+static LIST_HEAD(maple_sentq);
+
+/* mutex to protect queue of waiting packets */
+static DEFINE_MUTEX(maple_wlist_lock);
+
+static struct maple_driver maple_unsupported_device;
+static struct device maple_bus;
+static int subdevice_map[MAPLE_PORTS];
+static unsigned long *maple_sendbuf, *maple_sendptr, *maple_lastptr;
+static unsigned long maple_pnp_time;
+static int started, scanning, fullscan;
+static struct kmem_cache *maple_queue_cache;
+
+struct maple_device_specify {
+	int port;
+	int unit;
+};
+
+static bool checked[MAPLE_PORTS];
+static bool empty[MAPLE_PORTS];
+static struct maple_device *baseunits[MAPLE_PORTS];
+static const struct bus_type maple_bus_type;
+
+/**
+ * maple_driver_register - register a maple driver
+ * @drv: maple driver to be registered.
+ *
+ * Registers the passed in @drv, while updating the bus type.
+ * Devices with matching function IDs will be automatically probed.
+ */
+int maple_driver_register(struct maple_driver *drv)
+{
+	if (!drv)
+		return -EINVAL;
+
+	drv->drv.bus = &maple_bus_type;
+
+	return driver_register(&drv->drv);
+}
+EXPORT_SYMBOL_GPL(maple_driver_register);
+
+/**
+ * maple_driver_unregister - unregister a maple driver.
+ * @drv: maple driver to unregister.
+ *
+ * Cleans up after maple_driver_register(). To be invoked in the exit
+ * path of any module drivers.
+ */
+void maple_driver_unregister(struct maple_driver *drv)
+{
+	driver_unregister(&drv->drv);
+}
+EXPORT_SYMBOL_GPL(maple_driver_unregister);
+
+/* set hardware registers to enable next round of dma */
+static void maple_dma_reset(void)
+{
+	__raw_writel(MAPLE_MAGIC, MAPLE_RESET);
+	/* set trig type to 0 for software trigger, 1 for hardware (VBLANK) */
+	__raw_writel(1, MAPLE_TRIGTYPE);
+	/*
+	* Maple system register
+	* bits 31 - 16	timeout in units of 20nsec
+	* bit 12	hard trigger - set 0 to keep responding to VBLANK
+	* bits 9 - 8	set 00 for 2 Mbps, 01 for 1 Mbps
+	* bits 3 - 0	delay (in 1.3ms) between VBLANK and start of DMA
+	* max delay is 11
+	*/
+	__raw_writel(MAPLE_2MBPS | MAPLE_TIMEOUT(0xFFFF), MAPLE_SPEED);
+	__raw_writel(virt_to_phys(maple_sendbuf), MAPLE_DMAADDR);
+	__raw_writel(1, MAPLE_ENABLE);
+}
+
+/**
+ * maple_getcond_callback - setup handling MAPLE_COMMAND_GETCOND
+ * @dev: device responding
+ * @callback: handler callback
+ * @interval: interval in jiffies between callbacks
+ * @function: the function code for the device
+ */
+void maple_getcond_callback(struct maple_device *dev,
+			void (*callback) (struct mapleq *mq),
+			unsigned long interval, unsigned long function)
+{
+	dev->callback = callback;
+	dev->interval = interval;
+	dev->function = cpu_to_be32(function);
+	dev->when = jiffies;
+}
+EXPORT_SYMBOL_GPL(maple_getcond_callback);
+
+static int maple_dma_done(void)
+{
+	return (__raw_readl(MAPLE_STATE) & 1) == 0;
+}
+
+static void maple_release_device(struct device *dev)
+{
+	struct maple_device *mdev;
+	struct mapleq *mq;
+
+	mdev = to_maple_dev(dev);
+	mq = mdev->mq;
+	kmem_cache_free(maple_queue_cache, mq->recvbuf);
+	kfree(mq);
+	kfree(mdev);
+}
+
+/**
+ * maple_add_packet - add a single instruction to the maple bus queue
+ * @mdev: maple device
+ * @function: function on device being queried
+ * @command: maple command to add
+ * @length: length of command string (in 32 bit words)
+ * @data: remainder of command string
+ */
+int maple_add_packet(struct maple_device *mdev, u32 function, u32 command,
+	size_t length, void *data)
+{
+	int ret = 0;
+	void *sendbuf = NULL;
+
+	if (length) {
+		sendbuf = kcalloc(length, 4, GFP_KERNEL);
+		if (!sendbuf) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		((__be32 *)sendbuf)[0] = cpu_to_be32(function);
+	}
+
+	mdev->mq->command = command;
+	mdev->mq->length = length;
+	if (length > 1)
+		memcpy(sendbuf + 4, data, (length - 1) * 4);
+	mdev->mq->sendbuf = sendbuf;
+
+	mutex_lock(&maple_wlist_lock);
+	list_add_tail(&mdev->mq->list, &maple_waitq);
+	mutex_unlock(&maple_wlist_lock);
+out:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(maple_add_packet);
+
+static struct mapleq *maple_allocq(struct maple_device *mdev)
+{
+	struct mapleq *mq;
+
+	mq = kzalloc_obj(*mq);
+	if (!mq)
+		goto failed_nomem;
+
+	INIT_LIST_HEAD(&mq->list);
+	mq->dev = mdev;
+	mq->recvbuf = kmem_cache_zalloc(maple_queue_cache, GFP_KERNEL);
+	if (!mq->recvbuf)
+		goto failed_p2;
+	mq->recvbuf->buf = &((mq->recvbuf->bufx)[0]);
+
+	return mq;
+
+failed_p2:
+	kfree(mq);
+failed_nomem:
+	dev_err(&mdev->dev, "could not allocate memory for device (%d, %d)\n",
+		mdev->port, mdev->unit);
+	return NULL;
+}
+
+static struct maple_device *maple_alloc_dev(int port, int unit)
+{
+	struct maple_device *mdev;
+
+	/* zero this out to avoid kobj subsystem
+	* thinking it has already been registered */
+
+	mdev = kzalloc_obj(*mdev);
+	if (!mdev)
+		return NULL;
+
+	mdev->port = port;
+	mdev->unit = unit;
+
+	mdev->mq = maple_allocq(mdev);
+
+	if (!mdev->mq) {
+		kfree(mdev);
+		return NULL;
+	}
+	mdev->dev.bus = &maple_bus_type;
+	mdev->dev.parent = &maple_bus;
+	init_waitqueue_head(&mdev->maple_wait);
+	return mdev;
+}
+
+static void maple_free_dev(struct maple_device *mdev)
+{
+	kmem_cache_free(maple_queue_cache, mdev->mq->recvbuf);
+	kfree(mdev->mq);
+	kfree(mdev);
+}
+
+/* process the command queue into a maple command block
+ * terminating command has bit 32 of first long set to 0
+ */
+static void maple_build_block(struct mapleq *mq)
+{
+	int port, unit, from, to, len;
+	unsigned long *lsendbuf = mq->sendbuf;
+
+	port = mq->dev->port & 3;
+	unit = mq->dev->unit;
+	len = mq->length;
+	from = port << 6;
+	to = (port << 6) | (unit > 0 ? (1 << (unit - 1)) & 0x1f : 0x20);
+
+	*maple_lastptr &= 0x7fffffff;
+	maple_lastptr = maple_sendptr;
+
+	*maple_sendptr++ = (port << 16) | len | 0x80000000;
+	*maple_sendptr++ = virt_to_phys(mq->recvbuf->buf);
+	*maple_sendptr++ =
+	    mq->command | (to << 8) | (from << 16) | (len << 24);
+	while (len-- > 0)
+		*maple_sendptr++ = *lsendbuf++;
+}
+
+/* build up command queue */
+static void maple_send(void)
+{
+	int i, maple_packets = 0;
+	struct mapleq *mq, *nmq;
+
+	if (!maple_dma_done())
+		return;
+
+	/* disable DMA */
+	__raw_writel(0, MAPLE_ENABLE);
+
+	if (!list_empty(&maple_sentq))
+		goto finish;
+
+	mutex_lock(&maple_wlist_lock);
+	if (list_empty(&maple_waitq)) {
+		mutex_unlock(&maple_wlist_lock);
+		goto finish;
+	}
+
+	maple_lastptr = maple_sendbuf;
+	maple_sendptr = maple_sendbuf;
+
+	list_for_each_entry_safe(mq, nmq, &maple_waitq, list) {
+		maple_build_block(mq);
+		list_del_init(&mq->list);
+		list_add_tail(&mq->list, &maple_sentq);
+		if (maple_packets++ > MAPLE_MAXPACKETS)
+			break;
+	}
+	mutex_unlock(&maple_wlist_lock);
+	if (maple_packets > 0) {
+		for (i = 0; i < (1 << MAPLE_DMA_PAGES); i++)
+			__flush_purge_region(maple_sendbuf + i * PAGE_SIZE,
+					PAGE_SIZE);
+	}
+
+finish:
+	maple_dma_reset();
+}
+
+/* check if there is a driver registered likely to match this device */
+static int maple_check_matching_driver(struct device_driver *driver,
+					void *devptr)
+{
+	struct maple_driver *maple_drv;
+	struct maple_device *mdev;
+
+	mdev = devptr;
+	maple_drv = to_maple_driver(driver);
+	if (mdev->devinfo.function & cpu_to_be32(maple_drv->function))
+		return 1;
+	return 0;
+}
+
+static void maple_detach_driver(struct maple_device *mdev)
+{
+	device_unregister(&mdev->dev);
+}
+
+/* process initial MAPLE_COMMAND_DEVINFO for each device or port */
+static void maple_attach_driver(struct maple_device *mdev)
+{
+	char *p, *recvbuf;
+	unsigned long function;
+	int matched, error;
+
+	recvbuf = mdev->mq->recvbuf->buf;
+	/* copy the data as individual elements in
+	* case of memory optimisation */
+	memcpy(&mdev->devinfo.function, recvbuf + 4, 4);
+	memcpy(&mdev->devinfo.function_data[0], recvbuf + 8, 12);
+	memcpy(&mdev->devinfo.area_code, recvbuf + 20, 1);
+	memcpy(&mdev->devinfo.connector_direction, recvbuf + 21, 1);
+	memcpy(&mdev->devinfo.product_name[0], recvbuf + 22, 30);
+	memcpy(&mdev->devinfo.standby_power, recvbuf + 112, 2);
+	memcpy(&mdev->devinfo.max_power, recvbuf + 114, 2);
+	memcpy(mdev->product_name, mdev->devinfo.product_name, 30);
+	mdev->product_name[30] = '\0';
+	memcpy(mdev->product_licence, mdev->devinfo.product_licence, 60);
+	mdev->product_licence[60] = '\0';
+
+	for (p = mdev->product_name + 29; mdev->product_name <= p; p--)
+		if (*p == ' ')
+			*p = '\0';
+		else
+			break;
+	for (p = mdev->product_licence + 59; mdev->product_licence <= p; p--)
+		if (*p == ' ')
+			*p = '\0';
+		else
+			break;
+
+	function = be32_to_cpu(mdev->devinfo.function);
+
+	dev_info(&mdev->dev, "detected %s: function 0x%lX: at (%d, %d)\n",
+		mdev->product_name, function, mdev->port, mdev->unit);
+
+	if (function > 0x200) {
+		/* Do this silently - as not a real device */
+		function = 0;
+		mdev->driver = &maple_unsupported_device;
+		dev_set_name(&mdev->dev, "%d:0.port", mdev->port);
+	} else {
+		matched =
+			bus_for_each_drv(&maple_bus_type, NULL, mdev,
+				maple_check_matching_driver);
+
+		if (matched == 0) {
+			/* Driver does not exist yet */
+			dev_info(&mdev->dev, "no driver found\n");
+			mdev->driver = &maple_unsupported_device;
+		}
+		dev_set_name(&mdev->dev, "%d:0%d.%lX", mdev->port,
+			     mdev->unit, function);
+	}
+
+	mdev->function = function;
+	mdev->dev.release = &maple_release_device;
+
+	atomic_set(&mdev->busy, 0);
+	error = device_register(&mdev->dev);
+	if (error) {
+		dev_warn(&mdev->dev, "could not register device at"
+			" (%d, %d), with error 0x%X\n", mdev->unit,
+			mdev->port, error);
+		maple_free_dev(mdev);
+		mdev = NULL;
+		return;
+	}
+}
+
+/*
+ * if device has been registered for the given
+ * port and unit then return 1 - allows identification
+ * of which devices need to be attached or detached
+ */
+static int check_maple_device(struct device *device, void *portptr)
+{
+	struct maple_device_specify *ds;
+	struct maple_device *mdev;
+
+	ds = portptr;
+	mdev = to_maple_dev(device);
+	if (mdev->port == ds->port && mdev->unit == ds->unit)
+		return 1;
+	return 0;
+}
+
+static int setup_maple_commands(struct device *device, void *ignored)
+{
+	int add;
+	struct maple_device *mdev = to_maple_dev(device);
+	if (mdev->interval > 0 && atomic_read(&mdev->busy) == 0 &&
+		time_after(jiffies, mdev->when)) {
+		/* bounce if we cannot add */
+		add = maple_add_packet(mdev,
+			be32_to_cpu(mdev->devinfo.function),
+			MAPLE_COMMAND_GETCOND, 1, NULL);
+		if (!add)
+			mdev->when = jiffies + mdev->interval;
+	} else {
+		if (time_after(jiffies, maple_pnp_time))
+			/* Ensure we don't have block reads and devinfo
+			* calls interfering with one another - so flag the
+			* device as busy */
+			if (atomic_read(&mdev->busy) == 0) {
+				atomic_set(&mdev->busy, 1);
+				maple_add_packet(mdev, 0,
+					MAPLE_COMMAND_DEVINFO, 0, NULL);
+			}
+	}
+	return 0;
+}
+
+/* VBLANK bottom half - implemented via workqueue */
+static void maple_vblank_handler(struct work_struct *work)
+{
+	int x, locking;
+	struct maple_device *mdev;
+
+	if (!maple_dma_done())
+		return;
+
+	__raw_writel(0, MAPLE_ENABLE);
+
+	if (!list_empty(&maple_sentq))
+		goto finish;
+
+	/*
+	* Set up essential commands - to fetch data and
+	* check devices are still present
+	*/
+	bus_for_each_dev(&maple_bus_type, NULL, NULL,
+		setup_maple_commands);
+
+	if (time_after(jiffies, maple_pnp_time)) {
+		/*
+		* Scan the empty ports - bus is flakey and may have
+		* mis-reported emptyness
+		*/
+		for (x = 0; x < MAPLE_PORTS; x++) {
+			if (checked[x] && empty[x]) {
+				mdev = baseunits[x];
+				if (!mdev)
+					break;
+				atomic_set(&mdev->busy, 1);
+				locking = maple_add_packet(mdev, 0,
+					MAPLE_COMMAND_DEVINFO, 0, NULL);
+				if (!locking)
+					break;
+				}
+			}
+
+		maple_pnp_time = jiffies + MAPLE_PNP_INTERVAL;
+	}
+
+finish:
+	maple_send();
+}
+
+/* handle devices added via hotplugs - placing them on queue for DEVINFO */
+static void maple_map_subunits(struct maple_device *mdev, int submask)
+{
+	int retval, k, devcheck;
+	struct maple_device *mdev_add;
+	struct maple_device_specify ds;
+
+	ds.port = mdev->port;
+	for (k = 0; k < 5; k++) {
+		ds.unit = k + 1;
+		retval =
+		    bus_for_each_dev(&maple_bus_type, NULL, &ds,
+				     check_maple_device);
+		if (retval) {
+			submask = submask >> 1;
+			continue;
+		}
+		devcheck = submask & 0x01;
+		if (devcheck) {
+			mdev_add = maple_alloc_dev(mdev->port, k + 1);
+			if (!mdev_add)
+				return;
+			atomic_set(&mdev_add->busy, 1);
+			maple_add_packet(mdev_add, 0, MAPLE_COMMAND_DEVINFO,
+				0, NULL);
+			/* mark that we are checking sub devices */
+			scanning = 1;
+		}
+		submask = submask >> 1;
+	}
+}
+
+/* mark a device as removed */
+static void maple_clean_submap(struct maple_device *mdev)
+{
+	int killbit;
+
+	killbit = (mdev->unit > 0 ? (1 << (mdev->unit - 1)) & 0x1f : 0x20);
+	killbit = ~killbit;
+	killbit &= 0xFF;
+	subdevice_map[mdev->port] = subdevice_map[mdev->port] & killbit;
+}
+
+/* handle empty port or hotplug removal */
+static void maple_response_none(struct maple_device *mdev)
+{
+	maple_clean_submap(mdev);
+
+	if (likely(mdev->unit != 0)) {
+		/*
+		* Block devices play up
+		* and give the impression they have
+		* been removed even when still in place or
+		* trip the mtd layer when they have
+		* really gone - this code traps that eventuality
+		* and ensures we aren't overloaded with useless
+		* error messages
+		*/
+		if (mdev->can_unload) {
+			if (!mdev->can_unload(mdev)) {
+				atomic_set(&mdev->busy, 2);
+				wake_up(&mdev->maple_wait);
+				return;
+			}
+		}
+
+		dev_info(&mdev->dev, "detaching device at (%d, %d)\n",
+			mdev->port, mdev->unit);
+		maple_detach_driver(mdev);
+		return;
+	} else {
+		if (!started || !fullscan) {
+			if (checked[mdev->port] == false) {
+				checked[mdev->port] = true;
+				empty[mdev->port] = true;
+				dev_info(&mdev->dev, "no devices"
+					" to port %d\n", mdev->port);
+			}
+			return;
+		}
+	}
+	/* Some hardware devices generate false detach messages on unit 0 */
+	atomic_set(&mdev->busy, 0);
+}
+
+/* preprocess hotplugs or scans */
+static void maple_response_devinfo(struct maple_device *mdev,
+				   char *recvbuf)
+{
+	char submask;
+	if (!started || (scanning == 2) || !fullscan) {
+		if ((mdev->unit == 0) && (checked[mdev->port] == false)) {
+			checked[mdev->port] = true;
+			maple_attach_driver(mdev);
+		} else {
+			if (mdev->unit != 0)
+				maple_attach_driver(mdev);
+			if (mdev->unit == 0) {
+				empty[mdev->port] = false;
+				maple_attach_driver(mdev);
+			}
+		}
+	}
+	if (mdev->unit == 0) {
+		submask = recvbuf[2] & 0x1F;
+		if (submask ^ subdevice_map[mdev->port]) {
+			maple_map_subunits(mdev, submask);
+			subdevice_map[mdev->port] = submask;
+		}
+	}
+}
+
+static void maple_response_fileerr(struct maple_device *mdev, void *recvbuf)
+{
+	if (mdev->fileerr_handler) {
+		mdev->fileerr_handler(mdev, recvbuf);
+		return;
+	} else
+		dev_warn(&mdev->dev, "device at (%d, %d) reports"
+			"file error 0x%X\n", mdev->port, mdev->unit,
+			((int *)recvbuf)[1]);
+}
+
+static void maple_port_rescan(void)
+{
+	int i;
+	struct maple_device *mdev;
+
+	fullscan = 1;
+	for (i = 0; i < MAPLE_PORTS; i++) {
+		if (checked[i] == false) {
+			fullscan = 0;
+			mdev = baseunits[i];
+			maple_add_packet(mdev, 0, MAPLE_COMMAND_DEVINFO,
+				0, NULL);
+		}
+	}
+}
+
+/* maple dma end bottom half - implemented via workqueue */
+static void maple_dma_handler(struct work_struct *work)
+{
+	struct mapleq *mq, *nmq;
+	struct maple_device *mdev;
+	char *recvbuf;
+	enum maple_code code;
+
+	if (!maple_dma_done())
+		return;
+	__raw_writel(0, MAPLE_ENABLE);
+	if (!list_empty(&maple_sentq)) {
+		list_for_each_entry_safe(mq, nmq, &maple_sentq, list) {
+			mdev = mq->dev;
+			recvbuf = mq->recvbuf->buf;
+			__flush_invalidate_region(sh_cacheop_vaddr(recvbuf),
+					0x400);
+			code = recvbuf[0];
+			kfree(mq->sendbuf);
+			list_del_init(&mq->list);
+			switch (code) {
+			case MAPLE_RESPONSE_NONE:
+				maple_response_none(mdev);
+				break;
+
+			case MAPLE_RESPONSE_DEVINFO:
+				maple_response_devinfo(mdev, recvbuf);
+				atomic_set(&mdev->busy, 0);
+				break;
+
+			case MAPLE_RESPONSE_DATATRF:
+				if (mdev->callback)
+					mdev->callback(mq);
+				atomic_set(&mdev->busy, 0);
+				wake_up(&mdev->maple_wait);
+				break;
+
+			case MAPLE_RESPONSE_FILEERR:
+				maple_response_fileerr(mdev, recvbuf);
+				atomic_set(&mdev->busy, 0);
+				wake_up(&mdev->maple_wait);
+				break;
+
+			case MAPLE_RESPONSE_AGAIN:
+			case MAPLE_RESPONSE_BADCMD:
+			case MAPLE_RESPONSE_BADFUNC:
+				dev_warn(&mdev->dev, "non-fatal error"
+					" 0x%X at (%d, %d)\n", code,
+					mdev->port, mdev->unit);
+				atomic_set(&mdev->busy, 0);
+				break;
+
+			case MAPLE_RESPONSE_ALLINFO:
+				dev_notice(&mdev->dev, "extended"
+				" device information request for (%d, %d)"
+				" but call is not supported\n", mdev->port,
+				mdev->unit);
+				atomic_set(&mdev->busy, 0);
+				break;
+
+			case MAPLE_RESPONSE_OK:
+				atomic_set(&mdev->busy, 0);
+				wake_up(&mdev->maple_wait);
+				break;
+
+			default:
+				break;
+			}
+		}
+		/* if scanning is 1 then we have subdevices to check */
+		if (scanning == 1) {
+			maple_send();
+			scanning = 2;
+		} else
+			scanning = 0;
+		/*check if we have actually tested all ports yet */
+		if (!fullscan)
+			maple_port_rescan();
+		/* mark that we have been through the first scan */
+		started = 1;
+	}
+	maple_send();
+}
+
+static irqreturn_t maple_dma_interrupt(int irq, void *dev_id)
+{
+	/* Load everything into the bottom half */
+	schedule_work(&maple_dma_process);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t maple_vblank_interrupt(int irq, void *dev_id)
+{
+	schedule_work(&maple_vblank_process);
+	return IRQ_HANDLED;
+}
+
+static int maple_set_dma_interrupt_handler(void)
+{
+	return request_irq(HW_EVENT_MAPLE_DMA, maple_dma_interrupt,
+		IRQF_SHARED, "maple bus DMA", &maple_unsupported_device);
+}
+
+static int maple_set_vblank_interrupt_handler(void)
+{
+	return request_irq(HW_EVENT_VSYNC, maple_vblank_interrupt,
+		IRQF_SHARED, "maple bus VBLANK", &maple_unsupported_device);
+}
+
+static int maple_get_dma_buffer(void)
+{
+	maple_sendbuf =
+	    (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO,
+				      MAPLE_DMA_PAGES);
+	if (!maple_sendbuf)
+		return -ENOMEM;
+	return 0;
+}
+
+static int maple_match_bus_driver(struct device *devptr,
+				  const struct device_driver *drvptr)
+{
+	const struct maple_driver *maple_drv = to_maple_driver(drvptr);
+	struct maple_device *maple_dev = to_maple_dev(devptr);
+
+	/* Trap empty port case */
+	if (maple_dev->devinfo.function == 0xFFFFFFFF)
+		return 0;
+	else if (maple_dev->devinfo.function &
+		 cpu_to_be32(maple_drv->function))
+		return 1;
+	return 0;
+}
+
+static void maple_bus_release(struct device *dev)
+{
+}
+
+static struct maple_driver maple_unsupported_device = {
+	.drv = {
+		.name = "maple_unsupported_device",
+		.bus = &maple_bus_type,
+	},
+};
+/*
+ * maple_bus_type - core maple bus structure
+ */
+static const struct bus_type maple_bus_type = {
+	.name = "maple",
+	.match = maple_match_bus_driver,
+};
+
+static struct device maple_bus = {
+	.init_name = "maple",
+	.release = maple_bus_release,
+};
+
+static int __init maple_bus_init(void)
+{
+	int retval, i;
+	struct maple_device *mdev[MAPLE_PORTS];
+
+	__raw_writel(0, MAPLE_ENABLE);
+
+	retval = device_register(&maple_bus);
+	if (retval)
+		goto cleanup;
+
+	retval = bus_register(&maple_bus_type);
+	if (retval)
+		goto cleanup_device;
+
+	retval = driver_register(&maple_unsupported_device.drv);
+	if (retval)
+		goto cleanup_bus;
+
+	/* allocate memory for maple bus dma */
+	retval = maple_get_dma_buffer();
+	if (retval) {
+		dev_err(&maple_bus, "failed to allocate DMA buffers\n");
+		goto cleanup_basic;
+	}
+
+	/* set up DMA interrupt handler */
+	retval = maple_set_dma_interrupt_handler();
+	if (retval) {
+		dev_err(&maple_bus, "bus failed to grab maple "
+			"DMA IRQ\n");
+		goto cleanup_dma;
+	}
+
+	/* set up VBLANK interrupt handler */
+	retval = maple_set_vblank_interrupt_handler();
+	if (retval) {
+		dev_err(&maple_bus, "bus failed to grab VBLANK IRQ\n");
+		goto cleanup_irq;
+	}
+
+	maple_queue_cache = KMEM_CACHE(maple_buffer, SLAB_HWCACHE_ALIGN);
+
+	if (!maple_queue_cache) {
+		retval = -ENOMEM;
+		goto cleanup_bothirqs;
+	}
+
+	INIT_LIST_HEAD(&maple_waitq);
+	INIT_LIST_HEAD(&maple_sentq);
+
+	/* setup maple ports */
+	for (i = 0; i < MAPLE_PORTS; i++) {
+		checked[i] = false;
+		empty[i] = false;
+		mdev[i] = maple_alloc_dev(i, 0);
+		if (!mdev[i]) {
+			while (i-- > 0)
+				maple_free_dev(mdev[i]);
+			retval = -ENOMEM;
+			goto cleanup_cache;
+		}
+		baseunits[i] = mdev[i];
+		atomic_set(&mdev[i]->busy, 1);
+		maple_add_packet(mdev[i], 0, MAPLE_COMMAND_DEVINFO, 0, NULL);
+		subdevice_map[i] = 0;
+	}
+
+	maple_pnp_time = jiffies + HZ;
+	/* prepare initial queue */
+	maple_send();
+	dev_info(&maple_bus, "bus core now registered\n");
+
+	return 0;
+
+cleanup_cache:
+	kmem_cache_destroy(maple_queue_cache);
+
+cleanup_bothirqs:
+	free_irq(HW_EVENT_VSYNC, 0);
+
+cleanup_irq:
+	free_irq(HW_EVENT_MAPLE_DMA, 0);
+
+cleanup_dma:
+	free_pages((unsigned long) maple_sendbuf, MAPLE_DMA_PAGES);
+
+cleanup_basic:
+	driver_unregister(&maple_unsupported_device.drv);
+
+cleanup_bus:
+	bus_unregister(&maple_bus_type);
+
+cleanup_device:
+	device_unregister(&maple_bus);
+
+cleanup:
+	printk(KERN_ERR "Maple bus registration failed\n");
+	return retval;
+}
+/* Push init to later to ensure hardware gets detected */
+fs_initcall(maple_bus_init);