drivers/dma/dmatest.c - kernel/msm-4.9 - 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[20];
 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[20];
 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(max_channels,
 		"Maximum number of channels to use (default: all)");

 static unsigned int iterations;
 module_param(iterations, uint, S_IRUGO);
 MODULE_PARM_DESC(iterations,
 		"Iterations before stopping test (default: infinite)");

 static unsigned int xor_sources = 3;
 module_param(xor_sources, uint, S_IRUGO);
 MODULE_PARM_DESC(xor_sources,
 		"Number of xor source buffers (default: 3)");

 static unsigned int pq_sources = 3;
 module_param(pq_sources, uint, S_IRUGO);
 MODULE_PARM_DESC(pq_sources,
 		"Number of p+q source buffers (default: 3)");

 /*
  * 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			**srcs;
 	u8			**dsts;
 	enum dma_transaction_type type;
 };

 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 filter function 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(dma_chan_name(chan), test_channel) == 0;
 }

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

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

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

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

 	for (; (buf = *bufs); bufs++) {
 		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);
 		buf++;
 	}
 }

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

 	for (; (buf = *bufs); bufs++) {
 		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 **bufs, unsigned int start,
 		unsigned int end, unsigned int counter, u8 pattern,
 		bool is_srcbuf)
 {
 	unsigned int i;
 	unsigned int error_count = 0;
 	u8 actual;
 	u8 expected;
 	u8 *buf;
 	unsigned int counter_orig = counter;

 	for (; (buf = *bufs); bufs++) {
 		counter = counter_orig;
 		for (i = start; i < end; i++) {
 			actual = buf[i];
 			expected = pattern | (~counter & PATTERN_COUNT_MASK);
 			if (actual != expected) {
 				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;
 }

 static void dmatest_callback(void *completion)
 {
 	complete(completion);
 }

 /*
  * This function repeatedly tests DMA transfers of various lengths and
  * offsets for a given operation type 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;
 	enum dma_ctrl_flags 	flags;
 	u8			pq_coefs[pq_sources];
 	int			ret;
 	int			src_cnt;
 	int			dst_cnt;
 	int			i;

 	thread_name = current->comm;

 	ret = -ENOMEM;

 	smp_rmb();
 	chan = thread->chan;
 	if (thread->type == DMA_MEMCPY)
 		src_cnt = dst_cnt = 1;
 	else if (thread->type == DMA_XOR) {
 		src_cnt = xor_sources | 1; /* force odd to ensure dst = src */
 		dst_cnt = 1;
 	} else if (thread->type == DMA_PQ) {
 		src_cnt = pq_sources | 1; /* force odd to ensure dst = src */
 		dst_cnt = 2;
 		for (i = 0; i < pq_sources; i++)
 			pq_coefs[i] = 1;
 	} else
 		goto err_srcs;

 	thread->srcs = kcalloc(src_cnt+1, sizeof(u8 *), GFP_KERNEL);
 	if (!thread->srcs)
 		goto err_srcs;
 	for (i = 0; i < src_cnt; i++) {
 		thread->srcs[i] = kmalloc(test_buf_size, GFP_KERNEL);
 		if (!thread->srcs[i])
 			goto err_srcbuf;
 	}
 	thread->srcs[i] = NULL;

 	thread->dsts = kcalloc(dst_cnt+1, sizeof(u8 *), GFP_KERNEL);
 	if (!thread->dsts)
 		goto err_dsts;
 	for (i = 0; i < dst_cnt; i++) {
 		thread->dsts[i] = kmalloc(test_buf_size, GFP_KERNEL);
 		if (!thread->dsts[i])
 			goto err_dstbuf;
 	}
 	thread->dsts[i] = NULL;

 	set_user_nice(current, 10);

 	flags = DMA_CTRL_ACK | DMA_COMPL_SKIP_DEST_UNMAP | DMA_PREP_INTERRUPT;

 	while (!kthread_should_stop()
 	       && !(iterations && total_tests >= iterations)) {
 		struct dma_device *dev = chan->device;
 		struct dma_async_tx_descriptor *tx = NULL;
 		dma_addr_t dma_srcs[src_cnt];
 		dma_addr_t dma_dsts[dst_cnt];
 		struct completion cmp;
 		unsigned long tmo = msecs_to_jiffies(3000);
 		u8 align = 0;

 		total_tests++;

 		/* honor alignment restrictions */
 		if (thread->type == DMA_MEMCPY)
 			align = dev->copy_align;
 		else if (thread->type == DMA_XOR)
 			align = dev->xor_align;
 		else if (thread->type == DMA_PQ)
 			align = dev->pq_align;

 		if (1 << align > test_buf_size) {
 			pr_err("%u-byte buffer too small for %d-byte alignment\n",
 			       test_buf_size, 1 << align);
 			break;
 		}

 		len = dmatest_random() % test_buf_size + 1;
 		len = (len >> align) << align;
 		if (!len)
 			len = 1 << align;
 		src_off = dmatest_random() % (test_buf_size - len + 1);
 		dst_off = dmatest_random() % (test_buf_size - len + 1);

 		src_off = (src_off >> align) << align;
 		dst_off = (dst_off >> align) << align;

 		dmatest_init_srcs(thread->srcs, src_off, len);
 		dmatest_init_dsts(thread->dsts, dst_off, len);

 		for (i = 0; i < src_cnt; i++) {
 			u8 *buf = thread->srcs[i] + src_off;

 			dma_srcs[i] = dma_map_single(dev->dev, buf, len,
 						     DMA_TO_DEVICE);
 		}
 		/* map with DMA_BIDIRECTIONAL to force writeback/invalidate */
 		for (i = 0; i < dst_cnt; i++) {
 			dma_dsts[i] = dma_map_single(dev->dev, thread->dsts[i],
 						     test_buf_size,
 						     DMA_BIDIRECTIONAL);
 		}


 		if (thread->type == DMA_MEMCPY)
 			tx = dev->device_prep_dma_memcpy(chan,
 							 dma_dsts[0] + dst_off,
 							 dma_srcs[0], len,
 							 flags);
 		else if (thread->type == DMA_XOR)
 			tx = dev->device_prep_dma_xor(chan,
 						      dma_dsts[0] + dst_off,
 						      dma_srcs, xor_sources,
 						      len, flags);
 		else if (thread->type == DMA_PQ) {
 			dma_addr_t dma_pq[dst_cnt];

 			for (i = 0; i < dst_cnt; i++)
 				dma_pq[i] = dma_dsts[i] + dst_off;
 			tx = dev->device_prep_dma_pq(chan, dma_pq, dma_srcs,
 						     pq_sources, pq_coefs,
 						     len, flags);
 		}

 		if (!tx) {
 			for (i = 0; i < src_cnt; i++)
 				dma_unmap_single(dev->dev, dma_srcs[i], len,
 						 DMA_TO_DEVICE);
 			for (i = 0; i < dst_cnt; i++)
 				dma_unmap_single(dev->dev, dma_dsts[i],
 						 test_buf_size,
 						 DMA_BIDIRECTIONAL);
 			pr_warning("%s: #%u: prep error with src_off=0x%x "
 					"dst_off=0x%x len=0x%x\n",
 					thread_name, total_tests - 1,
 					src_off, dst_off, len);
 			msleep(100);
 			failed_tests++;
 			continue;
 		}

 		init_completion(&cmp);
 		tx->callback = dmatest_callback;
 		tx->callback_param = &cmp;
 		cookie = tx->tx_submit(tx);

 		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_issue_pending(chan);

 		tmo = wait_for_completion_timeout(&cmp, tmo);
 		status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);

 		if (tmo == 0) {
 			pr_warning("%s: #%u: test timed out\n",
 				   thread_name, total_tests - 1);
 			failed_tests++;
 			continue;
 		} else if (status != DMA_SUCCESS) {
 			pr_warning("%s: #%u: got completion callback,"
 				   " but status is \'%s\'\n",
 				   thread_name, total_tests - 1,
 				   status == DMA_ERROR ? "error" : "in progress");
 			failed_tests++;
 			continue;
 		}

 		/* Unmap by myself (see DMA_COMPL_SKIP_DEST_UNMAP above) */
 		for (i = 0; i < dst_cnt; i++)
 			dma_unmap_single(dev->dev, dma_dsts[i], test_buf_size,
 					 DMA_BIDIRECTIONAL);

 		error_count = 0;

 		pr_debug("%s: verifying source buffer...\n", thread_name);
 		error_count += dmatest_verify(thread->srcs, 0, src_off,
 				0, PATTERN_SRC, true);
 		error_count += dmatest_verify(thread->srcs, src_off,
 				src_off + len, src_off,
 				PATTERN_SRC | PATTERN_COPY, true);
 		error_count += dmatest_verify(thread->srcs, 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->dsts, 0, dst_off,
 				0, PATTERN_DST, false);
 		error_count += dmatest_verify(thread->dsts, dst_off,
 				dst_off + len, src_off,
 				PATTERN_SRC | PATTERN_COPY, false);
 		error_count += dmatest_verify(thread->dsts, 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;
 	for (i = 0; thread->dsts[i]; i++)
 		kfree(thread->dsts[i]);
 err_dstbuf:
 	kfree(thread->dsts);
 err_dsts:
 	for (i = 0; thread->srcs[i]; i++)
 		kfree(thread->srcs[i]);
 err_srcbuf:
 	kfree(thread->srcs);
 err_srcs:
 	pr_notice("%s: terminating after %u tests, %u failures (status %d)\n",
 			thread_name, total_tests, failed_tests, ret);

 	if (iterations > 0)
 		while (!kthread_should_stop()) {
 			DECLARE_WAIT_QUEUE_HEAD(wait_dmatest_exit);
 			interruptible_sleep_on(&wait_dmatest_exit);
 		}

 	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 int dmatest_add_threads(struct dmatest_chan *dtc, enum dma_transaction_type type)
 {
 	struct dmatest_thread *thread;
 	struct dma_chan *chan = dtc->chan;
 	char *op;
 	unsigned int i;

 	if (type == DMA_MEMCPY)
 		op = "copy";
 	else if (type == DMA_XOR)
 		op = "xor";
 	else if (type == DMA_PQ)
 		op = "pq";
 	else
 		return -EINVAL;

 	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-%s%u\n",
 				   dma_chan_name(chan), op, i);

 			break;
 		}
 		thread->chan = dtc->chan;
 		thread->type = type;
 		smp_wmb();
 		thread->task = kthread_run(dmatest_func, thread, "%s-%s%u",
 				dma_chan_name(chan), op, i);
 		if (IS_ERR(thread->task)) {
 			pr_warning("dmatest: Failed to run thread %s-%s%u\n",
 					dma_chan_name(chan), op, i);
 			kfree(thread);
 			break;
 		}

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

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

 	return i;
 }

 static int dmatest_add_channel(struct dma_chan *chan)
 {
 	struct dmatest_chan	*dtc;
 	struct dma_device	*dma_dev = chan->device;
 	unsigned int		thread_count = 0;
 	unsigned int		cnt;

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

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

 	if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask)) {
 		cnt = dmatest_add_threads(dtc, DMA_MEMCPY);
 		thread_count += cnt > 0 ? cnt : 0;
 	}
 	if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
 		cnt = dmatest_add_threads(dtc, DMA_XOR);
 		thread_count += cnt > 0 ? cnt : 0;
 	}
 	if (dma_has_cap(DMA_PQ, dma_dev->cap_mask)) {
 		cnt = dmatest_add_threads(dtc, DMA_PQ);
 		thread_count += cnt > 0 ?: 0;
 	}

 	pr_info("dmatest: Started %u threads using %s\n",
 		thread_count, dma_chan_name(chan));

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

 	return 0;
 }

 static bool filter(struct dma_chan *chan, void *param)
 {
 	if (!dmatest_match_channel(chan) || !dmatest_match_device(chan->device))
 		return false;
 	else
 		return true;
 }

 static int __init dmatest_init(void)
 {
 	dma_cap_mask_t mask;
 	struct dma_chan *chan;
 	int err = 0;

 	dma_cap_zero(mask);
 	dma_cap_set(DMA_MEMCPY, mask);
 	for (;;) {
 		chan = dma_request_channel(mask, filter, NULL);
 		if (chan) {
 			err = dmatest_add_channel(chan);
 			if (err) {
 				dma_release_channel(chan);
 				break; /* add_channel failed, punt */
 			}
 		} else
 			break; /* no more channels available */
 		if (max_channels && nr_channels >= max_channels)
 			break; /* we have all we need */
 	}

 	return err;
 }
 /* when compiled-in wait for drivers to load first */
 late_initcall(dmatest_init);

 static void __exit dmatest_exit(void)
 {
 	struct dmatest_chan *dtc, *_dtc;
 	struct dma_chan *chan;

 	list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
 		list_del(&dtc->node);
 		chan = dtc->chan;
 		dmatest_cleanup_channel(dtc);
 		pr_debug("dmatest: dropped channel %s\n",
 			 dma_chan_name(chan));
 		dma_release_channel(chan);
 	}
 }
 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[20];
	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[20];
	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(max_channels,
	"Maximum number of channels to use (default: all)");

	static unsigned int iterations;
	module_param(iterations, uint, S_IRUGO);
	MODULE_PARM_DESC(iterations,
	"Iterations before stopping test (default: infinite)");

	static unsigned int xor_sources = 3;
	module_param(xor_sources, uint, S_IRUGO);
	MODULE_PARM_DESC(xor_sources,
	"Number of xor source buffers (default: 3)");

	static unsigned int pq_sources = 3;
	module_param(pq_sources, uint, S_IRUGO);
	MODULE_PARM_DESC(pq_sources,
	"Number of p+q source buffers (default: 3)");

	/*
	* 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 **srcs;
	u8 **dsts;
	enum dma_transaction_type type;
	};

	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 filter function 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(dma_chan_name(chan), test_channel) == 0;
	}

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

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

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

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

	for (; (buf = *bufs); bufs++) {
	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);
	buf++;
	}
	}

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

	for (; (buf = *bufs); bufs++) {
	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 **bufs, unsigned int start,
	unsigned int end, unsigned int counter, u8 pattern,
	bool is_srcbuf)
	{
	unsigned int i;
	unsigned int error_count = 0;
	u8 actual;
	u8 expected;
	u8 *buf;
	unsigned int counter_orig = counter;

	for (; (buf = *bufs); bufs++) {
	counter = counter_orig;
	for (i = start; i < end; i++) {
	actual = buf[i];
	expected = pattern \| (~counter & PATTERN_COUNT_MASK);
	if (actual != expected) {
	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;
	}

	static void dmatest_callback(void *completion)
	{
	complete(completion);
	}

	/*
	* This function repeatedly tests DMA transfers of various lengths and
	* offsets for a given operation type 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;
	enum dma_ctrl_flags flags;
	u8 pq_coefs[pq_sources];
	int ret;
	int src_cnt;
	int dst_cnt;
	int i;

	thread_name = current->comm;

	ret = -ENOMEM;

	smp_rmb();
	chan = thread->chan;
	if (thread->type == DMA_MEMCPY)
	src_cnt = dst_cnt = 1;
	else if (thread->type == DMA_XOR) {
	src_cnt = xor_sources \| 1; /* force odd to ensure dst = src */
	dst_cnt = 1;
	} else if (thread->type == DMA_PQ) {
	src_cnt = pq_sources \| 1; /* force odd to ensure dst = src */
	dst_cnt = 2;
	for (i = 0; i < pq_sources; i++)
	pq_coefs[i] = 1;
	} else
	goto err_srcs;

	thread->srcs = kcalloc(src_cnt+1, sizeof(u8 *), GFP_KERNEL);
	if (!thread->srcs)
	goto err_srcs;
	for (i = 0; i < src_cnt; i++) {
	thread->srcs[i] = kmalloc(test_buf_size, GFP_KERNEL);
	if (!thread->srcs[i])
	goto err_srcbuf;
	}
	thread->srcs[i] = NULL;

	thread->dsts = kcalloc(dst_cnt+1, sizeof(u8 *), GFP_KERNEL);
	if (!thread->dsts)
	goto err_dsts;
	for (i = 0; i < dst_cnt; i++) {
	thread->dsts[i] = kmalloc(test_buf_size, GFP_KERNEL);
	if (!thread->dsts[i])
	goto err_dstbuf;
	}
	thread->dsts[i] = NULL;

	set_user_nice(current, 10);

	flags = DMA_CTRL_ACK \| DMA_COMPL_SKIP_DEST_UNMAP \| DMA_PREP_INTERRUPT;

	while (!kthread_should_stop()
	&& !(iterations && total_tests >= iterations)) {
	struct dma_device *dev = chan->device;
	struct dma_async_tx_descriptor *tx = NULL;
	dma_addr_t dma_srcs[src_cnt];
	dma_addr_t dma_dsts[dst_cnt];
	struct completion cmp;
	unsigned long tmo = msecs_to_jiffies(3000);
	u8 align = 0;

	total_tests++;

	/* honor alignment restrictions */
	if (thread->type == DMA_MEMCPY)
	align = dev->copy_align;
	else if (thread->type == DMA_XOR)
	align = dev->xor_align;
	else if (thread->type == DMA_PQ)
	align = dev->pq_align;

	if (1 << align > test_buf_size) {
	pr_err("%u-byte buffer too small for %d-byte alignment\n",
	test_buf_size, 1 << align);
	break;
	}

	len = dmatest_random() % test_buf_size + 1;
	len = (len >> align) << align;
	if (!len)
	len = 1 << align;
	src_off = dmatest_random() % (test_buf_size - len + 1);
	dst_off = dmatest_random() % (test_buf_size - len + 1);

	src_off = (src_off >> align) << align;
	dst_off = (dst_off >> align) << align;

	dmatest_init_srcs(thread->srcs, src_off, len);
	dmatest_init_dsts(thread->dsts, dst_off, len);

	for (i = 0; i < src_cnt; i++) {
	u8 *buf = thread->srcs[i] + src_off;

	dma_srcs[i] = dma_map_single(dev->dev, buf, len,
	DMA_TO_DEVICE);
	}
	/* map with DMA_BIDIRECTIONAL to force writeback/invalidate */
	for (i = 0; i < dst_cnt; i++) {
	dma_dsts[i] = dma_map_single(dev->dev, thread->dsts[i],
	test_buf_size,
	DMA_BIDIRECTIONAL);
	}


	if (thread->type == DMA_MEMCPY)
	tx = dev->device_prep_dma_memcpy(chan,
	dma_dsts[0] + dst_off,
	dma_srcs[0], len,
	flags);
	else if (thread->type == DMA_XOR)
	tx = dev->device_prep_dma_xor(chan,
	dma_dsts[0] + dst_off,
	dma_srcs, xor_sources,
	len, flags);
	else if (thread->type == DMA_PQ) {
	dma_addr_t dma_pq[dst_cnt];

	for (i = 0; i < dst_cnt; i++)
	dma_pq[i] = dma_dsts[i] + dst_off;
	tx = dev->device_prep_dma_pq(chan, dma_pq, dma_srcs,
	pq_sources, pq_coefs,
	len, flags);
	}

	if (!tx) {
	for (i = 0; i < src_cnt; i++)
	dma_unmap_single(dev->dev, dma_srcs[i], len,
	DMA_TO_DEVICE);
	for (i = 0; i < dst_cnt; i++)
	dma_unmap_single(dev->dev, dma_dsts[i],
	test_buf_size,
	DMA_BIDIRECTIONAL);
	pr_warning("%s: #%u: prep error with src_off=0x%x "
	"dst_off=0x%x len=0x%x\n",
	thread_name, total_tests - 1,
	src_off, dst_off, len);
	msleep(100);
	failed_tests++;
	continue;
	}

	init_completion(&cmp);
	tx->callback = dmatest_callback;
	tx->callback_param = &cmp;
	cookie = tx->tx_submit(tx);

	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_issue_pending(chan);

	tmo = wait_for_completion_timeout(&cmp, tmo);
	status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);

	if (tmo == 0) {
	pr_warning("%s: #%u: test timed out\n",
	thread_name, total_tests - 1);
	failed_tests++;
	continue;
	} else if (status != DMA_SUCCESS) {
	pr_warning("%s: #%u: got completion callback,"
	" but status is \'%s\'\n",
	thread_name, total_tests - 1,
	status == DMA_ERROR ? "error" : "in progress");
	failed_tests++;
	continue;
	}

	/* Unmap by myself (see DMA_COMPL_SKIP_DEST_UNMAP above) */
	for (i = 0; i < dst_cnt; i++)
	dma_unmap_single(dev->dev, dma_dsts[i], test_buf_size,
	DMA_BIDIRECTIONAL);

	error_count = 0;

	pr_debug("%s: verifying source buffer...\n", thread_name);
	error_count += dmatest_verify(thread->srcs, 0, src_off,
	0, PATTERN_SRC, true);
	error_count += dmatest_verify(thread->srcs, src_off,
	src_off + len, src_off,
	PATTERN_SRC \| PATTERN_COPY, true);
	error_count += dmatest_verify(thread->srcs, 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->dsts, 0, dst_off,
	0, PATTERN_DST, false);
	error_count += dmatest_verify(thread->dsts, dst_off,
	dst_off + len, src_off,
	PATTERN_SRC \| PATTERN_COPY, false);
	error_count += dmatest_verify(thread->dsts, 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;
	for (i = 0; thread->dsts[i]; i++)
	kfree(thread->dsts[i]);
	err_dstbuf:
	kfree(thread->dsts);
	err_dsts:
	for (i = 0; thread->srcs[i]; i++)
	kfree(thread->srcs[i]);
	err_srcbuf:
	kfree(thread->srcs);
	err_srcs:
	pr_notice("%s: terminating after %u tests, %u failures (status %d)\n",
	thread_name, total_tests, failed_tests, ret);

	if (iterations > 0)
	while (!kthread_should_stop()) {
	DECLARE_WAIT_QUEUE_HEAD(wait_dmatest_exit);
	interruptible_sleep_on(&wait_dmatest_exit);
	}

	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 int dmatest_add_threads(struct dmatest_chan *dtc, enum dma_transaction_type type)
	{
	struct dmatest_thread *thread;
	struct dma_chan *chan = dtc->chan;
	char *op;
	unsigned int i;

	if (type == DMA_MEMCPY)
	op = "copy";
	else if (type == DMA_XOR)
	op = "xor";
	else if (type == DMA_PQ)
	op = "pq";
	else
	return -EINVAL;

	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-%s%u\n",
	dma_chan_name(chan), op, i);

	break;
	}
	thread->chan = dtc->chan;
	thread->type = type;
	smp_wmb();
	thread->task = kthread_run(dmatest_func, thread, "%s-%s%u",
	dma_chan_name(chan), op, i);
	if (IS_ERR(thread->task)) {
	pr_warning("dmatest: Failed to run thread %s-%s%u\n",
	dma_chan_name(chan), op, i);
	kfree(thread);
	break;
	}

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

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

	return i;
	}

	static int dmatest_add_channel(struct dma_chan *chan)
	{
	struct dmatest_chan *dtc;
	struct dma_device *dma_dev = chan->device;
	unsigned int thread_count = 0;
	unsigned int cnt;

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

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

	if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask)) {
	cnt = dmatest_add_threads(dtc, DMA_MEMCPY);
	thread_count += cnt > 0 ? cnt : 0;
	}
	if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
	cnt = dmatest_add_threads(dtc, DMA_XOR);
	thread_count += cnt > 0 ? cnt : 0;
	}
	if (dma_has_cap(DMA_PQ, dma_dev->cap_mask)) {
	cnt = dmatest_add_threads(dtc, DMA_PQ);
	thread_count += cnt > 0 ?: 0;
	}

	pr_info("dmatest: Started %u threads using %s\n",
	thread_count, dma_chan_name(chan));

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

	return 0;
	}

	static bool filter(struct dma_chan chan, void param)
	{
	if (!dmatest_match_channel(chan) \|\| !dmatest_match_device(chan->device))
	return false;
	else
	return true;
	}

	static int __init dmatest_init(void)
	{
	dma_cap_mask_t mask;
	struct dma_chan *chan;
	int err = 0;

	dma_cap_zero(mask);
	dma_cap_set(DMA_MEMCPY, mask);
	for (;;) {
	chan = dma_request_channel(mask, filter, NULL);
	if (chan) {
	err = dmatest_add_channel(chan);
	if (err) {
	dma_release_channel(chan);
	break; /* add_channel failed, punt */
	}
	} else
	break; /* no more channels available */
	if (max_channels && nr_channels >= max_channels)
	break; /* we have all we need */
	}

	return err;
	}
	/* when compiled-in wait for drivers to load first */
	late_initcall(dmatest_init);

	static void __exit dmatest_exit(void)
	{
	struct dmatest_chan dtc, _dtc;
	struct dma_chan *chan;

	list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
	list_del(&dtc->node);
	chan = dtc->chan;
	dmatest_cleanup_channel(dtc);
	pr_debug("dmatest: dropped channel %s\n",
	dma_chan_name(chan));
	dma_release_channel(chan);
	}
	}
	module_exit(dmatest_exit);

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