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Linux/sound/soc/codecs/l3.c

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  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");
139 

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