/*
 * DMA Engine test module
 *
 * Copyright (C) 2007 Atmel Corporation
 * Copyright (C) 2013 Intel 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/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/freezer.h>
#include <linux/init.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/ctype.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>

static unsigned int test_buf_size = 16384;
module_param(test_buf_size, uint, S_IRUGO | S_IWUSR);
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 | S_IWUSR);
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 | S_IWUSR);
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 | S_IWUSR);
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 | S_IWUSR);
MODULE_PARM_DESC(max_channels,
                "Maximum number of channels to use (default: all)");

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

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

static int timeout = 3000;
module_param(timeout, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(timeout, "Transfer Timeout in msec (default: 3000), "
                 "Pass -1 for infinite timeout");

/* Maximum amount of mismatched bytes in buffer to print */
#define MAX_ERROR_COUNT         32

/*
 * 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

enum dmatest_error_type {
        DMATEST_ET_OK,
        DMATEST_ET_MAP_SRC,
        DMATEST_ET_MAP_DST,
        DMATEST_ET_PREP,
        DMATEST_ET_SUBMIT,
        DMATEST_ET_TIMEOUT,
        DMATEST_ET_DMA_ERROR,
        DMATEST_ET_DMA_IN_PROGRESS,
        DMATEST_ET_VERIFY,
        DMATEST_ET_VERIFY_BUF,
};

struct dmatest_verify_buffer {
        unsigned int    index;
        u8              expected;
        u8              actual;
};

struct dmatest_verify_result {
        unsigned int                    error_count;
        struct dmatest_verify_buffer    data[MAX_ERROR_COUNT];
        u8                              pattern;
        bool                            is_srcbuf;
};

struct dmatest_thread_result {
        struct list_head        node;
        unsigned int            n;
        unsigned int            src_off;
        unsigned int            dst_off;
        unsigned int            len;
        enum dmatest_error_type type;
        union {
                unsigned long                   data;
                dma_cookie_t                    cookie;
                enum dma_status                 status;
                int                             error;
                struct dmatest_verify_result    *vr;
        };
};

struct dmatest_result {
        struct list_head        node;
        char                    *name;
        struct list_head        results;
};

struct dmatest_info;

struct dmatest_thread {
        struct list_head        node;
        struct dmatest_info     *info;
        struct task_struct      *task;
        struct dma_chan         *chan;
        u8                      **srcs;
        u8                      **dsts;
        enum dma_transaction_type type;
        bool                    done;
};

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

/**
 * struct dmatest_params - test parameters.
 * @buf_size:           size of the memcpy test buffer
 * @channel:            bus ID of the channel to test
 * @device:             bus ID of the DMA Engine to test
 * @threads_per_chan:   number of threads to start per channel
 * @max_channels:       maximum number of channels to use
 * @iterations:         iterations before stopping test
 * @xor_sources:        number of xor source buffers
 * @pq_sources:         number of p+q source buffers
 * @timeout:            transfer timeout in msec, -1 for infinite timeout
 */
struct dmatest_params {
        unsigned int    buf_size;
        char            channel[20];
        char            device[20];
        unsigned int    threads_per_chan;
        unsigned int    max_channels;
        unsigned int    iterations;
        unsigned int    xor_sources;
        unsigned int    pq_sources;
        int             timeout;
};

/**
 * struct dmatest_info - test information.
 * @params:             test parameters
 * @lock:               access protection to the fields of this structure
 */
struct dmatest_info {
        /* Test parameters */
        struct dmatest_params   params;

        /* Internal state */
        struct list_head        channels;
        unsigned int            nr_channels;
        struct mutex            lock;

        /* debugfs related stuff */
        struct dentry           *root;

        /* Test results */
        struct list_head        results;
        struct mutex            results_lock;
};

static struct dmatest_info test_info;

static bool dmatest_match_channel(struct dmatest_params *params,
                struct dma_chan *chan)
{
        if (params->channel[0] == '\0')
                return true;
        return strcmp(dma_chan_name(chan), params->channel) == 0;
}

static bool dmatest_match_device(struct dmatest_params *params,
                struct dma_device *device)
{
        if (params->device[0] == '\0')
                return true;
        return strcmp(dev_name(device->dev), params->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 buf_size)
{
        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 < 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 buf_size)
{
        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 < buf_size; i++)
                        buf[i] = PATTERN_DST | (~i & PATTERN_COUNT_MASK);
        }
}

static unsigned int dmatest_verify(struct dmatest_verify_result *vr, 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;
        struct dmatest_verify_buffer *vb;

        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 < MAX_ERROR_COUNT && vr) {
                                        vb = &vr->data[error_count];
                                        vb->index = i;
                                        vb->expected = expected;
                                        vb->actual = actual;
                                }
                                error_count++;
                        }
                        counter++;
                }
        }

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

        return error_count;
}

/* poor man's completion - we want to use wait_event_freezable() on it */
struct dmatest_done {
        bool                    done;
        wait_queue_head_t       *wait;
};

static void dmatest_callback(void *arg)
{
        struct dmatest_done *done = arg;

        done->done = true;
        wake_up_all(done->wait);
}

static inline void unmap_src(struct device *dev, dma_addr_t *addr, size_t len,
                             unsigned int count)
{
        while (count--)
                dma_unmap_single(dev, addr[count], len, DMA_TO_DEVICE);
}

static inline void unmap_dst(struct device *dev, dma_addr_t *addr, size_t len,
                             unsigned int count)
{
        while (count--)
                dma_unmap_single(dev, addr[count], len, DMA_BIDIRECTIONAL);
}

static unsigned int min_odd(unsigned int x, unsigned int y)
{
        unsigned int val = min(x, y);

        return val % 2 ? val : val - 1;
}

static char *verify_result_get_one(struct dmatest_verify_result *vr,
                unsigned int i)
{
        struct dmatest_verify_buffer *vb = &vr->data[i];
        u8 diff = vb->actual ^ vr->pattern;
        static char buf[512];
        char *msg;

        if (vr->is_srcbuf)
                msg = "srcbuf overwritten!";
        else if ((vr->pattern & PATTERN_COPY)
                        && (diff & (PATTERN_COPY | PATTERN_OVERWRITE)))
                msg = "dstbuf not copied!";
        else if (diff & PATTERN_SRC)
                msg = "dstbuf was copied!";
        else
                msg = "dstbuf mismatch!";

        snprintf(buf, sizeof(buf) - 1, "%s [0x%x] Expected %02x, got %02x", msg,
                 vb->index, vb->expected, vb->actual);

        return buf;
}

static char *thread_result_get(const char *name,
                struct dmatest_thread_result *tr)
{
        static const char * const messages[] = {
                [DMATEST_ET_OK]                 = "No errors",
                [DMATEST_ET_MAP_SRC]            = "src mapping error",
                [DMATEST_ET_MAP_DST]            = "dst mapping error",
                [DMATEST_ET_PREP]               = "prep error",
                [DMATEST_ET_SUBMIT]             = "submit error",
                [DMATEST_ET_TIMEOUT]            = "test timed out",
                [DMATEST_ET_DMA_ERROR]          =
                        "got completion callback (DMA_ERROR)",
                [DMATEST_ET_DMA_IN_PROGRESS]    =
                        "got completion callback (DMA_IN_PROGRESS)",
                [DMATEST_ET_VERIFY]             = "errors",
                [DMATEST_ET_VERIFY_BUF]         = "verify errors",
        };
        static char buf[512];

        snprintf(buf, sizeof(buf) - 1,
                 "%s: #%u: %s with src_off=0x%x ""dst_off=0x%x len=0x%x (%lu)",
                 name, tr->n, messages[tr->type], tr->src_off, tr->dst_off,
                 tr->len, tr->data);

        return buf;
}

static int thread_result_add(struct dmatest_info *info,
                struct dmatest_result *r, enum dmatest_error_type type,
                unsigned int n, unsigned int src_off, unsigned int dst_off,
                unsigned int len, unsigned long data)
{
        struct dmatest_thread_result *tr;

        tr = kzalloc(sizeof(*tr), GFP_KERNEL);
        if (!tr)
                return -ENOMEM;

        tr->type = type;
        tr->n = n;
        tr->src_off = src_off;
        tr->dst_off = dst_off;
        tr->len = len;
        tr->data = data;

        mutex_lock(&info->results_lock);
        list_add_tail(&tr->node, &r->results);
        mutex_unlock(&info->results_lock);

        if (tr->type == DMATEST_ET_OK)
                pr_debug("%s\n", thread_result_get(r->name, tr));
        else
                pr_warn("%s\n", thread_result_get(r->name, tr));

        return 0;
}

static unsigned int verify_result_add(struct dmatest_info *info,
                struct dmatest_result *r, unsigned int n,
                unsigned int src_off, unsigned int dst_off, unsigned int len,
                u8 **bufs, int whence, unsigned int counter, u8 pattern,
                bool is_srcbuf)
{
        struct dmatest_verify_result *vr;
        unsigned int error_count;
        unsigned int buf_off = is_srcbuf ? src_off : dst_off;
        unsigned int start, end;

        if (whence < 0) {
                start = 0;
                end = buf_off;
        } else if (whence > 0) {
                start = buf_off + len;
                end = info->params.buf_size;
        } else {
                start = buf_off;
                end = buf_off + len;
        }

        vr = kmalloc(sizeof(*vr), GFP_KERNEL);
        if (!vr) {
                pr_warn("dmatest: No memory to store verify result\n");
                return dmatest_verify(NULL, bufs, start, end, counter, pattern,
                                      is_srcbuf);
        }

        vr->pattern = pattern;
        vr->is_srcbuf = is_srcbuf;

        error_count = dmatest_verify(vr, bufs, start, end, counter, pattern,
                                     is_srcbuf);
        if (error_count) {
                vr->error_count = error_count;
                thread_result_add(info, r, DMATEST_ET_VERIFY_BUF, n, src_off,
                                  dst_off, len, (unsigned long)vr);
                return error_count;
        }

        kfree(vr);
        return 0;
}

static void result_free(struct dmatest_info *info, const char *name)
{
        struct dmatest_result *r, *_r;

        mutex_lock(&info->results_lock);
        list_for_each_entry_safe(r, _r, &info->results, node) {
                struct dmatest_thread_result *tr, *_tr;

                if (name && strcmp(r->name, name))
                        continue;

                list_for_each_entry_safe(tr, _tr, &r->results, node) {
                        if (tr->type == DMATEST_ET_VERIFY_BUF)
                                kfree(tr->vr);
                        list_del(&tr->node);
                        kfree(tr);
                }

                kfree(r->name);
                list_del(&r->node);
                kfree(r);
        }

        mutex_unlock(&info->results_lock);
}

static struct dmatest_result *result_init(struct dmatest_info *info,
                const char *name)
{
        struct dmatest_result *r;

        r = kzalloc(sizeof(*r), GFP_KERNEL);
        if (r) {
                r->name = kstrdup(name, GFP_KERNEL);
                INIT_LIST_HEAD(&r->results);
                mutex_lock(&info->results_lock);
                list_add_tail(&r->node, &info->results);
                mutex_unlock(&info->results_lock);
        }
        return r;
}

/*
 * 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)
{
        DECLARE_WAIT_QUEUE_HEAD_ONSTACK(done_wait);
        struct dmatest_thread   *thread = data;
        struct dmatest_done     done = { .wait = &done_wait };
        struct dmatest_info     *info;
        struct dmatest_params   *params;
        struct dma_chan         *chan;
        struct dma_device       *dev;
        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 = NULL;
        int                     ret;
        int                     src_cnt;
        int                     dst_cnt;
        int                     i;
        struct dmatest_result   *result;

        thread_name = current->comm;
        set_freezable();

        ret = -ENOMEM;

        smp_rmb();
        info = thread->info;
        params = &info->params;
        chan = thread->chan;
        dev = chan->device;
        if (thread->type == DMA_MEMCPY)
                src_cnt = dst_cnt = 1;
        else if (thread->type == DMA_XOR) {
                /* force odd to ensure dst = src */
                src_cnt = min_odd(params->xor_sources | 1, dev->max_xor);
                dst_cnt = 1;
        } else if (thread->type == DMA_PQ) {
                /* force odd to ensure dst = src */
                src_cnt = min_odd(params->pq_sources | 1, dma_maxpq(dev, 0));
                dst_cnt = 2;

                pq_coefs = kmalloc(params->pq_sources+1, GFP_KERNEL);
                if (!pq_coefs)
                        goto err_thread_type;

                for (i = 0; i < src_cnt; i++)
                        pq_coefs[i] = 1;
        } else
                goto err_thread_type;

        result = result_init(info, thread_name);
        if (!result)
                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(params->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(params->buf_size, GFP_KERNEL);
                if (!thread->dsts[i])
                        goto err_dstbuf;
        }
        thread->dsts[i] = NULL;

        set_user_nice(current, 10);

        /*
         * src buffers are freed by the DMAEngine code with dma_unmap_single()
         * dst buffers are freed by ourselves below
         */
        flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT
              | DMA_COMPL_SKIP_DEST_UNMAP | DMA_COMPL_SRC_UNMAP_SINGLE;

        while (!kthread_should_stop()
               && !(params->iterations && total_tests >= params->iterations)) {
                struct dma_async_tx_descriptor *tx = NULL;
                dma_addr_t dma_srcs[src_cnt];
                dma_addr_t dma_dsts[dst_cnt];
                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 > params->buf_size) {
                        pr_err("%u-byte buffer too small for %d-byte alignment\n",
                               params->buf_size, 1 << align);
                        break;
                }

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

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

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

                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);
                        ret = dma_mapping_error(dev->dev, dma_srcs[i]);
                        if (ret) {
                                unmap_src(dev->dev, dma_srcs, len, i);
                                thread_result_add(info, result,
                                                  DMATEST_ET_MAP_SRC,
                                                  total_tests, src_off, dst_off,
                                                  len, ret);
                                failed_tests++;
                                continue;
                        }
                }
                /* 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],
                                                     params->buf_size,
                                                     DMA_BIDIRECTIONAL);
                        ret = dma_mapping_error(dev->dev, dma_dsts[i]);
                        if (ret) {
                                unmap_src(dev->dev, dma_srcs, len, src_cnt);
                                unmap_dst(dev->dev, dma_dsts, params->buf_size,
                                          i);
                                thread_result_add(info, result,
                                                  DMATEST_ET_MAP_DST,
                                                  total_tests, src_off, dst_off,
                                                  len, ret);
                                failed_tests++;
                                continue;
                        }
                }

                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, src_cnt,
                                                      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,
                                                     src_cnt, pq_coefs,
                                                     len, flags);
                }

                if (!tx) {
                        unmap_src(dev->dev, dma_srcs, len, src_cnt);
                        unmap_dst(dev->dev, dma_dsts, params->buf_size,
                                  dst_cnt);
                        thread_result_add(info, result, DMATEST_ET_PREP,
                                          total_tests, src_off, dst_off,
                                          len, 0);
                        msleep(100);
                        failed_tests++;
                        continue;
                }

                done.done = false;
                tx->callback = dmatest_callback;
                tx->callback_param = &done;
                cookie = tx->tx_submit(tx);

                if (dma_submit_error(cookie)) {
                        thread_result_add(info, result, DMATEST_ET_SUBMIT,
                                          total_tests, src_off, dst_off,
                                          len, cookie);
                        msleep(100);
                        failed_tests++;
                        continue;
                }
                dma_async_issue_pending(chan);

                wait_event_freezable_timeout(done_wait, done.done,
                                             msecs_to_jiffies(params->timeout));

                status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);

                if (!done.done) {
                        /*
                         * We're leaving the timed out dma operation with
                         * dangling pointer to done_wait.  To make this
                         * correct, we'll need to allocate wait_done for
                         * each test iteration and perform "who's gonna
                         * free it this time?" dancing.  For now, just
                         * leave it dangling.
                         */
                        thread_result_add(info, result, DMATEST_ET_TIMEOUT,
                                          total_tests, src_off, dst_off,
                                          len, 0);
                        failed_tests++;
                        continue;
                } else if (status != DMA_SUCCESS) {
                        enum dmatest_error_type type = (status == DMA_ERROR) ?
                                DMATEST_ET_DMA_ERROR : DMATEST_ET_DMA_IN_PROGRESS;
                        thread_result_add(info, result, type,
                                          total_tests, src_off, dst_off,
                                          len, status);
                        failed_tests++;
                        continue;
                }

                /* Unmap by myself (see DMA_COMPL_SKIP_DEST_UNMAP above) */
                unmap_dst(dev->dev, dma_dsts, params->buf_size, dst_cnt);

                error_count = 0;

                pr_debug("%s: verifying source buffer...\n", thread_name);
                error_count += verify_result_add(info, result, total_tests,
                                src_off, dst_off, len, thread->srcs, -1,
                                0, PATTERN_SRC, true);
                error_count += verify_result_add(info, result, total_tests,
                                src_off, dst_off, len, thread->srcs, 0,
                                src_off, PATTERN_SRC | PATTERN_COPY, true);
                error_count += verify_result_add(info, result, total_tests,
                                src_off, dst_off, len, thread->srcs, 1,
                                src_off + len, PATTERN_SRC, true);

                pr_debug("%s: verifying dest buffer...\n", thread_name);
                error_count += verify_result_add(info, result, total_tests,
                                src_off, dst_off, len, thread->dsts, -1,
                                0, PATTERN_DST, false);
                error_count += verify_result_add(info, result, total_tests,
                                src_off, dst_off, len, thread->dsts, 0,
                                src_off, PATTERN_SRC | PATTERN_COPY, false);
                error_count += verify_result_add(info, result, total_tests,
                                src_off, dst_off, len, thread->dsts, 1,
                                dst_off + len, PATTERN_DST, false);

                if (error_count) {
                        thread_result_add(info, result, DMATEST_ET_VERIFY,
                                          total_tests, src_off, dst_off,
                                          len, error_count);
                        failed_tests++;
                } else {
                        thread_result_add(info, result, DMATEST_ET_OK,
                                          total_tests, src_off, dst_off,
                                          len, 0);
                }
        }

        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:
        kfree(pq_coefs);
err_thread_type:
        pr_notice("%s: terminating after %u tests, %u failures (status %d)\n",
                        thread_name, total_tests, failed_tests, ret);

        /* terminate all transfers on specified channels */
        if (ret)
                dmaengine_terminate_all(chan);

        thread->done = true;

        if (params->iterations > 0)
                while (!kthread_should_stop()) {
                        DECLARE_WAIT_QUEUE_HEAD_ONSTACK(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);
        }

        /* terminate all transfers on specified channels */
        dmaengine_terminate_all(dtc->chan);

        kfree(dtc);
}

static int dmatest_add_threads(struct dmatest_info *info,
                struct dmatest_chan *dtc, enum dma_transaction_type type)
{
        struct dmatest_params *params = &info->params;
        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 < params->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->info = info;
                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 dmatest_info *info,
                struct dma_chan *chan)
{
        struct dmatest_chan     *dtc;
        struct dma_device       *dma_dev = chan->device;
        unsigned int            thread_count = 0;
        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(info, dtc, DMA_MEMCPY);
                thread_count += cnt > 0 ? cnt : 0;
        }
        if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
                cnt = dmatest_add_threads(info, dtc, DMA_XOR);
                thread_count += cnt > 0 ? cnt : 0;
        }
        if (dma_has_cap(DMA_PQ, dma_dev->cap_mask)) {
                cnt = dmatest_add_threads(info, dtc, DMA_PQ);
                thread_count += cnt > 0 ? cnt : 0;
        }

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

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

        return 0;
}

static bool filter(struct dma_chan *chan, void *param)
{
        struct dmatest_params *params = param;

        if (!dmatest_match_channel(params, chan) ||
            !dmatest_match_device(params, chan->device))
                return false;
        else
                return true;
}

static int __run_threaded_test(struct dmatest_info *info)
{
        dma_cap_mask_t mask;
        struct dma_chan *chan;
        struct dmatest_params *params = &info->params;
        int err = 0;

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

#ifndef MODULE
static int run_threaded_test(struct dmatest_info *info)
{
        int ret;

        mutex_lock(&info->lock);
        ret = __run_threaded_test(info);
        mutex_unlock(&info->lock);
        return ret;
}
#endif

static void __stop_threaded_test(struct dmatest_info *info)
{
        struct dmatest_chan *dtc, *_dtc;
        struct dma_chan *chan;

        list_for_each_entry_safe(dtc, _dtc, &info->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);
        }

        info->nr_channels = 0;
}

static void stop_threaded_test(struct dmatest_info *info)
{
        mutex_lock(&info->lock);
        __stop_threaded_test(info);
        mutex_unlock(&info->lock);
}

static int __restart_threaded_test(struct dmatest_info *info, bool run)
{
        struct dmatest_params *params = &info->params;

        /* Stop any running test first */
        __stop_threaded_test(info);

        if (run == false)
                return 0;

        /* Clear results from previous run */
        result_free(info, NULL);

        /* Copy test parameters */
        params->buf_size = test_buf_size;
        strlcpy(params->channel, strim(test_channel), sizeof(params->channel));
        strlcpy(params->device, strim(test_device), sizeof(params->device));
        params->threads_per_chan = threads_per_chan;
        params->max_channels = max_channels;
        params->iterations = iterations;
        params->xor_sources = xor_sources;
        params->pq_sources = pq_sources;
        params->timeout = timeout;

        /* Run test with new parameters */
        return __run_threaded_test(info);
}

static bool __is_threaded_test_run(struct dmatest_info *info)
{
        struct dmatest_chan *dtc;

        list_for_each_entry(dtc, &info->channels, node) {
                struct dmatest_thread *thread;

                list_for_each_entry(thread, &dtc->threads, node) {
                        if (!thread->done)
                                return true;
                }
        }

        return false;
}

static ssize_t dtf_read_run(struct file *file, char __user *user_buf,
                size_t count, loff_t *ppos)
{
        struct dmatest_info *info = file->private_data;
        char buf[3];

        mutex_lock(&info->lock);

        if (__is_threaded_test_run(info)) {
                buf[0] = 'Y';
        } else {
                __stop_threaded_test(info);
                buf[0] = 'N';
        }

        mutex_unlock(&info->lock);
        buf[1] = '\n';
        buf[2] = 0x00;
        return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}

static ssize_t dtf_write_run(struct file *file, const char __user *user_buf,
                size_t count, loff_t *ppos)
{
        struct dmatest_info *info = file->private_data;
        char buf[16];
        bool bv;
        int ret = 0;

        if (copy_from_user(buf, user_buf, min(count, (sizeof(buf) - 1))))
                return -EFAULT;

        if (strtobool(buf, &bv) == 0) {
                mutex_lock(&info->lock);

                if (__is_threaded_test_run(info))
                        ret = -EBUSY;
                else
                        ret = __restart_threaded_test(info, bv);

                mutex_unlock(&info->lock);
        }

        return ret ? ret : count;
}

static const struct file_operations dtf_run_fops = {
        .read   = dtf_read_run,
        .write  = dtf_write_run,
        .open   = simple_open,
        .llseek = default_llseek,
};

static int dtf_results_show(struct seq_file *sf, void *data)
{
        struct dmatest_info *info = sf->private;
        struct dmatest_result *result;
        struct dmatest_thread_result *tr;
        unsigned int i;

        mutex_lock(&info->results_lock);
        list_for_each_entry(result, &info->results, node) {
                list_for_each_entry(tr, &result->results, node) {
                        seq_printf(sf, "%s\n",
                                thread_result_get(result->name, tr));
                        if (tr->type == DMATEST_ET_VERIFY_BUF) {
                                for (i = 0; i < tr->vr->error_count; i++) {
                                        seq_printf(sf, "\t%s\n",
                                                verify_result_get_one(tr->vr, i));
                                }
                        }
                }
        }

        mutex_unlock(&info->results_lock);
        return 0;
}

static int dtf_results_open(struct inode *inode, struct file *file)
{
        return single_open(file, dtf_results_show, inode->i_private);
}

static const struct file_operations dtf_results_fops = {
        .open           = dtf_results_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int dmatest_register_dbgfs(struct dmatest_info *info)
{
        struct dentry *d;

        d = debugfs_create_dir("dmatest", NULL);
        if (IS_ERR(d))
                return PTR_ERR(d);
        if (!d)
                goto err_root;

        info->root = d;

        /* Run or stop threaded test */
        debugfs_create_file("run", S_IWUSR | S_IRUGO, info->root, info,
                            &dtf_run_fops);

        /* Results of test in progress */
        debugfs_create_file("results", S_IRUGO, info->root, info,
                            &dtf_results_fops);

        return 0;

err_root:
        pr_err("dmatest: Failed to initialize debugfs\n");
        return -ENOMEM;
}

static int __init dmatest_init(void)
{
        struct dmatest_info *info = &test_info;
        int ret;

        memset(info, 0, sizeof(*info));

        mutex_init(&info->lock);
        INIT_LIST_HEAD(&info->channels);

        mutex_init(&info->results_lock);
        INIT_LIST_HEAD(&info->results);

        ret = dmatest_register_dbgfs(info);
        if (ret)
                return ret;

#ifdef MODULE
        return 0;
#else
        return run_threaded_test(info);
#endif
}
/* when compiled-in wait for drivers to load first */
late_initcall(dmatest_init);

static void __exit dmatest_exit(void)
{
        struct dmatest_info *info = &test_info;

        debugfs_remove_recursive(info->root);
        stop_threaded_test(info);
        result_free(info, NULL);
}
module_exit(dmatest_exit);

MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
MODULE_LICENSE("GPL v2");