drivers/video/s6e63d6.c

/*
 * Copyright (C) 2009
 * Guennadi Liakhovetski, DENX Software Engineering, <lg@denx.de>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */
#include <common.h>
#include <spi.h>
#include <s6e63d6.h>

/*
 * Each transfer is performed as:
 * 1. chip-select active
 * 2. send 8-bit start code
 * 3. send 16-bit data
 * 4. chip-select inactive
 */
static int send_word(struct s6e63d6 *data, u8 rs, u16 word)
{
	/*
	 * The start byte looks like (binary):
	 * 01110<ID><RS><R/W>
	 * RS is 0 for index or 1 for data, and R/W is 0 for write.
	 */
	u32 buf8 = 0x70 | data->id | (rs & 2);
	u32 buf16 = cpu_to_le16(word);
	u32 buf_in;
	int err;

	err = spi_xfer(data->slave, 8, &buf8, &buf_in, SPI_XFER_BEGIN);
	if (err)
		return err;

	return spi_xfer(data->slave, 16, &buf16, &buf_in, SPI_XFER_END);
}

/* Index and param differ in Register Select bit */
int s6e63d6_index(struct s6e63d6 *data, u8 idx)
{
	return send_word(data, 0, idx);
}

int s6e63d6_param(struct s6e63d6 *data, u16 param)
{
	return send_word(data, 2, param);
}

int s6e63d6_init(struct s6e63d6 *data)
{
	if (data->id != 0 && data->id != 4) {
		printf("s6e63d6: invalid ID %u\n", data->id);
		return 1;
	}

	data->slave = spi_setup_slave(data->bus, data->cs, 100000, SPI_MODE_3);
	if (!data->slave)
		return 1;

	return 0;
}