diff options
Diffstat (limited to 'drivers/media/video/uvc/uvc_isight.c')
| -rw-r--r-- | drivers/media/video/uvc/uvc_isight.c | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/drivers/media/video/uvc/uvc_isight.c b/drivers/media/video/uvc/uvc_isight.c new file mode 100644 index 0000000..37bdefd --- /dev/null +++ b/drivers/media/video/uvc/uvc_isight.c @@ -0,0 +1,134 @@ +/* + * uvc_isight.c -- USB Video Class driver - iSight support + * + * Copyright (C) 2006-2007 + * Ivan N. Zlatev <contact@i-nz.net> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + */ + +#include <linux/usb.h> +#include <linux/kernel.h> +#include <linux/mm.h> + +#include "uvcvideo.h" + +/* Built-in iSight webcams implements most of UVC 1.0 except a + * different packet format. Instead of sending a header at the + * beginning of each isochronous transfer payload, the webcam sends a + * single header per image (on its own in a packet), followed by + * packets containing data only. + * + * Offset Size (bytes) Description + * ------------------------------------------------------------------ + * 0x00 1 Header length + * 0x01 1 Flags (UVC-compliant) + * 0x02 4 Always equal to '11223344' + * 0x06 8 Always equal to 'deadbeefdeadface' + * 0x0e 16 Unknown + * + * The header can be prefixed by an optional, unknown-purpose byte. + */ + +static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf, + const __u8 *data, unsigned int len) +{ + static const __u8 hdr[] = { + 0x11, 0x22, 0x33, 0x44, + 0xde, 0xad, 0xbe, 0xef, + 0xde, 0xad, 0xfa, 0xce + }; + + unsigned int maxlen, nbytes; + __u8 *mem; + int is_header = 0; + + if (buf == NULL) + return 0; + + if ((len >= 14 && memcmp(&data[2], hdr, 12) == 0) || + (len >= 15 && memcmp(&data[3], hdr, 12) == 0)) { + uvc_trace(UVC_TRACE_FRAME, "iSight header found\n"); + is_header = 1; + } + + /* Synchronize to the input stream by waiting for a header packet. */ + if (buf->state != UVC_BUF_STATE_ACTIVE) { + if (!is_header) { + uvc_trace(UVC_TRACE_FRAME, "Dropping packet (out of " + "sync).\n"); + return 0; + } + + buf->state = UVC_BUF_STATE_ACTIVE; + } + + /* Mark the buffer as done if we're at the beginning of a new frame. + * + * Empty buffers (bytesused == 0) don't trigger end of frame detection + * as it doesn't make sense to return an empty buffer. + */ + if (is_header && buf->buf.bytesused != 0) { + buf->state = UVC_BUF_STATE_DONE; + return -EAGAIN; + } + + /* Copy the video data to the buffer. Skip header packets, as they + * contain no data. + */ + if (!is_header) { + maxlen = buf->buf.length - buf->buf.bytesused; + mem = queue->mem + buf->buf.m.offset + buf->buf.bytesused; + nbytes = min(len, maxlen); + memcpy(mem, data, nbytes); + buf->buf.bytesused += nbytes; + + if (len > maxlen || buf->buf.bytesused == buf->buf.length) { + uvc_trace(UVC_TRACE_FRAME, "Frame complete " + "(overflow).\n"); + buf->state = UVC_BUF_STATE_DONE; + } + } + + return 0; +} + +void uvc_video_decode_isight(struct urb *urb, struct uvc_video_device *video, + struct uvc_buffer *buf) +{ + int ret, i; + + for (i = 0; i < urb->number_of_packets; ++i) { + if (urb->iso_frame_desc[i].status < 0) { + uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame " + "lost (%d).\n", + urb->iso_frame_desc[i].status); + } + + /* Decode the payload packet. + * uvc_video_decode is entered twice when a frame transition + * has been detected because the end of frame can only be + * reliably detected when the first packet of the new frame + * is processed. The first pass detects the transition and + * closes the previous frame's buffer, the second pass + * processes the data of the first payload of the new frame. + */ + do { + ret = isight_decode(&video->queue, buf, + urb->transfer_buffer + + urb->iso_frame_desc[i].offset, + urb->iso_frame_desc[i].actual_length); + + if (buf == NULL) + break; + + if (buf->state == UVC_BUF_STATE_DONE || + buf->state == UVC_BUF_STATE_ERROR) + buf = uvc_queue_next_buffer(&video->queue, buf); + } while (ret == -EAGAIN); + } +} |