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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * uvc_isight.c -- USB Video Class driver - iSight support4 *5 * Copyright (C) 2006-20076 * Ivan N. Zlatev <contact@i-nz.net>7 * Copyright (C) 2008-20098 * 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 a19 * different packet format. Instead of sending a header at the20 * beginning of each isochronous transfer payload, the webcam sends a21 * single header per image (on its own in a packet), followed by22 * packets containing data only.23 *24 * Offset Size (bytes) Description25 * ------------------------------------------------------------------26 * 0x00 1 Header length27 * 0x01 1 Flags (UVC-compliant)28 * 0x02 4 Always equal to '11223344'29 * 0x06 8 Always equal to 'deadbeefdeadface'30 * 0x0e 16 Unknown31 *32 * The header can be prefixed by an optional, unknown-purpose byte.33 */34 35static 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, 0xce42 };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 detection73 * 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 they82 * 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 101void 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 transition119 * has been detected because the end of frame can only be120 * reliably detected when the first packet of the new frame121 * is processed. The first pass detects the transition and122 * closes the previous frame's buffer, the second pass123 * 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