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 #ifdef CONFIG_AT91RM9200 /* need this for the at91rm9200 */ 34 #include <asm/io.h> 35 #include <asm/arch/hardware.h> 36 #endif 37 #ifdef CONFIG_IXP425 /* only valid for IXP425 */ 38 #include <asm/arch/ixp425.h> 39 #endif 40 #ifdef CONFIG_LPC2292 41 #include <asm/arch/hardware.h> 42 #endif 43 #ifdef CONFIG_MPC866 /* only valid for MPC866 */ 44 #include <asm/io.h> 45 #endif 46 #include <i2c.h> 47 48 /* #define DEBUG_I2C */ 49 50 #ifdef DEBUG_I2C 51 DECLARE_GLOBAL_DATA_PTR; 52 #endif 53 54 55 /*----------------------------------------------------------------------- 56 * Definitions 57 */ 58 59 #define RETRIES 0 60 61 62 #define I2C_ACK 0 /* PD_SDA level to ack a byte */ 63 #define I2C_NOACK 1 /* PD_SDA level to noack a byte */ 64 65 66 #ifdef DEBUG_I2C 67 #define PRINTD(fmt,args...) do { \ 68 if (gd->have_console) \ 69 printf (fmt ,##args); \ 70 } while (0) 71 #else 72 #define PRINTD(fmt,args...) 73 #endif 74 75 #if defined(CONFIG_I2C_MULTI_BUS) 76 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0; 77 #endif /* CONFIG_I2C_MULTI_BUS */ 78 79 /*----------------------------------------------------------------------- 80 * Local functions 81 */ 82 #if !defined(CONFIG_SYS_I2C_INIT_BOARD) 83 static void send_reset (void); 84 #endif 85 static void send_start (void); 86 static void send_stop (void); 87 static void send_ack (int); 88 static int write_byte (uchar byte); 89 static uchar read_byte (int); 90 91 #if !defined(CONFIG_SYS_I2C_INIT_BOARD) 92 /*----------------------------------------------------------------------- 93 * Send a reset sequence consisting of 9 clocks with the data signal high 94 * to clock any confused device back into an idle state. Also send a 95 * <stop> at the end of the sequence for belts & suspenders. 96 */ 97 static void send_reset(void) 98 { 99 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 100 int j; 101 102 I2C_SCL(1); 103 I2C_SDA(1); 104 #ifdef I2C_INIT 105 I2C_INIT; 106 #endif 107 I2C_TRISTATE; 108 for(j = 0; j < 9; j++) { 109 I2C_SCL(0); 110 I2C_DELAY; 111 I2C_DELAY; 112 I2C_SCL(1); 113 I2C_DELAY; 114 I2C_DELAY; 115 } 116 send_stop(); 117 I2C_TRISTATE; 118 } 119 #endif 120 121 /*----------------------------------------------------------------------- 122 * START: High -> Low on SDA while SCL is High 123 */ 124 static void send_start(void) 125 { 126 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 127 128 I2C_DELAY; 129 I2C_SDA(1); 130 I2C_ACTIVE; 131 I2C_DELAY; 132 I2C_SCL(1); 133 I2C_DELAY; 134 I2C_SDA(0); 135 I2C_DELAY; 136 } 137 138 /*----------------------------------------------------------------------- 139 * STOP: Low -> High on SDA while SCL is High 140 */ 141 static void send_stop(void) 142 { 143 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 144 145 I2C_SCL(0); 146 I2C_DELAY; 147 I2C_SDA(0); 148 I2C_ACTIVE; 149 I2C_DELAY; 150 I2C_SCL(1); 151 I2C_DELAY; 152 I2C_SDA(1); 153 I2C_DELAY; 154 I2C_TRISTATE; 155 } 156 157 158 /*----------------------------------------------------------------------- 159 * ack should be I2C_ACK or I2C_NOACK 160 */ 161 static void send_ack(int ack) 162 { 163 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 164 165 I2C_SCL(0); 166 I2C_DELAY; 167 I2C_ACTIVE; 168 I2C_SDA(ack); 169 I2C_DELAY; 170 I2C_SCL(1); 171 I2C_DELAY; 172 I2C_DELAY; 173 I2C_SCL(0); 174 I2C_DELAY; 175 } 176 177 178 /*----------------------------------------------------------------------- 179 * Send 8 bits and look for an acknowledgement. 180 */ 181 static int write_byte(uchar data) 182 { 183 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 184 int j; 185 int nack; 186 187 I2C_ACTIVE; 188 for(j = 0; j < 8; j++) { 189 I2C_SCL(0); 190 I2C_DELAY; 191 I2C_SDA(data & 0x80); 192 I2C_DELAY; 193 I2C_SCL(1); 194 I2C_DELAY; 195 I2C_DELAY; 196 197 data <<= 1; 198 } 199 200 /* 201 * Look for an <ACK>(negative logic) and return it. 202 */ 203 I2C_SCL(0); 204 I2C_DELAY; 205 I2C_SDA(1); 206 I2C_TRISTATE; 207 I2C_DELAY; 208 I2C_SCL(1); 209 I2C_DELAY; 210 I2C_DELAY; 211 nack = I2C_READ; 212 I2C_SCL(0); 213 I2C_DELAY; 214 I2C_ACTIVE; 215 216 return(nack); /* not a nack is an ack */ 217 } 218 219 #if defined(CONFIG_I2C_MULTI_BUS) 220 /* 221 * Functions for multiple I2C bus handling 222 */ 223 unsigned int i2c_get_bus_num(void) 224 { 225 return i2c_bus_num; 226 } 227 228 int i2c_set_bus_num(unsigned int bus) 229 { 230 #if defined(CONFIG_I2C_MUX) 231 if (bus < CONFIG_SYS_MAX_I2C_BUS) { 232 i2c_bus_num = bus; 233 } else { 234 int ret; 235 236 ret = i2x_mux_select_mux(bus); 237 if (ret == 0) 238 i2c_bus_num = bus; 239 else 240 return ret; 241 } 242 #else 243 if (bus >= CONFIG_SYS_MAX_I2C_BUS) 244 return -1; 245 i2c_bus_num = bus; 246 #endif 247 return 0; 248 } 249 250 /* TODO: add 100/400k switching */ 251 unsigned int i2c_get_bus_speed(void) 252 { 253 return CONFIG_SYS_I2C_SPEED; 254 } 255 256 int i2c_set_bus_speed(unsigned int speed) 257 { 258 if (speed != CONFIG_SYS_I2C_SPEED) 259 return -1; 260 261 return 0; 262 } 263 #endif 264 265 /*----------------------------------------------------------------------- 266 * if ack == I2C_ACK, ACK the byte so can continue reading, else 267 * send I2C_NOACK to end the read. 268 */ 269 static uchar read_byte(int ack) 270 { 271 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 272 int data; 273 int j; 274 275 /* 276 * Read 8 bits, MSB first. 277 */ 278 I2C_TRISTATE; 279 I2C_SDA(1); 280 data = 0; 281 for(j = 0; j < 8; j++) { 282 I2C_SCL(0); 283 I2C_DELAY; 284 I2C_SCL(1); 285 I2C_DELAY; 286 data <<= 1; 287 data |= I2C_READ; 288 I2C_DELAY; 289 } 290 send_ack(ack); 291 292 return(data); 293 } 294 295 /*=====================================================================*/ 296 /* Public Functions */ 297 /*=====================================================================*/ 298 299 /*----------------------------------------------------------------------- 300 * Initialization 301 */ 302 void i2c_init (int speed, int slaveaddr) 303 { 304 #if defined(CONFIG_SYS_I2C_INIT_BOARD) 305 /* call board specific i2c bus reset routine before accessing the */ 306 /* environment, which might be in a chip on that bus. For details */ 307 /* about this problem see doc/I2C_Edge_Conditions. */ 308 i2c_init_board(); 309 #else 310 /* 311 * WARNING: Do NOT save speed in a static variable: if the 312 * I2C routines are called before RAM is initialized (to read 313 * the DIMM SPD, for instance), RAM won't be usable and your 314 * system will crash. 315 */ 316 send_reset (); 317 #endif 318 } 319 320 /*----------------------------------------------------------------------- 321 * Probe to see if a chip is present. Also good for checking for the 322 * completion of EEPROM writes since the chip stops responding until 323 * the write completes (typically 10mSec). 324 */ 325 int i2c_probe(uchar addr) 326 { 327 int rc; 328 329 /* 330 * perform 1 byte write transaction with just address byte 331 * (fake write) 332 */ 333 send_start(); 334 rc = write_byte ((addr << 1) | 0); 335 send_stop(); 336 337 return (rc ? 1 : 0); 338 } 339 340 /*----------------------------------------------------------------------- 341 * Read bytes 342 */ 343 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len) 344 { 345 int shift; 346 PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n", 347 chip, addr, alen, buffer, len); 348 349 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW 350 /* 351 * EEPROM chips that implement "address overflow" are ones 352 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of 353 * address and the extra bits end up in the "chip address" 354 * bit slots. This makes a 24WC08 (1Kbyte) chip look like 355 * four 256 byte chips. 356 * 357 * Note that we consider the length of the address field to 358 * still be one byte because the extra address bits are 359 * hidden in the chip address. 360 */ 361 chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW); 362 363 PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n", 364 chip, addr); 365 #endif 366 367 /* 368 * Do the addressing portion of a write cycle to set the 369 * chip's address pointer. If the address length is zero, 370 * don't do the normal write cycle to set the address pointer, 371 * there is no address pointer in this chip. 372 */ 373 send_start(); 374 if(alen > 0) { 375 if(write_byte(chip << 1)) { /* write cycle */ 376 send_stop(); 377 PRINTD("i2c_read, no chip responded %02X\n", chip); 378 return(1); 379 } 380 shift = (alen-1) * 8; 381 while(alen-- > 0) { 382 if(write_byte(addr >> shift)) { 383 PRINTD("i2c_read, address not <ACK>ed\n"); 384 return(1); 385 } 386 shift -= 8; 387 } 388 send_stop(); /* reportedly some chips need a full stop */ 389 send_start(); 390 } 391 /* 392 * Send the chip address again, this time for a read cycle. 393 * Then read the data. On the last byte, we do a NACK instead 394 * of an ACK(len == 0) to terminate the read. 395 */ 396 write_byte((chip << 1) | 1); /* read cycle */ 397 while(len-- > 0) { 398 *buffer++ = read_byte(len == 0); 399 } 400 send_stop(); 401 return(0); 402 } 403 404 /*----------------------------------------------------------------------- 405 * Write bytes 406 */ 407 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len) 408 { 409 int shift, failures = 0; 410 411 PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n", 412 chip, addr, alen, buffer, len); 413 414 send_start(); 415 if(write_byte(chip << 1)) { /* write cycle */ 416 send_stop(); 417 PRINTD("i2c_write, 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_write, address not <ACK>ed\n"); 424 return(1); 425 } 426 shift -= 8; 427 } 428 429 while(len-- > 0) { 430 if(write_byte(*buffer++)) { 431 failures++; 432 } 433 } 434 send_stop(); 435 return(failures); 436 } 437