drivers/i2c/soft_i2c.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * (C) Copyright 2009
   4  * Heiko Schocher, DENX Software Engineering, hs@denx.de.
   5  * Changes for multibus/multiadapter I2C support.
   6  *
   7  * (C) Copyright 2001, 2002
   8  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   9  *
  10  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
  11  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
  12  * Neil Russell.
  13  *
  14  * NOTE: This driver should be converted to driver model before June 2017.
  15  * Please see doc/driver-model/i2c-howto.rst for instructions.
  16  */
  17
  18 #include <common.h>
  19 #if defined(CONFIG_AT91FAMILY)
  20 #include <asm/io.h>
  21 #include <asm/arch/hardware.h>
  22 #include <asm/arch/at91_pio.h>
  23 #ifdef CONFIG_ATMEL_LEGACY
  24 #include <asm/arch/gpio.h>
  25 #endif
  26 #endif
  27 #include <i2c.h>
  28 #include <linux/delay.h>
  29
  30 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  31 # include <asm/gpio.h>
  32
  33 # ifndef I2C_GPIO_SYNC
  34 #  define I2C_GPIO_SYNC
  35 # endif
  36
  37 # ifndef I2C_INIT
  38 #  define I2C_INIT \
  39         do { \
  40                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  41                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  42         } while (0)
  43 # endif
  44
  45 # ifndef I2C_ACTIVE
  46 #  define I2C_ACTIVE do { } while (0)
  47 # endif
  48
  49 # ifndef I2C_TRISTATE
  50 #  define I2C_TRISTATE do { } while (0)
  51 # endif
  52
  53 # ifndef I2C_READ
  54 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  55 # endif
  56
  57 # ifndef I2C_SDA
  58 #  define I2C_SDA(bit) \
  59         do { \
  60                 if (bit) \
  61                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  62                 else \
  63                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  64                 I2C_GPIO_SYNC; \
  65         } while (0)
  66 # endif
  67
  68 # ifndef I2C_SCL
  69 #  define I2C_SCL(bit) \
  70         do { \
  71                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  72                 I2C_GPIO_SYNC; \
  73         } while (0)
  74 # endif
  75
  76 # ifndef I2C_DELAY
  77 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
  78 # endif
  79
  80 #endif
  81
  82 /* #define      DEBUG_I2C       */
  83
  84 DECLARE_GLOBAL_DATA_PTR;
  85
  86 #ifndef I2C_SOFT_DECLARATIONS
  87 #  define I2C_SOFT_DECLARATIONS
  88 #endif
  89
  90 #if !defined(CONFIG_SYS_I2C_SOFT_SPEED)
  91 #define CONFIG_SYS_I2C_SOFT_SPEED CONFIG_SYS_I2C_SPEED
  92 #endif
  93 #if !defined(CONFIG_SYS_I2C_SOFT_SLAVE)
  94 #define CONFIG_SYS_I2C_SOFT_SLAVE CONFIG_SYS_I2C_SLAVE
  95 #endif
  96
  97 /*-----------------------------------------------------------------------
  98  * Definitions
  99  */
 100 #define RETRIES         0
 101
 102 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 103 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 104
 105
 106 #ifdef DEBUG_I2C
 107 #define PRINTD(fmt,args...)     do {    \
 108                 printf (fmt ,##args);   \
 109         } while (0)
 110 #else
 111 #define PRINTD(fmt,args...)
 112 #endif
 113
 114 /*-----------------------------------------------------------------------
 115  * Local functions
 116  */
 117 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 118 static void  send_reset (void);
 119 #endif
 120 static void  send_start (void);
 121 static void  send_stop  (void);
 122 static void  send_ack   (int);
 123 static int   write_byte (uchar byte);
 124 static uchar read_byte  (int);
 125
 126 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 127 /*-----------------------------------------------------------------------
 128  * Send a reset sequence consisting of 9 clocks with the data signal high
 129  * to clock any confused device back into an idle state.  Also send a
 130  * <stop> at the end of the sequence for belts & suspenders.
 131  */
 132 static void send_reset(void)
 133 {
 134         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 135         int j;
 136
 137         I2C_SCL(1);
 138         I2C_SDA(1);
 139 #ifdef  I2C_INIT
 140         I2C_INIT;
 141 #endif
 142         I2C_TRISTATE;
 143         for(j = 0; j < 9; j++) {
 144                 I2C_SCL(0);
 145                 I2C_DELAY;
 146                 I2C_DELAY;
 147                 I2C_SCL(1);
 148                 I2C_DELAY;
 149                 I2C_DELAY;
 150         }
 151         send_stop();
 152         I2C_TRISTATE;
 153 }
 154 #endif
 155
 156 /*-----------------------------------------------------------------------
 157  * START: High -> Low on SDA while SCL is High
 158  */
 159 static void send_start(void)
 160 {
 161         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 162
 163         I2C_DELAY;
 164         I2C_SDA(1);
 165         I2C_ACTIVE;
 166         I2C_DELAY;
 167         I2C_SCL(1);
 168         I2C_DELAY;
 169         I2C_SDA(0);
 170         I2C_DELAY;
 171 }
 172
 173 /*-----------------------------------------------------------------------
 174  * STOP: Low -> High on SDA while SCL is High
 175  */
 176 static void send_stop(void)
 177 {
 178         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 179
 180         I2C_SCL(0);
 181         I2C_DELAY;
 182         I2C_SDA(0);
 183         I2C_ACTIVE;
 184         I2C_DELAY;
 185         I2C_SCL(1);
 186         I2C_DELAY;
 187         I2C_SDA(1);
 188         I2C_DELAY;
 189         I2C_TRISTATE;
 190 }
 191
 192 /*-----------------------------------------------------------------------
 193  * ack should be I2C_ACK or I2C_NOACK
 194  */
 195 static void send_ack(int ack)
 196 {
 197         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 198
 199         I2C_SCL(0);
 200         I2C_DELAY;
 201         I2C_ACTIVE;
 202         I2C_SDA(ack);
 203         I2C_DELAY;
 204         I2C_SCL(1);
 205         I2C_DELAY;
 206         I2C_DELAY;
 207         I2C_SCL(0);
 208         I2C_DELAY;
 209 }
 210
 211 /*-----------------------------------------------------------------------
 212  * Send 8 bits and look for an acknowledgement.
 213  */
 214 static int write_byte(uchar data)
 215 {
 216         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 217         int j;
 218         int nack;
 219
 220         I2C_ACTIVE;
 221         for(j = 0; j < 8; j++) {
 222                 I2C_SCL(0);
 223                 I2C_DELAY;
 224                 I2C_SDA(data & 0x80);
 225                 I2C_DELAY;
 226                 I2C_SCL(1);
 227                 I2C_DELAY;
 228                 I2C_DELAY;
 229
 230                 data <<= 1;
 231         }
 232
 233         /*
 234          * Look for an <ACK>(negative logic) and return it.
 235          */
 236         I2C_SCL(0);
 237         I2C_DELAY;
 238         I2C_SDA(1);
 239         I2C_TRISTATE;
 240         I2C_DELAY;
 241         I2C_SCL(1);
 242         I2C_DELAY;
 243         I2C_DELAY;
 244         nack = I2C_READ;
 245         I2C_SCL(0);
 246         I2C_DELAY;
 247         I2C_ACTIVE;
 248
 249         return(nack);   /* not a nack is an ack */
 250 }
 251
 252 /*-----------------------------------------------------------------------
 253  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 254  * send I2C_NOACK to end the read.
 255  */
 256 static uchar read_byte(int ack)
 257 {
 258         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 259         int  data;
 260         int  j;
 261
 262         /*
 263          * Read 8 bits, MSB first.
 264          */
 265         I2C_TRISTATE;
 266         I2C_SDA(1);
 267         data = 0;
 268         for(j = 0; j < 8; j++) {
 269                 I2C_SCL(0);
 270                 I2C_DELAY;
 271                 I2C_SCL(1);
 272                 I2C_DELAY;
 273                 data <<= 1;
 274                 data |= I2C_READ;
 275                 I2C_DELAY;
 276         }
 277         send_ack(ack);
 278
 279         return(data);
 280 }
 281
 282 /*-----------------------------------------------------------------------
 283  * Initialization
 284  */
 285 static void soft_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
 286 {
 287 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 288         /* call board specific i2c bus reset routine before accessing the   */
 289         /* environment, which might be in a chip on that bus. For details   */
 290         /* about this problem see doc/I2C_Edge_Conditions.                  */
 291         i2c_init_board();
 292 #else
 293         /*
 294          * WARNING: Do NOT save speed in a static variable: if the
 295          * I2C routines are called before RAM is initialized (to read
 296          * the DIMM SPD, for instance), RAM won't be usable and your
 297          * system will crash.
 298          */
 299         send_reset ();
 300 #endif
 301 }
 302
 303 /*-----------------------------------------------------------------------
 304  * Probe to see if a chip is present.  Also good for checking for the
 305  * completion of EEPROM writes since the chip stops responding until
 306  * the write completes (typically 10mSec).
 307  */
 308 static int soft_i2c_probe(struct i2c_adapter *adap, uint8_t addr)
 309 {
 310         int rc;
 311
 312         /*
 313          * perform 1 byte write transaction with just address byte
 314          * (fake write)
 315          */
 316         send_start();
 317         rc = write_byte ((addr << 1) | 0);
 318         send_stop();
 319
 320         return (rc ? 1 : 0);
 321 }
 322
 323 /*-----------------------------------------------------------------------
 324  * Read bytes
 325  */
 326 static int  soft_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
 327                         int alen, uchar *buffer, int len)
 328 {
 329         int shift;
 330         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 331                 chip, addr, alen, buffer, len);
 332
 333 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 334         /*
 335          * EEPROM chips that implement "address overflow" are ones
 336          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 337          * address and the extra bits end up in the "chip address"
 338          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 339          * four 256 byte chips.
 340          *
 341          * Note that we consider the length of the address field to
 342          * still be one byte because the extra address bits are
 343          * hidden in the chip address.
 344          */
 345         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 346
 347         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 348                 chip, addr);
 349 #endif
 350
 351         /*
 352          * Do the addressing portion of a write cycle to set the
 353          * chip's address pointer.  If the address length is zero,
 354          * don't do the normal write cycle to set the address pointer,
 355          * there is no address pointer in this chip.
 356          */
 357         send_start();
 358         if(alen > 0) {
 359                 if(write_byte(chip << 1)) {     /* write cycle */
 360                         send_stop();
 361                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 362                         return(1);
 363                 }
 364                 shift = (alen-1) * 8;
 365                 while(alen-- > 0) {
 366                         if(write_byte(addr >> shift)) {
 367                                 PRINTD("i2c_read, address not <ACK>ed\n");
 368                                 return(1);
 369                         }
 370                         shift -= 8;
 371                 }
 372
 373                 /* Some I2C chips need a stop/start sequence here,
 374                  * other chips don't work with a full stop and need
 375                  * only a start.  Default behaviour is to send the
 376                  * stop/start sequence.
 377                  */
 378 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 379                 send_start();
 380 #else
 381                 send_stop();
 382                 send_start();
 383 #endif
 384         }
 385         /*
 386          * Send the chip address again, this time for a read cycle.
 387          * Then read the data.  On the last byte, we do a NACK instead
 388          * of an ACK(len == 0) to terminate the read.
 389          */
 390         write_byte((chip << 1) | 1);    /* read cycle */
 391         while(len-- > 0) {
 392                 *buffer++ = read_byte(len == 0);
 393         }
 394         send_stop();
 395         return(0);
 396 }
 397
 398 /*-----------------------------------------------------------------------
 399  * Write bytes
 400  */
 401 static int  soft_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
 402                         int alen, uchar *buffer, int len)
 403 {
 404         int shift, failures = 0;
 405
 406         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 407                 chip, addr, alen, buffer, len);
 408
 409         send_start();
 410         if(write_byte(chip << 1)) {     /* write cycle */
 411                 send_stop();
 412                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 413                 return(1);
 414         }
 415         shift = (alen-1) * 8;
 416         while(alen-- > 0) {
 417                 if(write_byte(addr >> shift)) {
 418                         PRINTD("i2c_write, address not <ACK>ed\n");
 419                         return(1);
 420                 }
 421                 shift -= 8;
 422         }
 423
 424         while(len-- > 0) {
 425                 if(write_byte(*buffer++)) {
 426                         failures++;
 427                 }
 428         }
 429         send_stop();
 430         return(failures);
 431 }
 432
 433 /*
 434  * Register soft i2c adapters
 435  */
 436 U_BOOT_I2C_ADAP_COMPLETE(soft00, soft_i2c_init, soft_i2c_probe,
 437                          soft_i2c_read, soft_i2c_write, NULL,
 438                          CONFIG_SYS_I2C_SOFT_SPEED, CONFIG_SYS_I2C_SOFT_SLAVE,
 439                          0)
 440 #if defined(I2C_SOFT_DECLARATIONS2)
 441 U_BOOT_I2C_ADAP_COMPLETE(soft01, soft_i2c_init, soft_i2c_probe,
 442                          soft_i2c_read, soft_i2c_write, NULL,
 443                          CONFIG_SYS_I2C_SOFT_SPEED_2,
 444                          CONFIG_SYS_I2C_SOFT_SLAVE_2,
 445                          1)
 446 #endif
 447 #if defined(I2C_SOFT_DECLARATIONS3)
 448 U_BOOT_I2C_ADAP_COMPLETE(soft02, soft_i2c_init, soft_i2c_probe,
 449                          soft_i2c_read, soft_i2c_write, NULL,
 450                          CONFIG_SYS_I2C_SOFT_SPEED_3,
 451                          CONFIG_SYS_I2C_SOFT_SLAVE_3,
 452                          2)
 453 #endif
 454 #if defined(I2C_SOFT_DECLARATIONS4)
 455 U_BOOT_I2C_ADAP_COMPLETE(soft03, soft_i2c_init, soft_i2c_probe,
 456                          soft_i2c_read, soft_i2c_write, NULL,
 457                          CONFIG_SYS_I2C_SOFT_SPEED_4,
 458                          CONFIG_SYS_I2C_SOFT_SLAVE_4,
 459                          3)
 460 #endif
 461 #if defined(I2C_SOFT_DECLARATIONS5)
 462 U_BOOT_I2C_ADAP_COMPLETE(soft04, soft_i2c_init, soft_i2c_probe,
 463                          soft_i2c_read, soft_i2c_write, NULL,
 464                          CONFIG_SYS_I2C_SOFT_SPEED_5,
 465                          CONFIG_SYS_I2C_SOFT_SLAVE_5,
 466                          4)
 467 #endif
 468 #if defined(I2C_SOFT_DECLARATIONS6)
 469 U_BOOT_I2C_ADAP_COMPLETE(soft05, soft_i2c_init, soft_i2c_probe,
 470                          soft_i2c_read, soft_i2c_write, NULL,
 471                          CONFIG_SYS_I2C_SOFT_SPEED_6,
 472                          CONFIG_SYS_I2C_SOFT_SLAVE_6,
 473                          5)
 474 #endif
 475 #if defined(I2C_SOFT_DECLARATIONS7)
 476 U_BOOT_I2C_ADAP_COMPLETE(soft06, soft_i2c_init, soft_i2c_probe,
 477                          soft_i2c_read, soft_i2c_write, NULL,
 478                          CONFIG_SYS_I2C_SOFT_SPEED_7,
 479                          CONFIG_SYS_I2C_SOFT_SLAVE_7,
 480                          6)
 481 #endif
 482 #if defined(I2C_SOFT_DECLARATIONS8)
 483 U_BOOT_I2C_ADAP_COMPLETE(soft07, soft_i2c_init, soft_i2c_probe,
 484                          soft_i2c_read, soft_i2c_write, NULL,
 485                          CONFIG_SYS_I2C_SOFT_SPEED_8,
 486                          CONFIG_SYS_I2C_SOFT_SLAVE_8,
 487                          7)
 488 #endif
 489 #if defined(I2C_SOFT_DECLARATIONS9)
 490 U_BOOT_I2C_ADAP_COMPLETE(soft08, soft_i2c_init, soft_i2c_probe,
 491                          soft_i2c_read, soft_i2c_write, NULL,
 492                          CONFIG_SYS_I2C_SOFT_SPEED_9,
 493                          CONFIG_SYS_I2C_SOFT_SLAVE_9,
 494                          8)
 495 #endif
 496 #if defined(I2C_SOFT_DECLARATIONS10)
 497 U_BOOT_I2C_ADAP_COMPLETE(soft09, soft_i2c_init, soft_i2c_probe,
 498                          soft_i2c_read, soft_i2c_write, NULL,
 499                          CONFIG_SYS_I2C_SOFT_SPEED_10,
 500                          CONFIG_SYS_I2C_SOFT_SLAVE_10,
 501                          9)
 502 #endif
 503 #if defined(I2C_SOFT_DECLARATIONS11)
 504 U_BOOT_I2C_ADAP_COMPLETE(soft10, soft_i2c_init, soft_i2c_probe,
 505                          soft_i2c_read, soft_i2c_write, NULL,
 506                          CONFIG_SYS_I2C_SOFT_SPEED_11,
 507                          CONFIG_SYS_I2C_SOFT_SLAVE_11,
 508                          10)
 509 #endif
 510 #if defined(I2C_SOFT_DECLARATIONS12)
 511 U_BOOT_I2C_ADAP_COMPLETE(soft11, soft_i2c_init, soft_i2c_probe,
 512                          soft_i2c_read, soft_i2c_write, NULL,
 513                          CONFIG_SYS_I2C_SOFT_SPEED_12,
 514                          CONFIG_SYS_I2C_SOFT_SLAVE_12,
 515                          11)
 516 #endif