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path: root/drivers/media/video/uvc/uvc_isight.c
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Diffstat (limited to 'drivers/media/video/uvc/uvc_isight.c')
-rw-r--r--drivers/media/video/uvc/uvc_isight.c134
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 000000000000..37bdefdbead5
--- /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);
+ }
+}