drivers/omap24xx_i2c.c

   1 /*
   2  * Basic I2C functions
   3  *
   4  * Copyright (c) 2004 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  * Adapted for OMAP2420 I2C, r-woodruff2@ti.com
  20  *
  21  */
  22
  23 #include <common.h>
  24
  25 #ifdef CONFIG_DRIVER_OMAP24XX_I2C
  26
  27 #include <asm/arch/i2c.h>
  28 #include <asm/io.h>
  29
  30 #define inw(a) __raw_readw(a)
  31 #define outw(a,v) __raw_writew(a,v)
  32
  33 static void wait_for_bb (void);
  34 static u16 wait_for_pin (void);
  35 static void flush_fifo(void);
  36
  37 void i2c_init (int speed, int slaveadd)
  38 {
  39         u16 scl;
  40
  41         outw(0x2, I2C_SYSC); /* for ES2 after soft reset */
  42         udelay(1000);
  43         outw(0x0, I2C_SYSC); /* will probably self clear but */
  44
  45         if (inw (I2C_CON) & I2C_CON_EN) {
  46                 outw (0, I2C_CON);
  47                 udelay (50000);
  48         }
  49
  50         /* 12Mhz I2C module clock */
  51         outw (0, I2C_PSC);
  52         speed = speed/1000;                 /* 100 or 400 */
  53         scl = ((12000/(speed*2)) - 7);  /* use 7 when PSC = 0 */
  54         outw (scl, I2C_SCLL);
  55         outw (scl, I2C_SCLH);
  56         /* own address */
  57         outw (slaveadd, I2C_OA);
  58         outw (I2C_CON_EN, I2C_CON);
  59
  60         /* have to enable intrrupts or OMAP i2c module doesn't work */
  61         outw (I2C_IE_XRDY_IE | I2C_IE_RRDY_IE | I2C_IE_ARDY_IE |
  62               I2C_IE_NACK_IE | I2C_IE_AL_IE, I2C_IE);
  63         udelay (1000);
  64         flush_fifo();
  65         outw (0xFFFF, I2C_STAT);
  66         outw (0, I2C_CNT);
  67 }
  68
  69 static int i2c_read_byte (u8 devaddr, u8 regoffset, u8 * value)
  70 {
  71         int i2c_error = 0;
  72         u16 status;
  73
  74         /* wait until bus not busy */
  75         wait_for_bb ();
  76
  77         /* one byte only */
  78         outw (1, I2C_CNT);
  79         /* set slave address */
  80         outw (devaddr, I2C_SA);
  81         /* no stop bit needed here */
  82         outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX, I2C_CON);
  83
  84         status = wait_for_pin ();
  85
  86         if (status & I2C_STAT_XRDY) {
  87                 /* Important: have to use byte access */
  88                 *(volatile u8 *) (I2C_DATA) = regoffset;
  89                 udelay (20000);
  90                 if (inw (I2C_STAT) & I2C_STAT_NACK) {
  91                         i2c_error = 1;
  92                 }
  93         } else {
  94                 i2c_error = 1;
  95         }
  96
  97         if (!i2c_error) {
  98                 /* free bus, otherwise we can't use a combined transction */
  99                 outw (0, I2C_CON);
 100                 while (inw (I2C_STAT) || (inw (I2C_CON) & I2C_CON_MST)) {
 101                         udelay (10000);
 102                         /* Have to clear pending interrupt to clear I2C_STAT */
 103                         outw (0xFFFF, I2C_STAT);
 104                 }
 105
 106                 wait_for_bb ();
 107                 /* set slave address */
 108                 outw (devaddr, I2C_SA);
 109                 /* read one byte from slave */
 110                 outw (1, I2C_CNT);
 111                 /* need stop bit here */
 112                 outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP,
 113                       I2C_CON);
 114
 115                 status = wait_for_pin ();
 116                 if (status & I2C_STAT_RRDY) {
 117                         *value = inw (I2C_DATA);
 118                         udelay (20000);
 119                 } else {
 120                         i2c_error = 1;
 121                 }
 122
 123                 if (!i2c_error) {
 124                         outw (I2C_CON_EN, I2C_CON);
 125                         while (inw (I2C_STAT)
 126                                || (inw (I2C_CON) & I2C_CON_MST)) {
 127                                 udelay (10000);
 128                                 outw (0xFFFF, I2C_STAT);
 129                         }
 130                 }
 131         }
 132         flush_fifo();
 133         outw (0xFFFF, I2C_STAT);
 134         outw (0, I2C_CNT);
 135         return i2c_error;
 136 }
 137
 138 static int i2c_write_byte (u8 devaddr, u8 regoffset, u8 value)
 139 {
 140         int i2c_error = 0;
 141         u16 status, stat;
 142
 143         /* wait until bus not busy */
 144         wait_for_bb ();
 145
 146         /* two bytes */
 147         outw (2, I2C_CNT);
 148         /* set slave address */
 149         outw (devaddr, I2C_SA);
 150         /* stop bit needed here */
 151         outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX |
 152               I2C_CON_STP, I2C_CON);
 153
 154         /* wait until state change */
 155         status = wait_for_pin ();
 156
 157         if (status & I2C_STAT_XRDY) {
 158                 /* send out two bytes */
 159                 outw ((value << 8) + regoffset, I2C_DATA);
 160                 /* must have enough delay to allow BB bit to go low */
 161                 udelay (50000);
 162                 if (inw (I2C_STAT) & I2C_STAT_NACK) {
 163                         i2c_error = 1;
 164                 }
 165         } else {
 166                 i2c_error = 1;
 167         }
 168
 169         if (!i2c_error) {
 170                 int eout = 200;
 171
 172                 outw (I2C_CON_EN, I2C_CON);
 173                 while ((stat = inw (I2C_STAT)) || (inw (I2C_CON) & I2C_CON_MST)) {
 174                         udelay (1000);
 175                         /* have to read to clear intrrupt */
 176                         outw (0xFFFF, I2C_STAT);
 177                         if(--eout == 0) /* better leave with error than hang */
 178                                 break;
 179                 }
 180         }
 181         flush_fifo();
 182         outw (0xFFFF, I2C_STAT);
 183         outw (0, I2C_CNT);
 184         return i2c_error;
 185 }
 186
 187 static void flush_fifo(void)
 188 {       u16 stat;
 189
 190         /* note: if you try and read data when its not there or ready
 191          * you get a bus error
 192          */
 193         while(1){
 194                 stat = inw(I2C_STAT);
 195                 if(stat == I2C_STAT_RRDY){
 196                         inw(I2C_DATA);
 197                         outw(I2C_STAT_RRDY,I2C_STAT);
 198                         udelay(1000);
 199                 }else
 200                         break;
 201         }
 202 }
 203
 204 int i2c_probe (uchar chip)
 205 {
 206         int res = 1; /* default = fail */
 207
 208         if (chip == inw (I2C_OA)) {
 209                 return res;
 210         }
 211
 212         /* wait until bus not busy */
 213         wait_for_bb ();
 214
 215         /* try to read one byte */
 216         outw (1, I2C_CNT);
 217         /* set slave address */
 218         outw (chip, I2C_SA);
 219         /* stop bit needed here */
 220         outw (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP, I2C_CON);
 221         /* enough delay for the NACK bit set */
 222         udelay (50000);
 223
 224         if (!(inw (I2C_STAT) & I2C_STAT_NACK)) {
 225                 res = 0;      /* success case */
 226                 flush_fifo();
 227                 outw(0xFFFF, I2C_STAT);
 228         } else {
 229                 outw(0xFFFF, I2C_STAT);  /* failue, clear sources*/
 230                 outw (inw (I2C_CON) | I2C_CON_STP, I2C_CON); /* finish up xfer */
 231                 udelay(20000);
 232                 wait_for_bb ();
 233         }
 234         flush_fifo();
 235         outw (0, I2C_CNT); /* don't allow any more data in...we don't want it.*/
 236         outw(0xFFFF, I2C_STAT);
 237         return res;
 238 }
 239
 240 int i2c_read (uchar chip, uint addr, int alen, uchar * buffer, int len)
 241 {
 242         int i;
 243
 244         if (alen > 1) {
 245                 printf ("I2C read: addr len %d not supported\n", alen);
 246                 return 1;
 247         }
 248
 249         if (addr + len > 256) {
 250                 printf ("I2C read: address out of range\n");
 251                 return 1;
 252         }
 253
 254         for (i = 0; i < len; i++) {
 255                 if (i2c_read_byte (chip, addr + i, &buffer[i])) {
 256                         printf ("I2C read: I/O error\n");
 257                         i2c_init (CFG_I2C_SPEED, CFG_I2C_SLAVE);
 258                         return 1;
 259                 }
 260         }
 261
 262         return 0;
 263 }
 264
 265 int i2c_write (uchar chip, uint addr, int alen, uchar * buffer, int len)
 266 {
 267         int i;
 268
 269         if (alen > 1) {
 270                 printf ("I2C read: addr len %d not supported\n", alen);
 271                 return 1;
 272         }
 273
 274         if (addr + len > 256) {
 275                 printf ("I2C read: address out of range\n");
 276                 return 1;
 277         }
 278
 279         for (i = 0; i < len; i++) {
 280                 if (i2c_write_byte (chip, addr + i, buffer[i])) {
 281                         printf ("I2C read: I/O error\n");
 282                         i2c_init (CFG_I2C_SPEED, CFG_I2C_SLAVE);
 283                         return 1;
 284                 }
 285         }
 286
 287         return 0;
 288 }
 289
 290 static void wait_for_bb (void)
 291 {
 292         int timeout = 10;
 293         u16 stat;
 294
 295         outw(0xFFFF, I2C_STAT);  /* clear current interruts...*/
 296         while ((stat = inw (I2C_STAT) & I2C_STAT_BB) && timeout--) {
 297                 outw (stat, I2C_STAT);
 298                 udelay (50000);
 299         }
 300
 301         if (timeout <= 0) {
 302                 printf ("timed out in wait_for_bb: I2C_STAT=%x\n",
 303                         inw (I2C_STAT));
 304         }
 305         outw(0xFFFF, I2C_STAT);  /* clear delayed stuff*/
 306 }
 307
 308 static u16 wait_for_pin (void)
 309 {
 310         u16 status;
 311         int timeout = 10;
 312
 313         do {
 314                 udelay (1000);
 315                 status = inw (I2C_STAT);
 316         } while (  !(status &
 317                    (I2C_STAT_ROVR | I2C_STAT_XUDF | I2C_STAT_XRDY |
 318                     I2C_STAT_RRDY | I2C_STAT_ARDY | I2C_STAT_NACK |
 319                     I2C_STAT_AL)) && timeout--);
 320
 321         if (timeout <= 0) {
 322                 printf ("timed out in wait_for_pin: I2C_STAT=%x\n",
 323                         inw (I2C_STAT));
 324                         outw(0xFFFF, I2C_STAT);
 325 }
 326         return status;
 327 }
 328
 329 #endif /* CONFIG_DRIVER_OMAP24XX_I2C */