linux/sound/soc/codecs/l3.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * L3 code
 *
 *  Copyright (C) 2008, Christian Pellegrin <chripell@evolware.org>
 *
 * based on:
 *
 * L3 bus algorithm module.
 *
 *  Copyright (C) 2001 Russell King, All Rights Reserved.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/gpio.h>

#include <sound/l3.h>

/*
 * Send one byte of data to the chip.  Data is latched into the chip on
 * the rising edge of the clock.
 */
static void sendbyte(struct l3_pins *adap, unsigned int byte)
{
	int i;

	for (i = 0; i < 8; i++) {
		adap->setclk(adap, 0);
		udelay(adap->data_hold);
		adap->setdat(adap, byte & 1);
		udelay(adap->data_setup);
		adap->setclk(adap, 1);
		udelay(adap->clock_high);
		byte >>= 1;
	}
}

/*
 * Send a set of bytes to the chip.  We need to pulse the MODE line
 * between each byte, but never at the start nor at the end of the
 * transfer.
 */
static void sendbytes(struct l3_pins *adap, const u8 *buf,
		      int len)
{
	int i;

	for (i = 0; i < len; i++) {
		if (i) {
			udelay(adap->mode_hold);
			adap->setmode(adap, 0);
			udelay(adap->mode);
		}
		adap->setmode(adap, 1);
		udelay(adap->mode_setup);
		sendbyte(adap, buf[i]);
	}
}

int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
{
	adap->setclk(adap, 1);
	adap->setdat(adap, 1);
	adap->setmode(adap, 1);
	udelay(adap->mode);

	adap->setmode(adap, 0);
	udelay(adap->mode_setup);
	sendbyte(adap, addr);
	udelay(adap->mode_hold);

	sendbytes(adap, data, len);

	adap->setclk(adap, 1);
	adap->setdat(adap, 1);
	adap->setmode(adap, 0);

	return len;
}
EXPORT_SYMBOL_GPL(l3_write);


static void l3_set_clk(struct l3_pins *adap, int val)
{
	gpio_set_value(adap->gpio_clk, val);
}

static void l3_set_data(struct l3_pins *adap, int val)
{
	gpio_set_value(adap->gpio_data, val);
}

static void l3_set_mode(struct l3_pins *adap, int val)
{
	gpio_set_value(adap->gpio_mode, val);
}

int l3_set_gpio_ops(struct device *dev, struct l3_pins *adap)
{
	int ret;

	if (!adap->use_gpios)
		return -EINVAL;

	ret = devm_gpio_request_one(dev, adap->gpio_data,
				GPIOF_OUT_INIT_LOW, "l3_data");
	if (ret < 0)
		return ret;
	adap->setdat = l3_set_data;

	ret = devm_gpio_request_one(dev, adap->gpio_clk,
				GPIOF_OUT_INIT_LOW, "l3_clk");
	if (ret < 0)
		return ret;
	adap->setclk = l3_set_clk;

	ret = devm_gpio_request_one(dev, adap->gpio_mode,
				GPIOF_OUT_INIT_LOW, "l3_mode");
	if (ret < 0)
		return ret;
	adap->setmode = l3_set_mode;

	return 0;
}
EXPORT_SYMBOL_GPL(l3_set_gpio_ops);

MODULE_DESCRIPTION("L3 bit-banging driver");
MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
MODULE_LICENSE("GPL");