Merge branch 'for-linus' of git://git.infradead.org/users/sameo/mfd-2.6
[linux-btrfs-devel.git] / drivers / media / video / uvc / uvc_isight.c
blob74bbe8f18f3e51a6b337a22963a8de2474809763
1 /*
2 * uvc_isight.c -- USB Video Class driver - iSight support
4 * Copyright (C) 2006-2007
5 * Ivan N. Zlatev <contact@i-nz.net>
6 * Copyright (C) 2008-2009
7 * Laurent Pinchart <laurent.pinchart@ideasonboard.com>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
16 #include <linux/usb.h>
17 #include <linux/kernel.h>
18 #include <linux/mm.h>
20 #include "uvcvideo.h"
22 /* Built-in iSight webcams implements most of UVC 1.0 except a
23 * different packet format. Instead of sending a header at the
24 * beginning of each isochronous transfer payload, the webcam sends a
25 * single header per image (on its own in a packet), followed by
26 * packets containing data only.
28 * Offset Size (bytes) Description
29 * ------------------------------------------------------------------
30 * 0x00 1 Header length
31 * 0x01 1 Flags (UVC-compliant)
32 * 0x02 4 Always equal to '11223344'
33 * 0x06 8 Always equal to 'deadbeefdeadface'
34 * 0x0e 16 Unknown
36 * The header can be prefixed by an optional, unknown-purpose byte.
39 static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf,
40 const __u8 *data, unsigned int len)
42 static const __u8 hdr[] = {
43 0x11, 0x22, 0x33, 0x44,
44 0xde, 0xad, 0xbe, 0xef,
45 0xde, 0xad, 0xfa, 0xce
48 unsigned int maxlen, nbytes;
49 __u8 *mem;
50 int is_header = 0;
52 if (buf == NULL)
53 return 0;
55 if ((len >= 14 && memcmp(&data[2], hdr, 12) == 0) ||
56 (len >= 15 && memcmp(&data[3], hdr, 12) == 0)) {
57 uvc_trace(UVC_TRACE_FRAME, "iSight header found\n");
58 is_header = 1;
61 /* Synchronize to the input stream by waiting for a header packet. */
62 if (buf->state != UVC_BUF_STATE_ACTIVE) {
63 if (!is_header) {
64 uvc_trace(UVC_TRACE_FRAME, "Dropping packet (out of "
65 "sync).\n");
66 return 0;
69 buf->state = UVC_BUF_STATE_ACTIVE;
72 /* Mark the buffer as done if we're at the beginning of a new frame.
74 * Empty buffers (bytesused == 0) don't trigger end of frame detection
75 * as it doesn't make sense to return an empty buffer.
77 if (is_header && buf->buf.bytesused != 0) {
78 buf->state = UVC_BUF_STATE_DONE;
79 return -EAGAIN;
82 /* Copy the video data to the buffer. Skip header packets, as they
83 * contain no data.
85 if (!is_header) {
86 maxlen = buf->buf.length - buf->buf.bytesused;
87 mem = queue->mem + buf->buf.m.offset + buf->buf.bytesused;
88 nbytes = min(len, maxlen);
89 memcpy(mem, data, nbytes);
90 buf->buf.bytesused += nbytes;
92 if (len > maxlen || buf->buf.bytesused == buf->buf.length) {
93 uvc_trace(UVC_TRACE_FRAME, "Frame complete "
94 "(overflow).\n");
95 buf->state = UVC_BUF_STATE_DONE;
99 return 0;
102 void uvc_video_decode_isight(struct urb *urb, struct uvc_streaming *stream,
103 struct uvc_buffer *buf)
105 int ret, i;
107 for (i = 0; i < urb->number_of_packets; ++i) {
108 if (urb->iso_frame_desc[i].status < 0) {
109 uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame "
110 "lost (%d).\n",
111 urb->iso_frame_desc[i].status);
114 /* Decode the payload packet.
115 * uvc_video_decode is entered twice when a frame transition
116 * has been detected because the end of frame can only be
117 * reliably detected when the first packet of the new frame
118 * is processed. The first pass detects the transition and
119 * closes the previous frame's buffer, the second pass
120 * processes the data of the first payload of the new frame.
122 do {
123 ret = isight_decode(&stream->queue, buf,
124 urb->transfer_buffer +
125 urb->iso_frame_desc[i].offset,
126 urb->iso_frame_desc[i].actual_length);
128 if (buf == NULL)
129 break;
131 if (buf->state == UVC_BUF_STATE_DONE ||
132 buf->state == UVC_BUF_STATE_ERROR)
133 buf = uvc_queue_next_buffer(&stream->queue,
134 buf);
135 } while (ret == -EAGAIN);