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 #endif 32 #ifdef CONFIG_AT91RM9200 /* need this for the at91rm9200 */ 33 #include <asm/io.h> 34 #include <asm/arch/hardware.h> 35 #endif 36 #ifdef CONFIG_IXP425 /* only valid for IXP425 */ 37 #include <asm/arch/ixp425.h> 38 #endif 39 #ifdef CONFIG_LPC2292 40 #include <asm/arch/hardware.h> 41 #endif 42 #include <i2c.h> 43 44 /* #define DEBUG_I2C */ 45 46 #ifdef DEBUG_I2C 47 DECLARE_GLOBAL_DATA_PTR; 48 #endif 49 50 51 /*----------------------------------------------------------------------- 52 * Definitions 53 */ 54 55 #define RETRIES 0 56 57 58 #define I2C_ACK 0 /* PD_SDA level to ack a byte */ 59 #define I2C_NOACK 1 /* PD_SDA level to noack a byte */ 60 61 62 #ifdef DEBUG_I2C 63 #define PRINTD(fmt,args...) do { \ 64 if (gd->have_console) \ 65 printf (fmt ,##args); \ 66 } while (0) 67 #else 68 #define PRINTD(fmt,args...) 69 #endif 70 71 #if defined(CONFIG_I2C_MULTI_BUS) 72 static unsigned int i2c_bus_num __attribute__ ((section ("data"))) = 0; 73 #endif /* CONFIG_I2C_MULTI_BUS */ 74 75 /*----------------------------------------------------------------------- 76 * Local functions 77 */ 78 #if !defined(CONFIG_SYS_I2C_INIT_BOARD) 79 static void send_reset (void); 80 #endif 81 static void send_start (void); 82 static void send_stop (void); 83 static void send_ack (int); 84 static int write_byte (uchar byte); 85 static uchar read_byte (int); 86 87 #if !defined(CONFIG_SYS_I2C_INIT_BOARD) 88 /*----------------------------------------------------------------------- 89 * Send a reset sequence consisting of 9 clocks with the data signal high 90 * to clock any confused device back into an idle state. Also send a 91 * <stop> at the end of the sequence for belts & suspenders. 92 */ 93 static void send_reset(void) 94 { 95 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 96 int j; 97 98 I2C_SCL(1); 99 I2C_SDA(1); 100 #ifdef I2C_INIT 101 I2C_INIT; 102 #endif 103 I2C_TRISTATE; 104 for(j = 0; j < 9; j++) { 105 I2C_SCL(0); 106 I2C_DELAY; 107 I2C_DELAY; 108 I2C_SCL(1); 109 I2C_DELAY; 110 I2C_DELAY; 111 } 112 send_stop(); 113 I2C_TRISTATE; 114 } 115 #endif 116 117 /*----------------------------------------------------------------------- 118 * START: High -> Low on SDA while SCL is High 119 */ 120 static void send_start(void) 121 { 122 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 123 124 I2C_DELAY; 125 I2C_SDA(1); 126 I2C_ACTIVE; 127 I2C_DELAY; 128 I2C_SCL(1); 129 I2C_DELAY; 130 I2C_SDA(0); 131 I2C_DELAY; 132 } 133 134 /*----------------------------------------------------------------------- 135 * STOP: Low -> High on SDA while SCL is High 136 */ 137 static void send_stop(void) 138 { 139 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 140 141 I2C_SCL(0); 142 I2C_DELAY; 143 I2C_SDA(0); 144 I2C_ACTIVE; 145 I2C_DELAY; 146 I2C_SCL(1); 147 I2C_DELAY; 148 I2C_SDA(1); 149 I2C_DELAY; 150 I2C_TRISTATE; 151 } 152 153 154 /*----------------------------------------------------------------------- 155 * ack should be I2C_ACK or I2C_NOACK 156 */ 157 static void send_ack(int ack) 158 { 159 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 160 161 I2C_SCL(0); 162 I2C_DELAY; 163 I2C_ACTIVE; 164 I2C_SDA(ack); 165 I2C_DELAY; 166 I2C_SCL(1); 167 I2C_DELAY; 168 I2C_DELAY; 169 I2C_SCL(0); 170 I2C_DELAY; 171 } 172 173 174 /*----------------------------------------------------------------------- 175 * Send 8 bits and look for an acknowledgement. 176 */ 177 static int write_byte(uchar data) 178 { 179 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 180 int j; 181 int nack; 182 183 I2C_ACTIVE; 184 for(j = 0; j < 8; j++) { 185 I2C_SCL(0); 186 I2C_DELAY; 187 I2C_SDA(data & 0x80); 188 I2C_DELAY; 189 I2C_SCL(1); 190 I2C_DELAY; 191 I2C_DELAY; 192 193 data <<= 1; 194 } 195 196 /* 197 * Look for an <ACK>(negative logic) and return it. 198 */ 199 I2C_SCL(0); 200 I2C_DELAY; 201 I2C_SDA(1); 202 I2C_TRISTATE; 203 I2C_DELAY; 204 I2C_SCL(1); 205 I2C_DELAY; 206 I2C_DELAY; 207 nack = I2C_READ; 208 I2C_SCL(0); 209 I2C_DELAY; 210 I2C_ACTIVE; 211 212 return(nack); /* not a nack is an ack */ 213 } 214 215 #if defined(CONFIG_I2C_MULTI_BUS) 216 /* 217 * Functions for multiple I2C bus handling 218 */ 219 unsigned int i2c_get_bus_num(void) 220 { 221 return i2c_bus_num; 222 } 223 224 int i2c_set_bus_num(unsigned int bus) 225 { 226 #if defined(CONFIG_I2C_MUX) 227 if (bus < CONFIG_SYS_MAX_I2C_BUS) { 228 i2c_bus_num = bus; 229 } else { 230 int ret; 231 232 ret = i2x_mux_select_mux(bus); 233 if (ret == 0) 234 i2c_bus_num = bus; 235 else 236 return ret; 237 } 238 #else 239 if (bus >= CONFIG_SYS_MAX_I2C_BUS) 240 return -1; 241 i2c_bus_num = bus; 242 #endif 243 return 0; 244 } 245 246 /* TODO: add 100/400k switching */ 247 unsigned int i2c_get_bus_speed(void) 248 { 249 return CONFIG_SYS_I2C_SPEED; 250 } 251 252 int i2c_set_bus_speed(unsigned int speed) 253 { 254 if (speed != CONFIG_SYS_I2C_SPEED) 255 return -1; 256 257 return 0; 258 } 259 #endif 260 261 /*----------------------------------------------------------------------- 262 * if ack == I2C_ACK, ACK the byte so can continue reading, else 263 * send I2C_NOACK to end the read. 264 */ 265 static uchar read_byte(int ack) 266 { 267 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 268 int data; 269 int j; 270 271 /* 272 * Read 8 bits, MSB first. 273 */ 274 I2C_TRISTATE; 275 I2C_SDA(1); 276 data = 0; 277 for(j = 0; j < 8; j++) { 278 I2C_SCL(0); 279 I2C_DELAY; 280 I2C_SCL(1); 281 I2C_DELAY; 282 data <<= 1; 283 data |= I2C_READ; 284 I2C_DELAY; 285 } 286 send_ack(ack); 287 288 return(data); 289 } 290 291 /*=====================================================================*/ 292 /* Public Functions */ 293 /*=====================================================================*/ 294 295 /*----------------------------------------------------------------------- 296 * Initialization 297 */ 298 void i2c_init (int speed, int slaveaddr) 299 { 300 #if defined(CONFIG_SYS_I2C_INIT_BOARD) 301 /* call board specific i2c bus reset routine before accessing the */ 302 /* environment, which might be in a chip on that bus. For details */ 303 /* about this problem see doc/I2C_Edge_Conditions. */ 304 i2c_init_board(); 305 #else 306 /* 307 * WARNING: Do NOT save speed in a static variable: if the 308 * I2C routines are called before RAM is initialized (to read 309 * the DIMM SPD, for instance), RAM won't be usable and your 310 * system will crash. 311 */ 312 send_reset (); 313 #endif 314 } 315 316 /*----------------------------------------------------------------------- 317 * Probe to see if a chip is present. Also good for checking for the 318 * completion of EEPROM writes since the chip stops responding until 319 * the write completes (typically 10mSec). 320 */ 321 int i2c_probe(uchar addr) 322 { 323 int rc; 324 325 /* 326 * perform 1 byte write transaction with just address byte 327 * (fake write) 328 */ 329 send_start(); 330 rc = write_byte ((addr << 1) | 0); 331 send_stop(); 332 333 return (rc ? 1 : 0); 334 } 335 336 /*----------------------------------------------------------------------- 337 * Read bytes 338 */ 339 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len) 340 { 341 int shift; 342 PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n", 343 chip, addr, alen, buffer, len); 344 345 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW 346 /* 347 * EEPROM chips that implement "address overflow" are ones 348 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of 349 * address and the extra bits end up in the "chip address" 350 * bit slots. This makes a 24WC08 (1Kbyte) chip look like 351 * four 256 byte chips. 352 * 353 * Note that we consider the length of the address field to 354 * still be one byte because the extra address bits are 355 * hidden in the chip address. 356 */ 357 chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW); 358 359 PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n", 360 chip, addr); 361 #endif 362 363 /* 364 * Do the addressing portion of a write cycle to set the 365 * chip's address pointer. If the address length is zero, 366 * don't do the normal write cycle to set the address pointer, 367 * there is no address pointer in this chip. 368 */ 369 send_start(); 370 if(alen > 0) { 371 if(write_byte(chip << 1)) { /* write cycle */ 372 send_stop(); 373 PRINTD("i2c_read, no chip responded %02X\n", chip); 374 return(1); 375 } 376 shift = (alen-1) * 8; 377 while(alen-- > 0) { 378 if(write_byte(addr >> shift)) { 379 PRINTD("i2c_read, address not <ACK>ed\n"); 380 return(1); 381 } 382 shift -= 8; 383 } 384 send_stop(); /* reportedly some chips need a full stop */ 385 send_start(); 386 } 387 /* 388 * Send the chip address again, this time for a read cycle. 389 * Then read the data. On the last byte, we do a NACK instead 390 * of an ACK(len == 0) to terminate the read. 391 */ 392 write_byte((chip << 1) | 1); /* read cycle */ 393 while(len-- > 0) { 394 *buffer++ = read_byte(len == 0); 395 } 396 send_stop(); 397 return(0); 398 } 399 400 /*----------------------------------------------------------------------- 401 * Write bytes 402 */ 403 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len) 404 { 405 int shift, failures = 0; 406 407 PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n", 408 chip, addr, alen, buffer, len); 409 410 send_start(); 411 if(write_byte(chip << 1)) { /* write cycle */ 412 send_stop(); 413 PRINTD("i2c_write, no chip responded %02X\n", chip); 414 return(1); 415 } 416 shift = (alen-1) * 8; 417 while(alen-- > 0) { 418 if(write_byte(addr >> shift)) { 419 PRINTD("i2c_write, address not <ACK>ed\n"); 420 return(1); 421 } 422 shift -= 8; 423 } 424 425 while(len-- > 0) { 426 if(write_byte(*buffer++)) { 427 failures++; 428 } 429 } 430 send_stop(); 431 return(failures); 432 } 433 434 /*----------------------------------------------------------------------- 435 * Read a register 436 */ 437 uchar i2c_reg_read(uchar i2c_addr, uchar reg) 438 { 439 uchar buf; 440 441 i2c_read(i2c_addr, reg, 1, &buf, 1); 442 443 return(buf); 444 } 445 446 /*----------------------------------------------------------------------- 447 * Write a register 448 */ 449 void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val) 450 { 451 i2c_write(i2c_addr, reg, 1, &val, 1); 452 } 453