xref: /openbmc/linux/drivers/media/usb/uvc/uvc_isight.c (revision 699b9a86)
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 
isight_decode(struct uvc_video_queue * queue,struct uvc_buffer * buf,const u8 * data,unsigned int len)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 is_header = 0;
48 
49 	if (buf == NULL)
50 		return 0;
51 
52 	if ((len >= 14 && memcmp(&data[2], hdr, 12) == 0) ||
53 	    (len >= 15 && memcmp(&data[3], hdr, 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 
uvc_video_decode_isight(struct uvc_urb * uvc_urb,struct uvc_buffer * buf,struct uvc_buffer * meta_buf)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(&stream->queue, buf,
127 					urb->transfer_buffer +
128 					urb->iso_frame_desc[i].offset,
129 					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(&stream->queue,
137 							buf);
138 		} while (ret == -EAGAIN);
139 	}
140 }
141