firmware/drivers/generic_i2c.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2006 by Linus Nielsen Feltzing
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include "config.h"
  22 #include "cpu.h"
  23 #include <stdbool.h>
  24 #include <stdlib.h>
  25 #include "debug.h"
  26 #include "generic_i2c.h"
  27
  28 #define MAX_I2C_INTERFACES 5
  29
  30 static int i2c_num_ifs = 0;
  31 static const struct i2c_interface *i2c_if[MAX_I2C_INTERFACES];
  32
  33 static void i2c_start(const struct i2c_interface *iface)
  34 {
  35     iface->sda_output();
  36
  37     iface->sda_hi();
  38     iface->scl_hi();
  39     iface->delay_su_sta();
  40     iface->sda_lo();
  41     iface->delay_hd_sta();
  42     iface->scl_lo();
  43     iface->delay_hd_dat();
  44 }
  45
  46 static void i2c_stop(const struct i2c_interface *iface)
  47 {
  48     iface->sda_output();
  49
  50     iface->sda_lo();
  51     iface->delay_su_dat();
  52     iface->scl_hi();
  53     iface->delay_su_sto();
  54     iface->sda_hi();
  55 }
  56
  57 static void i2c_ack(const struct i2c_interface *iface, bool ack)
  58 {
  59     iface->sda_output();
  60     if ( ack )
  61         iface->sda_lo();
  62     else
  63         iface->sda_hi();
  64
  65     iface->delay_su_dat();
  66     iface->scl_hi();
  67     iface->delay_thigh();
  68     iface->scl_lo();
  69     iface->delay_hd_dat();
  70 }
  71
  72 static int i2c_getack(const struct i2c_interface *iface)
  73 {
  74     int ret = 1;
  75
  76     iface->sda_input();
  77     iface->delay_su_dat();
  78     iface->scl_hi();
  79     iface->delay_thigh();
  80     if (iface->sda())
  81         ret = 0; /* ack failed */
  82     iface->scl_lo();
  83     iface->delay_hd_dat();
  84     return ret;
  85 }
  86
  87 static unsigned char i2c_inb(const struct i2c_interface *iface, bool ack)
  88 {
  89     int i;
  90     unsigned char byte = 0;
  91
  92     iface->sda_input();
  93
  94     iface->delay_su_dat();
  95     /* clock in each bit, MSB first */
  96     for ( i=0x80; i; i>>=1 ) {
  97         iface->scl_hi();
  98         iface->delay_thigh();
  99         if (iface->sda())
 100             byte |= i;
 101         iface->scl_lo();
 102         iface->delay_hd_dat();
 103     }
 104
 105     i2c_ack(iface, ack);
 106
 107     return byte;
 108 }
 109
 110 static int i2c_outb(const struct i2c_interface *iface, unsigned char byte)
 111 {
 112     int i;
 113
 114     iface->sda_output();
 115
 116     /* clock out each bit, MSB first */
 117     for (i=0x80; i; i>>=1) {
 118         if (i & byte)
 119             iface->sda_hi();
 120         else
 121             iface->sda_lo();
 122         iface->delay_su_dat();
 123         iface->scl_hi();
 124         iface->delay_thigh();
 125         iface->scl_lo();
 126         iface->delay_hd_dat();
 127    }
 128
 129    return i2c_getack(iface);
 130 }
 131
 132 int i2c_write_data(int bus_index, int bus_address, int address,
 133                    const unsigned char* buf, int count)
 134 {
 135     int i;
 136     int ret = 0;
 137     const struct i2c_interface *iface = i2c_if[bus_index];
 138
 139     i2c_start(iface);
 140     if (!i2c_outb(iface, bus_address & 0xfe))
 141     {
 142         ret = -2;
 143         goto end;
 144     }
 145
 146     if (address != -1)
 147     {
 148         if (!i2c_outb(iface, address))
 149         {
 150             ret = -3;
 151             goto end;
 152         }
 153     }
 154
 155     for(i = 0;i < count;i++)
 156     {
 157         if (!i2c_outb(iface, buf[i]))
 158         {
 159             ret = -4;
 160             break;
 161         }
 162     }
 163
 164 end:
 165     i2c_stop(iface);
 166     return ret;
 167 }
 168
 169 int i2c_read_data(int bus_index, int bus_address, int address,
 170                   unsigned char* buf, int count)
 171 {
 172     int i;
 173     int ret = 0;
 174     const struct i2c_interface *iface = i2c_if[bus_index];
 175
 176     if (address != -1)
 177     {
 178         i2c_start(iface);
 179         if (!i2c_outb(iface, bus_address & 0xfe))
 180         {
 181             ret = -2;
 182             goto end;
 183         }
 184         if (!i2c_outb(iface, address))
 185         {
 186             ret = -3;
 187             goto end;
 188         }
 189     }
 190
 191     i2c_start(iface);
 192     if (!i2c_outb(iface, bus_address | 1))
 193     {
 194         ret = -4;
 195         goto end;
 196     }
 197
 198     for(i = 0;i < count-1;i++)
 199         buf[i] = i2c_inb(iface, true);
 200
 201     buf[i] = i2c_inb(iface, false);
 202
 203 end:
 204     i2c_stop(iface);
 205     return ret;
 206 }
 207
 208 /* returns bus index which can be used as a handle, or <0 on error */
 209 int i2c_add_node(const struct i2c_interface *iface)
 210 {
 211     int bus_index;
 212
 213     if (i2c_num_ifs == MAX_I2C_INTERFACES)
 214         return -1;
 215
 216     bus_index = i2c_num_ifs++;
 217     i2c_if[bus_index] = iface;
 218
 219     iface->scl_output();
 220
 221     return bus_index;
 222 }