1 /* 2 * uvc_isight.c -- USB Video Class driver - iSight support 3 * 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> 8 * 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. 13 * 14 */ 15 16 #include <linux/usb.h> 17 #include <linux/kernel.h> 18 #include <linux/mm.h> 19 20 #include "uvcvideo.h" 21 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. 27 * 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 35 * 36 * The header can be prefixed by an optional, unknown-purpose byte. 37 */ 38 39 static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf, 40 const u8 *data, unsigned int len) 41 { 42 static const u8 hdr[] = { 43 0x11, 0x22, 0x33, 0x44, 44 0xde, 0xad, 0xbe, 0xef, 45 0xde, 0xad, 0xfa, 0xce 46 }; 47 48 unsigned int maxlen, nbytes; 49 u8 *mem; 50 int is_header = 0; 51 52 if (buf == NULL) 53 return 0; 54 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; 59 } 60 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; 67 } 68 69 buf->state = UVC_BUF_STATE_ACTIVE; 70 } 71 72 /* Mark the buffer as done if we're at the beginning of a new frame. 73 * 74 * Empty buffers (bytesused == 0) don't trigger end of frame detection 75 * as it doesn't make sense to return an empty buffer. 76 */ 77 if (is_header && buf->bytesused != 0) { 78 buf->state = UVC_BUF_STATE_DONE; 79 return -EAGAIN; 80 } 81 82 /* Copy the video data to the buffer. Skip header packets, as they 83 * contain no data. 84 */ 85 if (!is_header) { 86 maxlen = buf->length - buf->bytesused; 87 mem = buf->mem + buf->bytesused; 88 nbytes = min(len, maxlen); 89 memcpy(mem, data, nbytes); 90 buf->bytesused += nbytes; 91 92 if (len > maxlen || buf->bytesused == buf->length) { 93 uvc_trace(UVC_TRACE_FRAME, "Frame complete " 94 "(overflow).\n"); 95 buf->state = UVC_BUF_STATE_DONE; 96 } 97 } 98 99 return 0; 100 } 101 102 void uvc_video_decode_isight(struct uvc_urb *uvc_urb, struct uvc_buffer *buf, 103 struct uvc_buffer *meta_buf) 104 { 105 struct urb *urb = uvc_urb->urb; 106 struct uvc_streaming *stream = uvc_urb->stream; 107 int ret, i; 108 109 for (i = 0; i < urb->number_of_packets; ++i) { 110 if (urb->iso_frame_desc[i].status < 0) { 111 uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame " 112 "lost (%d).\n", 113 urb->iso_frame_desc[i].status); 114 } 115 116 /* Decode the payload packet. 117 * uvc_video_decode is entered twice when a frame transition 118 * has been detected because the end of frame can only be 119 * reliably detected when the first packet of the new frame 120 * is processed. The first pass detects the transition and 121 * closes the previous frame's buffer, the second pass 122 * processes the data of the first payload of the new frame. 123 */ 124 do { 125 ret = isight_decode(&stream->queue, buf, 126 urb->transfer_buffer + 127 urb->iso_frame_desc[i].offset, 128 urb->iso_frame_desc[i].actual_length); 129 130 if (buf == NULL) 131 break; 132 133 if (buf->state == UVC_BUF_STATE_DONE || 134 buf->state == UVC_BUF_STATE_ERROR) 135 buf = uvc_queue_next_buffer(&stream->queue, 136 buf); 137 } while (ret == -EAGAIN); 138 } 139 } 140