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
isight_decode(struct uvc_video_queue * queue,struct uvc_buffer * buf,const u8 * data,unsigned int len)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 struct uvc_streaming *stream = uvc_queue_to_stream(queue);
44 unsigned int maxlen, nbytes;
45 u8 *mem;
46 int is_header = 0;
47
48 if (buf == NULL)
49 return 0;
50
51 if ((len >= 14 && memcmp(&data[2], hdr, 12) == 0) ||
52 (len >= 15 && memcmp(&data[3], hdr, 12) == 0)) {
53 uvc_dbg(stream->dev, FRAME, "iSight header found\n");
54 is_header = 1;
55 }
56
57 /* Synchronize to the input stream by waiting for a header packet. */
58 if (buf->state != UVC_BUF_STATE_ACTIVE) {
59 if (!is_header) {
60 uvc_dbg(stream->dev, FRAME,
61 "Dropping packet (out of sync)\n");
62 return 0;
63 }
64
65 buf->state = UVC_BUF_STATE_ACTIVE;
66 }
67
68 /* Mark the buffer as done if we're at the beginning of a new frame.
69 *
70 * Empty buffers (bytesused == 0) don't trigger end of frame detection
71 * as it doesn't make sense to return an empty buffer.
72 */
73 if (is_header && buf->bytesused != 0) {
74 buf->state = UVC_BUF_STATE_DONE;
75 return -EAGAIN;
76 }
77
78 /* Copy the video data to the buffer. Skip header packets, as they
79 * contain no data.
80 */
81 if (!is_header) {
82 maxlen = buf->length - buf->bytesused;
83 mem = buf->mem + buf->bytesused;
84 nbytes = min(len, maxlen);
85 memcpy(mem, data, nbytes);
86 buf->bytesused += nbytes;
87
88 if (len > maxlen || buf->bytesused == buf->length) {
89 uvc_dbg(stream->dev, FRAME,
90 "Frame complete (overflow)\n");
91 buf->state = UVC_BUF_STATE_DONE;
92 }
93 }
94
95 return 0;
96 }
97
uvc_video_decode_isight(struct uvc_urb * uvc_urb,struct uvc_buffer * buf,struct uvc_buffer * meta_buf)98 void uvc_video_decode_isight(struct uvc_urb *uvc_urb, struct uvc_buffer *buf,
99 struct uvc_buffer *meta_buf)
100 {
101 struct urb *urb = uvc_urb->urb;
102 struct uvc_streaming *stream = uvc_urb->stream;
103 int ret, i;
104
105 for (i = 0; i < urb->number_of_packets; ++i) {
106 if (urb->iso_frame_desc[i].status < 0) {
107 uvc_dbg(stream->dev, FRAME,
108 "USB isochronous frame lost (%d)\n",
109 urb->iso_frame_desc[i].status);
110 }
111
112 /* Decode the payload packet.
113 * uvc_video_decode is entered twice when a frame transition
114 * has been detected because the end of frame can only be
115 * reliably detected when the first packet of the new frame
116 * is processed. The first pass detects the transition and
117 * closes the previous frame's buffer, the second pass
118 * processes the data of the first payload of the new frame.
119 */
120 do {
121 ret = isight_decode(&stream->queue, buf,
122 urb->transfer_buffer +
123 urb->iso_frame_desc[i].offset,
124 urb->iso_frame_desc[i].actual_length);
125
126 if (buf == NULL)
127 break;
128
129 if (buf->state == UVC_BUF_STATE_DONE ||
130 buf->state == UVC_BUF_STATE_ERROR)
131 buf = uvc_queue_next_buffer(&stream->queue,
132 buf);
133 } while (ret == -EAGAIN);
134 }
135 }
136