text: /*
   *      uvc_queue.c  --  USB Video Class driver - Buffers management
   *
   *      Copyright (C) 2005-2010
   *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
   *
   *      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/atomic.h>
  #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 <media/videobuf2-vmalloc.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 buffers are managed by videobuf2. The driver uses a mutex to protect
   * the videobuf2 queue operations by serializing calls to videobuf2 and a
   * spinlock to protect the IRQ queue that holds the buffers to be processed by
   * the driver.
   */
  
  /* -----------------------------------------------------------------------------
   * videobuf2 queue operations
   */
  
  static int uvc_queue_setup(struct vb2_queue *vq, const struct v4l2_format *fmt,
  			   unsigned int *nbuffers, unsigned int *nplanes,
  			   unsigned int sizes[], void *alloc_ctxs[])
  {
  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
  	struct uvc_streaming *stream =
  			container_of(queue, struct uvc_streaming, queue);
  
  	if (*nbuffers > UVC_MAX_VIDEO_BUFFERS)
  		*nbuffers = UVC_MAX_VIDEO_BUFFERS;
  
  	*nplanes = 1;
  
  	sizes[0] = stream->ctrl.dwMaxVideoFrameSize;
  
  	return 0;
  }
  
  static int uvc_buffer_prepare(struct vb2_buffer *vb)
  {
  	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
  	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
  
  	if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
  	    vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
  		uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
  		return -EINVAL;
  	}
  
  	if (unlikely(queue->flags & UVC_QUEUE_DISCONNECTED))
  		return -ENODEV;
  
  	buf->state = UVC_BUF_STATE_QUEUED;
  	buf->error = 0;
  	buf->mem = vb2_plane_vaddr(vb, 0);
  	buf->length = vb2_plane_size(vb, 0);
  	if (vb->v4l2_buf.type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
  		buf->bytesused = 0;
  	else
  		buf->bytesused = vb2_get_plane_payload(vb, 0);
  
  	return 0;
  }
  
  static void uvc_buffer_queue(struct vb2_buffer *vb)
  {
  	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
  	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
  	unsigned long flags;
  
  	spin_lock_irqsave(&queue->irqlock, flags);
  	if (likely(!(queue->flags & UVC_QUEUE_DISCONNECTED))) {
  		list_add_tail(&buf->queue, &queue->irqqueue);
  	} else {
  		/* If the device is disconnected return the buffer to userspace
  		 * directly. The next QBUF call will fail with -ENODEV.
  		 */
  		buf->state = UVC_BUF_STATE_ERROR;
  		vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
  	}
  
  	spin_unlock_irqrestore(&queue->irqlock, flags);
  }
  
  static int uvc_buffer_finish(struct vb2_buffer *vb)
  {
  	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
  	struct uvc_streaming *stream =
  			container_of(queue, struct uvc_streaming, queue);
  	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
  
  	uvc_video_clock_update(stream, &vb->v4l2_buf, buf);
  	return 0;
  }
  
  static void uvc_wait_prepare(struct vb2_queue *vq)
  {
  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
  
  	mutex_unlock(&queue->mutex);
  }
  
  static void uvc_wait_finish(struct vb2_queue *vq)
  {
  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
  
  	mutex_lock(&queue->mutex);
  }
  
  static struct vb2_ops uvc_queue_qops = {
  	.queue_setup = uvc_queue_setup,
  	.buf_prepare = uvc_buffer_prepare,
  	.buf_queue = uvc_buffer_queue,
  	.buf_finish = uvc_buffer_finish,
  	.wait_prepare = uvc_wait_prepare,
  	.wait_finish = uvc_wait_finish,
  };
  
  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
  		    int drop_corrupted)
  {
  	int ret;
  
  	queue->queue.type = type;
  	queue->queue.io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;
  	queue->queue.drv_priv = queue;
  	queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
  	queue->queue.ops = &uvc_queue_qops;
  	queue->queue.mem_ops = &vb2_vmalloc_memops;
  	queue->queue.timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
  	ret = vb2_queue_init(&queue->queue);
  	if (ret)
  		return ret;
  
  	mutex_init(&queue->mutex);
  	spin_lock_init(&queue->irqlock);
  	INIT_LIST_HEAD(&queue->irqqueue);
  	queue->flags = drop_corrupted ? UVC_QUEUE_DROP_CORRUPTED : 0;
  
  	return 0;
  }
  
  /* -----------------------------------------------------------------------------
   * V4L2 queue operations
   */
  
  int uvc_alloc_buffers(struct uvc_video_queue *queue,
  		      struct v4l2_requestbuffers *rb)
  {
  	int ret;
  
  	mutex_lock(&queue->mutex);
  	ret = vb2_reqbufs(&queue->queue, rb);
  	mutex_unlock(&queue->mutex);
  
  	return ret ? ret : rb->count;
  }
  
  void uvc_free_buffers(struct uvc_video_queue *queue)
  {
  	mutex_lock(&queue->mutex);
  	vb2_queue_release(&queue->queue);
  	mutex_unlock(&queue->mutex);
  }
  
  int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
  {
  	int ret;
  
  	mutex_lock(&queue->mutex);
  	ret = vb2_querybuf(&queue->queue, buf);
  	mutex_unlock(&queue->mutex);
  
  	return ret;
  }
  
  int uvc_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
  {
  	int ret;
  
  	mutex_lock(&queue->mutex);
  	ret = vb2_qbuf(&queue->queue, buf);
  	mutex_unlock(&queue->mutex);
  
  	return ret;
  }
  
  int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
  		       int nonblocking)
  {
  	int ret;
  
  	mutex_lock(&queue->mutex);
  	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
  	mutex_unlock(&queue->mutex);
  
  	return ret;
  }
  
  int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
  {
  	int ret;
  
  	mutex_lock(&queue->mutex);
  	ret = vb2_mmap(&queue->queue, vma);
  	mutex_unlock(&queue->mutex);
  
  	return ret;
  }
  
  #ifndef CONFIG_MMU
  unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
  		unsigned long pgoff)
  {
  	unsigned long ret;
  
  	mutex_lock(&queue->mutex);
  	ret = vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
  	mutex_unlock(&queue->mutex);
  	return ret;
  }
  #endif
  
  unsigned int uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
  			    poll_table *wait)
  {
  	unsigned int ret;
  
  	mutex_lock(&queue->mutex);
  	ret = vb2_poll(&queue->queue, file, wait);
  	mutex_unlock(&queue->mutex);
  
  	return ret;
  }
  
  /* -----------------------------------------------------------------------------
   *
   */
  
  /*
   * Check if buffers have been allocated.
   */
  int uvc_queue_allocated(struct uvc_video_queue *queue)
  {
  	int allocated;
  
  	mutex_lock(&queue->mutex);
  	allocated = vb2_is_busy(&queue->queue);
  	mutex_unlock(&queue->mutex);
  
  	return allocated;
  }
  
  /*
   * 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 returns -EBUSY if the queue is already enabled.
   *
   * 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 long flags;
  	int ret;
  
  	mutex_lock(&queue->mutex);
  	if (enable) {
  		ret = vb2_streamon(&queue->queue, queue->queue.type);
  		if (ret < 0)
  			goto done;
  
  		queue->buf_used = 0;
  	} else {
  		ret = vb2_streamoff(&queue->queue, queue->queue.type);
  		if (ret < 0)
  			goto done;
  
  		spin_lock_irqsave(&queue->irqlock, flags);
  		INIT_LIST_HEAD(&queue->irqqueue);
  		spin_unlock_irqrestore(&queue->irqlock, flags);
  	}
  
  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;
  		vb2_buffer_done(&buf->buf, VB2_BUF_STATE_ERROR);
  	}
  	/* This must be protected by the irqlock spinlock to avoid race
  	 * conditions between uvc_buffer_queue 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_QUEUE_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_CORRUPTED) && buf->error) {
  		buf->error = 0;
  		buf->state = UVC_BUF_STATE_QUEUED;
  		buf->bytesused = 0;
  		vb2_set_plane_payload(&buf->buf, 0, 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->state = buf->error ? VB2_BUF_STATE_ERROR : UVC_BUF_STATE_DONE;
  	vb2_set_plane_payload(&buf->buf, 0, buf->bytesused);
  	vb2_buffer_done(&buf->buf, VB2_BUF_STATE_DONE);
  
  	return nextbuf;
  }
  