LXR linux/sound/soc/codecs/l3.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * L3 code
   4 *
   5 *  Copyright (C) 2008, Christian Pellegrin <chripell@evolware.org>
   6 *
   7 * based on:
   8 *
   9 * L3 bus algorithm module.
  10 *
  11 *  Copyright (C) 2001 Russell King, All Rights Reserved.
  12 */
  13
  14#include <linux/module.h>
  15#include <linux/kernel.h>
  16#include <linux/delay.h>
  17#include <linux/device.h>
  18#include <linux/gpio.h>
  19
  20#include <sound/l3.h>
  21
  22/*
  23 * Send one byte of data to the chip.  Data is latched into the chip on
  24 * the rising edge of the clock.
  25 */
  26static void sendbyte(struct l3_pins *adap, unsigned int byte)
  27{
  28        int i;
  29
  30        for (i = 0; i < 8; i++) {
  31                adap->setclk(adap, 0);
  32                udelay(adap->data_hold);
  33                adap->setdat(adap, byte & 1);
  34                udelay(adap->data_setup);
  35                adap->setclk(adap, 1);
  36                udelay(adap->clock_high);
  37                byte >>= 1;
  38        }
  39}
  40
  41/*
  42 * Send a set of bytes to the chip.  We need to pulse the MODE line
  43 * between each byte, but never at the start nor at the end of the
  44 * transfer.
  45 */
  46static void sendbytes(struct l3_pins *adap, const u8 *buf,
  47                      int len)
  48{
  49        int i;
  50
  51        for (i = 0; i < len; i++) {
  52                if (i) {
  53                        udelay(adap->mode_hold);
  54                        adap->setmode(adap, 0);
  55                        udelay(adap->mode);
  56                }
  57                adap->setmode(adap, 1);
  58                udelay(adap->mode_setup);
  59                sendbyte(adap, buf[i]);
  60        }
  61}
  62
  63int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
  64{
  65        adap->setclk(adap, 1);
  66        adap->setdat(adap, 1);
  67        adap->setmode(adap, 1);
  68        udelay(adap->mode);
  69
  70        adap->setmode(adap, 0);
  71        udelay(adap->mode_setup);
  72        sendbyte(adap, addr);
  73        udelay(adap->mode_hold);
  74
  75        sendbytes(adap, data, len);
  76
  77        adap->setclk(adap, 1);
  78        adap->setdat(adap, 1);
  79        adap->setmode(adap, 0);
  80
  81        return len;
  82}
  83EXPORT_SYMBOL_GPL(l3_write);
  84
  85
  86static void l3_set_clk(struct l3_pins *adap, int val)
  87{
  88        gpio_set_value(adap->gpio_clk, val);
  89}
  90
  91static void l3_set_data(struct l3_pins *adap, int val)
  92{
  93        gpio_set_value(adap->gpio_data, val);
  94}
  95
  96static void l3_set_mode(struct l3_pins *adap, int val)
  97{
  98        gpio_set_value(adap->gpio_mode, val);
  99}
 100
 101int l3_set_gpio_ops(struct device *dev, struct l3_pins *adap)
 102{
 103        int ret;
 104
 105        if (!adap->use_gpios)
 106                return -EINVAL;
 107
 108        ret = devm_gpio_request_one(dev, adap->gpio_data,
 109                                GPIOF_OUT_INIT_LOW, "l3_data");
 110        if (ret < 0)
 111                return ret;
 112        adap->setdat = l3_set_data;
 113
 114        ret = devm_gpio_request_one(dev, adap->gpio_clk,
 115                                GPIOF_OUT_INIT_LOW, "l3_clk");
 116        if (ret < 0)
 117                return ret;
 118        adap->setclk = l3_set_clk;
 119
 120        ret = devm_gpio_request_one(dev, adap->gpio_mode,
 121                                GPIOF_OUT_INIT_LOW, "l3_mode");
 122        if (ret < 0)
 123                return ret;
 124        adap->setmode = l3_set_mode;
 125
 126        return 0;
 127}
 128EXPORT_SYMBOL_GPL(l3_set_gpio_ops);
 129
 130MODULE_DESCRIPTION("L3 bit-banging driver");
 131MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
 132MODULE_LICENSE("GPL");
 133