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 struct i2c_interface *i2c_if[MAX_I2C_INTERFACES];
  32
  33 static void i2c_start(struct i2c_interface *iface)
  34 {
  35     iface->sda_output();
  36
  37     iface->sda_hi();
  38     iface->scl_hi();
  39     iface->sda_lo();
  40     iface->delay_hd_sta();
  41     iface->scl_lo();
  42 }
  43
  44 static void i2c_stop(struct i2c_interface *iface)
  45 {
  46     iface->sda_output();
  47
  48     iface->sda_lo();
  49     iface->scl_hi();
  50     iface->delay_su_sto();
  51     iface->sda_hi();
  52 }
  53
  54 static void i2c_ack(struct i2c_interface *iface, bool ack)
  55 {
  56     iface->sda_output();
  57     iface->scl_lo();
  58     if ( ack )
  59         iface->sda_lo();
  60     else
  61         iface->sda_hi();
  62
  63     iface->delay_su_dat();
  64     iface->scl_hi();
  65     iface->delay_thigh();
  66     iface->scl_lo();
  67 }
  68
  69 static int i2c_getack(struct i2c_interface *iface)
  70 {
  71     int ret = 1;
  72
  73     iface->sda_input();
  74     iface->delay_su_dat();
  75     iface->scl_hi();
  76
  77     if (iface->sda())
  78         ret = 0; /* ack failed */
  79
  80     iface->delay_thigh();
  81     iface->scl_lo();
  82     iface->sda_hi();
  83     iface->sda_output();
  84     iface->delay_hd_dat();
  85     return ret;
  86 }
  87
  88 static unsigned char i2c_inb(struct i2c_interface *iface, bool ack)
  89 {
  90     int i;
  91     unsigned char byte = 0;
  92
  93     iface->sda_input();
  94
  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(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    iface->sda_hi();
 130
 131    return i2c_getack(iface);
 132 }
 133
 134 static struct i2c_interface *find_if(int address)
 135 {
 136     int i;
 137
 138     for(i = 0;i < i2c_num_ifs;i++) {
 139         if(i2c_if[i]->address == address)
 140             return i2c_if[i];
 141     }
 142     return NULL;
 143 }
 144
 145 int i2c_write_data(int bus_address, int address,
 146                    const unsigned char* buf, int count)
 147 {
 148     int i;
 149     int ret = 0;
 150     struct i2c_interface *iface = find_if(bus_address);
 151     if(!iface)
 152         return -1;
 153
 154     i2c_start(iface);
 155     if (!i2c_outb(iface, iface->address & 0xfe))
 156     {
 157         ret = -2;
 158         goto end;
 159     }
 160
 161     if (address != -1)
 162     {
 163         if (!i2c_outb(iface, address))
 164         {
 165             ret = -3;
 166             goto end;
 167         }
 168     }
 169
 170     for(i = 0;i < count;i++)
 171     {
 172         if (!i2c_outb(iface, buf[i]))
 173         {
 174             ret = -4;
 175             break;
 176         }
 177     }
 178
 179 end:
 180     i2c_stop(iface);
 181     return ret;
 182 }
 183
 184 int i2c_read_data(int bus_address, int address,
 185                   unsigned char* buf, int count)
 186 {
 187     int i;
 188     int ret = 0;
 189     struct i2c_interface *iface = find_if(bus_address);
 190     if(!iface)
 191         return -1;
 192
 193     if (address != -1)
 194     {
 195         i2c_start(iface);
 196         if (!i2c_outb(iface, iface->address & 0xfe))
 197         {
 198             ret = -2;
 199             goto end;
 200         }
 201         if (!i2c_outb(iface, address))
 202         {
 203             ret = -3;
 204             goto end;
 205         }
 206     }
 207
 208     i2c_start(iface);
 209     if (!i2c_outb(iface, iface->address | 1))
 210     {
 211         ret = -4;
 212         goto end;
 213     }
 214
 215     for(i = 0;i < count-1;i++)
 216         buf[i] = i2c_inb(iface, true);
 217
 218     buf[i] = i2c_inb(iface, false);
 219
 220 end:
 221     i2c_stop(iface);
 222     return ret;
 223 }
 224
 225 int i2c_add_node(struct i2c_interface *iface)
 226 {
 227     if (i2c_num_ifs == MAX_I2C_INTERFACES)
 228         return -1;
 229
 230     i2c_if[i2c_num_ifs++] = iface;
 231
 232     iface->scl_output();
 233
 234     return 0;
 235 }