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  * All files in this archive are subject to the GNU General Public License.
  13  * See the file COPYING in the source tree root for full license agreement.
  14  *
  15  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  16  * KIND, either express or implied.
  17  *
  18  ****************************************************************************/
  19 #include "config.h"
  20 #include "cpu.h"
  21 #include <stdbool.h>
  22 #include <stdlib.h>
  23 #include "debug.h"
  24 #include "logf.h"
  25 #include "generic_i2c.h"
  26
  27 int i2c_num_ifs = 0;
  28 struct i2c_interface *i2c_if[5];
  29
  30 static void i2c_start(struct i2c_interface *iface)
  31 {
  32     iface->sda_hi();
  33     iface->scl_hi();
  34     iface->sda_lo();
  35     iface->delay_hd_sta();
  36     iface->scl_lo();
  37 }
  38
  39 static void i2c_stop(struct i2c_interface *iface)
  40 {
  41     iface->sda_lo();
  42     iface->scl_hi();
  43     iface->delay_su_sto();
  44     iface->sda_hi();
  45 }
  46
  47 static void i2c_ack(struct i2c_interface *iface, bool ack)
  48 {
  49     iface->scl_lo();
  50     if ( ack )
  51         iface->sda_lo();
  52     else
  53         iface->sda_hi();
  54
  55     iface->delay_su_dat();
  56     iface->scl_hi();
  57     iface->delay_thigh();
  58     iface->scl_lo();
  59 }
  60
  61 static int i2c_getack(struct i2c_interface *iface)
  62 {
  63     int ret = 1;
  64
  65     iface->sda_input();
  66     iface->delay_su_dat();
  67     iface->scl_hi();
  68
  69     if (iface->sda())
  70         ret = 0; /* ack failed */
  71
  72     iface->delay_thigh();
  73     iface->scl_lo();
  74     iface->sda_hi();
  75     iface->sda_output();
  76     iface->delay_hd_dat();
  77     return ret;
  78 }
  79
  80 static unsigned char i2c_inb(struct i2c_interface *iface, bool ack)
  81 {
  82     int i;
  83     unsigned char byte = 0;
  84
  85     /* clock in each bit, MSB first */
  86     for ( i=0x80; i; i>>=1 ) {
  87         iface->sda_input();
  88         iface->scl_hi();
  89         iface->delay_thigh();
  90         if (iface->sda())
  91             byte |= i;
  92         iface->scl_lo();
  93         iface->delay_hd_dat();
  94         iface->sda_output();
  95     }
  96
  97     i2c_ack(iface, ack);
  98
  99     return byte;
 100 }
 101
 102 static void i2c_outb(struct i2c_interface *iface, unsigned char byte)
 103 {
 104    int i;
 105
 106    /* clock out each bit, MSB first */
 107    for (i=0x80; i; i>>=1) {
 108        if (i & byte)
 109            iface->sda_hi();
 110        else
 111            iface->sda_lo();
 112        iface->delay_su_dat();
 113        iface->scl_hi();
 114        iface->delay_thigh();
 115        iface->scl_lo();
 116        iface->delay_hd_dat();
 117    }
 118
 119    iface->sda_hi();
 120 }
 121
 122 static struct i2c_interface *find_if(int address)
 123 {
 124     int i;
 125
 126     for(i = 0;i < i2c_num_ifs;i++) {
 127         if(i2c_if[i]->address == address)
 128             return i2c_if[i];
 129     }
 130     return NULL;
 131 }
 132
 133 int i2c_write_data(int bus_address, int address,
 134                    const unsigned char* buf, int count)
 135 {
 136     int i;
 137     int ret = 0;
 138     struct i2c_interface *iface = find_if(bus_address);
 139     if(!iface)
 140         return -1;
 141
 142     i2c_start(iface);
 143     i2c_outb(iface, iface->address & 0xfe);
 144     if (i2c_getack(iface)) {
 145         i2c_outb(iface, address);
 146         if (i2c_getack(iface)) {
 147             for(i = 0;i < count;i++) {
 148                 i2c_outb(iface, buf[i]);
 149                 if (!i2c_getack(iface)) {
 150                     ret = -3;
 151                     break;
 152                 }
 153             }
 154         } else {
 155             ret = -2;
 156         }
 157     } else {
 158         logf("i2c_write_data() - no ack\n");
 159         ret = -1;
 160     }
 161
 162     i2c_stop(iface);
 163     return ret;
 164 }
 165
 166 int i2c_read_data(int bus_address, int address,
 167                   unsigned char* buf, int count)
 168 {
 169     int i;
 170     int ret = 0;
 171     struct i2c_interface *iface = find_if(bus_address);
 172     if(!iface)
 173         return -1;
 174
 175     i2c_start(iface);
 176     i2c_outb(iface, iface->address & 0xfe);
 177     if (i2c_getack(iface)) {
 178         i2c_outb(iface, address);
 179         if (i2c_getack(iface)) {
 180             i2c_start(iface);
 181             i2c_outb(iface, iface->address | 1);
 182             if (i2c_getack(iface)) {
 183                 for(i = 0;i < count-1;i++)
 184                     buf[i] = i2c_inb(iface, true);
 185
 186                 buf[i] = i2c_inb(iface, false);
 187             } else {
 188                 ret = -3;
 189             }
 190         } else {
 191             ret = -2;
 192         }
 193     } else {
 194         ret = -1;
 195     }
 196
 197     i2c_stop(iface);
 198     return ret;
 199 }
 200
 201 void i2c_add_node(struct i2c_interface *iface)
 202 {
 203     i2c_if[i2c_num_ifs++] = iface;
 204 }