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  */
  32 static 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  */
  52 static 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
  69 int 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 }
  89 EXPORT_SYMBOL_GPL(l3_write);
  90
  91
  92 static void l3_set_clk(struct l3_pins *adap, int val)
  93 {
  94         gpio_set_value(adap->gpio_clk, val);
  95 }
  96
  97 static void l3_set_data(struct l3_pins *adap, int val)
  98 {
  99         gpio_set_value(adap->gpio_data, val);
 100 }
 101
 102 static void l3_set_mode(struct l3_pins *adap, int val)
 103 {
 104         gpio_set_value(adap->gpio_mode, val);
 105 }
 106
 107 int 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 }
 134 EXPORT_SYMBOL_GPL(l3_set_gpio_ops);
 135
 136 MODULE_DESCRIPTION("L3 bit-banging driver");
 137 MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
 138 MODULE_LICENSE("GPL");