firmware/target/arm/iriver/h10/fmradio_i2c-h10.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  * Physical interface of the Philips TEA5767 in iriver H10 series
  10  *
  11  * Copyright (C) 2002 by Linus Nielsen Feltzing
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  19  * KIND, either express or implied.
  20  *
  21  ****************************************************************************/
  22 #include "config.h"
  23 #include "cpu.h"
  24 #include "logf.h"
  25 #include "system.h"
  26 #include "fmradio_i2c.h"
  27
  28 /* cute little functions, atomic read-modify-write */
  29
  30 #define SDA_OUTINIT GPIO_CLEAR_BITWISE(GPIOD_OUTPUT_VAL, 0x08)
  31 #define SDA_HI_IN   GPIO_CLEAR_BITWISE(GPIOD_OUTPUT_EN, 0x08)
  32 #define SDA_LO_OUT  GPIO_SET_BITWISE(GPIOD_OUTPUT_EN, 0x08)
  33 #define SDA         (GPIOD_INPUT_VAL & 0x08)
  34
  35 #define SCL_INPUT   GPIO_CLEAR_BITWISE(GPIOD_OUTPUT_EN, 0x10)
  36 #define SCL_OUTPUT  GPIO_SET_BITWISE(GPIOD_OUTPUT_EN, 0x10)
  37 #define SCL_LO      GPIO_CLEAR_BITWISE(GPIOD_OUTPUT_VAL, 0x10)
  38 #define SCL_HI      GPIO_SET_BITWISE(GPIOD_OUTPUT_VAL,0x10)
  39 #define SCL         (GPIOD_INPUT_VAL & 0x10)
  40
  41 #define DELAY   udelay(2)
  42
  43 static void fmradio_i2c_start(void)
  44 {
  45     SCL_HI;
  46     SCL_OUTPUT;
  47     SDA_HI_IN;
  48     SDA_OUTINIT;
  49     DELAY;
  50     SDA_LO_OUT;
  51     DELAY;
  52     SCL_LO;
  53 }
  54
  55 static void fmradio_i2c_stop(void)
  56 {
  57    SDA_LO_OUT;
  58    DELAY;
  59    SCL_HI;
  60    DELAY;
  61    SDA_HI_IN;
  62 }
  63
  64 /* Generate ACK or NACK */
  65 static void fmradio_i2c_ack(bool nack)
  66 {
  67     /* Here's the deal. The slave is slow, and sometimes needs to wait
  68        before it can receive the acknowledge. Therefore it forces the clock
  69        low until it is ready. We need to poll the clock line until it goes
  70        high before we release the ack.
  71
  72        In their infinite wisdom, iriver didn't pull up the SCL line, so
  73        we have to drive the SCL high repeatedly to simulate a pullup. */
  74
  75     if (nack)
  76         SDA_HI_IN;
  77     else
  78         SDA_LO_OUT;
  79     DELAY;
  80
  81     SCL_HI;
  82     do
  83     {
  84         SCL_OUTPUT;  /* Set the clock to output */
  85         SCL_INPUT;   /* Set the clock to input */
  86         DELAY;
  87     }
  88     while(!SCL);  /* and wait for the slave to release it */
  89
  90     SCL_OUTPUT;
  91     SCL_LO;
  92 }
  93
  94 static int fmradio_i2c_getack(void)
  95 {
  96     int ret = 1;
  97
  98     /* Here's the deal. The slave is slow, and sometimes needs to wait
  99        before it can send the acknowledge. Therefore it forces the clock
 100        low until it is ready. We need to poll the clock line until it goes
 101        high before we read the ack.
 102
 103        In their infinite wisdom, iriver didn't pull up the SCL line, so
 104        we have to drive the SCL high repeatedly to simulate a pullup. */
 105
 106     SDA_HI_IN;
 107     DELAY;
 108
 109     SCL_HI;          /* set clock to high */
 110     do
 111     {
 112         SCL_OUTPUT;  /* Set the clock to output */
 113         SCL_INPUT;   /* Set the clock to input */
 114         DELAY;
 115     }
 116     while(!SCL);     /* and wait for the slave to release it */
 117
 118     if (SDA)
 119         ret = 0;    /* ack failed */
 120
 121     SCL_OUTPUT;
 122     SCL_LO;
 123
 124     return ret;
 125 }
 126
 127 static void fmradio_i2c_outb(unsigned char byte)
 128 {
 129    int i;
 130
 131    /* clock out each bit, MSB first */
 132    for ( i=0x80; i; i>>=1 ) {
 133       if ( i & byte )
 134          SDA_HI_IN;
 135       else
 136          SDA_LO_OUT;
 137       DELAY;
 138       SCL_HI;
 139       DELAY;
 140       SCL_LO;
 141
 142       DELAY;
 143    }
 144 }
 145
 146 static unsigned char fmradio_i2c_inb(void)
 147 {
 148    int i;
 149    unsigned char byte = 0;
 150
 151    SDA_HI_IN;
 152    /* clock in each bit, MSB first */
 153    for ( i=0x80; i; i>>=1 ) {
 154        DELAY;
 155        SCL_HI;
 156        DELAY;
 157        if ( SDA )
 158            byte |= i;
 159        SCL_LO;
 160    }
 161
 162    return byte;
 163 }
 164
 165 int fmradio_i2c_write(unsigned char address, const unsigned char* buf, int count)
 166 {
 167     int i,x=0;
 168
 169     fmradio_i2c_start();
 170     fmradio_i2c_outb(address & 0xfe);
 171     if (fmradio_i2c_getack())
 172     {
 173         for (i=0; i<count; i++)
 174         {
 175             fmradio_i2c_outb(buf[i]);
 176             if (!fmradio_i2c_getack())
 177             {
 178                 x=-2;
 179                 break;
 180             }
 181         }
 182     }
 183     else
 184     {
 185         logf("fmradio_i2c_write() - no ack\n");
 186         x=-1;
 187     }
 188     fmradio_i2c_stop();
 189     return x;
 190 }
 191
 192 int fmradio_i2c_read(unsigned char address, unsigned char* buf, int count)
 193 {
 194     int i,x=0;
 195
 196     fmradio_i2c_start();
 197     fmradio_i2c_outb(address | 1);
 198
 199     if (fmradio_i2c_getack())
 200     {
 201         for (i=count; i>0; i--)
 202         {
 203             *buf++ = fmradio_i2c_inb();
 204             fmradio_i2c_ack(i == 1);
 205         }
 206     }
 207     else
 208         x=-1;
 209     fmradio_i2c_stop();
 210     return x;
 211 }