138 lines
3.8 KiB
C
138 lines
3.8 KiB
C
/*
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* uvc_isight.c -- USB Video Class driver - iSight support
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*
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* Copyright (C) 2006-2007
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* Ivan N. Zlatev <contact@i-nz.net>
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* Copyright (C) 2008-2009
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* Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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*/
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#include <linux/usb.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include "uvcvideo.h"
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/* Built-in iSight webcams implements most of UVC 1.0 except a
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* different packet format. Instead of sending a header at the
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* beginning of each isochronous transfer payload, the webcam sends a
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* single header per image (on its own in a packet), followed by
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* packets containing data only.
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*
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* Offset Size (bytes) Description
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* ------------------------------------------------------------------
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* 0x00 1 Header length
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* 0x01 1 Flags (UVC-compliant)
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* 0x02 4 Always equal to '11223344'
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* 0x06 8 Always equal to 'deadbeefdeadface'
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* 0x0e 16 Unknown
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*
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* The header can be prefixed by an optional, unknown-purpose byte.
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*/
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static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf,
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const __u8 *data, unsigned int len)
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{
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static const __u8 hdr[] = {
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0x11, 0x22, 0x33, 0x44,
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0xde, 0xad, 0xbe, 0xef,
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0xde, 0xad, 0xfa, 0xce
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};
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unsigned int maxlen, nbytes;
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__u8 *mem;
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int is_header = 0;
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if (buf == NULL)
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return 0;
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if ((len >= 14 && memcmp(&data[2], hdr, 12) == 0) ||
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(len >= 15 && memcmp(&data[3], hdr, 12) == 0)) {
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uvc_trace(UVC_TRACE_FRAME, "iSight header found\n");
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is_header = 1;
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}
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/* Synchronize to the input stream by waiting for a header packet. */
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if (buf->state != UVC_BUF_STATE_ACTIVE) {
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if (!is_header) {
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uvc_trace(UVC_TRACE_FRAME, "Dropping packet (out of "
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"sync).\n");
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return 0;
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}
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buf->state = UVC_BUF_STATE_ACTIVE;
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}
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/* Mark the buffer as done if we're at the beginning of a new frame.
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*
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* Empty buffers (bytesused == 0) don't trigger end of frame detection
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* as it doesn't make sense to return an empty buffer.
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*/
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if (is_header && buf->bytesused != 0) {
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buf->state = UVC_BUF_STATE_DONE;
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return -EAGAIN;
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}
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/* Copy the video data to the buffer. Skip header packets, as they
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* contain no data.
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*/
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if (!is_header) {
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maxlen = buf->length - buf->bytesused;
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mem = buf->mem + buf->bytesused;
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nbytes = min(len, maxlen);
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memcpy(mem, data, nbytes);
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buf->bytesused += nbytes;
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if (len > maxlen || buf->bytesused == buf->length) {
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uvc_trace(UVC_TRACE_FRAME, "Frame complete "
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"(overflow).\n");
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buf->state = UVC_BUF_STATE_DONE;
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}
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}
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return 0;
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}
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void uvc_video_decode_isight(struct urb *urb, struct uvc_streaming *stream,
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struct uvc_buffer *buf)
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{
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int ret, i;
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for (i = 0; i < urb->number_of_packets; ++i) {
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if (urb->iso_frame_desc[i].status < 0) {
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uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame "
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"lost (%d).\n",
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urb->iso_frame_desc[i].status);
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}
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/* Decode the payload packet.
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* uvc_video_decode is entered twice when a frame transition
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* has been detected because the end of frame can only be
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* reliably detected when the first packet of the new frame
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* is processed. The first pass detects the transition and
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* closes the previous frame's buffer, the second pass
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* processes the data of the first payload of the new frame.
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*/
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do {
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ret = isight_decode(&stream->queue, buf,
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urb->transfer_buffer +
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urb->iso_frame_desc[i].offset,
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urb->iso_frame_desc[i].actual_length);
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if (buf == NULL)
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break;
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if (buf->state == UVC_BUF_STATE_DONE ||
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buf->state == UVC_BUF_STATE_ERROR)
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buf = uvc_queue_next_buffer(&stream->queue,
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buf);
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} while (ret == -EAGAIN);
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}
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}
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