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     /* clock in each bit, MSB first */
  95     for ( i=0x80; i; i>>=1 ) {
  96         iface->delay_su_dat();
  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    }
 127
 128    return i2c_getack(iface);
 129 }
 130
 131 int i2c_write_data(int bus_index, int bus_address, int address,
 132                    const unsigned char* buf, int count)
 133 {
 134     int i;
 135     int ret = 0;
 136     const struct i2c_interface *iface = i2c_if[bus_index];
 137
 138     i2c_start(iface);
 139     if (!i2c_outb(iface, bus_address & 0xfe))
 140     {
 141         ret = -2;
 142         goto end;
 143     }
 144
 145     if (address != -1)
 146     {
 147         if (!i2c_outb(iface, address))
 148         {
 149             ret = -3;
 150             goto end;
 151         }
 152     }
 153
 154     for(i = 0;i < count;i++)
 155     {
 156         if (!i2c_outb(iface, buf[i]))
 157         {
 158             ret = -4;
 159             break;
 160         }
 161     }
 162
 163 end:
 164     i2c_stop(iface);
 165     return ret;
 166 }
 167
 168 int i2c_read_data(int bus_index, int bus_address, int address,
 169                   unsigned char* buf, int count)
 170 {
 171     int i;
 172     int ret = 0;
 173     const struct i2c_interface *iface = i2c_if[bus_index];
 174
 175     if (address != -1)
 176     {
 177         i2c_start(iface);
 178         if (!i2c_outb(iface, bus_address & 0xfe))
 179         {
 180             ret = -2;
 181             goto end;
 182         }
 183         if (!i2c_outb(iface, address))
 184         {
 185             ret = -3;
 186             goto end;
 187         }
 188     }
 189
 190     i2c_start(iface);
 191     if (!i2c_outb(iface, bus_address | 1))
 192     {
 193         ret = -4;
 194         goto end;
 195     }
 196
 197     for(i = 0;i < count-1;i++)
 198         buf[i] = i2c_inb(iface, true);
 199
 200     buf[i] = i2c_inb(iface, false);
 201
 202 end:
 203     i2c_stop(iface);
 204     return ret;
 205 }
 206
 207 /* returns bus index which can be used as a handle, or <0 on error */
 208 int i2c_add_node(const struct i2c_interface *iface)
 209 {
 210     int bus_index;
 211
 212     if (i2c_num_ifs == MAX_I2C_INTERFACES)
 213         return -1;
 214
 215     bus_index = i2c_num_ifs++;
 216     i2c_if[bus_index] = iface;
 217
 218     iface->scl_output();
 219
 220     return bus_index;
 221 }