drivers/media/usb/uvc/uvc_isight.c

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