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_AT91RM9200) || \
  34         defined(CONFIG_AT91SAM9260) ||  defined(CONFIG_AT91SAM9261) || \
  35         defined(CONFIG_AT91SAM9263)
  36 #include <asm/io.h>
  37 #include <asm/arch/hardware.h>
  38 #include <asm/arch/at91_pio.h>
  39 #ifdef CONFIG_AT91_LEGACY
  40 #include <asm/arch/gpio.h>
  41 #endif
  42 #endif
  43 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  44 #include <asm/arch/ixp425.h>
  45 #endif
  46 #ifdef CONFIG_LPC2292
  47 #include <asm/arch/hardware.h>
  48 #endif
  49 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  50 #include <asm/io.h>
  51 #endif
  52 #include <i2c.h>
  53
  54 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  55 # include <asm/gpio.h>
  56
  57 # ifndef I2C_GPIO_SYNC
  58 #  define I2C_GPIO_SYNC
  59 # endif
  60
  61 # ifndef I2C_INIT
  62 #  define I2C_INIT \
  63         do { \
  64                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  65                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  66         } while (0)
  67 # endif
  68
  69 # ifndef I2C_ACTIVE
  70 #  define I2C_ACTIVE do { } while (0)
  71 # endif
  72
  73 # ifndef I2C_TRISTATE
  74 #  define I2C_TRISTATE do { } while (0)
  75 # endif
  76
  77 # ifndef I2C_READ
  78 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  79 # endif
  80
  81 # ifndef I2C_SDA
  82 #  define I2C_SDA(bit) \
  83         do { \
  84                 if (bit) \
  85                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  86                 else \
  87                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  88                 I2C_GPIO_SYNC; \
  89         } while (0)
  90 # endif
  91
  92 # ifndef I2C_SCL
  93 #  define I2C_SCL(bit) \
  94         do { \
  95                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  96                 I2C_GPIO_SYNC; \
  97         } while (0)
  98 # endif
  99
 100 # ifndef I2C_DELAY
 101 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
 102 # endif
 103
 104 #endif
 105
 106 /* #define      DEBUG_I2C       */
 107
 108 #ifdef DEBUG_I2C
 109 DECLARE_GLOBAL_DATA_PTR;
 110 #endif
 111
 112 /*-----------------------------------------------------------------------
 113  * Definitions
 114  */
 115
 116 #define RETRIES         0
 117
 118 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 119 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 120
 121
 122 #ifdef DEBUG_I2C
 123 #define PRINTD(fmt,args...)     do {    \
 124         if (gd->have_console)           \
 125                 printf (fmt ,##args);   \
 126         } while (0)
 127 #else
 128 #define PRINTD(fmt,args...)
 129 #endif
 130
 131 #if defined(CONFIG_I2C_MULTI_BUS)
 132 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
 133 #endif /* CONFIG_I2C_MULTI_BUS */
 134
 135 /*-----------------------------------------------------------------------
 136  * Local functions
 137  */
 138 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 139 static void  send_reset (void);
 140 #endif
 141 static void  send_start (void);
 142 static void  send_stop  (void);
 143 static void  send_ack   (int);
 144 static int   write_byte (uchar byte);
 145 static uchar read_byte  (int);
 146
 147 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 148 /*-----------------------------------------------------------------------
 149  * Send a reset sequence consisting of 9 clocks with the data signal high
 150  * to clock any confused device back into an idle state.  Also send a
 151  * <stop> at the end of the sequence for belts & suspenders.
 152  */
 153 static void send_reset(void)
 154 {
 155         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 156         int j;
 157
 158         I2C_SCL(1);
 159         I2C_SDA(1);
 160 #ifdef  I2C_INIT
 161         I2C_INIT;
 162 #endif
 163         I2C_TRISTATE;
 164         for(j = 0; j < 9; j++) {
 165                 I2C_SCL(0);
 166                 I2C_DELAY;
 167                 I2C_DELAY;
 168                 I2C_SCL(1);
 169                 I2C_DELAY;
 170                 I2C_DELAY;
 171         }
 172         send_stop();
 173         I2C_TRISTATE;
 174 }
 175 #endif
 176
 177 /*-----------------------------------------------------------------------
 178  * START: High -> Low on SDA while SCL is High
 179  */
 180 static void send_start(void)
 181 {
 182         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 183
 184         I2C_DELAY;
 185         I2C_SDA(1);
 186         I2C_ACTIVE;
 187         I2C_DELAY;
 188         I2C_SCL(1);
 189         I2C_DELAY;
 190         I2C_SDA(0);
 191         I2C_DELAY;
 192 }
 193
 194 /*-----------------------------------------------------------------------
 195  * STOP: Low -> High on SDA while SCL is High
 196  */
 197 static void send_stop(void)
 198 {
 199         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 200
 201         I2C_SCL(0);
 202         I2C_DELAY;
 203         I2C_SDA(0);
 204         I2C_ACTIVE;
 205         I2C_DELAY;
 206         I2C_SCL(1);
 207         I2C_DELAY;
 208         I2C_SDA(1);
 209         I2C_DELAY;
 210         I2C_TRISTATE;
 211 }
 212
 213 /*-----------------------------------------------------------------------
 214  * ack should be I2C_ACK or I2C_NOACK
 215  */
 216 static void send_ack(int ack)
 217 {
 218         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 219
 220         I2C_SCL(0);
 221         I2C_DELAY;
 222         I2C_ACTIVE;
 223         I2C_SDA(ack);
 224         I2C_DELAY;
 225         I2C_SCL(1);
 226         I2C_DELAY;
 227         I2C_DELAY;
 228         I2C_SCL(0);
 229         I2C_DELAY;
 230 }
 231
 232 /*-----------------------------------------------------------------------
 233  * Send 8 bits and look for an acknowledgement.
 234  */
 235 static int write_byte(uchar data)
 236 {
 237         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 238         int j;
 239         int nack;
 240
 241         I2C_ACTIVE;
 242         for(j = 0; j < 8; j++) {
 243                 I2C_SCL(0);
 244                 I2C_DELAY;
 245                 I2C_SDA(data & 0x80);
 246                 I2C_DELAY;
 247                 I2C_SCL(1);
 248                 I2C_DELAY;
 249                 I2C_DELAY;
 250
 251                 data <<= 1;
 252         }
 253
 254         /*
 255          * Look for an <ACK>(negative logic) and return it.
 256          */
 257         I2C_SCL(0);
 258         I2C_DELAY;
 259         I2C_SDA(1);
 260         I2C_TRISTATE;
 261         I2C_DELAY;
 262         I2C_SCL(1);
 263         I2C_DELAY;
 264         I2C_DELAY;
 265         nack = I2C_READ;
 266         I2C_SCL(0);
 267         I2C_DELAY;
 268         I2C_ACTIVE;
 269
 270         return(nack);   /* not a nack is an ack */
 271 }
 272
 273 #if defined(CONFIG_I2C_MULTI_BUS)
 274 /*
 275  * Functions for multiple I2C bus handling
 276  */
 277 unsigned int i2c_get_bus_num(void)
 278 {
 279         return i2c_bus_num;
 280 }
 281
 282 int i2c_set_bus_num(unsigned int bus)
 283 {
 284 #if defined(CONFIG_I2C_MUX)
 285         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
 286                 i2c_bus_num = bus;
 287         } else {
 288                 int     ret;
 289
 290                 ret = i2x_mux_select_mux(bus);
 291                 if (ret == 0)
 292                         i2c_bus_num = bus;
 293                 else
 294                         return ret;
 295         }
 296 #else
 297         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
 298                 return -1;
 299         i2c_bus_num = bus;
 300 #endif
 301         return 0;
 302 }
 303 #endif
 304
 305 /*-----------------------------------------------------------------------
 306  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 307  * send I2C_NOACK to end the read.
 308  */
 309 static uchar read_byte(int ack)
 310 {
 311         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 312         int  data;
 313         int  j;
 314
 315         /*
 316          * Read 8 bits, MSB first.
 317          */
 318         I2C_TRISTATE;
 319         I2C_SDA(1);
 320         data = 0;
 321         for(j = 0; j < 8; j++) {
 322                 I2C_SCL(0);
 323                 I2C_DELAY;
 324                 I2C_SCL(1);
 325                 I2C_DELAY;
 326                 data <<= 1;
 327                 data |= I2C_READ;
 328                 I2C_DELAY;
 329         }
 330         send_ack(ack);
 331
 332         return(data);
 333 }
 334
 335 /*=====================================================================*/
 336 /*                         Public Functions                            */
 337 /*=====================================================================*/
 338
 339 /*-----------------------------------------------------------------------
 340  * Initialization
 341  */
 342 void i2c_init (int speed, int slaveaddr)
 343 {
 344 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 345         /* call board specific i2c bus reset routine before accessing the   */
 346         /* environment, which might be in a chip on that bus. For details   */
 347         /* about this problem see doc/I2C_Edge_Conditions.                  */
 348         i2c_init_board();
 349 #else
 350         /*
 351          * WARNING: Do NOT save speed in a static variable: if the
 352          * I2C routines are called before RAM is initialized (to read
 353          * the DIMM SPD, for instance), RAM won't be usable and your
 354          * system will crash.
 355          */
 356         send_reset ();
 357 #endif
 358 }
 359
 360 /*-----------------------------------------------------------------------
 361  * Probe to see if a chip is present.  Also good for checking for the
 362  * completion of EEPROM writes since the chip stops responding until
 363  * the write completes (typically 10mSec).
 364  */
 365 int i2c_probe(uchar addr)
 366 {
 367         int rc;
 368
 369         /*
 370          * perform 1 byte write transaction with just address byte
 371          * (fake write)
 372          */
 373         send_start();
 374         rc = write_byte ((addr << 1) | 0);
 375         send_stop();
 376
 377         return (rc ? 1 : 0);
 378 }
 379
 380 /*-----------------------------------------------------------------------
 381  * Read bytes
 382  */
 383 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 384 {
 385         int shift;
 386         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 387                 chip, addr, alen, buffer, len);
 388
 389 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 390         /*
 391          * EEPROM chips that implement "address overflow" are ones
 392          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 393          * address and the extra bits end up in the "chip address"
 394          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 395          * four 256 byte chips.
 396          *
 397          * Note that we consider the length of the address field to
 398          * still be one byte because the extra address bits are
 399          * hidden in the chip address.
 400          */
 401         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 402
 403         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 404                 chip, addr);
 405 #endif
 406
 407         /*
 408          * Do the addressing portion of a write cycle to set the
 409          * chip's address pointer.  If the address length is zero,
 410          * don't do the normal write cycle to set the address pointer,
 411          * there is no address pointer in this chip.
 412          */
 413         send_start();
 414         if(alen > 0) {
 415                 if(write_byte(chip << 1)) {     /* write cycle */
 416                         send_stop();
 417                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 418                         return(1);
 419                 }
 420                 shift = (alen-1) * 8;
 421                 while(alen-- > 0) {
 422                         if(write_byte(addr >> shift)) {
 423                                 PRINTD("i2c_read, address not <ACK>ed\n");
 424                                 return(1);
 425                         }
 426                         shift -= 8;
 427                 }
 428
 429                 /* Some I2C chips need a stop/start sequence here,
 430                  * other chips don't work with a full stop and need
 431                  * only a start.  Default behaviour is to send the
 432                  * stop/start sequence.
 433                  */
 434 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 435                 send_start();
 436 #else
 437                 send_stop();
 438                 send_start();
 439 #endif
 440         }
 441         /*
 442          * Send the chip address again, this time for a read cycle.
 443          * Then read the data.  On the last byte, we do a NACK instead
 444          * of an ACK(len == 0) to terminate the read.
 445          */
 446         write_byte((chip << 1) | 1);    /* read cycle */
 447         while(len-- > 0) {
 448                 *buffer++ = read_byte(len == 0);
 449         }
 450         send_stop();
 451         return(0);
 452 }
 453
 454 /*-----------------------------------------------------------------------
 455  * Write bytes
 456  */
 457 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 458 {
 459         int shift, failures = 0;
 460
 461         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 462                 chip, addr, alen, buffer, len);
 463
 464         send_start();
 465         if(write_byte(chip << 1)) {     /* write cycle */
 466                 send_stop();
 467                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 468                 return(1);
 469         }
 470         shift = (alen-1) * 8;
 471         while(alen-- > 0) {
 472                 if(write_byte(addr >> shift)) {
 473                         PRINTD("i2c_write, address not <ACK>ed\n");
 474                         return(1);
 475                 }
 476                 shift -= 8;
 477         }
 478
 479         while(len-- > 0) {
 480                 if(write_byte(*buffer++)) {
 481                         failures++;
 482                 }
 483         }
 484         send_stop();
 485         return(failures);
 486 }