path: root/drivers/media/video/uvc/uvc_v4l2.c

/*
 *      uvc_v4l2.c  --  USB Video Class driver - V4L2 API
 *
 *      Copyright (C) 2005-2008
 *          Laurent Pinchart (laurent.pinchart@skynet.be)
 *
 *      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/kernel.h>
#include <linux/version.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/videodev2.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/wait.h>
#include <asm/atomic.h>

#include <media/v4l2-common.h>

#include "uvcvideo.h"

/* ------------------------------------------------------------------------
 * V4L2 interface
 */

/*
 * Mapping V4L2 controls to UVC controls can be straighforward if done well.
 * Most of the UVC controls exist in V4L2, and can be mapped directly. Some
 * must be grouped (for instance the Red Balance, Blue Balance and Do White
 * Balance V4L2 controls use the White Balance Component UVC control) or
 * otherwise translated. The approach we take here is to use a translation
 * table for the controls which can be mapped directly, and handle the others
 * manually.
 */
static int uvc_v4l2_query_menu(struct uvc_video_device *video,
	struct v4l2_querymenu *query_menu)
{
	struct uvc_menu_info *menu_info;
	struct uvc_control_mapping *mapping;
	struct uvc_control *ctrl;

	ctrl = uvc_find_control(video, query_menu->id, &mapping);
	if (ctrl == NULL || mapping->v4l2_type != V4L2_CTRL_TYPE_MENU)
		return -EINVAL;

	if (query_menu->index >= mapping->menu_count)
		return -EINVAL;

	menu_info = &mapping->menu_info[query_menu->index];
	strncpy(query_menu->name, menu_info->name, 32);
	return 0;
}

/*
 * Find the frame interval closest to the requested frame interval for the
 * given frame format and size. This should be done by the device as part of
 * the Video Probe and Commit negotiation, but some hardware don't implement
 * that feature.
 */
static __u32 uvc_try_frame_interval(struct uvc_frame *frame, __u32 interval)
{
	unsigned int i;

	if (frame->bFrameIntervalType) {
		__u32 best = -1, dist;

		for (i = 0; i < frame->bFrameIntervalType; ++i) {
			dist = interval > frame->dwFrameInterval[i]
			     ? interval - frame->dwFrameInterval[i]
			     : frame->dwFrameInterval[i] - interval;

			if (dist > best)
				break;

			best = dist;
		}

		interval = frame->dwFrameInterval[i-1];
	} else {
		const __u32 min = frame->dwFrameInterval[0];
		const __u32 max = frame->dwFrameInterval[1];
		const __u32 step = frame->dwFrameInterval[2];

		interval = min + (interval - min + step/2) / step * step;
		if (interval > max)
			interval = max;
	}

	return interval;
}

static int uvc_v4l2_try_format(struct uvc_video_device *video,
	struct v4l2_format *fmt, struct uvc_streaming_control *probe,
	struct uvc_format **uvc_format, struct uvc_frame **uvc_frame)
{
	struct uvc_format *format = NULL;
	struct uvc_frame *frame = NULL;
	__u16 rw, rh;
	unsigned int d, maxd;
	unsigned int i;
	__u32 interval;
	int ret = 0;
	__u8 *fcc;

	if (fmt->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
		return -EINVAL;

	fcc = (__u8 *)&fmt->fmt.pix.pixelformat;
	uvc_trace(UVC_TRACE_FORMAT, "Trying format 0x%08x (%c%c%c%c): %ux%u.\n",
			fmt->fmt.pix.pixelformat,
			fcc[0], fcc[1], fcc[2], fcc[3],
			fmt->fmt.pix