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_AT91FAMILY)
  34 #include <asm/io.h>
  35 #include <asm/arch/hardware.h>
  36 #include <asm/arch/at91_pio.h>
  37 #ifdef CONFIG_AT91_LEGACY
  38 #include <asm/arch/gpio.h>
  39 #endif
  40 #endif
  41 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  42 #include <asm/arch/ixp425.h>
  43 #endif
  44 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  45 #include <asm/io.h>
  46 #endif
  47 #include <i2c.h>
  48
  49 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  50 # include <asm/gpio.h>
  51
  52 # ifndef I2C_GPIO_SYNC
  53 #  define I2C_GPIO_SYNC
  54 # endif
  55
  56 # ifndef I2C_INIT
  57 #  define I2C_INIT \
  58         do { \
  59                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  60                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  61         } while (0)
  62 # endif
  63
  64 # ifndef I2C_ACTIVE
  65 #  define I2C_ACTIVE do { } while (0)
  66 # endif
  67
  68 # ifndef I2C_TRISTATE
  69 #  define I2C_TRISTATE do { } while (0)
  70 # endif
  71
  72 # ifndef I2C_READ
  73 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  74 # endif
  75
  76 # ifndef I2C_SDA
  77 #  define I2C_SDA(bit) \
  78         do { \
  79                 if (bit) \
  80                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  81                 else \
  82                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  83                 I2C_GPIO_SYNC; \
  84         } while (0)
  85 # endif
  86
  87 # ifndef I2C_SCL
  88 #  define I2C_SCL(bit) \
  89         do { \
  90                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  91                 I2C_GPIO_SYNC; \
  92         } while (0)
  93 # endif
  94
  95 # ifndef I2C_DELAY
  96 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
  97 # endif
  98
  99 #endif
 100
 101 /* #define      DEBUG_I2C       */
 102
 103 #ifdef DEBUG_I2C
 104 DECLARE_GLOBAL_DATA_PTR;
 105 #endif
 106
 107 /*-----------------------------------------------------------------------
 108  * Definitions
 109  */
 110
 111 #define RETRIES         0
 112
 113 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 114 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 115
 116
 117 #ifdef DEBUG_I2C
 118 #define PRINTD(fmt,args...)     do {    \
 119                 printf (fmt ,##args);   \
 120         } while (0)
 121 #else
 122 #define PRINTD(fmt,args...)
 123 #endif
 124
 125 #if defined(CONFIG_I2C_MULTI_BUS)
 126 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
 127 #endif /* CONFIG_I2C_MULTI_BUS */
 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 #if defined(CONFIG_I2C_MULTI_BUS)
 268 /*
 269  * Functions for multiple I2C bus handling
 270  */
 271 unsigned int i2c_get_bus_num(void)
 272 {
 273         return i2c_bus_num;
 274 }
 275
 276 int i2c_set_bus_num(unsigned int bus)
 277 {
 278 #if defined(CONFIG_I2C_MUX)
 279         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
 280                 i2c_bus_num = bus;
 281         } else {
 282                 int     ret;
 283
 284                 ret = i2x_mux_select_mux(bus);
 285                 i2c_init_board();
 286                 if (ret == 0)
 287                         i2c_bus_num = bus;
 288                 else
 289                         return ret;
 290         }
 291 #else
 292         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
 293                 return -1;
 294         i2c_bus_num = bus;
 295 #endif
 296         return 0;
 297 }
 298 #endif
 299
 300 /*-----------------------------------------------------------------------
 301  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 302  * send I2C_NOACK to end the read.
 303  */
 304 static uchar read_byte(int ack)
 305 {
 306         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 307         int  data;
 308         int  j;
 309
 310         /*
 311          * Read 8 bits, MSB first.
 312          */
 313         I2C_TRISTATE;
 314         I2C_SDA(1);
 315         data = 0;
 316         for(j = 0; j < 8; j++) {
 317                 I2C_SCL(0);
 318                 I2C_DELAY;
 319                 I2C_SCL(1);
 320                 I2C_DELAY;
 321                 data <<= 1;
 322                 data |= I2C_READ;
 323                 I2C_DELAY;
 324         }
 325         send_ack(ack);
 326
 327         return(data);
 328 }
 329
 330 /*=====================================================================*/
 331 /*                         Public Functions                            */
 332 /*=====================================================================*/
 333
 334 /*-----------------------------------------------------------------------
 335  * Initialization
 336  */
 337 void i2c_init (int speed, int slaveaddr)
 338 {
 339 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 340         /* call board specific i2c bus reset routine before accessing the   */
 341         /* environment, which might be in a chip on that bus. For details   */
 342         /* about this problem see doc/I2C_Edge_Conditions.                  */
 343         i2c_init_board();
 344 #else
 345         /*
 346          * WARNING: Do NOT save speed in a static variable: if the
 347          * I2C routines are called before RAM is initialized (to read
 348          * the DIMM SPD, for instance), RAM won't be usable and your
 349          * system will crash.
 350          */
 351         send_reset ();
 352 #endif
 353 }
 354
 355 /*-----------------------------------------------------------------------
 356  * Probe to see if a chip is present.  Also good for checking for the
 357  * completion of EEPROM writes since the chip stops responding until
 358  * the write completes (typically 10mSec).
 359  */
 360 int i2c_probe(uchar addr)
 361 {
 362         int rc;
 363
 364         /*
 365          * perform 1 byte write transaction with just address byte
 366          * (fake write)
 367          */
 368         send_start();
 369         rc = write_byte ((addr << 1) | 0);
 370         send_stop();
 371
 372         return (rc ? 1 : 0);
 373 }
 374
 375 /*-----------------------------------------------------------------------
 376  * Read bytes
 377  */
 378 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 379 {
 380         int shift;
 381         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 382                 chip, addr, alen, buffer, len);
 383
 384 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 385         /*
 386          * EEPROM chips that implement "address overflow" are ones
 387          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 388          * address and the extra bits end up in the "chip address"
 389          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 390          * four 256 byte chips.
 391          *
 392          * Note that we consider the length of the address field to
 393          * still be one byte because the extra address bits are
 394          * hidden in the chip address.
 395          */
 396         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 397
 398         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 399                 chip, addr);
 400 #endif
 401
 402         /*
 403          * Do the addressing portion of a write cycle to set the
 404          * chip's address pointer.  If the address length is zero,
 405          * don't do the normal write cycle to set the address pointer,
 406          * there is no address pointer in this chip.
 407          */
 408         send_start();
 409         if(alen > 0) {
 410                 if(write_byte(chip << 1)) {     /* write cycle */
 411                         send_stop();
 412                         PRINTD("i2c_read, 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_read, address not <ACK>ed\n");
 419                                 return(1);
 420                         }
 421                         shift -= 8;
 422                 }
 423
 424                 /* Some I2C chips need a stop/start sequence here,
 425                  * other chips don't work with a full stop and need
 426                  * only a start.  Default behaviour is to send the
 427                  * stop/start sequence.
 428                  */
 429 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 430                 send_start();
 431 #else
 432                 send_stop();
 433                 send_start();
 434 #endif
 435         }
 436         /*
 437          * Send the chip address again, this time for a read cycle.
 438          * Then read the data.  On the last byte, we do a NACK instead
 439          * of an ACK(len == 0) to terminate the read.
 440          */
 441         write_byte((chip << 1) | 1);    /* read cycle */
 442         while(len-- > 0) {
 443                 *buffer++ = read_byte(len == 0);
 444         }
 445         send_stop();
 446         return(0);
 447 }
 448
 449 /*-----------------------------------------------------------------------
 450  * Write bytes
 451  */
 452 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 453 {
 454         int shift, failures = 0;
 455
 456         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 457                 chip, addr, alen, buffer, len);
 458
 459         send_start();
 460         if(write_byte(chip << 1)) {     /* write cycle */
 461                 send_stop();
 462                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 463                 return(1);
 464         }
 465         shift = (alen-1) * 8;
 466         while(alen-- > 0) {
 467                 if(write_byte(addr >> shift)) {
 468                         PRINTD("i2c_write, address not <ACK>ed\n");
 469                         return(1);
 470                 }
 471                 shift -= 8;
 472         }
 473
 474         while(len-- > 0) {
 475                 if(write_byte(*buffer++)) {
 476                         failures++;
 477                 }
 478         }
 479         send_stop();
 480         return(failures);
 481 }