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 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 } 100 101 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