drivers/dma/dmatest.c - kernel/msm-4.19 - Gitiles

 /*
  * DMA Engine test module
  *
  * Copyright (C) 2007 Atmel Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #include <linux/delay.h>
 #include <linux/dmaengine.h>
 #include <linux/init.h>
 #include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/random.h>
 #include <linux/wait.h>

 static unsigned int test_buf_size = 16384;
 module_param(test_buf_size, uint, S_IRUGO);
 MODULE_PARM_DESC(test_buf_size, "Size of the memcpy test buffer");

 static char test_channel[BUS_ID_SIZE];
 module_param_string(channel, test_channel, sizeof(test_channel), S_IRUGO);
 MODULE_PARM_DESC(channel, "Bus ID of the channel to test (default: any)");

 static char test_device[BUS_ID_SIZE];
 module_param_string(device, test_device, sizeof(test_device), S_IRUGO);
 MODULE_PARM_DESC(device, "Bus ID of the DMA Engine to test (default: any)");

 static unsigned int threads_per_chan = 1;
 module_param(threads_per_chan, uint, S_IRUGO);
 MODULE_PARM_DESC(threads_per_chan,
 		"Number of threads to start per channel (default: 1)");

 static unsigned int max_channels;
 module_param(max_channels, uint, S_IRUGO);
 MODULE_PARM_DESC(nr_channels,
 		"Maximum number of channels to use (default: all)");

 /*
  * Initialization patterns. All bytes in the source buffer has bit 7
  * set, all bytes in the destination buffer has bit 7 cleared.
  *
  * Bit 6 is set for all bytes which are to be copied by the DMA
  * engine. Bit 5 is set for all bytes which are to be overwritten by
  * the DMA engine.
  *
  * The remaining bits are the inverse of a counter which increments by
  * one for each byte address.
  */
 #define PATTERN_SRC		0x80
 #define PATTERN_DST		0x00
 #define PATTERN_COPY		0x40
 #define PATTERN_OVERWRITE	0x20
 #define PATTERN_COUNT_MASK	0x1f

 struct dmatest_thread {
 	struct list_head	node;
 	struct task_struct	*task;
 	struct dma_chan		*chan;
 	u8			*srcbuf;
 	u8			*dstbuf;
 };

 struct dmatest_chan {
 	struct list_head	node;
 	struct dma_chan		*chan;
 	struct list_head	threads;
 };

 /*
  * These are protected by dma_list_mutex since they're only used by
  * the DMA client event callback
  */
 static LIST_HEAD(dmatest_channels);
 static unsigned int nr_channels;

 static bool dmatest_match_channel(struct dma_chan *chan)
 {
 	if (test_channel[0] == '\0')
 		return true;
 	return strcmp(chan->dev.bus_id, test_channel) == 0;
 }

 static bool dmatest_match_device(struct dma_device *device)
 {
 	if (test_device[0] == '\0')
 		return true;
 	return strcmp(device->dev->bus_id, test_device) == 0;
 }

 static unsigned long dmatest_random(void)
 {
 	unsigned long buf;

 	get_random_bytes(&buf, sizeof(buf));
 	return buf;
 }

 static void dmatest_init_srcbuf(u8 *buf, unsigned int start, unsigned int len)
 {
 	unsigned int i;

 	for (i = 0; i < start; i++)
 		buf[i] = PATTERN_SRC | (~i & PATTERN_COUNT_MASK);
 	for ( ; i < start + len; i++)
 		buf[i] = PATTERN_SRC | PATTERN_COPY
 			| (~i & PATTERN_COUNT_MASK);;
 	for ( ; i < test_buf_size; i++)
 		buf[i] = PATTERN_SRC | (~i & PATTERN_COUNT_MASK);
 }

 static void dmatest_init_dstbuf(u8 *buf, unsigned int start, unsigned int len)
 {
 	unsigned int i;

 	for (i = 0; i < start; i++)
 		buf[i] = PATTERN_DST | (~i & PATTERN_COUNT_MASK);
 	for ( ; i < start + len; i++)
 		buf[i] = PATTERN_DST | PATTERN_OVERWRITE
 			| (~i & PATTERN_COUNT_MASK);
 	for ( ; i < test_buf_size; i++)
 		buf[i] = PATTERN_DST | (~i & PATTERN_COUNT_MASK);
 }

 static void dmatest_mismatch(u8 actual, u8 pattern, unsigned int index,
 		unsigned int counter, bool is_srcbuf)
 {
 	u8		diff = actual ^ pattern;
 	u8		expected = pattern | (~counter & PATTERN_COUNT_MASK);
 	const char	*thread_name = current->comm;

 	if (is_srcbuf)
 		pr_warning("%s: srcbuf[0x%x] overwritten!"
 				" Expected %02x, got %02x\n",
 				thread_name, index, expected, actual);
 	else if ((pattern & PATTERN_COPY)
 			&& (diff & (PATTERN_COPY | PATTERN_OVERWRITE)))
 		pr_warning("%s: dstbuf[0x%x] not copied!"
 				" Expected %02x, got %02x\n",
 				thread_name, index, expected, actual);
 	else if (diff & PATTERN_SRC)
 		pr_warning("%s: dstbuf[0x%x] was copied!"
 				" Expected %02x, got %02x\n",
 				thread_name, index, expected, actual);
 	else
 		pr_warning("%s: dstbuf[0x%x] mismatch!"
 				" Expected %02x, got %02x\n",
 				thread_name, index, expected, actual);
 }

 static unsigned int dmatest_verify(u8 *buf, unsigned int start,
 		unsigned int end, unsigned int counter, u8 pattern,
 		bool is_srcbuf)
 {
 	unsigned int i;
 	unsigned int error_count = 0;
 	u8 actual;

 	for (i = start; i < end; i++) {
 		actual = buf[i];
 		if (actual != (pattern | (~counter & PATTERN_COUNT_MASK))) {
 			if (error_count < 32)
 				dmatest_mismatch(actual, pattern, i, counter,
 						is_srcbuf);
 			error_count++;
 		}
 		counter++;
 	}

 	if (error_count > 32)
 		pr_warning("%s: %u errors suppressed\n",
 			current->comm, error_count - 32);

 	return error_count;
 }

 /*
  * This function repeatedly tests DMA transfers of various lengths and
  * offsets until it is told to exit by kthread_stop(). There may be
  * multiple threads running this function in parallel for a single
  * channel, and there may be multiple channels being tested in
  * parallel.
  *
  * Before each test, the source and destination buffer is initialized
  * with a known pattern. This pattern is different depending on
  * whether it's in an area which is supposed to be copied or
  * overwritten, and different in the source and destination buffers.
  * So if the DMA engine doesn't copy exactly what we tell it to copy,
  * we'll notice.
  */
 static int dmatest_func(void *data)
 {
 	struct dmatest_thread	*thread = data;
 	struct dma_chan		*chan;
 	const char		*thread_name;
 	unsigned int		src_off, dst_off, len;
 	unsigned int		error_count;
 	unsigned int		failed_tests = 0;
 	unsigned int		total_tests = 0;
 	dma_cookie_t		cookie;
 	enum dma_status		status;
 	int			ret;

 	thread_name = current->comm;

 	ret = -ENOMEM;
 	thread->srcbuf = kmalloc(test_buf_size, GFP_KERNEL);
 	if (!thread->srcbuf)
 		goto err_srcbuf;
 	thread->dstbuf = kmalloc(test_buf_size, GFP_KERNEL);
 	if (!thread->dstbuf)
 		goto err_dstbuf;

 	smp_rmb();
 	chan = thread->chan;
 	dma_chan_get(chan);

 	while (!kthread_should_stop()) {
 		total_tests++;

 		len = dmatest_random() % test_buf_size + 1;
 		src_off = dmatest_random() % (test_buf_size - len + 1);
 		dst_off = dmatest_random() % (test_buf_size - len + 1);

 		dmatest_init_srcbuf(thread->srcbuf, src_off, len);
 		dmatest_init_dstbuf(thread->dstbuf, dst_off, len);

 		cookie = dma_async_memcpy_buf_to_buf(chan,
 				thread->dstbuf + dst_off,
 				thread->srcbuf + src_off,
 				len);
 		if (dma_submit_error(cookie)) {
 			pr_warning("%s: #%u: submit error %d with src_off=0x%x "
 					"dst_off=0x%x len=0x%x\n",
 					thread_name, total_tests - 1, cookie,
 					src_off, dst_off, len);
 			msleep(100);
 			failed_tests++;
 			continue;
 		}
 		dma_async_memcpy_issue_pending(chan);

 		do {
 			msleep(1);
 			status = dma_async_memcpy_complete(
 					chan, cookie, NULL, NULL);
 		} while (status == DMA_IN_PROGRESS);

 		if (status == DMA_ERROR) {
 			pr_warning("%s: #%u: error during copy\n",
 					thread_name, total_tests - 1);
 			failed_tests++;
 			continue;
 		}

 		error_count = 0;

 		pr_debug("%s: verifying source buffer...\n", thread_name);
 		error_count += dmatest_verify(thread->srcbuf, 0, src_off,
 				0, PATTERN_SRC, true);
 		error_count += dmatest_verify(thread->srcbuf, src_off,
 				src_off + len, src_off,
 				PATTERN_SRC | PATTERN_COPY, true);
 		error_count += dmatest_verify(thread->srcbuf, src_off + len,
 				test_buf_size, src_off + len,
 				PATTERN_SRC, true);

 		pr_debug("%s: verifying dest buffer...\n",
 				thread->task->comm);
 		error_count += dmatest_verify(thread->dstbuf, 0, dst_off,
 				0, PATTERN_DST, false);
 		error_count += dmatest_verify(thread->dstbuf, dst_off,
 				dst_off + len, src_off,
 				PATTERN_SRC | PATTERN_COPY, false);
 		error_count += dmatest_verify(thread->dstbuf, dst_off + len,
 				test_buf_size, dst_off + len,
 				PATTERN_DST, false);

 		if (error_count) {
 			pr_warning("%s: #%u: %u errors with "
 				"src_off=0x%x dst_off=0x%x len=0x%x\n",
 				thread_name, total_tests - 1, error_count,
 				src_off, dst_off, len);
 			failed_tests++;
 		} else {
 			pr_debug("%s: #%u: No errors with "
 				"src_off=0x%x dst_off=0x%x len=0x%x\n",
 				thread_name, total_tests - 1,
 				src_off, dst_off, len);
 		}
 	}

 	ret = 0;
 	dma_chan_put(chan);
 	kfree(thread->dstbuf);
 err_dstbuf:
 	kfree(thread->srcbuf);
 err_srcbuf:
 	pr_notice("%s: terminating after %u tests, %u failures (status %d)\n",
 			thread_name, total_tests, failed_tests, ret);
 	return ret;
 }

 static void dmatest_cleanup_channel(struct dmatest_chan *dtc)
 {
 	struct dmatest_thread	*thread;
 	struct dmatest_thread	*_thread;
 	int			ret;

 	list_for_each_entry_safe(thread, _thread, &dtc->threads, node) {
 		ret = kthread_stop(thread->task);
 		pr_debug("dmatest: thread %s exited with status %d\n",
 				thread->task->comm, ret);
 		list_del(&thread->node);
 		kfree(thread);
 	}
 	kfree(dtc);
 }

 static enum dma_state_client dmatest_add_channel(struct dma_chan *chan)
 {
 	struct dmatest_chan	*dtc;
 	struct dmatest_thread	*thread;
 	unsigned int		i;

 	/* Have we already been told about this channel? */
 	list_for_each_entry(dtc, &dmatest_channels, node)
 		if (dtc->chan == chan)
 			return DMA_DUP;

 	dtc = kmalloc(sizeof(struct dmatest_chan), GFP_KERNEL);
 	if (!dtc) {
 		pr_warning("dmatest: No memory for %s\n", chan->dev.bus_id);
 		return DMA_NAK;
 	}

 	dtc->chan = chan;
 	INIT_LIST_HEAD(&dtc->threads);

 	for (i = 0; i < threads_per_chan; i++) {
 		thread = kzalloc(sizeof(struct dmatest_thread), GFP_KERNEL);
 		if (!thread) {
 			pr_warning("dmatest: No memory for %s-test%u\n",
 					chan->dev.bus_id, i);
 			break;
 		}
 		thread->chan = dtc->chan;
 		smp_wmb();
 		thread->task = kthread_run(dmatest_func, thread, "%s-test%u",
 				chan->dev.bus_id, i);
 		if (IS_ERR(thread->task)) {
 			pr_warning("dmatest: Failed to run thread %s-test%u\n",
 					chan->dev.bus_id, i);
 			kfree(thread);
 			break;
 		}

 		/* srcbuf and dstbuf are allocated by the thread itself */

 		list_add_tail(&thread->node, &dtc->threads);
 	}

 	pr_info("dmatest: Started %u threads using %s\n", i, chan->dev.bus_id);

 	list_add_tail(&dtc->node, &dmatest_channels);
 	nr_channels++;

 	return DMA_ACK;
 }

 static enum dma_state_client dmatest_remove_channel(struct dma_chan *chan)
 {
 	struct dmatest_chan	*dtc, *_dtc;

 	list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
 		if (dtc->chan == chan) {
 			list_del(&dtc->node);
 			dmatest_cleanup_channel(dtc);
 			pr_debug("dmatest: lost channel %s\n",
 					chan->dev.bus_id);
 			return DMA_ACK;
 		}
 	}

 	return DMA_DUP;
 }

 /*
  * Start testing threads as new channels are assigned to us, and kill
  * them when the channels go away.
  *
  * When we unregister the client, all channels are removed so this
  * will also take care of cleaning things up when the module is
  * unloaded.
  */
 static enum dma_state_client
 dmatest_event(struct dma_client *client, struct dma_chan *chan,
 		enum dma_state state)
 {
 	enum dma_state_client	ack = DMA_NAK;

 	switch (state) {
 	case DMA_RESOURCE_AVAILABLE:
 		if (!dmatest_match_channel(chan)
 				|| !dmatest_match_device(chan->device))
 			ack = DMA_DUP;
 		else if (max_channels && nr_channels >= max_channels)
 			ack = DMA_NAK;
 		else
 			ack = dmatest_add_channel(chan);
 		break;

 	case DMA_RESOURCE_REMOVED:
 		ack = dmatest_remove_channel(chan);
 		break;

 	default:
 		pr_info("dmatest: Unhandled event %u (%s)\n",
 				state, chan->dev.bus_id);
 		break;
 	}

 	return ack;
 }

 static struct dma_client dmatest_client = {
 	.event_callback	= dmatest_event,
 };

 static int __init dmatest_init(void)
 {
 	dma_cap_set(DMA_MEMCPY, dmatest_client.cap_mask);
 	dma_async_client_register(&dmatest_client);
 	dma_async_client_chan_request(&dmatest_client);

 	return 0;
 }
 module_init(dmatest_init);

 static void __exit dmatest_exit(void)
 {
 	dma_async_client_unregister(&dmatest_client);
 }
 module_exit(dmatest_exit);

 MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
 MODULE_LICENSE("GPL v2");
	/*
	* DMA Engine test module
	*
	* Copyright (C) 2007 Atmel Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#include <linux/delay.h>
	#include <linux/dmaengine.h>
	#include <linux/init.h>
	#include <linux/kthread.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/random.h>
	#include <linux/wait.h>

	static unsigned int test_buf_size = 16384;
	module_param(test_buf_size, uint, S_IRUGO);
	MODULE_PARM_DESC(test_buf_size, "Size of the memcpy test buffer");

	static char test_channel[BUS_ID_SIZE];
	module_param_string(channel, test_channel, sizeof(test_channel), S_IRUGO);
	MODULE_PARM_DESC(channel, "Bus ID of the channel to test (default: any)");

	static char test_device[BUS_ID_SIZE];
	module_param_string(device, test_device, sizeof(test_device), S_IRUGO);
	MODULE_PARM_DESC(device, "Bus ID of the DMA Engine to test (default: any)");

	static unsigned int threads_per_chan = 1;
	module_param(threads_per_chan, uint, S_IRUGO);
	MODULE_PARM_DESC(threads_per_chan,
	"Number of threads to start per channel (default: 1)");

	static unsigned int max_channels;
	module_param(max_channels, uint, S_IRUGO);
	MODULE_PARM_DESC(nr_channels,
	"Maximum number of channels to use (default: all)");

	/*
	* Initialization patterns. All bytes in the source buffer has bit 7
	* set, all bytes in the destination buffer has bit 7 cleared.
	*
	* Bit 6 is set for all bytes which are to be copied by the DMA
	* engine. Bit 5 is set for all bytes which are to be overwritten by
	* the DMA engine.
	*
	* The remaining bits are the inverse of a counter which increments by
	* one for each byte address.
	*/
	#define PATTERN_SRC 0x80
	#define PATTERN_DST 0x00
	#define PATTERN_COPY 0x40
	#define PATTERN_OVERWRITE 0x20
	#define PATTERN_COUNT_MASK 0x1f

	struct dmatest_thread {
	struct list_head node;
	struct task_struct *task;
	struct dma_chan *chan;
	u8 *srcbuf;
	u8 *dstbuf;
	};

	struct dmatest_chan {
	struct list_head node;
	struct dma_chan *chan;
	struct list_head threads;
	};

	/*
	* These are protected by dma_list_mutex since they're only used by
	* the DMA client event callback
	*/
	static LIST_HEAD(dmatest_channels);
	static unsigned int nr_channels;

	static bool dmatest_match_channel(struct dma_chan *chan)
	{
	if (test_channel[0] == '\0')
	return true;
	return strcmp(chan->dev.bus_id, test_channel) == 0;
	}

	static bool dmatest_match_device(struct dma_device *device)
	{
	if (test_device[0] == '\0')
	return true;
	return strcmp(device->dev->bus_id, test_device) == 0;
	}

	static unsigned long dmatest_random(void)
	{
	unsigned long buf;

	get_random_bytes(&buf, sizeof(buf));
	return buf;
	}

	static void dmatest_init_srcbuf(u8 *buf, unsigned int start, unsigned int len)
	{
	unsigned int i;

	for (i = 0; i < start; i++)
	buf[i] = PATTERN_SRC \| (~i & PATTERN_COUNT_MASK);
	for ( ; i < start + len; i++)
	buf[i] = PATTERN_SRC \| PATTERN_COPY
	\| (~i & PATTERN_COUNT_MASK);;
	for ( ; i < test_buf_size; i++)
	buf[i] = PATTERN_SRC \| (~i & PATTERN_COUNT_MASK);
	}

	static void dmatest_init_dstbuf(u8 *buf, unsigned int start, unsigned int len)
	{
	unsigned int i;

	for (i = 0; i < start; i++)
	buf[i] = PATTERN_DST \| (~i & PATTERN_COUNT_MASK);
	for ( ; i < start + len; i++)
	buf[i] = PATTERN_DST \| PATTERN_OVERWRITE
	\| (~i & PATTERN_COUNT_MASK);
	for ( ; i < test_buf_size; i++)
	buf[i] = PATTERN_DST \| (~i & PATTERN_COUNT_MASK);
	}

	static void dmatest_mismatch(u8 actual, u8 pattern, unsigned int index,
	unsigned int counter, bool is_srcbuf)
	{
	u8 diff = actual ^ pattern;
	u8 expected = pattern \| (~counter & PATTERN_COUNT_MASK);
	const char *thread_name = current->comm;

	if (is_srcbuf)
	pr_warning("%s: srcbuf[0x%x] overwritten!"
	" Expected %02x, got %02x\n",
	thread_name, index, expected, actual);
	else if ((pattern & PATTERN_COPY)
	&& (diff & (PATTERN_COPY \| PATTERN_OVERWRITE)))
	pr_warning("%s: dstbuf[0x%x] not copied!"
	" Expected %02x, got %02x\n",
	thread_name, index, expected, actual);
	else if (diff & PATTERN_SRC)
	pr_warning("%s: dstbuf[0x%x] was copied!"
	" Expected %02x, got %02x\n",
	thread_name, index, expected, actual);
	else
	pr_warning("%s: dstbuf[0x%x] mismatch!"
	" Expected %02x, got %02x\n",
	thread_name, index, expected, actual);
	}

	static unsigned int dmatest_verify(u8 *buf, unsigned int start,
	unsigned int end, unsigned int counter, u8 pattern,
	bool is_srcbuf)
	{
	unsigned int i;
	unsigned int error_count = 0;
	u8 actual;

	for (i = start; i < end; i++) {
	actual = buf[i];
	if (actual != (pattern \| (~counter & PATTERN_COUNT_MASK))) {
	if (error_count < 32)
	dmatest_mismatch(actual, pattern, i, counter,
	is_srcbuf);
	error_count++;
	}
	counter++;
	}

	if (error_count > 32)
	pr_warning("%s: %u errors suppressed\n",
	current->comm, error_count - 32);

	return error_count;
	}

	/*
	* This function repeatedly tests DMA transfers of various lengths and
	* offsets until it is told to exit by kthread_stop(). There may be
	* multiple threads running this function in parallel for a single
	* channel, and there may be multiple channels being tested in
	* parallel.
	*
	* Before each test, the source and destination buffer is initialized
	* with a known pattern. This pattern is different depending on
	* whether it's in an area which is supposed to be copied or
	* overwritten, and different in the source and destination buffers.
	* So if the DMA engine doesn't copy exactly what we tell it to copy,
	* we'll notice.
	*/
	static int dmatest_func(void *data)
	{
	struct dmatest_thread *thread = data;
	struct dma_chan *chan;
	const char *thread_name;
	unsigned int src_off, dst_off, len;
	unsigned int error_count;
	unsigned int failed_tests = 0;
	unsigned int total_tests = 0;
	dma_cookie_t cookie;
	enum dma_status status;
	int ret;

	thread_name = current->comm;

	ret = -ENOMEM;
	thread->srcbuf = kmalloc(test_buf_size, GFP_KERNEL);
	if (!thread->srcbuf)
	goto err_srcbuf;
	thread->dstbuf = kmalloc(test_buf_size, GFP_KERNEL);
	if (!thread->dstbuf)
	goto err_dstbuf;

	smp_rmb();
	chan = thread->chan;
	dma_chan_get(chan);

	while (!kthread_should_stop()) {
	total_tests++;

	len = dmatest_random() % test_buf_size + 1;
	src_off = dmatest_random() % (test_buf_size - len + 1);
	dst_off = dmatest_random() % (test_buf_size - len + 1);

	dmatest_init_srcbuf(thread->srcbuf, src_off, len);
	dmatest_init_dstbuf(thread->dstbuf, dst_off, len);

	cookie = dma_async_memcpy_buf_to_buf(chan,
	thread->dstbuf + dst_off,
	thread->srcbuf + src_off,
	len);
	if (dma_submit_error(cookie)) {
	pr_warning("%s: #%u: submit error %d with src_off=0x%x "
	"dst_off=0x%x len=0x%x\n",
	thread_name, total_tests - 1, cookie,
	src_off, dst_off, len);
	msleep(100);
	failed_tests++;
	continue;
	}
	dma_async_memcpy_issue_pending(chan);

	do {
	msleep(1);
	status = dma_async_memcpy_complete(
	chan, cookie, NULL, NULL);
	} while (status == DMA_IN_PROGRESS);

	if (status == DMA_ERROR) {
	pr_warning("%s: #%u: error during copy\n",
	thread_name, total_tests - 1);
	failed_tests++;
	continue;
	}

	error_count = 0;

	pr_debug("%s: verifying source buffer...\n", thread_name);
	error_count += dmatest_verify(thread->srcbuf, 0, src_off,
	0, PATTERN_SRC, true);
	error_count += dmatest_verify(thread->srcbuf, src_off,
	src_off + len, src_off,
	PATTERN_SRC \| PATTERN_COPY, true);
	error_count += dmatest_verify(thread->srcbuf, src_off + len,
	test_buf_size, src_off + len,
	PATTERN_SRC, true);

	pr_debug("%s: verifying dest buffer...\n",
	thread->task->comm);
	error_count += dmatest_verify(thread->dstbuf, 0, dst_off,
	0, PATTERN_DST, false);
	error_count += dmatest_verify(thread->dstbuf, dst_off,
	dst_off + len, src_off,
	PATTERN_SRC \| PATTERN_COPY, false);
	error_count += dmatest_verify(thread->dstbuf, dst_off + len,
	test_buf_size, dst_off + len,
	PATTERN_DST, false);

	if (error_count) {
	pr_warning("%s: #%u: %u errors with "
	"src_off=0x%x dst_off=0x%x len=0x%x\n",
	thread_name, total_tests - 1, error_count,
	src_off, dst_off, len);
	failed_tests++;
	} else {
	pr_debug("%s: #%u: No errors with "
	"src_off=0x%x dst_off=0x%x len=0x%x\n",
	thread_name, total_tests - 1,
	src_off, dst_off, len);
	}
	}

	ret = 0;
	dma_chan_put(chan);
	kfree(thread->dstbuf);
	err_dstbuf:
	kfree(thread->srcbuf);
	err_srcbuf:
	pr_notice("%s: terminating after %u tests, %u failures (status %d)\n",
	thread_name, total_tests, failed_tests, ret);
	return ret;
	}

	static void dmatest_cleanup_channel(struct dmatest_chan *dtc)
	{
	struct dmatest_thread *thread;
	struct dmatest_thread *_thread;
	int ret;

	list_for_each_entry_safe(thread, _thread, &dtc->threads, node) {
	ret = kthread_stop(thread->task);
	pr_debug("dmatest: thread %s exited with status %d\n",
	thread->task->comm, ret);
	list_del(&thread->node);
	kfree(thread);
	}
	kfree(dtc);
	}

	static enum dma_state_client dmatest_add_channel(struct dma_chan *chan)
	{
	struct dmatest_chan *dtc;
	struct dmatest_thread *thread;
	unsigned int i;

	/* Have we already been told about this channel? */
	list_for_each_entry(dtc, &dmatest_channels, node)
	if (dtc->chan == chan)
	return DMA_DUP;

	dtc = kmalloc(sizeof(struct dmatest_chan), GFP_KERNEL);
	if (!dtc) {
	pr_warning("dmatest: No memory for %s\n", chan->dev.bus_id);
	return DMA_NAK;
	}

	dtc->chan = chan;
	INIT_LIST_HEAD(&dtc->threads);

	for (i = 0; i < threads_per_chan; i++) {
	thread = kzalloc(sizeof(struct dmatest_thread), GFP_KERNEL);
	if (!thread) {
	pr_warning("dmatest: No memory for %s-test%u\n",
	chan->dev.bus_id, i);
	break;
	}
	thread->chan = dtc->chan;
	smp_wmb();
	thread->task = kthread_run(dmatest_func, thread, "%s-test%u",
	chan->dev.bus_id, i);
	if (IS_ERR(thread->task)) {
	pr_warning("dmatest: Failed to run thread %s-test%u\n",
	chan->dev.bus_id, i);
	kfree(thread);
	break;
	}

	/* srcbuf and dstbuf are allocated by the thread itself */

	list_add_tail(&thread->node, &dtc->threads);
	}

	pr_info("dmatest: Started %u threads using %s\n", i, chan->dev.bus_id);

	list_add_tail(&dtc->node, &dmatest_channels);
	nr_channels++;

	return DMA_ACK;
	}

	static enum dma_state_client dmatest_remove_channel(struct dma_chan *chan)
	{
	struct dmatest_chan dtc, _dtc;

	list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
	if (dtc->chan == chan) {
	list_del(&dtc->node);
	dmatest_cleanup_channel(dtc);
	pr_debug("dmatest: lost channel %s\n",
	chan->dev.bus_id);
	return DMA_ACK;
	}
	}

	return DMA_DUP;
	}

	/*
	* Start testing threads as new channels are assigned to us, and kill
	* them when the channels go away.
	*
	* When we unregister the client, all channels are removed so this
	* will also take care of cleaning things up when the module is
	* unloaded.
	*/
	static enum dma_state_client
	dmatest_event(struct dma_client client, struct dma_chan chan,
	enum dma_state state)
	{
	enum dma_state_client ack = DMA_NAK;

	switch (state) {
	case DMA_RESOURCE_AVAILABLE:
	if (!dmatest_match_channel(chan)
	\|\| !dmatest_match_device(chan->device))
	ack = DMA_DUP;
	else if (max_channels && nr_channels >= max_channels)
	ack = DMA_NAK;
	else
	ack = dmatest_add_channel(chan);
	break;

	case DMA_RESOURCE_REMOVED:
	ack = dmatest_remove_channel(chan);
	break;

	default:
	pr_info("dmatest: Unhandled event %u (%s)\n",
	state, chan->dev.bus_id);
	break;
	}

	return ack;
	}

	static struct dma_client dmatest_client = {
	.event_callback = dmatest_event,
	};

	static int __init dmatest_init(void)
	{
	dma_cap_set(DMA_MEMCPY, dmatest_client.cap_mask);
	dma_async_client_register(&dmatest_client);
	dma_async_client_chan_request(&dmatest_client);

	return 0;
	}
	module_init(dmatest_init);

	static void __exit dmatest_exit(void)
	{
	dma_async_client_unregister(&dmatest_client);
	}
	module_exit(dmatest_exit);

	MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
	MODULE_LICENSE("GPL v2");