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  */
  26 static 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  */
  46 static 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
  63 int 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 }
  83 EXPORT_SYMBOL_GPL(l3_write);
  84
  85
  86 static void l3_set_clk(struct l3_pins *adap, int val)
  87 {
  88         gpio_set_value(adap->gpio_clk, val);
  89 }
  90
  91 static void l3_set_data(struct l3_pins *adap, int val)
  92 {
  93         gpio_set_value(adap->gpio_data, val);
  94 }
  95
  96 static void l3_set_mode(struct l3_pins *adap, int val)
  97 {
  98         gpio_set_value(adap->gpio_mode, val);
  99 }
 100
 101 int 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 }
 128 EXPORT_SYMBOL_GPL(l3_set_gpio_ops);
 129
 130 MODULE_DESCRIPTION("L3 bit-banging driver");
 131 MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
 132 MODULE_LICENSE("GPL");