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 static void send_reset (void); 79 static void send_start (void); 80 static void send_stop (void); 81 static void send_ack (int); 82 static int write_byte (uchar byte); 83 static uchar read_byte (int); 84 85 86 /*----------------------------------------------------------------------- 87 * Send a reset sequence consisting of 9 clocks with the data signal high 88 * to clock any confused device back into an idle state. Also send a 89 * <stop> at the end of the sequence for belts & suspenders. 90 */ 91 static void send_reset(void) 92 { 93 #ifdef CONFIG_MPC8260 94 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 95 #endif 96 #ifdef CONFIG_8xx 97 volatile immap_t *immr = (immap_t *)CFG_IMMR; 98 #endif 99 int j; 100 101 I2C_SCL(1); 102 I2C_SDA(1); 103 #ifdef I2C_INIT 104 I2C_INIT; 105 #endif 106 I2C_TRISTATE; 107 for(j = 0; j < 9; j++) { 108 I2C_SCL(0); 109 I2C_DELAY; 110 I2C_DELAY; 111 I2C_SCL(1); 112 I2C_DELAY; 113 I2C_DELAY; 114 } 115 send_stop(); 116 I2C_TRISTATE; 117 } 118 119 /*----------------------------------------------------------------------- 120 * START: High -> Low on SDA while SCL is High 121 */ 122 static void send_start(void) 123 { 124 #ifdef CONFIG_MPC8260 125 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 126 #endif 127 #ifdef CONFIG_8xx 128 volatile immap_t *immr = (immap_t *)CFG_IMMR; 129 #endif 130 131 I2C_DELAY; 132 I2C_SDA(1); 133 I2C_ACTIVE; 134 I2C_DELAY; 135 I2C_SCL(1); 136 I2C_DELAY; 137 I2C_SDA(0); 138 I2C_DELAY; 139 } 140 141 /*----------------------------------------------------------------------- 142 * STOP: Low -> High on SDA while SCL is High 143 */ 144 static void send_stop(void) 145 { 146 #ifdef CONFIG_MPC8260 147 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 148 #endif 149 #ifdef CONFIG_8xx 150 volatile immap_t *immr = (immap_t *)CFG_IMMR; 151 #endif 152 153 I2C_SCL(0); 154 I2C_DELAY; 155 I2C_SDA(0); 156 I2C_ACTIVE; 157 I2C_DELAY; 158 I2C_SCL(1); 159 I2C_DELAY; 160 I2C_SDA(1); 161 I2C_DELAY; 162 I2C_TRISTATE; 163 } 164 165 166 /*----------------------------------------------------------------------- 167 * ack should be I2C_ACK or I2C_NOACK 168 */ 169 static void send_ack(int ack) 170 { 171 #ifdef CONFIG_MPC8260 172 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 173 #endif 174 #ifdef CONFIG_8xx 175 volatile immap_t *immr = (immap_t *)CFG_IMMR; 176 #endif 177 178 I2C_SCL(0); 179 I2C_DELAY; 180 I2C_ACTIVE; 181 I2C_SDA(ack); 182 I2C_DELAY; 183 I2C_SCL(1); 184 I2C_DELAY; 185 I2C_DELAY; 186 I2C_SCL(0); 187 I2C_DELAY; 188 } 189 190 191 /*----------------------------------------------------------------------- 192 * Send 8 bits and look for an acknowledgement. 193 */ 194 static int write_byte(uchar data) 195 { 196 #ifdef CONFIG_MPC8260 197 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 198 #endif 199 #ifdef CONFIG_8xx 200 volatile immap_t *immr = (immap_t *)CFG_IMMR; 201 #endif 202 int j; 203 int nack; 204 205 I2C_ACTIVE; 206 for(j = 0; j < 8; j++) { 207 I2C_SCL(0); 208 I2C_DELAY; 209 I2C_SDA(data & 0x80); 210 I2C_DELAY; 211 I2C_SCL(1); 212 I2C_DELAY; 213 I2C_DELAY; 214 215 data <<= 1; 216 } 217 218 /* 219 * Look for an <ACK>(negative logic) and return it. 220 */ 221 I2C_SCL(0); 222 I2C_DELAY; 223 I2C_SDA(1); 224 I2C_TRISTATE; 225 I2C_DELAY; 226 I2C_SCL(1); 227 I2C_DELAY; 228 I2C_DELAY; 229 nack = I2C_READ; 230 I2C_SCL(0); 231 I2C_DELAY; 232 I2C_ACTIVE; 233 234 return(nack); /* not a nack is an ack */ 235 } 236 237 #if defined(CONFIG_I2C_MULTI_BUS) 238 /* 239 * Functions for multiple I2C bus handling 240 */ 241 unsigned int i2c_get_bus_num(void) 242 { 243 return i2c_bus_num; 244 } 245 246 int i2c_set_bus_num(unsigned int bus) 247 { 248 if (bus >= CFG_MAX_I2C_BUS) 249 return -1; 250 i2c_bus_num = bus; 251 252 return 0; 253 } 254 255 /* TODO: add 100/400k switching */ 256 unsigned int i2c_get_bus_speed(void) 257 { 258 return CFG_I2C_SPEED; 259 } 260 261 int i2c_set_bus_speed(unsigned int speed) 262 { 263 if (speed != CFG_I2C_SPEED) 264 return -1; 265 266 return 0; 267 } 268 #endif 269 270 /*----------------------------------------------------------------------- 271 * if ack == I2C_ACK, ACK the byte so can continue reading, else 272 * send I2C_NOACK to end the read. 273 */ 274 static uchar read_byte(int ack) 275 { 276 #ifdef CONFIG_MPC8260 277 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 278 #endif 279 #ifdef CONFIG_8xx 280 volatile immap_t *immr = (immap_t *)CFG_IMMR; 281 #endif 282 int data; 283 int j; 284 285 /* 286 * Read 8 bits, MSB first. 287 */ 288 I2C_TRISTATE; 289 I2C_SDA(1); 290 data = 0; 291 for(j = 0; j < 8; j++) { 292 I2C_SCL(0); 293 I2C_DELAY; 294 I2C_SCL(1); 295 I2C_DELAY; 296 data <<= 1; 297 data |= I2C_READ; 298 I2C_DELAY; 299 } 300 send_ack(ack); 301 302 return(data); 303 } 304 305 /*=====================================================================*/ 306 /* Public Functions */ 307 /*=====================================================================*/ 308 309 /*----------------------------------------------------------------------- 310 * Initialization 311 */ 312 void i2c_init (int speed, int slaveaddr) 313 { 314 /* 315 * WARNING: Do NOT save speed in a static variable: if the 316 * I2C routines are called before RAM is initialized (to read 317 * the DIMM SPD, for instance), RAM won't be usable and your 318 * system will crash. 319 */ 320 send_reset (); 321 } 322 323 /*----------------------------------------------------------------------- 324 * Probe to see if a chip is present. Also good for checking for the 325 * completion of EEPROM writes since the chip stops responding until 326 * the write completes (typically 10mSec). 327 */ 328 int i2c_probe(uchar addr) 329 { 330 int rc; 331 332 /* 333 * perform 1 byte write transaction with just address byte 334 * (fake write) 335 */ 336 send_start(); 337 rc = write_byte ((addr << 1) | 0); 338 send_stop(); 339 340 return (rc ? 1 : 0); 341 } 342 343 /*----------------------------------------------------------------------- 344 * Read bytes 345 */ 346 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len) 347 { 348 int shift; 349 PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n", 350 chip, addr, alen, buffer, len); 351 352 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW 353 /* 354 * EEPROM chips that implement "address overflow" are ones 355 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of 356 * address and the extra bits end up in the "chip address" 357 * bit slots. This makes a 24WC08 (1Kbyte) chip look like 358 * four 256 byte chips. 359 * 360 * Note that we consider the length of the address field to 361 * still be one byte because the extra address bits are 362 * hidden in the chip address. 363 */ 364 chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW); 365 366 PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n", 367 chip, addr); 368 #endif 369 370 /* 371 * Do the addressing portion of a write cycle to set the 372 * chip's address pointer. If the address length is zero, 373 * don't do the normal write cycle to set the address pointer, 374 * there is no address pointer in this chip. 375 */ 376 send_start(); 377 if(alen > 0) { 378 if(write_byte(chip << 1)) { /* write cycle */ 379 send_stop(); 380 PRINTD("i2c_read, no chip responded %02X\n", chip); 381 return(1); 382 } 383 shift = (alen-1) * 8; 384 while(alen-- > 0) { 385 if(write_byte(addr >> shift)) { 386 PRINTD("i2c_read, address not <ACK>ed\n"); 387 return(1); 388 } 389 shift -= 8; 390 } 391 send_stop(); /* reportedly some chips need a full stop */ 392 send_start(); 393 } 394 /* 395 * Send the chip address again, this time for a read cycle. 396 * Then read the data. On the last byte, we do a NACK instead 397 * of an ACK(len == 0) to terminate the read. 398 */ 399 write_byte((chip << 1) | 1); /* read cycle */ 400 while(len-- > 0) { 401 *buffer++ = read_byte(len == 0); 402 } 403 send_stop(); 404 return(0); 405 } 406 407 /*----------------------------------------------------------------------- 408 * Write bytes 409 */ 410 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len) 411 { 412 int shift, failures = 0; 413 414 PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n", 415 chip, addr, alen, buffer, len); 416 417 send_start(); 418 if(write_byte(chip << 1)) { /* write cycle */ 419 send_stop(); 420 PRINTD("i2c_write, no chip responded %02X\n", chip); 421 return(1); 422 } 423 shift = (alen-1) * 8; 424 while(alen-- > 0) { 425 if(write_byte(addr >> shift)) { 426 PRINTD("i2c_write, address not <ACK>ed\n"); 427 return(1); 428 } 429 shift -= 8; 430 } 431 432 while(len-- > 0) { 433 if(write_byte(*buffer++)) { 434 failures++; 435 } 436 } 437 send_stop(); 438 return(failures); 439 } 440 441 /*----------------------------------------------------------------------- 442 * Read a register 443 */ 444 uchar i2c_reg_read(uchar i2c_addr, uchar reg) 445 { 446 uchar buf; 447 448 i2c_read(i2c_addr, reg, 1, &buf, 1); 449 450 return(buf); 451 } 452 453 /*----------------------------------------------------------------------- 454 * Write a register 455 */ 456 void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val) 457 { 458 i2c_write(i2c_addr, reg, 1, &val, 1); 459 } 460