drivers/i2c/soft_i2c.c

   1 /*
   2  * (C) Copyright 2001, 2002
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  *
   7  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
   8  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
   9  * Neil Russell.
  10  */
  11
  12 #include <common.h>
  13 #ifdef  CONFIG_MPC8260                  /* only valid for MPC8260 */
  14 #include <ioports.h>
  15 #include <asm/io.h>
  16 #endif
  17 #if defined(CONFIG_AVR32)
  18 #include <asm/arch/portmux.h>
  19 #endif
  20 #if defined(CONFIG_AT91FAMILY)
  21 #include <asm/io.h>
  22 #include <asm/arch/hardware.h>
  23 #include <asm/arch/at91_pio.h>
  24 #ifdef CONFIG_AT91_LEGACY
  25 #include <asm/arch/gpio.h>
  26 #endif
  27 #endif
  28 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  29 #include <asm/arch/ixp425.h>
  30 #endif
  31 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  32 #include <asm/io.h>
  33 #endif
  34 #include <i2c.h>
  35
  36 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  37 # include <asm/gpio.h>
  38
  39 # ifndef I2C_GPIO_SYNC
  40 #  define I2C_GPIO_SYNC
  41 # endif
  42
  43 # ifndef I2C_INIT
  44 #  define I2C_INIT \
  45         do { \
  46                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  47                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  48         } while (0)
  49 # endif
  50
  51 # ifndef I2C_ACTIVE
  52 #  define I2C_ACTIVE do { } while (0)
  53 # endif
  54
  55 # ifndef I2C_TRISTATE
  56 #  define I2C_TRISTATE do { } while (0)
  57 # endif
  58
  59 # ifndef I2C_READ
  60 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  61 # endif
  62
  63 # ifndef I2C_SDA
  64 #  define I2C_SDA(bit) \
  65         do { \
  66                 if (bit) \
  67                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  68                 else \
  69                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  70                 I2C_GPIO_SYNC; \
  71         } while (0)
  72 # endif
  73
  74 # ifndef I2C_SCL
  75 #  define I2C_SCL(bit) \
  76         do { \
  77                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  78                 I2C_GPIO_SYNC; \
  79         } while (0)
  80 # endif
  81
  82 # ifndef I2C_DELAY
  83 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
  84 # endif
  85
  86 #endif
  87
  88 /* #define      DEBUG_I2C       */
  89
  90 #ifdef DEBUG_I2C
  91 DECLARE_GLOBAL_DATA_PTR;
  92 #endif
  93
  94 /*-----------------------------------------------------------------------
  95  * Definitions
  96  */
  97
  98 #define RETRIES         0
  99
 100 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 101 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 102
 103
 104 #ifdef DEBUG_I2C
 105 #define PRINTD(fmt,args...)     do {    \
 106                 printf (fmt ,##args);   \
 107         } while (0)
 108 #else
 109 #define PRINTD(fmt,args...)
 110 #endif
 111
 112 #if defined(CONFIG_I2C_MULTI_BUS)
 113 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
 114 #endif /* CONFIG_I2C_MULTI_BUS */
 115
 116 /*-----------------------------------------------------------------------
 117  * Local functions
 118  */
 119 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 120 static void  send_reset (void);
 121 #endif
 122 static void  send_start (void);
 123 static void  send_stop  (void);
 124 static void  send_ack   (int);
 125 static int   write_byte (uchar byte);
 126 static uchar read_byte  (int);
 127
 128 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 129 /*-----------------------------------------------------------------------
 130  * Send a reset sequence consisting of 9 clocks with the data signal high
 131  * to clock any confused device back into an idle state.  Also send a
 132  * <stop> at the end of the sequence for belts & suspenders.
 133  */
 134 static void send_reset(void)
 135 {
 136         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 137         int j;
 138
 139         I2C_SCL(1);
 140         I2C_SDA(1);
 141 #ifdef  I2C_INIT
 142         I2C_INIT;
 143 #endif
 144         I2C_TRISTATE;
 145         for(j = 0; j < 9; j++) {
 146                 I2C_SCL(0);
 147                 I2C_DELAY;
 148                 I2C_DELAY;
 149                 I2C_SCL(1);
 150                 I2C_DELAY;
 151                 I2C_DELAY;
 152         }
 153         send_stop();
 154         I2C_TRISTATE;
 155 }
 156 #endif
 157
 158 /*-----------------------------------------------------------------------
 159  * START: High -> Low on SDA while SCL is High
 160  */
 161 static void send_start(void)
 162 {
 163         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 164
 165         I2C_DELAY;
 166         I2C_SDA(1);
 167         I2C_ACTIVE;
 168         I2C_DELAY;
 169         I2C_SCL(1);
 170         I2C_DELAY;
 171         I2C_SDA(0);
 172         I2C_DELAY;
 173 }
 174
 175 /*-----------------------------------------------------------------------
 176  * STOP: Low -> High on SDA while SCL is High
 177  */
 178 static void send_stop(void)
 179 {
 180         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 181
 182         I2C_SCL(0);
 183         I2C_DELAY;
 184         I2C_SDA(0);
 185         I2C_ACTIVE;
 186         I2C_DELAY;
 187         I2C_SCL(1);
 188         I2C_DELAY;
 189         I2C_SDA(1);
 190         I2C_DELAY;
 191         I2C_TRISTATE;
 192 }
 193
 194 /*-----------------------------------------------------------------------
 195  * ack should be I2C_ACK or I2C_NOACK
 196  */
 197 static void send_ack(int ack)
 198 {
 199         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 200
 201         I2C_SCL(0);
 202         I2C_DELAY;
 203         I2C_ACTIVE;
 204         I2C_SDA(ack);
 205         I2C_DELAY;
 206         I2C_SCL(1);
 207         I2C_DELAY;
 208         I2C_DELAY;
 209         I2C_SCL(0);
 210         I2C_DELAY;
 211 }
 212
 213 /*-----------------------------------------------------------------------
 214  * Send 8 bits and look for an acknowledgement.
 215  */
 216 static int write_byte(uchar data)
 217 {
 218         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 219         int j;
 220         int nack;
 221
 222         I2C_ACTIVE;
 223         for(j = 0; j < 8; j++) {
 224                 I2C_SCL(0);
 225                 I2C_DELAY;
 226                 I2C_SDA(data & 0x80);
 227                 I2C_DELAY;
 228                 I2C_SCL(1);
 229                 I2C_DELAY;
 230                 I2C_DELAY;
 231
 232                 data <<= 1;
 233         }
 234
 235         /*
 236          * Look for an <ACK>(negative logic) and return it.
 237          */
 238         I2C_SCL(0);
 239         I2C_DELAY;
 240         I2C_SDA(1);
 241         I2C_TRISTATE;
 242         I2C_DELAY;
 243         I2C_SCL(1);
 244         I2C_DELAY;
 245         I2C_DELAY;
 246         nack = I2C_READ;
 247         I2C_SCL(0);
 248         I2C_DELAY;
 249         I2C_ACTIVE;
 250
 251         return(nack);   /* not a nack is an ack */
 252 }
 253
 254 #if defined(CONFIG_I2C_MULTI_BUS)
 255 /*
 256  * Functions for multiple I2C bus handling
 257  */
 258 unsigned int i2c_get_bus_num(void)
 259 {
 260         return i2c_bus_num;
 261 }
 262
 263 int i2c_set_bus_num(unsigned int bus)
 264 {
 265 #if defined(CONFIG_I2C_MUX)
 266         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
 267                 i2c_bus_num = bus;
 268         } else {
 269                 int     ret;
 270
 271                 ret = i2x_mux_select_mux(bus);
 272                 i2c_init_board();
 273                 if (ret == 0)
 274                         i2c_bus_num = bus;
 275                 else
 276                         return ret;
 277         }
 278 #else
 279         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
 280                 return -1;
 281         i2c_bus_num = bus;
 282 #endif
 283         return 0;
 284 }
 285 #endif
 286
 287 /*-----------------------------------------------------------------------
 288  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 289  * send I2C_NOACK to end the read.
 290  */
 291 static uchar read_byte(int ack)
 292 {
 293         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 294         int  data;
 295         int  j;
 296
 297         /*
 298          * Read 8 bits, MSB first.
 299          */
 300         I2C_TRISTATE;
 301         I2C_SDA(1);
 302         data = 0;
 303         for(j = 0; j < 8; j++) {
 304                 I2C_SCL(0);
 305                 I2C_DELAY;
 306                 I2C_SCL(1);
 307                 I2C_DELAY;
 308                 data <<= 1;
 309                 data |= I2C_READ;
 310                 I2C_DELAY;
 311         }
 312         send_ack(ack);
 313
 314         return(data);
 315 }
 316
 317 /*=====================================================================*/
 318 /*                         Public Functions                            */
 319 /*=====================================================================*/
 320
 321 /*-----------------------------------------------------------------------
 322  * Initialization
 323  */
 324 void i2c_init (int speed, int slaveaddr)
 325 {
 326 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 327         /* call board specific i2c bus reset routine before accessing the   */
 328         /* environment, which might be in a chip on that bus. For details   */
 329         /* about this problem see doc/I2C_Edge_Conditions.                  */
 330         i2c_init_board();
 331 #else
 332         /*
 333          * WARNING: Do NOT save speed in a static variable: if the
 334          * I2C routines are called before RAM is initialized (to read
 335          * the DIMM SPD, for instance), RAM won't be usable and your
 336          * system will crash.
 337          */
 338         send_reset ();
 339 #endif
 340 }
 341
 342 /*-----------------------------------------------------------------------
 343  * Probe to see if a chip is present.  Also good for checking for the
 344  * completion of EEPROM writes since the chip stops responding until
 345  * the write completes (typically 10mSec).
 346  */
 347 int i2c_probe(uchar addr)
 348 {
 349         int rc;
 350
 351         /*
 352          * perform 1 byte write transaction with just address byte
 353          * (fake write)
 354          */
 355         send_start();
 356         rc = write_byte ((addr << 1) | 0);
 357         send_stop();
 358
 359         return (rc ? 1 : 0);
 360 }
 361
 362 /*-----------------------------------------------------------------------
 363  * Read bytes
 364  */
 365 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 366 {
 367         int shift;
 368         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 369                 chip, addr, alen, buffer, len);
 370
 371 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 372         /*
 373          * EEPROM chips that implement "address overflow" are ones
 374          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 375          * address and the extra bits end up in the "chip address"
 376          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 377          * four 256 byte chips.
 378          *
 379          * Note that we consider the length of the address field to
 380          * still be one byte because the extra address bits are
 381          * hidden in the chip address.
 382          */
 383         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 384
 385         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 386                 chip, addr);
 387 #endif
 388
 389         /*
 390          * Do the addressing portion of a write cycle to set the
 391          * chip's address pointer.  If the address length is zero,
 392          * don't do the normal write cycle to set the address pointer,
 393          * there is no address pointer in this chip.
 394          */
 395         send_start();
 396         if(alen > 0) {
 397                 if(write_byte(chip << 1)) {     /* write cycle */
 398                         send_stop();
 399                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 400                         return(1);
 401                 }
 402                 shift = (alen-1) * 8;
 403                 while(alen-- > 0) {
 404                         if(write_byte(addr >> shift)) {
 405                                 PRINTD("i2c_read, address not <ACK>ed\n");
 406                                 return(1);
 407                         }
 408                         shift -= 8;
 409                 }
 410
 411                 /* Some I2C chips need a stop/start sequence here,
 412                  * other chips don't work with a full stop and need
 413                  * only a start.  Default behaviour is to send the
 414                  * stop/start sequence.
 415                  */
 416 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 417                 send_start();
 418 #else
 419                 send_stop();
 420                 send_start();
 421 #endif
 422         }
 423         /*
 424          * Send the chip address again, this time for a read cycle.
 425          * Then read the data.  On the last byte, we do a NACK instead
 426          * of an ACK(len == 0) to terminate the read.
 427          */
 428         write_byte((chip << 1) | 1);    /* read cycle */
 429         while(len-- > 0) {
 430                 *buffer++ = read_byte(len == 0);
 431         }
 432         send_stop();
 433         return(0);
 434 }
 435
 436 /*-----------------------------------------------------------------------
 437  * Write bytes
 438  */
 439 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 440 {
 441         int shift, failures = 0;
 442
 443         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 444                 chip, addr, alen, buffer, len);
 445
 446         send_start();
 447         if(write_byte(chip << 1)) {     /* write cycle */
 448                 send_stop();
 449                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 450                 return(1);
 451         }
 452         shift = (alen-1) * 8;
 453         while(alen-- > 0) {
 454                 if(write_byte(addr >> shift)) {
 455                         PRINTD("i2c_write, address not <ACK>ed\n");
 456                         return(1);
 457                 }
 458                 shift -= 8;
 459         }
 460
 461         while(len-- > 0) {
 462                 if(write_byte(*buffer++)) {
 463                         failures++;
 464                 }
 465         }
 466         send_stop();
 467         return(failures);
 468 }