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 | /* |
18 | * Built-in iSight webcams implements most of UVC 1.0 except a |
19 | * different packet format. Instead of sending a header at the |
20 | * beginning of each isochronous transfer payload, the webcam sends a |
21 | * single header per image (on its own in a packet), followed by |
22 | * packets containing data only. |
23 | * |
24 | * Offset Size (bytes) Description |
25 | * ------------------------------------------------------------------ |
26 | * 0x00 1 Header length |
27 | * 0x01 1 Flags (UVC-compliant) |
28 | * 0x02 4 Always equal to '11223344' |
29 | * 0x06 8 Always equal to 'deadbeefdeadface' |
30 | * 0x0e 16 Unknown |
31 | * |
32 | * The header can be prefixed by an optional, unknown-purpose byte. |
33 | */ |
34 | |
35 | static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf, |
36 | const u8 *data, unsigned int len) |
37 | { |
38 | static const u8 hdr[] = { |
39 | 0x11, 0x22, 0x33, 0x44, |
40 | 0xde, 0xad, 0xbe, 0xef, |
41 | 0xde, 0xad, 0xfa, 0xce |
42 | }; |
43 | |
44 | struct uvc_streaming *stream = uvc_queue_to_stream(queue); |
45 | unsigned int maxlen, nbytes; |
46 | u8 *mem; |
47 | int = 0; |
48 | |
49 | if (buf == NULL) |
50 | return 0; |
51 | |
52 | if ((len >= 14 && memcmp(p: &data[2], q: hdr, size: 12) == 0) || |
53 | (len >= 15 && memcmp(p: &data[3], q: hdr, size: 12) == 0)) { |
54 | uvc_dbg(stream->dev, FRAME, "iSight header found\n" ); |
55 | is_header = 1; |
56 | } |
57 | |
58 | /* Synchronize to the input stream by waiting for a header packet. */ |
59 | if (buf->state != UVC_BUF_STATE_ACTIVE) { |
60 | if (!is_header) { |
61 | uvc_dbg(stream->dev, FRAME, |
62 | "Dropping packet (out of sync)\n" ); |
63 | return 0; |
64 | } |
65 | |
66 | buf->state = UVC_BUF_STATE_ACTIVE; |
67 | } |
68 | |
69 | /* |
70 | * Mark the buffer as done if we're at the beginning of a new frame. |
71 | * |
72 | * Empty buffers (bytesused == 0) don't trigger end of frame detection |
73 | * as it doesn't make sense to return an empty buffer. |
74 | */ |
75 | if (is_header && buf->bytesused != 0) { |
76 | buf->state = UVC_BUF_STATE_DONE; |
77 | return -EAGAIN; |
78 | } |
79 | |
80 | /* |
81 | * Copy the video data to the buffer. Skip header packets, as they |
82 | * contain no data. |
83 | */ |
84 | if (!is_header) { |
85 | maxlen = buf->length - buf->bytesused; |
86 | mem = buf->mem + buf->bytesused; |
87 | nbytes = min(len, maxlen); |
88 | memcpy(mem, data, nbytes); |
89 | buf->bytesused += nbytes; |
90 | |
91 | if (len > maxlen || buf->bytesused == buf->length) { |
92 | uvc_dbg(stream->dev, FRAME, |
93 | "Frame complete (overflow)\n" ); |
94 | buf->state = UVC_BUF_STATE_DONE; |
95 | } |
96 | } |
97 | |
98 | return 0; |
99 | } |
100 | |
101 | void uvc_video_decode_isight(struct uvc_urb *uvc_urb, struct uvc_buffer *buf, |
102 | struct uvc_buffer *meta_buf) |
103 | { |
104 | struct urb *urb = uvc_urb->urb; |
105 | struct uvc_streaming *stream = uvc_urb->stream; |
106 | int ret, i; |
107 | |
108 | for (i = 0; i < urb->number_of_packets; ++i) { |
109 | if (urb->iso_frame_desc[i].status < 0) { |
110 | uvc_dbg(stream->dev, FRAME, |
111 | "USB isochronous frame lost (%d)\n" , |
112 | urb->iso_frame_desc[i].status); |
113 | } |
114 | |
115 | /* |
116 | * Decode the payload packet. |
117 | * |
118 | * uvc_video_decode is entered twice when a frame transition |
119 | * has been detected because the end of frame can only be |
120 | * reliably detected when the first packet of the new frame |
121 | * is processed. The first pass detects the transition and |
122 | * closes the previous frame's buffer, the second pass |
123 | * processes the data of the first payload of the new frame. |
124 | */ |
125 | do { |
126 | ret = isight_decode(queue: &stream->queue, buf, |
127 | data: urb->transfer_buffer + |
128 | urb->iso_frame_desc[i].offset, |
129 | len: urb->iso_frame_desc[i].actual_length); |
130 | |
131 | if (buf == NULL) |
132 | break; |
133 | |
134 | if (buf->state == UVC_BUF_STATE_DONE || |
135 | buf->state == UVC_BUF_STATE_ERROR) |
136 | buf = uvc_queue_next_buffer(queue: &stream->queue, |
137 | buf); |
138 | } while (ret == -EAGAIN); |
139 | } |
140 | } |
141 | |