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

   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");
 139