ispqueue.c

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/*
 * ispqueue.c
 *
 * TI OMAP3 ISP - Video buffers queue handling
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Contacts: Laurent Pinchart <[email protected]>
 *       Sakari Ailus <[email protected]>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <asm/cacheflush.h>
#include <linux/dma-mapping.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include "ispqueue.h"

/* -----------------------------------------------------------------------------
 * Video buffers management
 */

/*
 * isp_video_buffer_cache_sync - Keep the buffers coherent between CPU and ISP
 *
 * The typical operation required here is Cache Invalidation across
 * the (user space) buffer address range. And this _must_ be done
 * at QBUF stage (and *only* at QBUF).
 *
 * We try to use optimal cache invalidation function:
 * - dmac_map_area:
 *    - used when the number of pages are _low_.
 *    - it becomes quite slow as the number of pages increase.
 *       - for 648x492 viewfinder (150 pages) it takes 1.3 ms.
 *       - for 5 Mpix buffer (2491 pages) it takes between 25-50 ms.
 *
 * - flush_cache_all:
 *    - used when the number of pages are _high_.
 *    - time taken in the range of 500-900 us.
 *    - has a higher penalty but, as whole dcache + icache is invalidated
 */
/*
 * FIXME: dmac_inv_range crashes randomly on the user space buffer
 *        address. Fall back to flush_cache_all for now.
 */
#define ISP_CACHE_FLUSH_PAGES_MAX       0

static void isp_video_buffer_cache_sync(struct isp_video_buffer *buf)
{
    if (buf->skip_cache)
        return;

    if (buf->vbuf.m.userptr == 0 || buf->npages == 0 ||
        buf->npages > ISP_CACHE_FLUSH_PAGES_MAX)
        flush_cache_all();
    else {
        dmac_map_area((void *)buf->vbuf.m.userptr, buf->vbuf.length,
                  DMA_FROM_DEVICE);
        outer_inv_range(buf->vbuf.m.userptr,
                buf->vbuf.m.userptr + buf->vbuf.length);
    }
}

/*
 * isp_video_buffer_lock_vma - Prevent VMAs from being unmapped
 *
 * Lock the VMAs underlying the given buffer into memory. This avoids the
 * userspace buffer mapping from being swapped out, making VIPT cache handling
 * easier.
 *
 * Note that the pages will not be freed as the buffers have been locked to
 * memory using by a call to get_user_pages(), but the userspace mapping could
 * still disappear if the VMAs are not locked. This is caused by the memory
 * management code trying to be as lock-less as possible, which results in the
 * userspace mapping manager not finding out that the pages are locked under
 * some conditions.
 */
static int isp_video_buffer_lock_vma(struct isp_video_buffer *buf, int lock)
{
    struct vm_area_struct *vma;
    unsigned long start;
    unsigned long end;
    int ret = 0;

    if (buf->vbuf.memory == V4L2_MEMORY_MMAP)
        return 0;

    /* We can be called from workqueue context if the current task dies to
     * unlock the VMAs. In that case there's no current memory management
     * context so unlocking can't be performed, but the VMAs have been or
     * are getting destroyed anyway so it doesn't really matter.
     */
    if (!current || !current->mm)
        return lock ? -EINVAL : 0;

    start = buf->vbuf.m.userptr;
    end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

    down_write(&current->mm->mmap_sem);
    spin_lock(&current->mm->page_table_lock);

    do {
        vma = find_vma(current->mm, start);
        if (vma == NULL) {
            ret = -EFAULT;
            goto out;
        }

        if (lock)
            vma->vm_flags |= VM_LOCKED;
        else
            vma->vm_flags &= ~VM_LOCKED;

        start = vma->vm_end + 1;
    } while (vma->vm_end < end);

    if (lock)
        buf->vm_flags |= VM_LOCKED;
    else
        buf->vm_flags &= ~VM_LOCKED;

out:
    spin_unlock(&current->mm->page_table_lock);
    up_write(&current->mm->mmap_sem);
    return ret;
}

/*
 * isp_video_buffer_sglist_kernel - Build a scatter list for a vmalloc'ed buffer
 *
 * Iterate over the vmalloc'ed area and create a scatter list entry for every
 * page.
 */
static int isp_video_buffer_sglist_kernel(struct isp_video_buffer *buf)
{
    struct scatterlist *sglist;
    unsigned int npages;
    unsigned int i;
    void *addr;

    addr = buf->vaddr;
    npages = PAGE_ALIGN(buf->vbuf.length) >> PAGE_SHIFT;

    sglist = vmalloc(npages * sizeof(*sglist));
    if (sglist == NULL)
        return -ENOMEM;

    sg_init_table(sglist, npages);

    for (i = 0; i < npages; ++i, addr += PAGE_SIZE) {
        struct page *page = vmalloc_to_page(addr);

        if (page == NULL || PageHighMem(page)) {
            vfree(sglist);
            return -EINVAL;
        }

        sg_set_page(&sglist[i], page, PAGE_SIZE, 0);
    }

    buf->sglen = npages;
    buf->sglist = sglist;

    return 0;
}

/*
 * isp_video_buffer_sglist_user - Build a scatter list for a userspace buffer
 *
 * Walk the buffer pages list and create a 1:1 mapping to a scatter list.
 */
static int isp_video_buffer_sglist_user(struct isp_video_buffer *buf)
{
    struct scatterlist *sglist;
    unsigned int offset = buf->offset;
    unsigned int i;

    sglist = vmalloc(buf->npages * sizeof(*sglist));
    if (sglist == NULL)
        return -ENOMEM;

    sg_init_table(sglist, buf->npages);

    for (i = 0; i < buf->npages; ++i) {
        if (PageHighMem(buf->pages[i])) {
            vfree(sglist);
            return -EINVAL;
        }

        sg_set_page(&sglist[i], buf->pages[i], PAGE_SIZE - offset,
                offset);
        offset = 0;
    }

    buf->sglen = buf->npages;
    buf->sglist = sglist;

    return 0;
}

/*
 * isp_video_buffer_sglist_pfnmap - Build a scatter list for a VM_PFNMAP buffer
 *
 * Create a scatter list of physically contiguous pages starting at the buffer
 * memory physical address.
 */
static int isp_video_buffer_sglist_pfnmap(struct isp_video_buffer *buf)
{
    struct scatterlist *sglist;
    unsigned int offset = buf->offset;
    unsigned long pfn = buf->paddr >> PAGE_SHIFT;
    unsigned int i;

    sglist = vmalloc(buf->npages * sizeof(*sglist));
    if (sglist == NULL)
        return -ENOMEM;

    sg_init_table(sglist, buf->npages);

    for (i = 0; i < buf->npages; ++i, ++pfn) {
        sg_set_page(&sglist[i], pfn_to_page(pfn), PAGE_SIZE - offset,
                offset);
        /* PFNMAP buffers will not get DMA-mapped, set the DMA address
         * manually.
         */
        sg_dma_address(&sglist[i]) = (pfn << PAGE_SHIFT) + offset;
        offset = 0;
    }

    buf->sglen = buf->npages;
    buf->sglist = sglist;

    return 0;
}

/*
 * isp_video_buffer_cleanup - Release pages for a userspace VMA.
 *
 * Release pages locked by a call isp_video_buffer_prepare_user and free the
 * pages table.
 */
static void isp_video_buffer_cleanup(struct isp_video_buffer *buf)
{
    enum dma_data_direction direction;
    unsigned int i;

    if (buf->queue->ops->buffer_cleanup)
        buf->queue->ops->buffer_cleanup(buf);

    if (!(buf->vm_flags & VM_PFNMAP)) {
        direction = buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE
              ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
        dma_unmap_sg(buf->queue->dev, buf->sglist, buf->sglen,
                 direction);
    }

    vfree(buf->sglist);
    buf->sglist = NULL;
    buf->sglen = 0;

    if (buf->pages != NULL) {
        isp_video_buffer_lock_vma(buf, 0);

        for (i = 0; i < buf->npages; ++i)
            page_cache_release(buf->pages[i]);

        vfree(buf->pages);
        buf->pages = NULL;
    }

    buf->npages = 0;
    buf->skip_cache = false;
}

/*
 * isp_video_buffer_prepare_user - Pin userspace VMA pages to memory.
 *
 * This function creates a list of pages for a userspace VMA. The number of
 * pages is first computed based on the buffer size, and pages are then
 * retrieved by a call to get_user_pages.
 *
 * Pages are pinned to memory by get_user_pages, making them available for DMA
 * transfers. However, due to memory management optimization, it seems the
 * get_user_pages doesn't guarantee that the pinned pages will not be written
 * to swap and removed from the userspace mapping(s). When this happens, a page
 * fault can be generated when accessing those unmapped pages.
 *
 * If the fault is triggered by a page table walk caused by VIPT cache
 * management operations, the page fault handler might oops if the MM semaphore
 * is held, as it can't handle kernel page faults in that case. To fix that, a
 * fixup entry needs to be added to the cache management code, or the userspace
 * VMA must be locked to avoid removing pages from the userspace mapping in the
 * first place.
 *
 * If the number of pages retrieved is smaller than the number required by the
 * buffer size, the function returns -EFAULT.
 */
static int isp_video_buffer_prepare_user(struct isp_video_buffer *buf)
{
    unsigned long data;
    unsigned int first;
    unsigned int last;
    int ret;

    data = buf->vbuf.m.userptr;
    first = (data & PAGE_MASK) >> PAGE_SHIFT;
    last = ((data + buf->vbuf.length - 1) & PAGE_MASK) >> PAGE_SHIFT;

    buf->offset = data & ~PAGE_MASK;
    buf->npages = last - first + 1;
    buf->pages = vmalloc(buf->npages * sizeof(buf->pages[0]));
    if (buf->pages == NULL)
        return -ENOMEM;

    down_read(&current->mm->mmap_sem);
    ret = get_user_pages(current, current->mm, data & PAGE_MASK,
                 buf->npages,
                 buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE, 0,
                 buf->pages, NULL);
    up_read(&current->mm->mmap_sem);

    if (ret != buf->npages) {
        buf->npages = ret < 0 ? 0 : ret;
        isp_video_buffer_cleanup(buf);
        return -EFAULT;
    }

    ret = isp_video_buffer_lock_vma(buf, 1);
    if (ret < 0)
        isp_video_buffer_cleanup(buf);

    return ret;
}

/*
 * isp_video_buffer_prepare_pfnmap - Validate a VM_PFNMAP userspace buffer
 *
 * Userspace VM_PFNMAP buffers are supported only if they are contiguous in
 * memory and if they span a single VMA.
 *
 * Return 0 if the buffer is valid, or -EFAULT otherwise.
 */
static int isp_video_buffer_prepare_pfnmap(struct isp_video_buffer *buf)
{
    struct vm_area_struct *vma;
    unsigned long prev_pfn;
    unsigned long this_pfn;
    unsigned long start;
    unsigned long end;
    dma_addr_t pa;
    int ret = -EFAULT;

    start = buf->vbuf.m.userptr;
    end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

    buf->offset = start & ~PAGE_MASK;
    buf->npages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
    buf->pages = NULL;

    down_read(&current->mm->mmap_sem);
    vma = find_vma(current->mm, start);
    if (vma == NULL || vma->vm_end < end)
        goto done;

    for (prev_pfn = 0; start <= end; start += PAGE_SIZE) {
        ret = follow_pfn(vma, start, &this_pfn);
        if (ret)
            goto done;

        if (prev_pfn == 0)
            pa = this_pfn << PAGE_SHIFT;
        else if (this_pfn != prev_pfn + 1) {
            ret = -EFAULT;
            goto done;
        }

        prev_pfn = this_pfn;
    }

    buf->paddr = pa + buf->offset;
    ret = 0;

done:
    up_read(&current->mm->mmap_sem);
    return ret;
}

/*
 * isp_video_buffer_prepare_vm_flags - Get VMA flags for a userspace address
 *
 * This function locates the VMAs for the buffer's userspace address and checks
 * that their flags match. The only flag that we need to care for at the moment
 * is VM_PFNMAP.
 *
 * The buffer vm_flags field is set to the first VMA flags.
 *
 * Return -EFAULT if no VMA can be found for part of the buffer, or if the VMAs
 * have incompatible flags.
 */
static int isp_video_buffer_prepare_vm_flags(struct isp_video_buffer *buf)
{
    struct vm_area_struct *vma;
    pgprot_t vm_page_prot;
    unsigned long start;
    unsigned long end;
    int ret = -EFAULT;

    start = buf->vbuf.m.userptr;
    end = buf->vbuf.m.userptr + buf->vbuf.length - 1;

    down_read(&current->mm->mmap_sem);

    do {
        vma = find_vma(current->mm, start);
        if (vma == NULL)
            goto done;

        if (start == buf->vbuf.m.userptr) {
            buf->vm_flags = vma->vm_flags;
            vm_page_prot = vma->vm_page_prot;
        }

        if ((buf->vm_flags ^ vma->vm_flags) & VM_PFNMAP)
            goto done;

        if (vm_page_prot != vma->vm_page_prot)
            goto done;

        start = vma->vm_end + 1;
    } while (vma->vm_end < end);

    /* Skip cache management to enhance performances for non-cached or
     * write-combining buffers.
     */
    if (vm_page_prot == pgprot_noncached(vm_page_prot) ||
        vm_page_prot == pgprot_writecombine(vm_page_prot))
        buf->skip_cache = true;

    ret = 0;

done:
    up_read(&current->mm->mmap_sem);
    return ret;
}

/*
 * isp_video_buffer_prepare - Make a buffer ready for operation
 *
 * Preparing a buffer involves:
 *
 * - validating VMAs (userspace buffers only)
 * - locking pages and VMAs into memory (userspace buffers only)
 * - building page and scatter-gather lists
 * - mapping buffers for DMA operation
 * - performing driver-specific preparation
 *
 * The function must be called in userspace context with a valid mm context
 * (this excludes cleanup paths such as sys_close when the userspace process
 * segfaults).
 */
static int isp_video_buffer_prepare(struct isp_video_buffer *buf)
{
    enum dma_data_direction direction;
    int ret;

    switch (buf->vbuf.memory) {
    case V4L2_MEMORY_MMAP:
        ret = isp_video_buffer_sglist_kernel(buf);
        break;

    case V4L2_MEMORY_USERPTR:
        ret = isp_video_buffer_prepare_vm_flags(buf);
        if (ret < 0)
            return ret;

        if (buf->vm_flags & VM_PFNMAP) {
            ret = isp_video_buffer_prepare_pfnmap(buf);
            if (ret < 0)
                return ret;

            ret = isp_video_buffer_sglist_pfnmap(buf);
        } else {
            ret = isp_video_buffer_prepare_user(buf);
            if (ret < 0)
                return ret;

            ret = isp_video_buffer_sglist_user(buf);
        }
        break;

    default:
        return -EINVAL;
    }

    if (ret < 0)
        goto done;

    if (!(buf->vm_flags & VM_PFNMAP)) {
        direction = buf->vbuf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE
              ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
        ret = dma_map_sg(buf->queue->dev, buf->sglist, buf->sglen,
                 direction);
        if (ret != buf->sglen) {
            ret = -EFAULT;
            goto done;
        }
    }

    if (buf->queue->ops->buffer_prepare)
        ret = buf->queue->ops->buffer_prepare(buf);

done:
    if (ret < 0) {
        isp_video_buffer_cleanup(buf);
        return ret;
    }

    return ret;
}

/*
 * isp_video_queue_query - Query the status of a given buffer
 *
 * Locking: must be called with the queue lock held.
 */
static void isp_video_buffer_query(struct isp_video_buffer *buf,
                   struct v4l2_buffer *vbuf)
{
    memcpy(vbuf, &buf->vbuf, sizeof(*vbuf));

    if (buf->vma_use_count)
        vbuf->flags |= V4L2_BUF_FLAG_MAPPED;

    switch (buf->state) {
    case ISP_BUF_STATE_ERROR:
        vbuf->flags |= V4L2_BUF_FLAG_ERROR;
    case ISP_BUF_STATE_DONE:
        vbuf->flags |= V4L2_BUF_FLAG_DONE;
    case ISP_BUF_STATE_QUEUED:
    case ISP_BUF_STATE_ACTIVE:
        vbuf->flags |= V4L2_BUF_FLAG_QUEUED;
        break;
    case ISP_BUF_STATE_IDLE:
    default:
        break;
    }
}

/*
 * isp_video_buffer_wait - Wait for a buffer to be ready
 *
 * In non-blocking mode, return immediately with 0 if the buffer is ready or
 * -EAGAIN if the buffer is in the QUEUED or ACTIVE state.
 *
 * In blocking mode, wait (interruptibly but with no timeout) on the buffer wait
 * queue using the same condition.
 */
static int isp_video_buffer_wait(struct isp_video_buffer *buf, int nonblocking)
{
    if (nonblocking) {
        return (buf->state != ISP_BUF_STATE_QUEUED &&
            buf->state != ISP_BUF_STATE_ACTIVE)
            ? 0 : -EAGAIN;
    }

    return wait_event_interruptible(buf->wait,
        buf->state != ISP_BUF_STATE_QUEUED &&
        buf->state != ISP_BUF_STATE_ACTIVE);
}

/* -----------------------------------------------------------------------------
 * Queue management
 */

/*
 * isp_video_queue_free - Free video buffers memory
 *
 * Buffers can only be freed if the queue isn't streaming and if no buffer is
 * mapped to userspace. Return -EBUSY if those conditions aren't statisfied.
 *
 * This function must be called with the queue lock held.
 */
static int isp_video_queue_free(struct isp_video_queue *queue)
{
    unsigned int i;

    if (queue->streaming)
        return -EBUSY;

    for (i = 0; i < queue->count; ++i) {
        if (queue->buffers[i]->vma_use_count != 0)
            return -EBUSY;
    }

    for (i = 0; i < queue->count; ++i) {
        struct isp_video_buffer *buf = queue->buffers[i];

        isp_video_buffer_cleanup(buf);

        vfree(buf->vaddr);
        buf->vaddr = NULL;

        kfree(buf);
        queue->buffers[i] = NULL;
    }

    INIT_LIST_HEAD(&queue->queue);
    queue->count = 0;
    return 0;
}

/*
 * isp_video_queue_alloc - Allocate video buffers memory
 *
 * This function must be called with the queue lock held.
 */
static int isp_video_queue_alloc(struct isp_video_queue *queue,
                 unsigned int nbuffers,
                 unsigned int size, enum v4l2_memory memory)
{
    struct isp_video_buffer *buf;
    unsigned int i;
    void *mem;
    int ret;

    /* Start by freeing the buffers. */
    ret = isp_video_queue_free(queue);
    if (ret < 0)
        return ret;

    /* Bail out if no buffers should be allocated. */
    if (nbuffers == 0)
        return 0;

    /* Initialize the allocated buffers. */
    for (i = 0; i < nbuffers; ++i) {
        buf = kzalloc(queue->bufsize, GFP_KERNEL);
        if (buf == NULL)
            break;

        if (memory == V4L2_MEMORY_MMAP) {
            /* Allocate video buffers memory for mmap mode. Align
             * the size to the page size.
             */
            mem = vmalloc_32_user(PAGE_ALIGN(size));
            if (mem == NULL) {
                kfree(buf);
                break;
            }

            buf->vbuf.m.offset = i * PAGE_ALIGN(size);
            buf->vaddr = mem;
        }

        buf->vbuf.index = i;
        buf->vbuf.length = size;
        buf->vbuf.type = queue->type;
        buf->vbuf.field = V4L2_FIELD_NONE;
        buf->vbuf.memory = memory;

        buf->queue = queue;
        init_waitqueue_head(&buf->wait);

        queue->buffers[i] = buf;
    }

    if (i == 0)
        return -ENOMEM;

    queue->count = i;
    return nbuffers;
}

int omap3isp_video_queue_cleanup(struct isp_video_queue *queue)
{
    return isp_video_queue_free(queue);
}

int omap3isp_video_queue_init(struct isp_video_queue *queue,
                  enum v4l2_buf_type type,
                  const struct isp_video_queue_operations *ops,
                  struct device *dev, unsigned int bufsize)
{
    INIT_LIST_HEAD(&queue->queue);
    mutex_init(&queue->lock);
    spin_lock_init(&queue->irqlock);

    queue->type = type;
    queue->ops = ops;
    queue->dev = dev;
    queue->bufsize = bufsize;

    return 0;
}

/* -----------------------------------------------------------------------------
 * V4L2 operations
 */

int omap3isp_video_queue_reqbufs(struct isp_video_queue *queue,
                 struct v4l2_requestbuffers *rb)
{
    unsigned int nbuffers = rb->count;
    unsigned int size;
    int ret;

    if (rb->type != queue->type)
        return -EINVAL;

    queue->ops->queue_prepare(queue, &nbuffers, &size);
    if (size == 0)
        return -EINVAL;

    nbuffers = min_t(unsigned int, nbuffers, ISP_VIDEO_MAX_BUFFERS);

    mutex_lock(&queue->lock);

    ret = isp_video_queue_alloc(queue, nbuffers, size, rb->memory);
    if (ret < 0)
        goto done;

    rb->count = ret;
    ret = 0;

done:
    mutex_unlock(&queue->lock);
    return ret;
}

int omap3isp_video_queue_querybuf(struct isp_video_queue *queue,
                  struct v4l2_buffer *vbuf)
{
    struct isp_video_buffer *buf;
    int ret = 0;

    if (vbuf->type != queue->type)
        return -EINVAL;

    mutex_lock(&queue->lock);

    if (vbuf->index >= queue->count) {
        ret = -EINVAL;
        goto done;
    }

    buf = queue->buffers[vbuf->index];
    isp_video_buffer_query(buf, vbuf);

done:
    mutex_unlock(&queue->lock);
    return ret;
}

int omap3isp_video_queue_qbuf(struct isp_video_queue *queue,
                  struct v4l2_buffer *vbuf)
{
    struct isp_video_buffer *buf;
    unsigned long flags;
    int ret = -EINVAL;

    if (vbuf->type != queue->type)
        goto done;

    mutex_lock(&queue->lock);

    if (vbuf->index >= queue->count)
        goto done;

    buf = queue->buffers[vbuf->index];

    if (vbuf->memory != buf->vbuf.memory)
        goto done;

    if (buf->state != ISP_BUF_STATE_IDLE)
        goto done;

    if (vbuf->memory == V4L2_MEMORY_USERPTR &&
        vbuf->length < buf->vbuf.length)
        goto done;

    if (vbuf->memory == V4L2_MEMORY_USERPTR &&
        vbuf->m.userptr != buf->vbuf.m.userptr) {
        isp_video_buffer_cleanup(buf);
        buf->vbuf.m.userptr = vbuf->m.userptr;
        buf->prepared = 0;
    }

    if (!buf->prepared) {
        ret = isp_video_buffer_prepare(buf);
        if (ret < 0)
            goto done;
        buf->prepared = 1;
    }

    isp_video_buffer_cache_sync(buf);

    buf->state = ISP_BUF_STATE_QUEUED;
    list_add_tail(&buf->stream, &queue->queue);

    if (queue->streaming) {
        spin_lock_irqsave(&queue->irqlock, flags);
        queue->ops->buffer_queue(buf);
        spin_unlock_irqrestore(&queue->irqlock, flags);
    }

    ret = 0;

done:
    mutex_unlock(&queue->lock);
    return ret;
}

int omap3isp_video_queue_dqbuf(struct isp_video_queue *queue,
                   struct v4l2_buffer *vbuf, int nonblocking)
{
    struct isp_video_buffer *buf;
    int ret;

    if (vbuf->type != queue->type)
        return -EINVAL;

    mutex_lock(&queue->lock);

    if (list_empty(&queue->queue)) {
        ret = -EINVAL;
        goto done;
    }

    buf = list_first_entry(&queue->queue, struct isp_video_buffer, stream);
    ret = isp_video_buffer_wait(buf, nonblocking);
    if (ret < 0)
        goto done;

    list_del(&buf->stream);

    isp_video_buffer_query(buf, vbuf);
    buf->state = ISP_BUF_STATE_IDLE;
    vbuf->flags &= ~V4L2_BUF_FLAG_QUEUED;

done:
    mutex_unlock(&queue->lock);
    return ret;
}

int omap3isp_video_queue_streamon(struct isp_video_queue *queue)
{
    struct isp_video_buffer *buf;
    unsigned long flags;

    mutex_lock(&queue->lock);

    if (queue->streaming)
        goto done;

    queue->streaming = 1;

    spin_lock_irqsave(&queue->irqlock, flags);
    list_for_each_entry(buf, &queue->queue, stream)
        queue->ops->buffer_queue(buf);
    spin_unlock_irqrestore(&queue->irqlock, flags);

done:
    mutex_unlock(&queue->lock);
    return 0;
}

void omap3isp_video_queue_streamoff(struct isp_video_queue *queue)
{
    struct isp_video_buffer *buf;
    unsigned long flags;
    unsigned int i;

    mutex_lock(&queue->lock);

    if (!queue->streaming)
        goto done;

    queue->streaming = 0;

    spin_lock_irqsave(&queue->irqlock, flags);
    for (i = 0; i < queue->count; ++i) {
        buf = queue->buffers[i];

        if (buf->state == ISP_BUF_STATE_ACTIVE)
            wake_up(&buf->wait);

        buf->state = ISP_BUF_STATE_IDLE;
    }
    spin_unlock_irqrestore(&queue->irqlock, flags);

    INIT_LIST_HEAD(&queue->queue);

done:
    mutex_unlock(&queue->lock);
}

void omap3isp_video_queue_discard_done(struct isp_video_queue *queue)
{
    struct isp_video_buffer *buf;
    unsigned int i;

    mutex_lock(&queue->lock);

    if (!queue->streaming)
        goto done;

    for (i = 0; i < queue->count; ++i) {
        buf = queue->buffers[i];

        if (buf->state == ISP_BUF_STATE_DONE)
            buf->state = ISP_BUF_STATE_ERROR;
    }

done:
    mutex_unlock(&queue->lock);
}

static void isp_video_queue_vm_open(struct vm_area_struct *vma)
{
    struct isp_video_buffer *buf = vma->vm_private_data;

    buf->vma_use_count++;
}

static void isp_video_queue_vm_close(struct vm_area_struct *vma)
{
    struct isp_video_buffer *buf = vma->vm_private_data;

    buf->vma_use_count--;
}

static const struct vm_operations_struct isp_video_queue_vm_ops = {
    .open = isp_video_queue_vm_open,
    .close = isp_video_queue_vm_close,
};

int omap3isp_video_queue_mmap(struct isp_video_queue *queue,
             struct vm_area_struct *vma)
{
    struct isp_video_buffer *uninitialized_var(buf);
    unsigned long size;
    unsigned int i;
    int ret = 0;

    mutex_lock(&queue->lock);

    for (i = 0; i < queue->count; ++i) {
        buf = queue->buffers[i];
        if ((buf->vbuf.m.offset >> PAGE_SHIFT) == vma->vm_pgoff)
            break;
    }

    if (i == queue->count) {
        ret = -EINVAL;
        goto done;
    }

    size = vma->vm_end - vma->vm_start;

    if (buf->vbuf.memory != V4L2_MEMORY_MMAP ||
        size != PAGE_ALIGN(buf->vbuf.length)) {
        ret = -EINVAL;
        goto done;
    }

    ret = remap_vmalloc_range(vma, buf->vaddr, 0);
    if (ret < 0)
        goto done;

    vma->vm_ops = &isp_video_queue_vm_ops;
    vma->vm_private_data = buf;
    isp_video_queue_vm_open(vma);

done:
    mutex_unlock(&queue->lock);
    return ret;
}

unsigned int omap3isp_video_queue_poll(struct isp_video_queue *queue,
                       struct file *file, poll_table *wait)
{
    struct isp_video_buffer *buf;
    unsigned int mask = 0;

    mutex_lock(&queue->lock);
    if (list_empty(&queue->queue)) {
        mask |= POLLERR;
        goto done;
    }
    buf = list_first_entry(&queue->queue, struct isp_video_buffer, stream);

    poll_wait(file, &buf->wait, wait);
    if (buf->state == ISP_BUF_STATE_DONE ||
        buf->state == ISP_BUF_STATE_ERROR) {
        if (queue->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
            mask |= POLLIN | POLLRDNORM;
        else
            mask |= POLLOUT | POLLWRNORM;
    }

done:
    mutex_unlock(&queue->lock);
    return mask;
}