1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * uvc_isight.c -- USB Video Class driver - iSight support
4 *
5 * Copyright (C) 2006-2007
6 * Ivan N. Zlatev <contact@i-nz.net>
7 * Copyright (C) 2008-2009
8 * Laurent Pinchart <laurent.pinchart@ideasonboard.com>
9 */
10
11 #include <linux/usb.h>
12 #include <linux/kernel.h>
13 #include <linux/mm.h>
14
15 #include "uvcvideo.h"
16
17 /* Built-in iSight webcams implements most of UVC 1.0 except a
18 * different packet format. Instead of sending a header at the
19 * beginning of each isochronous transfer payload, the webcam sends a
20 * single header per image (on its own in a packet), followed by
21 * packets containing data only.
22 *
23 * Offset Size (bytes) Description
24 * ------------------------------------------------------------------
25 * 0x00 1 Header length
26 * 0x01 1 Flags (UVC-compliant)
27 * 0x02 4 Always equal to '11223344'
28 * 0x06 8 Always equal to 'deadbeefdeadface'
29 * 0x0e 16 Unknown
30 *
31 * The header can be prefixed by an optional, unknown-purpose byte.
32 */
33
34 static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf,
35 const u8 *data, unsigned int len)
36 {
37 static const u8 hdr[] = {
38 0x11, 0x22, 0x33, 0x44,
39 0xde, 0xad, 0xbe, 0xef,
40 0xde, 0xad, 0xfa, 0xce
41 };
42
43 unsigned int maxlen, nbytes;
44 u8 *mem;
45 int is_header = 0;
46
47 if (buf == NULL)
48 return 0;
49
50 if ((len >= 14 && memcmp(&data[2], hdr, 12) == 0) ||
51 (len >= 15 && memcmp(&data[3], hdr, 12) == 0)) {
52 uvc_trace(UVC_TRACE_FRAME, "iSight header found\n");
53 is_header = 1;
54 }
55
56 /* Synchronize to the input stream by waiting for a header packet. */
57 if (buf->state != UVC_BUF_STATE_ACTIVE) {
58 if (!is_header) {
59 uvc_trace(UVC_TRACE_FRAME, "Dropping packet (out of "
60 "sync).\n");
61 return 0;
62 }
63
64 buf->state = UVC_BUF_STATE_ACTIVE;
65 }
66
67 /* Mark the buffer as done if we're at the beginning of a new frame.
68 *
69 * Empty buffers (bytesused == 0) don't trigger end of frame detection
70 * as it doesn't make sense to return an empty buffer.
71 */
72 if (is_header && buf->bytesused != 0) {
73 buf->state = UVC_BUF_STATE_DONE;
74 return -EAGAIN;
75 }
76
77 /* Copy the video data to the buffer. Skip header packets, as they
78 * contain no data.
79 */
80 if (!is_header) {
81 maxlen = buf->length - buf->bytesused;
82 mem = buf->mem + buf->bytesused;
83 nbytes = min(len, maxlen);
84 memcpy(mem, data, nbytes);
85 buf->bytesused += nbytes;
86
87 if (len > maxlen || buf->bytesused == buf->length) {
88 uvc_trace(UVC_TRACE_FRAME, "Frame complete "
89 "(overflow).\n");
90 buf->state = UVC_BUF_STATE_DONE;
91 }
92 }
93
94 return 0;
95 }
96
97 void uvc_video_decode_isight(struct uvc_urb *uvc_urb, struct uvc_buffer *buf,
98 struct uvc_buffer *meta_buf)
99 {
100 struct urb *urb = uvc_urb->urb;
101 struct uvc_streaming *stream = uvc_urb->stream;
102 int ret, i;
103
104 for (i = 0; i < urb->number_of_packets; ++i) {
105 if (urb->iso_frame_desc[i].status < 0) {
106 uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame "
107 "lost (%d).\n",
108 urb->iso_frame_desc[i].status);
109 }
110
111 /* Decode the payload packet.
112 * uvc_video_decode is entered twice when a frame transition
113 * has been detected because the end of frame can only be
114 * reliably detected when the first packet of the new frame
115 * is processed. The first pass detects the transition and
116 * closes the previous frame's buffer, the second pass
117 * processes the data of the first payload of the new frame.
118 */
119 do {
120 ret = isight_decode(&stream->queue, buf,
121 urb->transfer_buffer +
122 urb->iso_frame_desc[i].offset,
123 urb->iso_frame_desc[i].actual_length);
124
125 if (buf == NULL)
126 break;
127
128 if (buf->state == UVC_BUF_STATE_DONE ||
129 buf->state == UVC_BUF_STATE_ERROR)
130 buf = uvc_queue_next_buffer(&stream->queue,
131 buf);
132 } while (ret == -EAGAIN);
133 }
134 }