uvc_video.c

linux camera下的uvc driver驱动源码

			return;
		}

		video->bulk.header_size = ret;
		memcpy(video->bulk.header, mem, video->bulk.header_size);

		mem += ret;
		len -= ret;
	}

	/* The buffer queue might have been cancelled while a bulk transfer
	 * was in progress, so we can reach here with buf equal to NULL. Make
	 * sure buf is never dereferenced if NULL.
	 */

	/* Process video data. */
	if (!video->bulk.skip_payload && buf != NULL)
		uvc_video_decode_data(video, buf, mem, len);

	/* Detect the payload end by a URB smaller than the maximum size (or
	 * a payload size equal to the maximum) and process the header again.
	 */
	if (urb->actual_length < urb->transfer_buffer_length ||
	    video->bulk.payload_size >= video->bulk.max_payload_size) {
		if (!video->bulk.skip_payload && buf != NULL) {
			uvc_video_decode_end(video, buf, video->bulk.header,
				video->bulk.header_size);
			if (buf->state == UVC_BUF_STATE_DONE ||
			    buf->state == UVC_BUF_STATE_ERROR)
				buf = uvc_queue_next_buffer(&video->queue, buf);
		}

		video->bulk.header_size = 0;
		video->bulk.skip_payload = 0;
		video->bulk.payload_size = 0;
	}
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
static void uvc_video_complete(struct urb *urb, struct pt_regs *regs)
#else
static void uvc_video_complete(struct urb *urb)
#endif
{
	struct uvc_video_device *video = urb->context;
	struct uvc_video_queue *queue = &video->queue;
	struct uvc_buffer *buf = NULL;
	unsigned long flags;
	int ret;

	switch (urb->status) {
	case 0:
		break;

	default:
		uvc_printk(KERN_WARNING, "Non-zero status (%d) in video "
			"completion handler.\n", urb->status);

	case -ENOENT:		/* usb_kill_urb() called. */
		if (queue->frozen)
			return;

	case -ECONNRESET:	/* usb_unlink_urb() called. */
	case -ESHUTDOWN:	/* The endpoint is being disabled. */
		uvc_queue_cancel(queue);
		return;
	}

	spin_lock_irqsave(&queue->irqlock, flags);
	if (!list_empty(&queue->irqqueue))
		buf = list_first_entry(&queue->irqqueue, struct uvc_buffer, queue);
	spin_unlock_irqrestore(&queue->irqlock, flags);

	video->decode(urb, video, buf);

	if ((ret = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
		uvc_printk(KERN_ERR, "Failed to resubmit video URB (%d).\n",
			ret);
        }
}

/*
 * Uninitialize isochronous/bulk URBs and free transfer buffers.
 */
static void uvc_uninit_video(struct uvc_video_device *video)
{
	struct urb *urb;
	unsigned int i;

	for (i = 0; i < UVC_URBS; ++i) {
		if ((urb = video->urb[i]) == NULL)
			continue;

		usb_kill_urb(urb);
		/* urb->transfer_buffer_length is not touched by USB core, so
		 * we can use it here as the buffer length.
		 */
		if (video->urb_buffer[i]) {
			usb_buffer_free(video->dev->udev,
				urb->transfer_buffer_length,
				video->urb_buffer[i], urb->transfer_dma);
			video->urb_buffer[i] = NULL;
		}

		usb_free_urb(urb);
		video->urb[i] = NULL;
	}
}

/*
 * Initialize isochronous URBs and allocate transfer buffers. The packet size
 * is given by the endpoint.
 */
static int uvc_init_video_isoc(struct uvc_video_device *video, struct usb_host_endpoint *ep)
{
	struct urb *urb;
	unsigned int npackets, i, j;
	__u16 psize;
	__u32 size;

	/* Compute the number of isochronous packets to allocate by dividing
	 * the maximum video frame size by the packet size. Limit the result
	 * to UVC_MAX_ISO_PACKETS.
	 */
	psize = le16_to_cpu(ep->desc.wMaxPacketSize);
	psize = (psize & 0x07ff) * (1 + ((psize >> 11) & 3));

	size = video->streaming->ctrl.dwMaxVideoFrameSize;
	if (size > UVC_MAX_FRAME_SIZE)
		return -EINVAL;

	npackets = (size + psize - 1) / psize;
	if (npackets > UVC_MAX_ISO_PACKETS)
		npackets = UVC_MAX_ISO_PACKETS;

	size = npackets * psize;

	for (i = 0; i < UVC_URBS; ++i) {
		urb = usb_alloc_urb(npackets, GFP_KERNEL);
		if (urb == NULL) {
			uvc_uninit_video(video);
			return -ENOMEM;
		}

		video->urb_buffer[i] = usb_buffer_alloc(video->dev->udev,
			size, GFP_KERNEL, &urb->transfer_dma);
		if (video->urb_buffer[i] == NULL) {
			usb_free_urb(urb);
			uvc_uninit_video(video);
			return -ENOMEM;
		}

		urb->dev = video->dev->udev;
		urb->context = video;
		urb->pipe = usb_rcvisocpipe(video->dev->udev,
				ep->desc.bEndpointAddress);
		urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
		urb->interval = ep->desc.bInterval;
		urb->transfer_buffer = video->urb_buffer[i];
		urb->complete = uvc_video_complete;
		urb->number_of_packets = npackets;
		urb->transfer_buffer_length = size;

		for (j = 0; j < npackets; ++j) {
			urb->iso_frame_desc[j].offset = j * psize;
			urb->iso_frame_desc[j].length = psize;
		}

		video->urb[i] = urb;
	}

	return 0;
}

/*
 * Initialize bulk URBs and allocate transfer buffers. The packet size is
 * given by the endpoint.
 */
static int uvc_init_video_bulk(struct uvc_video_device *video, struct usb_host_endpoint *ep)
{
	struct urb *urb;
	unsigned int pipe, i;
	__u16 psize;
	__u32 size;

	/* Compute the bulk URB size. Some devices set the maximum payload
	 * size to a value too high for memory-constrained devices. We must
	 * then transfer the payload accross multiple URBs. To be consistant
	 * with isochronous mode, allocate maximum UVC_MAX_ISO_PACKETS per bulk
	 * URB.
	 */
	psize = le16_to_cpu(ep->desc.wMaxPacketSize) & 0x07ff;
	size = video->streaming->ctrl.dwMaxPayloadTransferSize;
	video->bulk.max_payload_size = size;
	if (size > psize * UVC_MAX_ISO_PACKETS)
		size = psize * UVC_MAX_ISO_PACKETS;

	pipe = usb_rcvbulkpipe(video->dev->udev, ep->desc.bEndpointAddress);

	for (i = 0; i < UVC_URBS; ++i) {
		urb = usb_alloc_urb(0, GFP_KERNEL);
		if (urb == NULL) {
			uvc_uninit_video(video);
			return -ENOMEM;
		}

		video->urb_buffer[i] = usb_buffer_alloc(video->dev->udev,
			size, GFP_KERNEL, &urb->transfer_dma);
		if (video->urb_buffer[i] == NULL) {
			usb_free_urb(urb);
			uvc_uninit_video(video);
			return -ENOMEM;
		}

		usb_fill_bulk_urb(urb, video->dev->udev, pipe,
			video->urb_buffer[i], size, uvc_video_complete,
			video);
		urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;

		video->urb[i] = urb;
	}

	return 0;
}

/*
 * Initialize isochronous/bulk URBs and allocate transfer buffers.
 */
static int uvc_init_video(struct uvc_video_device *video)
{
	struct usb_interface *intf = video->streaming->intf;
	struct usb_host_interface *alts;
	struct usb_host_endpoint *ep = NULL;
	int intfnum = video->streaming->intfnum;
	unsigned int bandwidth, psize, i;
	int ret;

	video->last_fid = -1;
	video->bulk.header_size = 0;
	video->bulk.skip_payload = 0;
	video->bulk.payload_size = 0;

	if (intf->num_altsetting > 1) {
		/* Isochronous endpoint, select the alternate setting. */
		bandwidth = video->streaming->ctrl.dwMaxPayloadTransferSize;

		if (bandwidth == 0) {
			uvc_printk(KERN_WARNING, "device %s requested null "
				"bandwidth, defaulting to lowest.\n",
				video->vdev->name);
			bandwidth = 1;
		}

		for (i = 0; i < intf->num_altsetting; ++i) {
			alts = &intf->altsetting[i];
			ep = uvc_find_endpoint(alts,
				video->streaming->header.bEndpointAddress);
			if (ep == NULL)
				continue;

			/* Check if the bandwidth is high enough. */
			psize = le16_to_cpu(ep->desc.wMaxPacketSize);
			psize = (psize & 0x07ff) * (1 + ((psize >> 11) & 3));
			if (psize >= bandwidth)
				break;
		}

		if (i >= intf->num_altsetting)
			return -EIO;

		if ((ret = usb_set_interface(video->dev->udev, intfnum, i)) < 0)
			return ret;

		ret = uvc_init_video_isoc(video, ep);
	} else {
		/* Bulk endpoint, proceed to URB initialization. */
		ep = uvc_find_endpoint(&intf->altsetting[0],
				video->streaming->header.bEndpointAddress);
		if (ep == NULL)
			return -EIO;

		ret = uvc_init_video_bulk(video, ep);
	}

	if (ret < 0)
		return ret;

	/* Submit the URBs. */
	for (i = 0; i < UVC_URBS; ++i) {
		if ((ret = usb_submit_urb(video->urb[i], GFP_KERNEL)) < 0) {
			uvc_printk(KERN_ERR, "Failed to submit URB %u "
					"(%d).\n", i, ret);
			uvc_uninit_video(video);
			return ret;
		}
	}

	return 0;
}

/* --------------------------------------------------------------------------
 * Suspend/resume
 */

/*
 * Stop streaming without disabling the video queue.
 *
 * To let userspace applications resume without trouble, we must not touch the
 * video buffers in any way. We mark the queue as frozen to make sure the URB
 * completion handler won't try to cancel the queue when we kill the URBs.
 */
int uvc_video_suspend(struct uvc_video_device *video)
{
	if (!video->queue.streaming)
		return 0;

	video->queue.frozen = 1;
	uvc_uninit_video(video);
	usb_set_interface(video->dev->udev, video->streaming->intfnum, 0);
	return 0;
}

/*
 * Reconfigure the video interface and restart streaming if it was enable
 * before suspend.
 *
 * If an error occurs, disable the video queue. This will wake all pending
 * buffers, making sure userspace applications are notified of the problem
 * instead of waiting forever.
 */
int uvc_video_resume(struct uvc_video_device *video)
{
	int ret;

	video->queue.frozen = 0;

	if ((ret = uvc_set_video_ctrl(video, &video->streaming->ctrl, 0)) < 0) {
		uvc_queue_enable(&video->queue, 0);
		return ret;
	}

	if (!video->queue.streaming)
		return 0;

	if ((ret = uvc_init_video(video)) < 0)
		uvc_queue_enable(&video->queue, 0);

	return ret;
}

/* ------------------------------------------------------------------------
 * Video device
 */

/*
 * Initialize the UVC video device by retrieving the default format and
 * committing it.
 *
 * Some cameras (namely the Fuji Finepix) set the format and frame
 * indexes to zero. The UVC standard doesn't clearly make this a spec
 * violation, so try to silently fix the values if possible.
 *
 * This function is called before registering the device with V4L.
 */
int uvc_video_init(struct uvc_video_device *video)
{
	struct uvc_streaming_control *probe = &video->streaming->ctrl;
	struct uvc_format *format = NULL;
	struct uvc_frame *frame = NULL;
	unsigned int i;
	int ret;

	if (video->streaming->nformats == 0) {
		uvc_printk(KERN_INFO, "No supported video formats found.\n");
		return -EINVAL;
	}

	/* Alternate setting 0 should be the default, yet the XBox Live Vision
	 * Cam (and possibly other devices) crash or otherwise misbehave if
	 * they don't receive a SET_INTERFACE request before any other video
	 * control request.
	 */
	usb_set_interface(video->dev->udev, video->streaming->intfnum, 0);

	/* Some webcams don't suport GET_DEF request on the probe control. We
	 * fall back to GET_CUR if GET_DEF fails.
	 */
	if ((ret = uvc_get_video_ctrl(video, probe, 1, GET_DEF)) < 0 &&
	    (ret = uvc_get_video_ctrl(video, probe, 1, GET_CUR)) < 0)
		return ret;

	/* Check if the default format descriptor exists. Use the first
	 * available format otherwise.
	 */
	for (i = video->streaming->nformats; i > 0; --i) {
		format = &video->streaming->format[i-1];
		if (format->index == probe->bFormatIndex)
			break;
	}

	if (format->nframes == 0) {
		uvc_printk(KERN_INFO, "No frame descriptor found for the "
			"default format.\n");
		return -EINVAL;
	}

	/* Zero bFrameIndex might be correct. Stream-based formats (including
	 * MPEG-2 TS and DV) do not support frames but have a dummy frame
	 * descriptor with bFrameIndex set to zero. If the default frame
	 * descriptor is not found, use the first avalable frame.
	 */
	for (i = format->nframes; i > 0; --i) {
		frame = &format->frame[i-1];
		if (frame->bFrameIndex == probe->bFrameIndex)
			break;
	}

	/* Commit the default settings. */
	probe->bFormatIndex = format->index;
	probe->bFrameIndex = frame->bFrameIndex;
	if ((ret = uvc_set_video_ctrl(video, probe, 0)) < 0)
		return ret;

	video->streaming->cur_format = format;
	video->streaming->cur_frame = frame;
	atomic_set(&video->active, 0);

	/* Select the video decoding function */
	if (video->dev->quirks & UVC_QUIRK_BUILTIN_ISIGHT)
		video->decode = uvc_video_decode_isight;
	else if (video->streaming->intf->num_altsetting > 1)
		video->decode = uvc_video_decode_isoc;
	else 
		video->decode = uvc_video_decode_bulk;

	return 0;
}

/*
 * Enable or disable the video stream.
 */
int uvc_video_enable(struct uvc_video_device *video, int enable)
{
	int ret;

	if (!enable) {
		uvc_uninit_video(video);
		usb_set_interface(video->dev->udev,
			video->streaming->intfnum, 0);
		uvc_queue_enable(&video->queue, 0);
		return 0;
	}

	if ((ret = uvc_queue_enable(&video->queue, 1)) < 0)
		return ret;

	return uvc_init_video(video);
}