path: root/drivers/video/hdmi.c

/*
 * Copyright (C) 2012 Avionic Design GmbH
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/hdmi.h>
#include <linux/string.h>
#include <linux/device.h>

#define hdmi_log(fmt, ...) dev_printk(level, dev, fmt, ##__VA_ARGS__)

static u8 hdmi_infoframe_checksum(u8 *ptr, size_t size)
{
	u8 csum = 0;
	size_t i;

	/* compute checksum */
	for (i = 0; i < size; i++)
		csum += ptr[i];

	return 256 - csum;
}

static void hdmi_infoframe_set_checksum(void *buffer, size_t size)
{
	u8 *ptr = buffer;

	ptr[3] = hdmi_infoframe_checksum(buffer, size);
}

/**
 * hdmi_avi_infoframe_init() - initialize an HDMI AVI infoframe
 * @frame: HDMI AVI infoframe
 *
 * Returns 0 on success or a negative error code on failure.
 */
int hdmi_avi_infoframe_init(struct hdmi_avi_infoframe *frame)
{
	memset(frame, 0, sizeof(*frame));

	frame->type = HDMI_INFOFRAME_TYPE_AVI;
	frame->version = 2;
	frame->length = HDMI_AVI_INFOFRAME_SIZE;

	return 0;
}
EXPORT_SYMBOL(hdmi_avi_infoframe_init);

/**
 * hdmi_avi_infoframe_pack() - write HDMI AVI infoframe to binary buffer
 * @frame: HDMI AVI infoframe
 * @buffer: destination buffer
 * @size: size of buffer
 *
 * Packs the information contained in the @frame structure into a binary
 * representation that can be written into the corresponding controller
 * registers. Also computes the checksum as required by section 5.3.5 of
 * the HDMI 1.4 specification.
 *
 * Returns the number of bytes packed into the binary buffer or a negative
 * error code on failure.
 */
ssize_t hdmi_avi_infoframe_pack(struct hdmi_avi_infoframe *frame, void *buffer,
				size_t size)
{
	u8 *ptr = buffer;
	size_t length;

	length = HDMI_INFOFRAME_HEADER_SIZE + frame->length;

	if (size < length)
		return -ENOSPC;

	memset(buffer, 0, size);

	ptr[0] = frame->type;
	ptr[1] = frame->version;
	ptr[2] = frame->length;
	ptr[3] = 0; /* checksum */

	/* start infoframe payload */
	ptr += HDMI_INFOFRAME_HEADER_SIZE;

	ptr[0] = ((frame->colorspace & 0x3) << 5) | (frame->scan_mode & 0x3);

	/*
	 * Data byte 1, bit 4 has to be set if we provide the active format
	 * aspect ratio
	 */
	if (frame->active_aspect & 0xf)
		ptr[0] |= BIT(4);

	/* Bit 3 and 2 indicate if we transmit horizontal/vertical bar data */
	if (frame->top_bar || frame->bottom_bar)
		ptr[0] |= BIT(3);

	if (frame->left_bar || frame->right_bar)
		ptr[0] |= BIT(2);

	ptr[1] = ((frame->colorimetry & 0x3) << 6) |
		 ((frame->picture_aspect & 0x3) << 4) |
		 (frame->active_aspect & 0xf);

	ptr[2] = ((frame->extended_colorimetry & 0x7) << 4) |
		 ((frame->quantization_range & 0x3) << 2) |
		 (frame->nups & 0x3);

	if (frame->itc)
		ptr[2] |= BIT(