/*
* uvc_queue.c -- USB Video Class driver - Buffers management
*
* Copyright (C) 2005-2009
* Laurent Pinchart (laurent.pinchart@skynet.be)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/videodev2.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>
#include <asm/atomic.h>
#include "uvcvideo.h"
/* ------------------------------------------------------------------------
* Video buffers queue management.
*
* Video queues is initialized by uvc_queue_init(). The function performs
* basic initialization of the uvc_video_queue struct and never fails.
*
* Video buffer allocation and freeing are performed by uvc_alloc_buffers and
* uvc_free_buffers respectively. The former acquires the video queue lock,
* while the later must be called with the lock held (so that allocation can
* free previously allocated buffers). Trying to free buffers that are mapped
* to user space will return -EBUSY.
*
* Video buffers are managed using two queues. However, unlike most USB video
* drivers that use an in queue and an out queue, we use a main queue to hold
* all queued buffers (both 'empty' and 'done' buffers), and an irq queue to
* hold empty buffers. This design (copied from video-buf) minimizes locking
* in interrupt, as only one queue is shared between interrupt and user
* contexts.
*
* Use cases
* ---------
*
* Unless stated otherwise, all operations that modify the irq buffers queue
* are protected by the irq spinlock.
*
* 1. The user queues the buffers, starts streaming and dequeues a buffer.
*
* The buffers are added to the main and irq queues. Both operations are
* protected by the queue lock, and the later is protected by the irq
* spinlock as well.
*
* The completion handler fetches a buffer from the irq queue and fills it
* with video data. If no buffer is available (irq queue empty), the handler
* returns immediately.
*
* When the buffer is full, the completion handler removes it from the irq
* queue, marks it as ready (UVC_BUF_STATE_DONE) and wakes its wait queue.
* At that point, any process waiting on the buffer will be woken up. If a
* process tries to dequeue a buffer after it has been marked ready, the
* dequeing will succeed immediately.
*
* 2. Buffers are queued, user is waiting on a buffer and the device gets
* disconnected.
*
* When the device is disconnected, the kernel calls the completion handler
* with an appropriate status code. The handler marks all buffers in the
* irq queue as being erroneous (UVC_BUF_STATE_ERROR) and wakes them up so
* that any process waiting on a buffer gets woken up.
*
* Waking up up the first buffer on the irq list is not enough, as the
* process waiting on the buffer might restart the dequeue operation
* immediately.
*
*/
void uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
{
mutex_init(&queue->mutex);
spin_lock_init(&queue->irqlock);
INIT_LIST_HEAD(&queue->mainqueue);
INIT_LIST_HEAD(&queue->irqqueue);
queue->type = type;
}
/*
* Allocate the video buffers.
*
* Pages are reserved to make sure they will not be swapped, as they will be
* filled in the URB completion handler.
*
* Buffers will be individually mapped, so they must all be page aligned.
*/
int uvc_alloc_buffers(struct uvc_video_queue *queue, unsigned int nbuffers,
unsigned int buflength)
{
unsigned int bufsize = PAGE_ALIGN(buflength);
unsigned int i;
void *mem = NULL;
int ret;
if (nbuffers > UVC_MAX_VIDEO_BUFFERS)
nbuffers = UVC_MAX_VIDEO_BUFFERS;
mutex_lock(&queue->mutex);
if ((ret = uvc_free_buffers(queue)) < 0)
goto done;
/* Bail out if no buffers should be allocated. */
if (nbuffers == 0)
goto done;
/* Decrement the number of buffers until allocation succeeds. */
for (; nbuffers > 0; --nbuffers) {
mem = vmalloc_32(nbuffers * bufsize);
if (mem != NULL)
break;
}
if (mem == NULL) {
ret = -ENOMEM;
goto done;
}
for (i = 0; i < nbuffers; ++i) {
memset(&queue->buffer[i], 0, sizeof queue->buffer[i]);
queue->buffer[i].buf.index = i;
queue->buffer[i].buf.m.offset = i * bufsize;
queue->buffer[i].buf.length = buflength;
queue->buffer[i].buf.type = queue->type;
queue->buffer[i].buf.sequence = 0;
queue->buffer[i].buf.field = V4L2_FIELD_NONE;
queue->buffer[i].buf.memory = V4L2_MEMORY_MMAP;
queue->buffer[i].buf.flags = 0;
init_waitqueue_head(&queue->buffer[i].wait);
}
queue->mem = mem;
queue->count = nbuffers;
queue->buf_size = bufsize;
ret = nbuffers;
done:
mutex_unlock(&queue->mutex);
return ret;
}
/*
* Free the video buffers.
*
* This function must be called with the queue lock held.
*/
int uvc_free_buffers(struct uvc_video_queue *queue)
{
unsigned int i;
for (i = 0; i < queue->count; ++i) {
if (queue->buffer[i].vma_use_count != 0)
return -EBUSY;
}
if (queue->count) {
vfree(queue->mem);
queue->count = 0;
}
return 0;
}
/*
* Check if buffers have been allocated.
*/
int uvc_queue_allocated(struct uvc_video_queue *queue)
{
int allocated;
mutex_lock(&queue->mutex);
allocated = queue->count != 0;
mutex_unlock(&queue->mutex);
return allocated;
}
static void __uvc_query_buffer(struct uvc_buffer *buf,
struct v4l2_buffer *v4l2_buf)
{
memcpy(v4l2_buf, &buf->buf, sizeof *v4l2_buf);
if (buf->vma_use_count)
v4l2_buf->flags |= V4L2_BUF_FLAG_MAPPED;
switch (buf->state) {
case UVC_BUF_STATE_ERROR:
case UVC_BUF_STATE_DONE:
v4l2_buf->flags |= V4L2_BUF_FLAG_DONE;
break;
case UVC_BUF_STATE_QUEUED:
case UVC_BUF_STATE_ACTIVE:
v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED;
break;
case UVC_BUF_STATE_IDLE:
default:
break;
}
}
int uvc_query_buffer(struct uvc_video_queue *queue,
struct v4l2_buffer *v4l2_buf)
{
int ret = 0;
mutex_lock(&queue->mutex);
if (v4l2_buf->index >= queue->count) {
ret = -EINVAL;
goto done;
}
__uvc_query_buffer(&queue->buffer[v4l2_buf->index], v4l2_buf);
done:
mutex_unlock(&queue->mutex);
return ret;
}
/*
* Queue a video buffer. Attempting to queue a buffer that has already been
* queued will return -EINVAL.
*/
int uvc_queue_buffer(struct uvc_video_queue *queue,
struct v4l2_buffer *v4l2_buf)
{
struct uvc_buffer *buf;
unsigned long flags;
int ret = 0;
uvc_trace(UVC_TRACE_CAPTURE, "Queuing buffer %u.\n", v4l2_buf->index);
if (v4l2_buf->type != queue->type ||
v4l2_buf->memory != V4L2_MEMORY_MMAP) {
uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) "
"and/or memory (%u).\n", v4l2_buf->type,
v4l2_buf->memory);
return -EINVAL;
}
mutex_lock(&queue->mutex);
if (v4l2_buf->index >= queue->count) {
uvc_trace(UVC_TRACE_CAPTURE, "[E] Out of range index.\n");
ret = -EINVAL;
goto done;
}
buf = &queue->buffer[v4l2_buf->index];
if (buf->state != UVC_BUF_STATE_IDLE) {
uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state "
"(%u).\n", buf->state);
ret = -EINVAL;
goto done;
}
if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
v4l2_buf->bytesused > buf->buf.length) {
uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
ret = -EINVAL;
goto done;
}
spin_lock_irqsave(&queue->irqlock, flags);
if (queue->flags & UVC_QUEUE_DISCONNECTED) {
spin_unlock_irqrestore(&queue->irqlock, flags);
ret = -ENODEV;
goto done;
}
buf->state = UVC_BUF_STATE_QUEUED;
if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
buf->buf.bytesused = 0;
else
buf->buf.bytesused = v4l2_buf->bytesused;
list_add_tail(&buf->stream, &queue->mainqueue);
list_add_tail(&buf->queue, &queue->irqqueue);
spin_unlock_irqrestore(&queue->irqlock, flags);
done:
mutex_unlock(&queue->mutex);
return ret;
}
static int uvc_queue_waiton(struct uvc_buffer *buf, int nonblocking)
{
if (nonblocking) {
return (buf->state != UVC_BUF_STATE_QUEUED &&
buf->state != UVC_BUF_STATE_ACTIVE)
? 0 : -EAGAIN;
}
return wait_event_interruptible(buf->wait,
buf->state != UVC_BUF_STATE_QUEUED &&
buf->state != UVC_BUF_STATE_ACTIVE);
}
/*
* Dequeue a video buffer. If nonblocking is false, block until a buffer is
* available.
*/
int uvc_dequeue_buffer(struct uvc_video_queue *queue,
struct v4l2_buffer *v4l2_buf, int nonblocking)
{
struct uvc_buffer *buf;
int ret = 0;
if (v4l2_buf->type != queue->type ||
v4l2_buf->memory != V4L2_MEMORY_MMAP) {
uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) "
"and/or memory (%u).\n", v4l2_buf->type,
v4l2_buf->memory);
return -EINVAL;
}
mutex_lock(&queue->mutex);
if (list_empty(&queue->mainqueue)) {
uvc_trace(UVC_TRACE_CAPTURE, "[E] Empty buffer queue.\n");
ret = -EINVAL;
goto done;
}
buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream);
if ((ret = uvc_queue_waiton(buf, nonblocking)) < 0)
goto done;
uvc_trace(UVC_TRACE_CAPTURE, "Dequeuing buffer %u (%u, %u bytes).\n",
buf->buf.index, buf->state, buf->buf.bytesused);
switch (buf->state) {
case UVC_BUF_STATE_ERROR:
uvc_trace(UVC_TRACE_CAPTURE, "[W] Corrupted data "
"(transmission error).\n");
ret = -EIO;
case UVC_BUF_STATE_DONE:
buf->state = UVC_BUF_STATE_IDLE;
break;
case UVC_BUF_STATE_IDLE:
case UVC_BUF_STATE_QUEUED:
case UVC_BUF_STATE_ACTIVE:
default:
uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state %u "
"(driver bug?).\n", buf->state);
ret = -EINVAL;
goto done;
}
list_del(&buf->stream);
__uvc_query_buffer(buf, v4l2_buf);
done:
mutex_unlock(&queue->mutex);
return ret;
}
/*
* Poll the video queue.
*
* This function implements video queue polling and is intended to be used by
* the device poll handler.
*/
unsigned int uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
poll_table *wait)
{
struct uvc_buffer *buf;
unsigned int mask = 0;
mutex_lock(&queue->mutex);
if (list_empty(&queue->mainqueue)) {
mask |= POLLERR;
goto done;
}
buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream);
poll_wait(file, &buf->wait, wait);
if (buf->state == UVC_BUF_STATE_DONE ||
buf->state == UVC_BUF_STATE_ERROR)
mask |= POLLIN | POLLRDNORM;
done:
mutex_unlock(&queue->mutex);
return mask;
}
/*
* Enable or disable the video buffers queue.
*
* The queue must be enabled before starting video acquisition and must be
* disabled after stopping it. This ensures that the video buffers queue
* state can be properly initialized before buffers are accessed from the
* interrupt handler.
*
* Enabling the video queue initializes parameters (such as sequence number,
* sync pattern, ...). If the queue is already enabled, return -EBUSY.
*
* Disabling the video queue cancels the queue and removes all buffers from
* the main queue.
*
* This function can't be called from interrupt context. Use
* uvc_queue_cancel() instead.
*/
int uvc_queue_enable(struct uvc_video_queue *queue, int enable)
{
unsigned int i;
int ret = 0;
mutex_lock(&queue->mutex);
if (enable) {
if (uvc_queue_streaming(queue)) {
ret = -EBUSY;
goto done;
}
queue->sequence = 0;
queue->flags |= UVC_QUEUE_STREAMING;
queue->buf_used = 0;
} else {
uvc_queue_cancel(queue, 0);
INIT_LIST_HEAD(&queue->mainqueue);
for (i = 0; i < queue->count; ++i)
queue->buffer[i].state = UVC_BUF_STATE_IDLE;
queue->flags &= ~UVC_QUEUE_STREAMING;
}
done:
mutex_unlock(&queue->mutex);
return ret;
}
/*
* Cancel the video buffers queue.
*
* Cancelling the queue marks all buffers on the irq queue as erroneous,
* wakes them up and removes them from the queue.
*
* If the disconnect parameter is set, further calls to uvc_queue_buffer will
* fail with -ENODEV.
*
* This function acquires the irq spinlock and can be called from interrupt
* context.
*/
void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect)
{
struct uvc_buffer *buf;
unsigned long flags;
spin_lock_irqsave(&queue->irqlock, flags);
while (!list_empty(&queue->irqqueue)) {
buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
queue);
list_del(&buf->queue);
buf->state = UVC_BUF_STATE_ERROR;
wake_up(&buf->wait);
}
/* This must be protected by the irqlock spinlock to avoid race
* conditions between uvc_queue_buffer and the disconnection event that
* could result in an interruptible wait in uvc_dequeue_buffer. Do not
* blindly replace this logic by checking for the UVC_DEV_DISCONNECTED
* state outside the queue code.
*/
if (disconnect)
queue->flags |= UVC_QUEUE_DISCONNECTED;
spin_unlock_irqrestore(&queue->irqlock, flags);
}
struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
struct uvc_buffer *buf)
{
struct uvc_buffer *nextbuf;
unsigned long flags;
if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&
buf->buf.length != buf->buf.bytesused) {
buf->state = UVC_BUF_STATE_QUEUED;
buf->buf.bytesused = 0;
return buf;
}
spin_lock_irqsave(&queue->irqlock, flags);
list_del(&buf->queue);
if (!list_empty(&queue->irqqueue))
nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
queue);
else
nextbuf = NULL;
spin_unlock_irqrestore(&queue->irqlock, flags);
buf->buf.sequence = queue->sequence++;
do_gettimeofday(&buf->buf.timestamp);
wake_up(&buf->wait);
return nextbuf;
}
