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  * See file CREDITS for list of people who contributed to this
  10  * project.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of
  15  * the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  25  * MA 02111-1307 USA
  26  *
  27  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
  28  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
  29  * Neil Russell.
  30  */
  31
  32 #include <common.h>
  33 #ifdef  CONFIG_MPC8260                  /* only valid for MPC8260 */
  34 #include <ioports.h>
  35 #include <asm/io.h>
  36 #endif
  37 #if defined(CONFIG_AVR32)
  38 #include <asm/arch/portmux.h>
  39 #endif
  40 #if defined(CONFIG_AT91FAMILY)
  41 #include <asm/io.h>
  42 #include <asm/arch/hardware.h>
  43 #include <asm/arch/at91_pio.h>
  44 #ifdef CONFIG_AT91_LEGACY
  45 #include <asm/arch/gpio.h>
  46 #endif
  47 #endif
  48 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  49 #include <asm/arch/ixp425.h>
  50 #endif
  51 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  52 #include <asm/io.h>
  53 #endif
  54 #include <i2c.h>
  55
  56 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  57 # include <asm/gpio.h>
  58
  59 # ifndef I2C_GPIO_SYNC
  60 #  define I2C_GPIO_SYNC
  61 # endif
  62
  63 # ifndef I2C_INIT
  64 #  define I2C_INIT \
  65         do { \
  66                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  67                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  68         } while (0)
  69 # endif
  70
  71 # ifndef I2C_ACTIVE
  72 #  define I2C_ACTIVE do { } while (0)
  73 # endif
  74
  75 # ifndef I2C_TRISTATE
  76 #  define I2C_TRISTATE do { } while (0)
  77 # endif
  78
  79 # ifndef I2C_READ
  80 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  81 # endif
  82
  83 # ifndef I2C_SDA
  84 #  define I2C_SDA(bit) \
  85         do { \
  86                 if (bit) \
  87                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  88                 else \
  89                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  90                 I2C_GPIO_SYNC; \
  91         } while (0)
  92 # endif
  93
  94 # ifndef I2C_SCL
  95 #  define I2C_SCL(bit) \
  96         do { \
  97                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  98                 I2C_GPIO_SYNC; \
  99         } while (0)
 100 # endif
 101
 102 # ifndef I2C_DELAY
 103 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
 104 # endif
 105
 106 #endif
 107
 108 /* #define      DEBUG_I2C       */
 109
 110 DECLARE_GLOBAL_DATA_PTR;
 111
 112 #ifndef I2C_SOFT_DECLARATIONS
 113 # if defined(CONFIG_MPC8260)
 114 #  define I2C_SOFT_DECLARATIONS volatile ioport_t *iop = \
 115                 ioport_addr((immap_t *)CONFIG_SYS_IMMR, I2C_PORT);
 116 # elif defined(CONFIG_8xx)
 117 #  define I2C_SOFT_DECLARATIONS volatile immap_t *immr = \
 118                 (immap_t *)CONFIG_SYS_IMMR;
 119 # else
 120 #  define I2C_SOFT_DECLARATIONS
 121 # endif
 122 #endif
 123
 124 #if !defined(CONFIG_SYS_SOFT_I2C_SPEED)
 125 #define CONFIG_SYS_SOFT_I2C_SPEED CONFIG_SYS_I2C_SPEED
 126 #endif
 127 #if !defined(CONFIG_SYS_SOFT_I2C_SLAVE)
 128 #define CONFIG_SYS_SOFT_I2C_SLAVE CONFIG_SYS_I2C_SLAVE
 129 #endif
 130
 131 /*-----------------------------------------------------------------------
 132  * Definitions
 133  */
 134 #define RETRIES         0
 135
 136 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 137 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 138
 139
 140 #ifdef DEBUG_I2C
 141 #define PRINTD(fmt,args...)     do {    \
 142                 printf (fmt ,##args);   \
 143         } while (0)
 144 #else
 145 #define PRINTD(fmt,args...)
 146 #endif
 147
 148 /*-----------------------------------------------------------------------
 149  * Local functions
 150  */
 151 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 152 static void  send_reset (void);
 153 #endif
 154 static void  send_start (void);
 155 static void  send_stop  (void);
 156 static void  send_ack   (int);
 157 static int   write_byte (uchar byte);
 158 static uchar read_byte  (int);
 159
 160 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 161 /*-----------------------------------------------------------------------
 162  * Send a reset sequence consisting of 9 clocks with the data signal high
 163  * to clock any confused device back into an idle state.  Also send a
 164  * <stop> at the end of the sequence for belts & suspenders.
 165  */
 166 static void send_reset(void)
 167 {
 168         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 169         int j;
 170
 171         I2C_SCL(1);
 172         I2C_SDA(1);
 173 #ifdef  I2C_INIT
 174         I2C_INIT;
 175 #endif
 176         I2C_TRISTATE;
 177         for(j = 0; j < 9; j++) {
 178                 I2C_SCL(0);
 179                 I2C_DELAY;
 180                 I2C_DELAY;
 181                 I2C_SCL(1);
 182                 I2C_DELAY;
 183                 I2C_DELAY;
 184         }
 185         send_stop();
 186         I2C_TRISTATE;
 187 }
 188 #endif
 189
 190 /*-----------------------------------------------------------------------
 191  * START: High -> Low on SDA while SCL is High
 192  */
 193 static void send_start(void)
 194 {
 195         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 196
 197         I2C_DELAY;
 198         I2C_SDA(1);
 199         I2C_ACTIVE;
 200         I2C_DELAY;
 201         I2C_SCL(1);
 202         I2C_DELAY;
 203         I2C_SDA(0);
 204         I2C_DELAY;
 205 }
 206
 207 /*-----------------------------------------------------------------------
 208  * STOP: Low -> High on SDA while SCL is High
 209  */
 210 static void send_stop(void)
 211 {
 212         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 213
 214         I2C_SCL(0);
 215         I2C_DELAY;
 216         I2C_SDA(0);
 217         I2C_ACTIVE;
 218         I2C_DELAY;
 219         I2C_SCL(1);
 220         I2C_DELAY;
 221         I2C_SDA(1);
 222         I2C_DELAY;
 223         I2C_TRISTATE;
 224 }
 225
 226 /*-----------------------------------------------------------------------
 227  * ack should be I2C_ACK or I2C_NOACK
 228  */
 229 static void send_ack(int ack)
 230 {
 231         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 232
 233         I2C_SCL(0);
 234         I2C_DELAY;
 235         I2C_ACTIVE;
 236         I2C_SDA(ack);
 237         I2C_DELAY;
 238         I2C_SCL(1);
 239         I2C_DELAY;
 240         I2C_DELAY;
 241         I2C_SCL(0);
 242         I2C_DELAY;
 243 }
 244
 245 /*-----------------------------------------------------------------------
 246  * Send 8 bits and look for an acknowledgement.
 247  */
 248 static int write_byte(uchar data)
 249 {
 250         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 251         int j;
 252         int nack;
 253
 254         I2C_ACTIVE;
 255         for(j = 0; j < 8; j++) {
 256                 I2C_SCL(0);
 257                 I2C_DELAY;
 258                 I2C_SDA(data & 0x80);
 259                 I2C_DELAY;
 260                 I2C_SCL(1);
 261                 I2C_DELAY;
 262                 I2C_DELAY;
 263
 264                 data <<= 1;
 265         }
 266
 267         /*
 268          * Look for an <ACK>(negative logic) and return it.
 269          */
 270         I2C_SCL(0);
 271         I2C_DELAY;
 272         I2C_SDA(1);
 273         I2C_TRISTATE;
 274         I2C_DELAY;
 275         I2C_SCL(1);
 276         I2C_DELAY;
 277         I2C_DELAY;
 278         nack = I2C_READ;
 279         I2C_SCL(0);
 280         I2C_DELAY;
 281         I2C_ACTIVE;
 282
 283         return(nack);   /* not a nack is an ack */
 284 }
 285
 286 /*-----------------------------------------------------------------------
 287  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 288  * send I2C_NOACK to end the read.
 289  */
 290 static uchar read_byte(int ack)
 291 {
 292         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 293         int  data;
 294         int  j;
 295
 296         /*
 297          * Read 8 bits, MSB first.
 298          */
 299         I2C_TRISTATE;
 300         I2C_SDA(1);
 301         data = 0;
 302         for(j = 0; j < 8; j++) {
 303                 I2C_SCL(0);
 304                 I2C_DELAY;
 305                 I2C_SCL(1);
 306                 I2C_DELAY;
 307                 data <<= 1;
 308                 data |= I2C_READ;
 309                 I2C_DELAY;
 310         }
 311         send_ack(ack);
 312
 313         return(data);
 314 }
 315
 316 /*-----------------------------------------------------------------------
 317  * Initialization
 318  */
 319 static void soft_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
 320 {
 321 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 322         /* call board specific i2c bus reset routine before accessing the   */
 323         /* environment, which might be in a chip on that bus. For details   */
 324         /* about this problem see doc/I2C_Edge_Conditions.                  */
 325         i2c_init_board();
 326 #else
 327         /*
 328          * WARNING: Do NOT save speed in a static variable: if the
 329          * I2C routines are called before RAM is initialized (to read
 330          * the DIMM SPD, for instance), RAM won't be usable and your
 331          * system will crash.
 332          */
 333         send_reset ();
 334 #endif
 335 }
 336
 337 /*-----------------------------------------------------------------------
 338  * Probe to see if a chip is present.  Also good for checking for the
 339  * completion of EEPROM writes since the chip stops responding until
 340  * the write completes (typically 10mSec).
 341  */
 342 static int soft_i2c_probe(struct i2c_adapter *adap, uint8_t addr)
 343 {
 344         int rc;
 345
 346         /*
 347          * perform 1 byte write transaction with just address byte
 348          * (fake write)
 349          */
 350         send_start();
 351         rc = write_byte ((addr << 1) | 0);
 352         send_stop();
 353
 354         return (rc ? 1 : 0);
 355 }
 356
 357 /*-----------------------------------------------------------------------
 358  * Read bytes
 359  */
 360 static int  soft_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
 361                         int alen, uchar *buffer, int len)
 362 {
 363         int shift;
 364         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 365                 chip, addr, alen, buffer, len);
 366
 367 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 368         /*
 369          * EEPROM chips that implement "address overflow" are ones
 370          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 371          * address and the extra bits end up in the "chip address"
 372          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 373          * four 256 byte chips.
 374          *
 375          * Note that we consider the length of the address field to
 376          * still be one byte because the extra address bits are
 377          * hidden in the chip address.
 378          */
 379         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 380
 381         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 382                 chip, addr);
 383 #endif
 384
 385         /*
 386          * Do the addressing portion of a write cycle to set the
 387          * chip's address pointer.  If the address length is zero,
 388          * don't do the normal write cycle to set the address pointer,
 389          * there is no address pointer in this chip.
 390          */
 391         send_start();
 392         if(alen > 0) {
 393                 if(write_byte(chip << 1)) {     /* write cycle */
 394                         send_stop();
 395                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 396                         return(1);
 397                 }
 398                 shift = (alen-1) * 8;
 399                 while(alen-- > 0) {
 400                         if(write_byte(addr >> shift)) {
 401                                 PRINTD("i2c_read, address not <ACK>ed\n");
 402                                 return(1);
 403                         }
 404                         shift -= 8;
 405                 }
 406
 407                 /* Some I2C chips need a stop/start sequence here,
 408                  * other chips don't work with a full stop and need
 409                  * only a start.  Default behaviour is to send the
 410                  * stop/start sequence.
 411                  */
 412 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 413                 send_start();
 414 #else
 415                 send_stop();
 416                 send_start();
 417 #endif
 418         }
 419         /*
 420          * Send the chip address again, this time for a read cycle.
 421          * Then read the data.  On the last byte, we do a NACK instead
 422          * of an ACK(len == 0) to terminate the read.
 423          */
 424         write_byte((chip << 1) | 1);    /* read cycle */
 425         while(len-- > 0) {
 426                 *buffer++ = read_byte(len == 0);
 427         }
 428         send_stop();
 429         return(0);
 430 }
 431
 432 /*-----------------------------------------------------------------------
 433  * Write bytes
 434  */
 435 static int  soft_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
 436                         int alen, uchar *buffer, int len)
 437 {
 438         int shift, failures = 0;
 439
 440         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 441                 chip, addr, alen, buffer, len);
 442
 443         send_start();
 444         if(write_byte(chip << 1)) {     /* write cycle */
 445                 send_stop();
 446                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 447                 return(1);
 448         }
 449         shift = (alen-1) * 8;
 450         while(alen-- > 0) {
 451                 if(write_byte(addr >> shift)) {
 452                         PRINTD("i2c_write, address not <ACK>ed\n");
 453                         return(1);
 454                 }
 455                 shift -= 8;
 456         }
 457
 458         while(len-- > 0) {
 459                 if(write_byte(*buffer++)) {
 460                         failures++;
 461                 }
 462         }
 463         send_stop();
 464         return(failures);
 465 }
 466
 467 /*
 468  * Register soft i2c adapters
 469  */
 470 U_BOOT_I2C_ADAP_COMPLETE(soft0, soft_i2c_init, soft_i2c_probe,
 471                          soft_i2c_read, soft_i2c_write, NULL,
 472                          CONFIG_SYS_I2C_SOFT_SPEED, CONFIG_SYS_I2C_SOFT_SLAVE,
 473                          0)
 474 #if defined(I2C_SOFT_DECLARATIONS2)
 475 U_BOOT_I2C_ADAP_COMPLETE(soft1, soft_i2c_init, soft_i2c_probe,
 476                          soft_i2c_read, soft_i2c_write, NULL,
 477                          CONFIG_SYS_I2C_SOFT_SPEED_2,
 478                          CONFIG_SYS_I2C_SOFT_SLAVE_2,
 479                          1)
 480 #endif
 481 #if defined(I2C_SOFT_DECLARATIONS3)
 482 U_BOOT_I2C_ADAP_COMPLETE(soft2, soft_i2c_init, soft_i2c_probe,
 483                          soft_i2c_read, soft_i2c_write, NULL,
 484                          CONFIG_SYS_I2C_SOFT_SPEED_3,
 485                          CONFIG_SYS_I2C_SOFT_SLAVE_3,
 486                          2)
 487 #endif
 488 #if defined(I2C_SOFT_DECLARATIONS4)
 489 U_BOOT_I2C_ADAP_COMPLETE(soft3, soft_i2c_init, soft_i2c_probe,
 490                          soft_i2c_read, soft_i2c_write, NULL,
 491                          CONFIG_SYS_I2C_SOFT_SPEED_4,
 492                          CONFIG_SYS_I2C_SOFT_SLAVE_4,
 493                          3)
 494 #endif