drivers/i2c/soft_i2c.c

   1 /*
   2  * (C) Copyright 2001, 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  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
  24  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
  25  * Neil Russell.
  26  */
  27
  28 #include <common.h>
  29 #ifdef  CONFIG_MPC8260                  /* only valid for MPC8260 */
  30 #include <ioports.h>
  31 #endif
  32 #ifdef  CONFIG_AT91RM9200               /* need this for the at91rm9200 */
  33 #include <asm/io.h>
  34 #include <asm/arch/hardware.h>
  35 #endif
  36 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  37 #include <asm/arch/ixp425.h>
  38 #endif
  39 #ifdef CONFIG_LPC2292
  40 #include <asm/arch/hardware.h>
  41 #endif
  42 #include <i2c.h>
  43
  44 /* #define      DEBUG_I2C       */
  45
  46 #ifdef DEBUG_I2C
  47 DECLARE_GLOBAL_DATA_PTR;
  48 #endif
  49
  50
  51 /*-----------------------------------------------------------------------
  52  * Definitions
  53  */
  54
  55 #define RETRIES         0
  56
  57
  58 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
  59 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
  60
  61
  62 #ifdef DEBUG_I2C
  63 #define PRINTD(fmt,args...)     do {    \
  64         if (gd->have_console)           \
  65                 printf (fmt ,##args);   \
  66         } while (0)
  67 #else
  68 #define PRINTD(fmt,args...)
  69 #endif
  70
  71 /*-----------------------------------------------------------------------
  72  * Local functions
  73  */
  74 static void  send_reset (void);
  75 static void  send_start (void);
  76 static void  send_stop  (void);
  77 static void  send_ack   (int);
  78 static int   write_byte (uchar byte);
  79 static uchar read_byte  (int);
  80
  81
  82 /*-----------------------------------------------------------------------
  83  * Send a reset sequence consisting of 9 clocks with the data signal high
  84  * to clock any confused device back into an idle state.  Also send a
  85  * <stop> at the end of the sequence for belts & suspenders.
  86  */
  87 static void send_reset(void)
  88 {
  89 #ifdef  CONFIG_MPC8260
  90         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
  91 #endif
  92 #ifdef  CONFIG_8xx
  93         volatile immap_t *immr = (immap_t *)CFG_IMMR;
  94 #endif
  95         int j;
  96
  97         I2C_SCL(1);
  98         I2C_SDA(1);
  99 #ifdef  I2C_INIT
 100         I2C_INIT;
 101 #endif
 102         I2C_TRISTATE;
 103         for(j = 0; j < 9; j++) {
 104                 I2C_SCL(0);
 105                 I2C_DELAY;
 106                 I2C_DELAY;
 107                 I2C_SCL(1);
 108                 I2C_DELAY;
 109                 I2C_DELAY;
 110         }
 111         send_stop();
 112         I2C_TRISTATE;
 113 }
 114
 115 /*-----------------------------------------------------------------------
 116  * START: High -> Low on SDA while SCL is High
 117  */
 118 static void send_start(void)
 119 {
 120 #ifdef  CONFIG_MPC8260
 121         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 122 #endif
 123 #ifdef  CONFIG_8xx
 124         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 125 #endif
 126
 127         I2C_DELAY;
 128         I2C_SDA(1);
 129         I2C_ACTIVE;
 130         I2C_DELAY;
 131         I2C_SCL(1);
 132         I2C_DELAY;
 133         I2C_SDA(0);
 134         I2C_DELAY;
 135 }
 136
 137 /*-----------------------------------------------------------------------
 138  * STOP: Low -> High on SDA while SCL is High
 139  */
 140 static void send_stop(void)
 141 {
 142 #ifdef  CONFIG_MPC8260
 143         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 144 #endif
 145 #ifdef  CONFIG_8xx
 146         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 147 #endif
 148
 149         I2C_SCL(0);
 150         I2C_DELAY;
 151         I2C_SDA(0);
 152         I2C_ACTIVE;
 153         I2C_DELAY;
 154         I2C_SCL(1);
 155         I2C_DELAY;
 156         I2C_SDA(1);
 157         I2C_DELAY;
 158         I2C_TRISTATE;
 159 }
 160
 161
 162 /*-----------------------------------------------------------------------
 163  * ack should be I2C_ACK or I2C_NOACK
 164  */
 165 static void send_ack(int ack)
 166 {
 167 #ifdef  CONFIG_MPC8260
 168         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 169 #endif
 170 #ifdef  CONFIG_8xx
 171         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 172 #endif
 173
 174         I2C_SCL(0);
 175         I2C_DELAY;
 176         I2C_ACTIVE;
 177         I2C_SDA(ack);
 178         I2C_DELAY;
 179         I2C_SCL(1);
 180         I2C_DELAY;
 181         I2C_DELAY;
 182         I2C_SCL(0);
 183         I2C_DELAY;
 184 }
 185
 186
 187 /*-----------------------------------------------------------------------
 188  * Send 8 bits and look for an acknowledgement.
 189  */
 190 static int write_byte(uchar data)
 191 {
 192 #ifdef  CONFIG_MPC8260
 193         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 194 #endif
 195 #ifdef  CONFIG_8xx
 196         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 197 #endif
 198         int j;
 199         int nack;
 200
 201         I2C_ACTIVE;
 202         for(j = 0; j < 8; j++) {
 203                 I2C_SCL(0);
 204                 I2C_DELAY;
 205                 I2C_SDA(data & 0x80);
 206                 I2C_DELAY;
 207                 I2C_SCL(1);
 208                 I2C_DELAY;
 209                 I2C_DELAY;
 210
 211                 data <<= 1;
 212         }
 213
 214         /*
 215          * Look for an <ACK>(negative logic) and return it.
 216          */
 217         I2C_SCL(0);
 218         I2C_DELAY;
 219         I2C_SDA(1);
 220         I2C_TRISTATE;
 221         I2C_DELAY;
 222         I2C_SCL(1);
 223         I2C_DELAY;
 224         I2C_DELAY;
 225         nack = I2C_READ;
 226         I2C_SCL(0);
 227         I2C_DELAY;
 228         I2C_ACTIVE;
 229
 230         return(nack);   /* not a nack is an ack */
 231 }
 232
 233
 234 /*-----------------------------------------------------------------------
 235  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 236  * send I2C_NOACK to end the read.
 237  */
 238 static uchar read_byte(int ack)
 239 {
 240 #ifdef  CONFIG_MPC8260
 241         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 242 #endif
 243 #ifdef  CONFIG_8xx
 244         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 245 #endif
 246         int  data;
 247         int  j;
 248
 249         /*
 250          * Read 8 bits, MSB first.
 251          */
 252         I2C_TRISTATE;
 253         I2C_SDA(1);
 254         data = 0;
 255         for(j = 0; j < 8; j++) {
 256                 I2C_SCL(0);
 257                 I2C_DELAY;
 258                 I2C_SCL(1);
 259                 I2C_DELAY;
 260                 data <<= 1;
 261                 data |= I2C_READ;
 262                 I2C_DELAY;
 263         }
 264         send_ack(ack);
 265
 266         return(data);
 267 }
 268
 269 /*=====================================================================*/
 270 /*                         Public Functions                            */
 271 /*=====================================================================*/
 272
 273 /*-----------------------------------------------------------------------
 274  * Initialization
 275  */
 276 void i2c_init (int speed, int slaveaddr)
 277 {
 278         /*
 279          * WARNING: Do NOT save speed in a static variable: if the
 280          * I2C routines are called before RAM is initialized (to read
 281          * the DIMM SPD, for instance), RAM won't be usable and your
 282          * system will crash.
 283          */
 284         send_reset ();
 285 }
 286
 287 /*-----------------------------------------------------------------------
 288  * Probe to see if a chip is present.  Also good for checking for the
 289  * completion of EEPROM writes since the chip stops responding until
 290  * the write completes (typically 10mSec).
 291  */
 292 int i2c_probe(uchar addr)
 293 {
 294         int rc;
 295
 296         /*
 297          * perform 1 byte write transaction with just address byte
 298          * (fake write)
 299          */
 300         send_start();
 301         rc = write_byte ((addr << 1) | 0);
 302         send_stop();
 303
 304         return (rc ? 1 : 0);
 305 }
 306
 307 /*-----------------------------------------------------------------------
 308  * Read bytes
 309  */
 310 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 311 {
 312         int shift;
 313         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 314                 chip, addr, alen, buffer, len);
 315
 316 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
 317         /*
 318          * EEPROM chips that implement "address overflow" are ones
 319          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 320          * address and the extra bits end up in the "chip address"
 321          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 322          * four 256 byte chips.
 323          *
 324          * Note that we consider the length of the address field to
 325          * still be one byte because the extra address bits are
 326          * hidden in the chip address.
 327          */
 328         chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
 329
 330         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 331                 chip, addr);
 332 #endif
 333
 334         /*
 335          * Do the addressing portion of a write cycle to set the
 336          * chip's address pointer.  If the address length is zero,
 337          * don't do the normal write cycle to set the address pointer,
 338          * there is no address pointer in this chip.
 339          */
 340         send_start();
 341         if(alen > 0) {
 342                 if(write_byte(chip << 1)) {     /* write cycle */
 343                         send_stop();
 344                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 345                         return(1);
 346                 }
 347                 shift = (alen-1) * 8;
 348                 while(alen-- > 0) {
 349                         if(write_byte(addr >> shift)) {
 350                                 PRINTD("i2c_read, address not <ACK>ed\n");
 351                                 return(1);
 352                         }
 353                         shift -= 8;
 354                 }
 355                 send_stop();    /* reportedly some chips need a full stop */
 356                 send_start();
 357         }
 358         /*
 359          * Send the chip address again, this time for a read cycle.
 360          * Then read the data.  On the last byte, we do a NACK instead
 361          * of an ACK(len == 0) to terminate the read.
 362          */
 363         write_byte((chip << 1) | 1);    /* read cycle */
 364         while(len-- > 0) {
 365                 *buffer++ = read_byte(len == 0);
 366         }
 367         send_stop();
 368         return(0);
 369 }
 370
 371 /*-----------------------------------------------------------------------
 372  * Write bytes
 373  */
 374 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 375 {
 376         int shift, failures = 0;
 377
 378         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 379                 chip, addr, alen, buffer, len);
 380
 381         send_start();
 382         if(write_byte(chip << 1)) {     /* write cycle */
 383                 send_stop();
 384                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 385                 return(1);
 386         }
 387         shift = (alen-1) * 8;
 388         while(alen-- > 0) {
 389                 if(write_byte(addr >> shift)) {
 390                         PRINTD("i2c_write, address not <ACK>ed\n");
 391                         return(1);
 392                 }
 393                 shift -= 8;
 394         }
 395
 396         while(len-- > 0) {
 397                 if(write_byte(*buffer++)) {
 398                         failures++;
 399                 }
 400         }
 401         send_stop();
 402         return(failures);
 403 }
 404
 405 /*-----------------------------------------------------------------------
 406  * Read a register
 407  */
 408 uchar i2c_reg_read(uchar i2c_addr, uchar reg)
 409 {
 410         uchar buf;
 411
 412         i2c_read(i2c_addr, reg, 1, &buf, 1);
 413
 414         return(buf);
 415 }
 416
 417 /*-----------------------------------------------------------------------
 418  * Write a register
 419  */
 420 void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
 421 {
 422         i2c_write(i2c_addr, reg, 1, &val, 1);
 423 }