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 #include <asm/io.h>
  32 #endif
  33 #if defined(CONFIG_AVR32)
  34 #include <asm/arch/portmux.h>
  35 #endif
  36 #if defined(CONFIG_AT91FAMILY)
  37 #include <asm/io.h>
  38 #include <asm/arch/hardware.h>
  39 #include <asm/arch/at91_pio.h>
  40 #ifdef CONFIG_AT91_LEGACY
  41 #include <asm/arch/gpio.h>
  42 #endif
  43 #endif
  44 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  45 #include <asm/arch/ixp425.h>
  46 #endif
  47 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  48 #include <asm/io.h>
  49 #endif
  50 #include <i2c.h>
  51
  52 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  53 # include <asm/gpio.h>
  54
  55 # ifndef I2C_GPIO_SYNC
  56 #  define I2C_GPIO_SYNC
  57 # endif
  58
  59 # ifndef I2C_INIT
  60 #  define I2C_INIT \
  61         do { \
  62                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  63                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  64         } while (0)
  65 # endif
  66
  67 # ifndef I2C_ACTIVE
  68 #  define I2C_ACTIVE do { } while (0)
  69 # endif
  70
  71 # ifndef I2C_TRISTATE
  72 #  define I2C_TRISTATE do { } while (0)
  73 # endif
  74
  75 # ifndef I2C_READ
  76 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  77 # endif
  78
  79 # ifndef I2C_SDA
  80 #  define I2C_SDA(bit) \
  81         do { \
  82                 if (bit) \
  83                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  84                 else \
  85                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  86                 I2C_GPIO_SYNC; \
  87         } while (0)
  88 # endif
  89
  90 # ifndef I2C_SCL
  91 #  define I2C_SCL(bit) \
  92         do { \
  93                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  94                 I2C_GPIO_SYNC; \
  95         } while (0)
  96 # endif
  97
  98 # ifndef I2C_DELAY
  99 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
 100 # endif
 101
 102 #endif
 103
 104 /* #define      DEBUG_I2C       */
 105
 106 #ifdef DEBUG_I2C
 107 DECLARE_GLOBAL_DATA_PTR;
 108 #endif
 109
 110 /*-----------------------------------------------------------------------
 111  * Definitions
 112  */
 113
 114 #define RETRIES         0
 115
 116 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 117 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 118
 119
 120 #ifdef DEBUG_I2C
 121 #define PRINTD(fmt,args...)     do {    \
 122                 printf (fmt ,##args);   \
 123         } while (0)
 124 #else
 125 #define PRINTD(fmt,args...)
 126 #endif
 127
 128 #if defined(CONFIG_I2C_MULTI_BUS)
 129 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
 130 #endif /* CONFIG_I2C_MULTI_BUS */
 131
 132 /*-----------------------------------------------------------------------
 133  * Local functions
 134  */
 135 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 136 static void  send_reset (void);
 137 #endif
 138 static void  send_start (void);
 139 static void  send_stop  (void);
 140 static void  send_ack   (int);
 141 static int   write_byte (uchar byte);
 142 static uchar read_byte  (int);
 143
 144 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 145 /*-----------------------------------------------------------------------
 146  * Send a reset sequence consisting of 9 clocks with the data signal high
 147  * to clock any confused device back into an idle state.  Also send a
 148  * <stop> at the end of the sequence for belts & suspenders.
 149  */
 150 static void send_reset(void)
 151 {
 152         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 153         int j;
 154
 155         I2C_SCL(1);
 156         I2C_SDA(1);
 157 #ifdef  I2C_INIT
 158         I2C_INIT;
 159 #endif
 160         I2C_TRISTATE;
 161         for(j = 0; j < 9; j++) {
 162                 I2C_SCL(0);
 163                 I2C_DELAY;
 164                 I2C_DELAY;
 165                 I2C_SCL(1);
 166                 I2C_DELAY;
 167                 I2C_DELAY;
 168         }
 169         send_stop();
 170         I2C_TRISTATE;
 171 }
 172 #endif
 173
 174 /*-----------------------------------------------------------------------
 175  * START: High -> Low on SDA while SCL is High
 176  */
 177 static void send_start(void)
 178 {
 179         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 180
 181         I2C_DELAY;
 182         I2C_SDA(1);
 183         I2C_ACTIVE;
 184         I2C_DELAY;
 185         I2C_SCL(1);
 186         I2C_DELAY;
 187         I2C_SDA(0);
 188         I2C_DELAY;
 189 }
 190
 191 /*-----------------------------------------------------------------------
 192  * STOP: Low -> High on SDA while SCL is High
 193  */
 194 static void send_stop(void)
 195 {
 196         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 197
 198         I2C_SCL(0);
 199         I2C_DELAY;
 200         I2C_SDA(0);
 201         I2C_ACTIVE;
 202         I2C_DELAY;
 203         I2C_SCL(1);
 204         I2C_DELAY;
 205         I2C_SDA(1);
 206         I2C_DELAY;
 207         I2C_TRISTATE;
 208 }
 209
 210 /*-----------------------------------------------------------------------
 211  * ack should be I2C_ACK or I2C_NOACK
 212  */
 213 static void send_ack(int ack)
 214 {
 215         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 216
 217         I2C_SCL(0);
 218         I2C_DELAY;
 219         I2C_ACTIVE;
 220         I2C_SDA(ack);
 221         I2C_DELAY;
 222         I2C_SCL(1);
 223         I2C_DELAY;
 224         I2C_DELAY;
 225         I2C_SCL(0);
 226         I2C_DELAY;
 227 }
 228
 229 /*-----------------------------------------------------------------------
 230  * Send 8 bits and look for an acknowledgement.
 231  */
 232 static int write_byte(uchar data)
 233 {
 234         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 235         int j;
 236         int nack;
 237
 238         I2C_ACTIVE;
 239         for(j = 0; j < 8; j++) {
 240                 I2C_SCL(0);
 241                 I2C_DELAY;
 242                 I2C_SDA(data & 0x80);
 243                 I2C_DELAY;
 244                 I2C_SCL(1);
 245                 I2C_DELAY;
 246                 I2C_DELAY;
 247
 248                 data <<= 1;
 249         }
 250
 251         /*
 252          * Look for an <ACK>(negative logic) and return it.
 253          */
 254         I2C_SCL(0);
 255         I2C_DELAY;
 256         I2C_SDA(1);
 257         I2C_TRISTATE;
 258         I2C_DELAY;
 259         I2C_SCL(1);
 260         I2C_DELAY;
 261         I2C_DELAY;
 262         nack = I2C_READ;
 263         I2C_SCL(0);
 264         I2C_DELAY;
 265         I2C_ACTIVE;
 266
 267         return(nack);   /* not a nack is an ack */
 268 }
 269
 270 #if defined(CONFIG_I2C_MULTI_BUS)
 271 /*
 272  * Functions for multiple I2C bus handling
 273  */
 274 unsigned int i2c_get_bus_num(void)
 275 {
 276         return i2c_bus_num;
 277 }
 278
 279 int i2c_set_bus_num(unsigned int bus)
 280 {
 281 #if defined(CONFIG_I2C_MUX)
 282         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
 283                 i2c_bus_num = bus;
 284         } else {
 285                 int     ret;
 286
 287                 ret = i2x_mux_select_mux(bus);
 288                 i2c_init_board();
 289                 if (ret == 0)
 290                         i2c_bus_num = bus;
 291                 else
 292                         return ret;
 293         }
 294 #else
 295         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
 296                 return -1;
 297         i2c_bus_num = bus;
 298 #endif
 299         return 0;
 300 }
 301 #endif
 302
 303 /*-----------------------------------------------------------------------
 304  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 305  * send I2C_NOACK to end the read.
 306  */
 307 static uchar read_byte(int ack)
 308 {
 309         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 310         int  data;
 311         int  j;
 312
 313         /*
 314          * Read 8 bits, MSB first.
 315          */
 316         I2C_TRISTATE;
 317         I2C_SDA(1);
 318         data = 0;
 319         for(j = 0; j < 8; j++) {
 320                 I2C_SCL(0);
 321                 I2C_DELAY;
 322                 I2C_SCL(1);
 323                 I2C_DELAY;
 324                 data <<= 1;
 325                 data |= I2C_READ;
 326                 I2C_DELAY;
 327         }
 328         send_ack(ack);
 329
 330         return(data);
 331 }
 332
 333 /*=====================================================================*/
 334 /*                         Public Functions                            */
 335 /*=====================================================================*/
 336
 337 /*-----------------------------------------------------------------------
 338  * Initialization
 339  */
 340 void i2c_init (int speed, int slaveaddr)
 341 {
 342 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 343         /* call board specific i2c bus reset routine before accessing the   */
 344         /* environment, which might be in a chip on that bus. For details   */
 345         /* about this problem see doc/I2C_Edge_Conditions.                  */
 346         i2c_init_board();
 347 #else
 348         /*
 349          * WARNING: Do NOT save speed in a static variable: if the
 350          * I2C routines are called before RAM is initialized (to read
 351          * the DIMM SPD, for instance), RAM won't be usable and your
 352          * system will crash.
 353          */
 354         send_reset ();
 355 #endif
 356 }
 357
 358 /*-----------------------------------------------------------------------
 359  * Probe to see if a chip is present.  Also good for checking for the
 360  * completion of EEPROM writes since the chip stops responding until
 361  * the write completes (typically 10mSec).
 362  */
 363 int i2c_probe(uchar addr)
 364 {
 365         int rc;
 366
 367         /*
 368          * perform 1 byte write transaction with just address byte
 369          * (fake write)
 370          */
 371         send_start();
 372         rc = write_byte ((addr << 1) | 0);
 373         send_stop();
 374
 375         return (rc ? 1 : 0);
 376 }
 377
 378 /*-----------------------------------------------------------------------
 379  * Read bytes
 380  */
 381 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 382 {
 383         int shift;
 384         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 385                 chip, addr, alen, buffer, len);
 386
 387 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 388         /*
 389          * EEPROM chips that implement "address overflow" are ones
 390          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 391          * address and the extra bits end up in the "chip address"
 392          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 393          * four 256 byte chips.
 394          *
 395          * Note that we consider the length of the address field to
 396          * still be one byte because the extra address bits are
 397          * hidden in the chip address.
 398          */
 399         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 400
 401         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 402                 chip, addr);
 403 #endif
 404
 405         /*
 406          * Do the addressing portion of a write cycle to set the
 407          * chip's address pointer.  If the address length is zero,
 408          * don't do the normal write cycle to set the address pointer,
 409          * there is no address pointer in this chip.
 410          */
 411         send_start();
 412         if(alen > 0) {
 413                 if(write_byte(chip << 1)) {     /* write cycle */
 414                         send_stop();
 415                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 416                         return(1);
 417                 }
 418                 shift = (alen-1) * 8;
 419                 while(alen-- > 0) {
 420                         if(write_byte(addr >> shift)) {
 421                                 PRINTD("i2c_read, address not <ACK>ed\n");
 422                                 return(1);
 423                         }
 424                         shift -= 8;
 425                 }
 426
 427                 /* Some I2C chips need a stop/start sequence here,
 428                  * other chips don't work with a full stop and need
 429                  * only a start.  Default behaviour is to send the
 430                  * stop/start sequence.
 431                  */
 432 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 433                 send_start();
 434 #else
 435                 send_stop();
 436                 send_start();
 437 #endif
 438         }
 439         /*
 440          * Send the chip address again, this time for a read cycle.
 441          * Then read the data.  On the last byte, we do a NACK instead
 442          * of an ACK(len == 0) to terminate the read.
 443          */
 444         write_byte((chip << 1) | 1);    /* read cycle */
 445         while(len-- > 0) {
 446                 *buffer++ = read_byte(len == 0);
 447         }
 448         send_stop();
 449         return(0);
 450 }
 451
 452 /*-----------------------------------------------------------------------
 453  * Write bytes
 454  */
 455 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 456 {
 457         int shift, failures = 0;
 458
 459         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 460                 chip, addr, alen, buffer, len);
 461
 462         send_start();
 463         if(write_byte(chip << 1)) {     /* write cycle */
 464                 send_stop();
 465                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 466                 return(1);
 467         }
 468         shift = (alen-1) * 8;
 469         while(alen-- > 0) {
 470                 if(write_byte(addr >> shift)) {
 471                         PRINTD("i2c_write, address not <ACK>ed\n");
 472                         return(1);
 473                 }
 474                 shift -= 8;
 475         }
 476
 477         while(len-- > 0) {
 478                 if(write_byte(*buffer++)) {
 479                         failures++;
 480                 }
 481         }
 482         send_stop();
 483         return(failures);
 484 }