board/pcippc2/i2c.c

   1 /*
   2  * (C) Copyright 2002
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <config.h>
  25 #include <common.h>
  26 #include <asm/io.h>
  27
  28 #include "hardware.h"
  29 #include "i2c.h"
  30
  31 static void             i2c_start       (void);
  32 static void             i2c_stop        (void);
  33 static int              i2c_write       (u8             data);
  34 static void             i2c_read        (u8 *           data);
  35
  36 static inline void      i2c_port_start  (void);
  37 static inline void      i2c_clock       (unsigned int   val);
  38 static inline void      i2c_data        (unsigned int   val);
  39 static inline unsigned int
  40                         i2c_in          (void);
  41 static inline void      i2c_write_bit   (unsigned int   val);
  42 static inline unsigned int
  43                         i2c_read_bit    (void);
  44
  45 static inline void      i2c_udelay      (unsigned int   time);
  46
  47 int i2c_read_byte (
  48   u8 *                  data,
  49   u8                    dev,
  50   u8                    offset)
  51 {
  52   int                   err = 0;
  53
  54   i2c_start();
  55
  56   err = ! i2c_write(dev);
  57
  58   if (! err)
  59   {
  60     err = ! i2c_write(offset);
  61   }
  62
  63   if (! err)
  64   {
  65     i2c_start();
  66   }
  67
  68   if (! err)
  69   {
  70     err = ! i2c_write(dev | 0x01);
  71   }
  72
  73   if (! err)
  74   {
  75     i2c_read(data);
  76   }
  77
  78   i2c_stop();
  79
  80   return ! err;
  81 }
  82
  83 static inline void i2c_udelay (
  84   unsigned int          time)
  85 {
  86   int                   v;
  87
  88   asm volatile("mtdec %0" : : "r" (time * ((CONFIG_SYS_BUS_CLK / 4) / 1000000)));
  89
  90   do
  91   {
  92     asm volatile("isync; mfdec %0" : "=r" (v));
  93   } while (v >= 0);
  94 }
  95
  96   /* Low-level hardware access
  97    */
  98
  99 #define BIT_GPDATA              0x80000000
 100 #define BIT_GPCLK               0x40000000
 101
 102 static inline void i2c_port_start (void)
 103 {
 104   out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~(BIT_GPCLK | BIT_GPDATA));
 105   out32(REG(CPC0, GPOUT), in32(REG(CPC0, GPOUT)) & ~(BIT_GPCLK | BIT_GPDATA));
 106   iobarrier_rw();
 107
 108   i2c_udelay(1);
 109 }
 110
 111 static inline void i2c_clock (
 112   unsigned int          val)
 113 {
 114   if (val)
 115   {
 116     out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~BIT_GPCLK);
 117   }
 118   else
 119   {
 120     out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) | BIT_GPCLK);
 121   }
 122
 123   iobarrier_rw();
 124
 125   i2c_udelay(1);
 126 }
 127
 128 static inline void i2c_data (
 129   unsigned int          val)
 130 {
 131   if (val)
 132   {
 133     out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~BIT_GPDATA);
 134   }
 135   else
 136   {
 137     out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) | BIT_GPDATA);
 138   }
 139
 140   iobarrier_rw();
 141
 142   i2c_udelay(1);
 143 }
 144
 145 static inline unsigned int i2c_in (void)
 146 {
 147   unsigned int          val = ((in32(REG(CPC0, GPIN)) & BIT_GPDATA) != 0)?1:0;
 148
 149   iobarrier_rw();
 150
 151   return val;
 152 }
 153
 154
 155   /* Protocol implementation
 156    */
 157
 158 static inline void i2c_write_bit (
 159   unsigned int          val)
 160 {
 161   i2c_data(val);
 162   i2c_udelay(10);
 163   i2c_clock(1);
 164   i2c_udelay(10);
 165   i2c_clock(0);
 166   i2c_udelay(10);
 167 }
 168
 169 static inline unsigned int i2c_read_bit (void)
 170 {
 171   unsigned int          val;
 172
 173   i2c_data(1);
 174   i2c_udelay(10);
 175
 176   i2c_clock(1);
 177   i2c_udelay(10);
 178
 179   val = i2c_in();
 180
 181   i2c_clock(0);
 182   i2c_udelay(10);
 183
 184   return val;
 185 }
 186
 187 unsigned int i2c_reset (void)
 188 {
 189   unsigned int          val;
 190   int i;
 191
 192   i2c_port_start();
 193
 194   i=0;
 195   do {
 196     i2c_udelay(10);
 197     i2c_clock(0);
 198     i2c_udelay(10);
 199     i2c_clock(1);
 200     i2c_udelay(10);
 201     val = i2c_in();
 202     i++;
 203   }  while ((i<9)&&(val==0));
 204   return (val);
 205 }
 206
 207
 208 static void i2c_start (void)
 209 {
 210   i2c_data(1);
 211   i2c_clock(1);
 212   i2c_udelay(10);
 213   i2c_data(0);
 214   i2c_udelay(10);
 215   i2c_clock(0);
 216   i2c_udelay(10);
 217 }
 218
 219 static void i2c_stop (void)
 220 {
 221   i2c_data(0);
 222   i2c_udelay(10);
 223   i2c_clock(1);
 224   i2c_udelay(10);
 225   i2c_data(1);
 226   i2c_udelay(10);
 227 }
 228
 229 static int i2c_write (
 230   u8                    data)
 231 {
 232   unsigned int          i;
 233
 234   for (i = 0; i < 8; i++)
 235   {
 236     i2c_write_bit(data >> 7);
 237     data <<= 1;
 238   }
 239
 240   return i2c_read_bit() == 0;
 241 }
 242
 243 static void i2c_read (
 244   u8 *                  data)
 245 {
 246   unsigned int          i;
 247   u8                    val = 0;
 248
 249   for (i = 0; i < 8; i++)
 250   {
 251     val <<= 1;
 252     val |= i2c_read_bit();
 253   }
 254
 255   *data = val;
 256   i2c_write_bit(1); /* NoAck */
 257 }