drivers/omap1510_i2c.c

   1 /*
   2  * Basic I2C functions
   3  *
   4  * Copyright (c) 2003 Texas Instruments
   5  *
   6  * This package is free software;  you can redistribute it and/or
   7  * modify it under the terms of the license found in the file
   8  * named COPYING that should have accompanied this file.
   9  *
  10  * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  11  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  12  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  13  *
  14  * Author: Jian Zhang jzhang@ti.com, Texas Instruments
  15  *
  16  * Copyright (c) 2003 Wolfgang Denk, wd@denx.de
  17  * Rewritten to fit into the current U-Boot framework
  18  *
  19  */
  20
  21 #include <common.h>
  22
  23 #ifdef CONFIG_DRIVER_OMAP1510_I2C
  24
  25 static void wait_for_bb (void);
  26 static u16 wait_for_pin (void);
  27
  28 void i2c_init (int speed, int slaveadd)
  29 {
  30         u16 scl;
  31
  32         if (inw (I2C_CON) & I2C_CON_EN) {
  33                 outw (0, I2C_CON);
  34                 udelay (5000);
  35         }
  36
  37         /* 12Mhz I2C module clock */
  38         outw (0, I2C_PSC);
  39         outw (I2C_CON_EN, I2C_CON);
  40         outw (0, I2C_SYSTEST);
  41         /* have to enable intrrupts or OMAP i2c module doesn't work */
  42         outw (I2C_IE_XRDY_IE | I2C_IE_RRDY_IE | I2C_IE_ARDY_IE |
  43               I2C_IE_NACK_IE | I2C_IE_AL_IE, I2C_IE);
  44         scl = (12000000 / 2) / speed - 6;
  45         outw (scl, I2C_SCLL);
  46         outw (scl, I2C_SCLH);
  47         /* own address */
  48         outw (slaveadd, I2C_OA);
  49         outw (0, I2C_CNT);
  50         udelay (1000);
  51 }
  52
  53 static int i2c_read_byte (u8 devaddr, u8 regoffset, u8 * value)
  54 {
  55         int i2c_error = 0;
  56         u16 status;
  57
  58         /* wait until bus not busy */
  59         wait_for_bb ();
  60
  61         /* one byte only */
  62         outw (1, I2C_CNT);
  63         /* set slave address */
  64         outw (devaddr, I2C_SA);
  65         /* no stop bit needed here */
  66         outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX, I2C_CON);
  67
  68         status = wait_for_pin ();
  69
  70         if (status & I2C_STAT_XRDY) {
  71                 /* Important: have to use byte access */
  72                 *(volatile u8 *) (I2C_DATA) = regoffset;
  73                 udelay (20000);
  74                 if (inw (I2C_STAT) & I2C_STAT_NACK) {
  75                         i2c_error = 1;
  76                 }
  77         } else {
  78                 i2c_error = 1;
  79         }
  80
  81         if (!i2c_error) {
  82                 /* free bus, otherwise we can't use a combined transction */
  83                 outw (0, I2C_CON);
  84                 while (inw (I2C_STAT) || (inw (I2C_CON) & I2C_CON_MST)) {
  85                         udelay (10000);
  86                         /* Have to clear pending interrupt to clear I2C_STAT */
  87                         inw (I2C_IV);
  88                 }
  89
  90                 wait_for_bb ();
  91                 /* set slave address */
  92                 outw (devaddr, I2C_SA);
  93                 /* read one byte from slave */
  94                 outw (1, I2C_CNT);
  95                 /* need stop bit here */
  96                 outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP,
  97                       I2C_CON);
  98
  99                 status = wait_for_pin ();
 100                 if (status & I2C_STAT_RRDY) {
 101                         *value = inw (I2C_DATA);
 102                         udelay (20000);
 103                 } else {
 104                         i2c_error = 1;
 105                 }
 106
 107                 if (!i2c_error) {
 108                         outw (I2C_CON_EN, I2C_CON);
 109                         while (inw (I2C_STAT)
 110                                || (inw (I2C_CON) & I2C_CON_MST)) {
 111                                 udelay (10000);
 112                                 inw (I2C_IV);
 113                         }
 114                 }
 115         }
 116
 117         return i2c_error;
 118 }
 119
 120 static int i2c_write_byte (u8 devaddr, u8 regoffset, u8 value)
 121 {
 122         int i2c_error = 0;
 123         u16 status;
 124
 125         /* wait until bus not busy */
 126         wait_for_bb ();
 127
 128         /* two bytes */
 129         outw (2, I2C_CNT);
 130         /* set slave address */
 131         outw (devaddr, I2C_SA);
 132         /* stop bit needed here */
 133         outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX |
 134               I2C_CON_STP, I2C_CON);
 135
 136         /* wait until state change */
 137         status = wait_for_pin ();
 138
 139         if (status & I2C_STAT_XRDY) {
 140                 /* send out two bytes */
 141                 outw ((value << 8) + regoffset, I2C_DATA);
 142                 /* must have enough delay to allow BB bit to go low */
 143                 udelay (30000);
 144                 if (inw (I2C_STAT) & I2C_STAT_NACK) {
 145                         i2c_error = 1;
 146                 }
 147         } else {
 148                 i2c_error = 1;
 149         }
 150
 151         if (!i2c_error) {
 152                 outw (I2C_CON_EN, I2C_CON);
 153                 while (inw (I2C_STAT) || (inw (I2C_CON) & I2C_CON_MST)) {
 154                         udelay (1000);
 155                         /* have to read to clear intrrupt */
 156                         inw (I2C_IV);
 157                 }
 158         }
 159
 160         return i2c_error;
 161 }
 162
 163 int i2c_probe (uchar chip)
 164 {
 165         int res = 1;
 166
 167         if (chip == inw (I2C_OA)) {
 168                 return res;
 169         }
 170
 171         /* wait until bus not busy */
 172         wait_for_bb ();
 173
 174         /* try to read one byte */
 175         outw (1, I2C_CNT);
 176         /* set slave address */
 177         outw (chip, I2C_SA);
 178         /* stop bit needed here */
 179         outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP, I2C_CON);
 180         /* enough delay for the NACK bit set */
 181         udelay (2000);
 182         if (!(inw (I2C_STAT) & I2C_STAT_NACK)) {
 183                 res = 0;
 184         } else {
 185                 outw (inw (I2C_CON) | I2C_CON_STP, I2C_CON);
 186                 udelay (20);
 187                 wait_for_bb ();
 188         }
 189
 190         return res;
 191 }
 192
 193 int i2c_read (uchar chip, uint addr, int alen, uchar * buffer, int len)
 194 {
 195         int i;
 196
 197         if (alen > 1) {
 198                 printf ("I2C read: addr len %d not supported\n", alen);
 199                 return 1;
 200         }
 201
 202         if (addr + len > 256) {
 203                 printf ("I2C read: address out of range\n");
 204                 return 1;
 205         }
 206
 207         for (i = 0; i < len; i++) {
 208                 if (i2c_read_byte (chip, addr + i, &buffer[i])) {
 209                         printf ("I2C read: I/O error\n");
 210                         i2c_init (CFG_I2C_SPEED, CFG_I2C_SLAVE);
 211                         return 1;
 212                 }
 213         }
 214
 215         return 0;
 216 }
 217
 218 int i2c_write (uchar chip, uint addr, int alen, uchar * buffer, int len)
 219 {
 220         int i;
 221
 222         if (alen > 1) {
 223                 printf ("I2C read: addr len %d not supported\n", alen);
 224                 return 1;
 225         }
 226
 227         if (addr + len > 256) {
 228                 printf ("I2C read: address out of range\n");
 229                 return 1;
 230         }
 231
 232         for (i = 0; i < len; i++) {
 233                 if (i2c_write_byte (chip, addr + i, buffer[i])) {
 234                         printf ("I2C read: I/O error\n");
 235                         i2c_init (CFG_I2C_SPEED, CFG_I2C_SLAVE);
 236                         return 1;
 237                 }
 238         }
 239
 240         return 0;
 241 }
 242
 243 static void wait_for_bb (void)
 244 {
 245         int timeout = 10;
 246
 247         while ((inw (I2C_STAT) & I2C_STAT_BB) && timeout--) {
 248                 inw (I2C_IV);
 249                 udelay (1000);
 250         }
 251
 252         if (timeout <= 0) {
 253                 printf ("timed out in wait_for_bb: I2C_STAT=%x\n",
 254                         inw (I2C_STAT));
 255         }
 256 }
 257
 258 static u16 wait_for_pin (void)
 259 {
 260         u16 status, iv;
 261         int timeout = 10;
 262
 263         do {
 264                 udelay (1000);
 265                 status = inw (I2C_STAT);
 266                 iv = inw (I2C_IV);
 267         } while (!iv &&
 268                  !(status &
 269                    (I2C_STAT_ROVR | I2C_STAT_XUDF | I2C_STAT_XRDY |
 270                     I2C_STAT_RRDY | I2C_STAT_ARDY | I2C_STAT_NACK |
 271                     I2C_STAT_AL)) && timeout--);
 272
 273         if (timeout <= 0) {
 274                 printf ("timed out in wait_for_pin: I2C_STAT=%x\n",
 275                         inw (I2C_STAT));
 276         }
 277
 278         return status;
 279 }
 280
 281 #endif /* CONFIG_DRIVER_OMAP1510_I2C */