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
  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 */
  30static 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 */
  50static 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
  67int 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}
  87EXPORT_SYMBOL_GPL(l3_write);
  88
  89MODULE_DESCRIPTION("L3 bit-banging driver");
  90MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
  91MODULE_LICENSE("GPL");
  92