/*
 * 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.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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>

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[32];
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");

static bool noverify;
module_param(noverify, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(noverify, "Disable random data setup and verification");

static bool verbose;
module_param(verbose, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(verbose, "Enable \"success\" result messages (default: off)");

/**
 * 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[32];
        unsigned int    threads_per_chan;
        unsigned int    max_channels;
        unsigned int    iterations;
        unsigned int    xor_sources;
        unsigned int    pq_sources;
        int             timeout;
        bool            noverify;
};

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

        /* Internal state */
        struct list_head        channels;
        unsigned int            nr_channels;
        struct mutex            lock;
        bool                    did_init;
} test_info = {
        .channels = LIST_HEAD_INIT(test_info.channels),
        .lock = __MUTEX_INITIALIZER(test_info.lock),
};

static int dmatest_run_set(const char *val, const struct kernel_param *kp);
static int dmatest_run_get(char *val, const struct kernel_param *kp);
static const struct kernel_param_ops run_ops = {
        .set = dmatest_run_set,
        .get = dmatest_run_get,
};
static bool dmatest_run;
module_param_cb(run, &run_ops, &dmatest_run, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(run, "Run the test (default: false)");

/* 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

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;
};

static DECLARE_WAIT_QUEUE_HEAD(thread_wait);
static bool wait;

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 int dmatest_wait_get(char *val, const struct kernel_param *kp)
{
        struct dmatest_info *info = &test_info;
        struct dmatest_params *params = &info->params;

        if (params->iterations)
                wait_event(thread_wait, !is_threaded_test_run(info));
        wait = true;
        return param_get_bool(val, kp);
}

static const struct kernel_param_ops wait_ops = {
        .get = dmatest_wait_get,
        .set = param_set_bool,
};
module_param_cb(wait, &wait_ops, &wait, S_IRUGO);
MODULE_PARM_DESC(wait, "Wait for tests to complete (default: false)");

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;

        prandom_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 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_warn("%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_warn("%s: dstbuf[0x%x] not copied! Expected %02x, got %02x\n",
                        thread_name, index, expected, actual);
        else if (diff & PATTERN_SRC)
                pr_warn("%s: dstbuf[0x%x] was copied! Expected %02x, got %02x\n",
                        thread_name, index, expected, actual);
        else
                pr_warn("%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 < MAX_ERROR_COUNT)
                                        dmatest_mismatch(actual, pattern, i,
                                                         counter, is_srcbuf);
                                error_count++;
                        }
                        counter++;
                }
        }

        if (error_count > MAX_ERROR_COUNT)
                pr_warn("%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 unsigned int min_odd(unsigned int x, unsigned int y)
{
        unsigned int val = min(x, y);

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

static void result(const char *err, unsigned int n, unsigned int src_off,
                   unsigned int dst_off, unsigned int len, unsigned long data)
{
        pr_info("%s: result #%u: '%s' with src_off=0x%x dst_off=0x%x len=0x%x (%lu)\n",
                current->comm, n, err, src_off, dst_off, len, data);
}

static void dbg_result(const char *err, unsigned int n, unsigned int src_off,
                       unsigned int dst_off, unsigned int len,
                       unsigned long data)
{
        pr_debug("%s: result #%u: '%s' with src_off=0x%x dst_off=0x%x len=0x%x (%lu)\n",
                 current->comm, n, err, src_off, dst_off, len, data);
}

#define verbose_result(err, n, src_off, dst_off, len, data) ({  \
        if (verbose)                                            \
                result(err, n, src_off, dst_off, len, data);    \
        else                                                    \
                dbg_result(err, n, src_off, dst_off, len, data);\
})

static unsigned long long dmatest_persec(s64 runtime, unsigned int val)
{
        unsigned long long per_sec = 1000000;

        if (runtime <= 0)
                return 0;

        /* drop precision until runtime is 32-bits */
        while (runtime > UINT_MAX) {
                runtime >>= 1;
                per_sec <<= 1;
        }

        per_sec *= val;
        do_div(per_sec, runtime);
        return per_sec;
}

static unsigned long long dmatest_KBs(s64 runtime, unsigned long long len)
{
        return dmatest_persec(runtime, len >> 10);
}

/*
 * 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;
        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;
        ktime_t                 ktime;
        s64                     runtime = 0;
        unsigned long long      total_len = 0;

        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;

        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 and dst buffers are freed by ourselves below
         */
        flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;

        ktime = ktime_get();
        while (!kthread_should_stop()
               && !(params->iterations && total_tests >= params->iterations)) {
                struct dma_async_tx_descriptor *tx = NULL;
                struct dmaengine_unmap_data *um;
                dma_addr_t srcs[src_cnt];
                dma_addr_t *dsts;
                unsigned int src_off, dst_off, len;
                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;
                }

                if (params->noverify)
                        len = params->buf_size;
                else
                        len = dmatest_random() % params->buf_size + 1;

                len = (len >> align) << align;
                if (!len)
                        len = 1 << align;

                total_len += len;

                if (params->noverify) {
                        src_off = 0;
                        dst_off = 0;
                } else {
                        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);
                }

                um = dmaengine_get_unmap_data(dev->dev, src_cnt+dst_cnt,
                                              GFP_KERNEL);
                if (!um) {
                        failed_tests++;
                        result("unmap data NULL", total_tests,
                               src_off, dst_off, len, ret);
                        continue;
                }

                um->len = params->buf_size;
                for (i = 0; i < src_cnt; i++) {
                        void *buf = thread->srcs[i];
                        struct page *pg = virt_to_page(buf);
                        unsigned pg_off = (unsigned long) buf & ~PAGE_MASK;

                        um->addr[i] = dma_map_page(dev->dev, pg, pg_off,
                                                   um->len, DMA_TO_DEVICE);
                        srcs[i] = um->addr[i] + src_off;
                        ret = dma_mapping_error(dev->dev, um->addr[i]);
                        if (ret) {
                                dmaengine_unmap_put(um);
                                result("src mapping error", total_tests,
                                       src_off, dst_off, len, ret);
                                failed_tests++;
                                continue;
                        }
                        um->to_cnt++;
                }
                /* map with DMA_BIDIRECTIONAL to force writeback/invalidate */
                dsts = &um->addr[src_cnt];
                for (i = 0; i < dst_cnt; i++) {
                        void *buf = thread->dsts[i];
                        struct page *pg = virt_to_page(buf);
                        unsigned pg_off = (unsigned long) buf & ~PAGE_MASK;

                        dsts[i] = dma_map_page(dev->dev, pg, pg_off, um->len,
                                               DMA_BIDIRECTIONAL);
                        ret = dma_mapping_error(dev->dev, dsts[i]);
                        if (ret) {
                                dmaengine_unmap_put(um);
                                result("dst mapping error", total_tests,
                                       src_off, dst_off, len, ret);
                                failed_tests++;
                                continue;
                        }
                        um->bidi_cnt++;
                }

                if (thread->type == DMA_MEMCPY)
                        tx = dev->device_prep_dma_memcpy(chan,
                                                         dsts[0] + dst_off,
                                                         srcs[0], len, flags);
                else if (thread->type == DMA_XOR)
                        tx = dev->device_prep_dma_xor(chan,
                                                      dsts[0] + dst_off,
                                                      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] = dsts[i] + dst_off;
                        tx = dev->device_prep_dma_pq(chan, dma_pq, srcs,
                                                     src_cnt, pq_coefs,
                                                     len, flags);
                }

                if (!tx) {
                        dmaengine_unmap_put(um);
                        result("prep error", total_tests, src_off,
                               dst_off, len, ret);
                        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)) {
                        dmaengine_unmap_put(um);
                        result("submit error", total_tests, src_off,
                               dst_off, len, ret);
                        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.
                         */
                        dmaengine_unmap_put(um);
                        result("test timed out", total_tests, src_off, dst_off,
                               len, 0);
                        failed_tests++;
                        continue;
                } else if (status != DMA_COMPLETE) {
                        dmaengine_unmap_put(um);
                        result(status == DMA_ERROR ?
                               "completion error status" :
                               "completion busy status", total_tests, src_off,
                               dst_off, len, ret);
                        failed_tests++;
                        continue;
                }

                dmaengine_unmap_put(um);

                if (params->noverify) {
                        verbose_result("test passed", total_tests, src_off,
                                       dst_off, len, 0);
                        continue;
                }

                pr_debug("%s: verifying source buffer...\n", current->comm);
                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,
                                params->buf_size, src_off + len,
                                PATTERN_SRC, true);

                pr_debug("%s: verifying dest buffer...\n", current->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,
                                params->buf_size, dst_off + len,
                                PATTERN_DST, false);

                if (error_count) {
                        result("data error", total_tests, src_off, dst_off,
                               len, error_count);
                        failed_tests++;
                } else {
                        verbose_result("test passed", total_tests, src_off,
                                       dst_off, len, 0);
                }
        }
        runtime = ktime_us_delta(ktime_get(), ktime);

        ret = 0;
err_dstbuf:
        for (i = 0; thread->dsts[i]; i++)
                kfree(thread->dsts[i]);
        kfree(thread->dsts);
err_dsts:
err_srcbuf:
        for (i = 0; thread->srcs[i]; i++)
                kfree(thread->srcs[i]);
        kfree(thread->srcs);
err_srcs:
        kfree(pq_coefs);
err_thread_type:
        pr_info("%s: summary %u tests, %u failures %llu iops %llu KB/s (%d)\n",
                current->comm, total_tests, failed_tests,
                dmatest_persec(runtime, total_tests),
                dmatest_KBs(runtime, total_len), ret);

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

        thread->done = true;
        wake_up(&thread_wait);

        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("thread %s exited with status %d\n",
                         thread->task->comm, ret);
                list_del(&thread->node);
                put_task_struct(thread->task);
                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_warn("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_create(dmatest_func, thread, "%s-%s%u",
                                dma_chan_name(chan), op, i);
                if (IS_ERR(thread->task)) {
                        pr_warn("Failed to create thread %s-%s%u\n",
                                dma_chan_name(chan), op, i);
                        kfree(thread);
                        break;
                }

                /* srcbuf and dstbuf are allocated by the thread itself */
                get_task_struct(thread->task);
                list_add_tail(&thread->node, &dtc->threads);
                wake_up_process(thread->task);
        }

        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_warn("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("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 void request_channels(struct dmatest_info *info,
                             enum dma_transaction_type type)
{
        dma_cap_mask_t mask;

        dma_cap_zero(mask);
        dma_cap_set(type, mask);
        for (;;) {
                struct dmatest_params *params = &info->params;
                struct dma_chan *chan;

                chan = dma_request_channel(mask, filter, params);
                if (chan) {
                        if (dmatest_add_channel(info, chan)) {
                                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 */
        }
}

static void run_threaded_test(struct dmatest_info *info)
{
        struct dmatest_params *params = &info->params;

        /* 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;
        params->noverify = noverify;

        request_channels(info, DMA_MEMCPY);
        request_channels(info, DMA_XOR);
        request_channels(info, DMA_PQ);
}

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("dropped channel %s\n", dma_chan_name(chan));
                dma_release_channel(chan);
        }

        info->nr_channels = 0;
}

static void restart_threaded_test(struct dmatest_info *info, bool run)
{
        /* we might be called early to set run=, defer running until all
         * parameters have been evaluated
         */
        if (!info->did_init)
                return;

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

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

static int dmatest_run_get(char *val, const struct kernel_param *kp)
{
        struct dmatest_info *info = &test_info;

        mutex_lock(&info->lock);
        if (is_threaded_test_run(info)) {
                dmatest_run = true;
        } else {
                stop_threaded_test(info);
                dmatest_run = false;
        }
        mutex_unlock(&info->lock);

        return param_get_bool(val, kp);
}

static int dmatest_run_set(const char *val, const struct kernel_param *kp)
{
        struct dmatest_info *info = &test_info;
        int ret;

        mutex_lock(&info->lock);
        ret = param_set_bool(val, kp);
        if (ret) {
                mutex_unlock(&info->lock);
                return ret;
        }

        if (is_threaded_test_run(info))
                ret = -EBUSY;
        else if (dmatest_run)
                restart_threaded_test(info, dmatest_run);

        mutex_unlock(&info->lock);

        return ret;
}

static int __init dmatest_init(void)
{
        struct dmatest_info *info = &test_info;
        struct dmatest_params *params = &info->params;

        if (dmatest_run) {
                mutex_lock(&info->lock);
                run_threaded_test(info);
                mutex_unlock(&info->lock);
        }

        if (params->iterations && wait)
                wait_event(thread_wait, !is_threaded_test_run(info));

        /* module parameters are stable, inittime tests are started,
         * let userspace take over 'run' control
         */
        info->did_init = true;

        return 0;
}
/* 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;

        mutex_lock(&info->lock);
        stop_threaded_test(info);
        mutex_unlock(&info->lock);
}
module_exit(dmatest_exit);

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