drivers/i2c/soft_i2c.c

   1 /*
   2  * (C) Copyright 2009
   3  * Heiko Schocher, DENX Software Engineering, hs@denx.de.
   4  * Changes for multibus/multiadapter I2C support.
   5  *
   6  * (C) Copyright 2001, 2002
   7  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   8  *
   9  * SPDX-License-Identifier:     GPL-2.0+
  10  *
  11  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
  12  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
  13  * Neil Russell.
  14  */
  15
  16 #include <common.h>
  17 #ifdef  CONFIG_MPC8260                  /* only valid for MPC8260 */
  18 #include <ioports.h>
  19 #include <asm/io.h>
  20 #endif
  21 #if defined(CONFIG_AVR32)
  22 #include <asm/arch/portmux.h>
  23 #endif
  24 #if defined(CONFIG_AT91FAMILY)
  25 #include <asm/io.h>
  26 #include <asm/arch/hardware.h>
  27 #include <asm/arch/at91_pio.h>
  28 #ifdef CONFIG_ATMEL_LEGACY
  29 #include <asm/arch/gpio.h>
  30 #endif
  31 #endif
  32 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  33 #include <asm/io.h>
  34 #endif
  35 #include <i2c.h>
  36
  37 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  38 # include <asm/gpio.h>
  39
  40 # ifndef I2C_GPIO_SYNC
  41 #  define I2C_GPIO_SYNC
  42 # endif
  43
  44 # ifndef I2C_INIT
  45 #  define I2C_INIT \
  46         do { \
  47                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  48                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  49         } while (0)
  50 # endif
  51
  52 # ifndef I2C_ACTIVE
  53 #  define I2C_ACTIVE do { } while (0)
  54 # endif
  55
  56 # ifndef I2C_TRISTATE
  57 #  define I2C_TRISTATE do { } while (0)
  58 # endif
  59
  60 # ifndef I2C_READ
  61 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  62 # endif
  63
  64 # ifndef I2C_SDA
  65 #  define I2C_SDA(bit) \
  66         do { \
  67                 if (bit) \
  68                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  69                 else \
  70                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  71                 I2C_GPIO_SYNC; \
  72         } while (0)
  73 # endif
  74
  75 # ifndef I2C_SCL
  76 #  define I2C_SCL(bit) \
  77         do { \
  78                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  79                 I2C_GPIO_SYNC; \
  80         } while (0)
  81 # endif
  82
  83 # ifndef I2C_DELAY
  84 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
  85 # endif
  86
  87 #endif
  88
  89 /* #define      DEBUG_I2C       */
  90
  91 DECLARE_GLOBAL_DATA_PTR;
  92
  93 #ifndef I2C_SOFT_DECLARATIONS
  94 # if defined(CONFIG_MPC8260)
  95 #  define I2C_SOFT_DECLARATIONS volatile ioport_t *iop = \
  96                 ioport_addr((immap_t *)CONFIG_SYS_IMMR, I2C_PORT);
  97 # elif defined(CONFIG_8xx)
  98 #  define I2C_SOFT_DECLARATIONS volatile immap_t *immr = \
  99                 (immap_t *)CONFIG_SYS_IMMR;
 100 # else
 101 #  define I2C_SOFT_DECLARATIONS
 102 # endif
 103 #endif
 104
 105 #if !defined(CONFIG_SYS_I2C_SOFT_SPEED)
 106 #define CONFIG_SYS_I2C_SOFT_SPEED CONFIG_SYS_I2C_SPEED
 107 #endif
 108 #if !defined(CONFIG_SYS_I2C_SOFT_SLAVE)
 109 #define CONFIG_SYS_I2C_SOFT_SLAVE CONFIG_SYS_I2C_SLAVE
 110 #endif
 111
 112 /*-----------------------------------------------------------------------
 113  * Definitions
 114  */
 115 #define RETRIES         0
 116
 117 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 118 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 119
 120
 121 #ifdef DEBUG_I2C
 122 #define PRINTD(fmt,args...)     do {    \
 123                 printf (fmt ,##args);   \
 124         } while (0)
 125 #else
 126 #define PRINTD(fmt,args...)
 127 #endif
 128
 129 /*-----------------------------------------------------------------------
 130  * Local functions
 131  */
 132 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 133 static void  send_reset (void);
 134 #endif
 135 static void  send_start (void);
 136 static void  send_stop  (void);
 137 static void  send_ack   (int);
 138 static int   write_byte (uchar byte);
 139 static uchar read_byte  (int);
 140
 141 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 142 /*-----------------------------------------------------------------------
 143  * Send a reset sequence consisting of 9 clocks with the data signal high
 144  * to clock any confused device back into an idle state.  Also send a
 145  * <stop> at the end of the sequence for belts & suspenders.
 146  */
 147 static void send_reset(void)
 148 {
 149         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 150         int j;
 151
 152         I2C_SCL(1);
 153         I2C_SDA(1);
 154 #ifdef  I2C_INIT
 155         I2C_INIT;
 156 #endif
 157         I2C_TRISTATE;
 158         for(j = 0; j < 9; j++) {
 159                 I2C_SCL(0);
 160                 I2C_DELAY;
 161                 I2C_DELAY;
 162                 I2C_SCL(1);
 163                 I2C_DELAY;
 164                 I2C_DELAY;
 165         }
 166         send_stop();
 167         I2C_TRISTATE;
 168 }
 169 #endif
 170
 171 /*-----------------------------------------------------------------------
 172  * START: High -> Low on SDA while SCL is High
 173  */
 174 static void send_start(void)
 175 {
 176         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 177
 178         I2C_DELAY;
 179         I2C_SDA(1);
 180         I2C_ACTIVE;
 181         I2C_DELAY;
 182         I2C_SCL(1);
 183         I2C_DELAY;
 184         I2C_SDA(0);
 185         I2C_DELAY;
 186 }
 187
 188 /*-----------------------------------------------------------------------
 189  * STOP: Low -> High on SDA while SCL is High
 190  */
 191 static void send_stop(void)
 192 {
 193         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 194
 195         I2C_SCL(0);
 196         I2C_DELAY;
 197         I2C_SDA(0);
 198         I2C_ACTIVE;
 199         I2C_DELAY;
 200         I2C_SCL(1);
 201         I2C_DELAY;
 202         I2C_SDA(1);
 203         I2C_DELAY;
 204         I2C_TRISTATE;
 205 }
 206
 207 /*-----------------------------------------------------------------------
 208  * ack should be I2C_ACK or I2C_NOACK
 209  */
 210 static void send_ack(int ack)
 211 {
 212         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 213
 214         I2C_SCL(0);
 215         I2C_DELAY;
 216         I2C_ACTIVE;
 217         I2C_SDA(ack);
 218         I2C_DELAY;
 219         I2C_SCL(1);
 220         I2C_DELAY;
 221         I2C_DELAY;
 222         I2C_SCL(0);
 223         I2C_DELAY;
 224 }
 225
 226 /*-----------------------------------------------------------------------
 227  * Send 8 bits and look for an acknowledgement.
 228  */
 229 static int write_byte(uchar data)
 230 {
 231         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 232         int j;
 233         int nack;
 234
 235         I2C_ACTIVE;
 236         for(j = 0; j < 8; j++) {
 237                 I2C_SCL(0);
 238                 I2C_DELAY;
 239                 I2C_SDA(data & 0x80);
 240                 I2C_DELAY;
 241                 I2C_SCL(1);
 242                 I2C_DELAY;
 243                 I2C_DELAY;
 244
 245                 data <<= 1;
 246         }
 247
 248         /*
 249          * Look for an <ACK>(negative logic) and return it.
 250          */
 251         I2C_SCL(0);
 252         I2C_DELAY;
 253         I2C_SDA(1);
 254         I2C_TRISTATE;
 255         I2C_DELAY;
 256         I2C_SCL(1);
 257         I2C_DELAY;
 258         I2C_DELAY;
 259         nack = I2C_READ;
 260         I2C_SCL(0);
 261         I2C_DELAY;
 262         I2C_ACTIVE;
 263
 264         return(nack);   /* not a nack is an ack */
 265 }
 266
 267 /*-----------------------------------------------------------------------
 268  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 269  * send I2C_NOACK to end the read.
 270  */
 271 static uchar read_byte(int ack)
 272 {
 273         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 274         int  data;
 275         int  j;
 276
 277         /*
 278          * Read 8 bits, MSB first.
 279          */
 280         I2C_TRISTATE;
 281         I2C_SDA(1);
 282         data = 0;
 283         for(j = 0; j < 8; j++) {
 284                 I2C_SCL(0);
 285                 I2C_DELAY;
 286                 I2C_SCL(1);
 287                 I2C_DELAY;
 288                 data <<= 1;
 289                 data |= I2C_READ;
 290                 I2C_DELAY;
 291         }
 292         send_ack(ack);
 293
 294         return(data);
 295 }
 296
 297 /*-----------------------------------------------------------------------
 298  * Initialization
 299  */
 300 static void soft_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
 301 {
 302 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 303         /* call board specific i2c bus reset routine before accessing the   */
 304         /* environment, which might be in a chip on that bus. For details   */
 305         /* about this problem see doc/I2C_Edge_Conditions.                  */
 306         i2c_init_board();
 307 #else
 308         /*
 309          * WARNING: Do NOT save speed in a static variable: if the
 310          * I2C routines are called before RAM is initialized (to read
 311          * the DIMM SPD, for instance), RAM won't be usable and your
 312          * system will crash.
 313          */
 314         send_reset ();
 315 #endif
 316 }
 317
 318 /*-----------------------------------------------------------------------
 319  * Probe to see if a chip is present.  Also good for checking for the
 320  * completion of EEPROM writes since the chip stops responding until
 321  * the write completes (typically 10mSec).
 322  */
 323 static int soft_i2c_probe(struct i2c_adapter *adap, uint8_t addr)
 324 {
 325         int rc;
 326
 327         /*
 328          * perform 1 byte write transaction with just address byte
 329          * (fake write)
 330          */
 331         send_start();
 332         rc = write_byte ((addr << 1) | 0);
 333         send_stop();
 334
 335         return (rc ? 1 : 0);
 336 }
 337
 338 /*-----------------------------------------------------------------------
 339  * Read bytes
 340  */
 341 static int  soft_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
 342                         int alen, uchar *buffer, int len)
 343 {
 344         int shift;
 345         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 346                 chip, addr, alen, buffer, len);
 347
 348 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 349         /*
 350          * EEPROM chips that implement "address overflow" are ones
 351          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 352          * address and the extra bits end up in the "chip address"
 353          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 354          * four 256 byte chips.
 355          *
 356          * Note that we consider the length of the address field to
 357          * still be one byte because the extra address bits are
 358          * hidden in the chip address.
 359          */
 360         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 361
 362         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 363                 chip, addr);
 364 #endif
 365
 366         /*
 367          * Do the addressing portion of a write cycle to set the
 368          * chip's address pointer.  If the address length is zero,
 369          * don't do the normal write cycle to set the address pointer,
 370          * there is no address pointer in this chip.
 371          */
 372         send_start();
 373         if(alen > 0) {
 374                 if(write_byte(chip << 1)) {     /* write cycle */
 375                         send_stop();
 376                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 377                         return(1);
 378                 }
 379                 shift = (alen-1) * 8;
 380                 while(alen-- > 0) {
 381                         if(write_byte(addr >> shift)) {
 382                                 PRINTD("i2c_read, address not <ACK>ed\n");
 383                                 return(1);
 384                         }
 385                         shift -= 8;
 386                 }
 387
 388                 /* Some I2C chips need a stop/start sequence here,
 389                  * other chips don't work with a full stop and need
 390                  * only a start.  Default behaviour is to send the
 391                  * stop/start sequence.
 392                  */
 393 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 394                 send_start();
 395 #else
 396                 send_stop();
 397                 send_start();
 398 #endif
 399         }
 400         /*
 401          * Send the chip address again, this time for a read cycle.
 402          * Then read the data.  On the last byte, we do a NACK instead
 403          * of an ACK(len == 0) to terminate the read.
 404          */
 405         write_byte((chip << 1) | 1);    /* read cycle */
 406         while(len-- > 0) {
 407                 *buffer++ = read_byte(len == 0);
 408         }
 409         send_stop();
 410         return(0);
 411 }
 412
 413 /*-----------------------------------------------------------------------
 414  * Write bytes
 415  */
 416 static int  soft_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
 417                         int alen, uchar *buffer, int len)
 418 {
 419         int shift, failures = 0;
 420
 421         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 422                 chip, addr, alen, buffer, len);
 423
 424         send_start();
 425         if(write_byte(chip << 1)) {     /* write cycle */
 426                 send_stop();
 427                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 428                 return(1);
 429         }
 430         shift = (alen-1) * 8;
 431         while(alen-- > 0) {
 432                 if(write_byte(addr >> shift)) {
 433                         PRINTD("i2c_write, address not <ACK>ed\n");
 434                         return(1);
 435                 }
 436                 shift -= 8;
 437         }
 438
 439         while(len-- > 0) {
 440                 if(write_byte(*buffer++)) {
 441                         failures++;
 442                 }
 443         }
 444         send_stop();
 445         return(failures);
 446 }
 447
 448 /*
 449  * Register soft i2c adapters
 450  */
 451 U_BOOT_I2C_ADAP_COMPLETE(soft0, soft_i2c_init, soft_i2c_probe,
 452                          soft_i2c_read, soft_i2c_write, NULL,
 453                          CONFIG_SYS_I2C_SOFT_SPEED, CONFIG_SYS_I2C_SOFT_SLAVE,
 454                          0)
 455 #if defined(I2C_SOFT_DECLARATIONS2)
 456 U_BOOT_I2C_ADAP_COMPLETE(soft1, soft_i2c_init, soft_i2c_probe,
 457                          soft_i2c_read, soft_i2c_write, NULL,
 458                          CONFIG_SYS_I2C_SOFT_SPEED_2,
 459                          CONFIG_SYS_I2C_SOFT_SLAVE_2,
 460                          1)
 461 #endif
 462 #if defined(I2C_SOFT_DECLARATIONS3)
 463 U_BOOT_I2C_ADAP_COMPLETE(soft2, soft_i2c_init, soft_i2c_probe,
 464                          soft_i2c_read, soft_i2c_write, NULL,
 465                          CONFIG_SYS_I2C_SOFT_SPEED_3,
 466                          CONFIG_SYS_I2C_SOFT_SLAVE_3,
 467                          2)
 468 #endif
 469 #if defined(I2C_SOFT_DECLARATIONS4)
 470 U_BOOT_I2C_ADAP_COMPLETE(soft3, soft_i2c_init, soft_i2c_probe,
 471                          soft_i2c_read, soft_i2c_write, NULL,
 472                          CONFIG_SYS_I2C_SOFT_SPEED_4,
 473                          CONFIG_SYS_I2C_SOFT_SLAVE_4,
 474                          3)
 475 #endif