platform/msm_shared/spi.c

/*
 * Copyright (c) 2012, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <platform/timer.h>
#include <dev/gpio.h>

void spi_bit_bang_write(uint8_t spi_sclk, uint8_t spi_mosi, uint8_t dc, uint8_t data)
{
	uint8_t bit;
	uint8_t bnum;

	gpio_set(spi_sclk, 0); /* clk low */
	/* dc: 0 for command, 1 for parameter */
	gpio_set(spi_mosi, dc);
	udelay(1);	/* at least 20 ns */
	gpio_set(spi_sclk, 1); /* clk high */
	udelay(1);	/* at least 20 ns */
	bnum = 8;	/* 8 data bits */
	bit = 0x80;
	while(bnum){
		gpio_set(spi_sclk, 0); /* clk low */
		if (data & bit)
			gpio_set(spi_mosi, 1);
		else
			gpio_set(spi_mosi, 0);
		udelay(1);
		gpio_set(spi_sclk, 1); /* clk high */
		udelay(1);
		bit >>= 1;
		bnum--;
	}
}