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
  24 #include <sound/l3.h>
  25
  26 /*
  27  * Send one byte of data to the chip.  Data is latched into the chip on
  28  * the rising edge of the clock.
  29  */
  30 static void sendbyte(struct l3_pins *adap, unsigned int byte)
  31 {
  32         int i;
  33
  34         for (i = 0; i < 8; i++) {
  35                 adap->setclk(0);
  36                 udelay(adap->data_hold);
  37                 adap->setdat(byte & 1);
  38                 udelay(adap->data_setup);
  39                 adap->setclk(1);
  40                 udelay(adap->clock_high);
  41                 byte >>= 1;
  42         }
  43 }
  44
  45 /*
  46  * Send a set of bytes to the chip.  We need to pulse the MODE line
  47  * between each byte, but never at the start nor at the end of the
  48  * transfer.
  49  */
  50 static void sendbytes(struct l3_pins *adap, const u8 *buf,
  51                       int len)
  52 {
  53         int i;
  54
  55         for (i = 0; i < len; i++) {
  56                 if (i) {
  57                         udelay(adap->mode_hold);
  58                         adap->setmode(0);
  59                         udelay(adap->mode);
  60                 }
  61                 adap->setmode(1);
  62                 udelay(adap->mode_setup);
  63                 sendbyte(adap, buf[i]);
  64         }
  65 }
  66
  67 int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
  68 {
  69         adap->setclk(1);
  70         adap->setdat(1);
  71         adap->setmode(1);
  72         udelay(adap->mode);
  73
  74         adap->setmode(0);
  75         udelay(adap->mode_setup);
  76         sendbyte(adap, addr);
  77         udelay(adap->mode_hold);
  78
  79         sendbytes(adap, data, len);
  80
  81         adap->setclk(1);
  82         adap->setdat(1);
  83         adap->setmode(0);
  84
  85         return len;
  86 }
  87 EXPORT_SYMBOL_GPL(l3_write);
  88
  89 MODULE_DESCRIPTION("L3 bit-banging driver");
  90 MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
  91 MODULE_LICENSE("GPL");