1/*
  2 * L3 code
  3 *
  4 *  Copyright (C) 2008, Christian Pellegrin <chripell@evolware.org>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 *
 10 *
 11 * based on:
 12 *
 13 * L3 bus algorithm module.
 14 *
 15 *  Copyright (C) 2001 Russell King, All Rights Reserved.
 16 *
 17 *
 18 */
 19
 20#include <linux/module.h>
 21#include <linux/kernel.h>
 22#include <linux/delay.h>
 23#include <linux/device.h>
 24#include <linux/gpio.h>
 25
 26#include <sound/l3.h>
 27
 28/*
 29 * Send one byte of data to the chip.  Data is latched into the chip on
 30 * the rising edge of the clock.
 31 */
 32static void sendbyte(struct l3_pins *adap, unsigned int byte)
 33{
 34	int i;
 35
 36	for (i = 0; i < 8; i++) {
 37		adap->setclk(adap, 0);
 38		udelay(adap->data_hold);
 39		adap->setdat(adap, byte & 1);
 40		udelay(adap->data_setup);
 41		adap->setclk(adap, 1);
 42		udelay(adap->clock_high);
 43		byte >>= 1;
 44	}
 45}
 46
 47/*
 48 * Send a set of bytes to the chip.  We need to pulse the MODE line
 49 * between each byte, but never at the start nor at the end of the
 50 * transfer.
 51 */
 52static void sendbytes(struct l3_pins *adap, const u8 *buf,
 53		      int len)
 54{
 55	int i;
 56
 57	for (i = 0; i < len; i++) {
 58		if (i) {
 59			udelay(adap->mode_hold);
 60			adap->setmode(adap, 0);
 61			udelay(adap->mode);
 62		}
 63		adap->setmode(adap, 1);
 64		udelay(adap->mode_setup);
 65		sendbyte(adap, buf[i]);
 66	}
 67}
 68
 69int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
 70{
 71	adap->setclk(adap, 1);
 72	adap->setdat(adap, 1);
 73	adap->setmode(adap, 1);
 74	udelay(adap->mode);
 75
 76	adap->setmode(adap, 0);
 77	udelay(adap->mode_setup);
 78	sendbyte(adap, addr);
 79	udelay(adap->mode_hold);
 80
 81	sendbytes(adap, data, len);
 82
 83	adap->setclk(adap, 1);
 84	adap->setdat(adap, 1);
 85	adap->setmode(adap, 0);
 86
 87	return len;
 88}
 89EXPORT_SYMBOL_GPL(l3_write);
 90
 91
 92static void l3_set_clk(struct l3_pins *adap, int val)
 93{
 94	gpio_set_value(adap->gpio_clk, val);
 95}
 96
 97static void l3_set_data(struct l3_pins *adap, int val)
 98{
 99	gpio_set_value(adap->gpio_data, val);
100}
101
102static void l3_set_mode(struct l3_pins *adap, int val)
103{
104	gpio_set_value(adap->gpio_mode, val);
105}
106
107int l3_set_gpio_ops(struct device *dev, struct l3_pins *adap)
108{
109	int ret;
110
111	if (!adap->use_gpios)
112		return -EINVAL;
113
114	ret = devm_gpio_request_one(dev, adap->gpio_data,
115				GPIOF_OUT_INIT_LOW, "l3_data");
116	if (ret < 0)
117		return ret;
118	adap->setdat = l3_set_data;
119
120	ret = devm_gpio_request_one(dev, adap->gpio_clk,
121				GPIOF_OUT_INIT_LOW, "l3_clk");
122	if (ret < 0)
123		return ret;
124	adap->setclk = l3_set_clk;
125
126	ret = devm_gpio_request_one(dev, adap->gpio_mode,
127				GPIOF_OUT_INIT_LOW, "l3_mode");
128	if (ret < 0)
129		return ret;
130	adap->setmode = l3_set_mode;
131
132	return 0;
133}
134EXPORT_SYMBOL_GPL(l3_set_gpio_ops);
135
136MODULE_DESCRIPTION("L3 bit-banging driver");
137MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
138MODULE_LICENSE("GPL");