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 #if defined(CONFIG_MPC852T) || defined(CONFIG_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 * Definitions 56 */ 57 58 #define RETRIES 0 59 60 #define I2C_ACK 0 /* PD_SDA level to ack a byte */ 61 #define I2C_NOACK 1 /* PD_SDA level to noack a byte */ 62 63 64 #ifdef DEBUG_I2C 65 #define PRINTD(fmt,args...) do { \ 66 if (gd->have_console) \ 67 printf (fmt ,##args); \ 68 } while (0) 69 #else 70 #define PRINTD(fmt,args...) 71 #endif 72 73 #if defined(CONFIG_I2C_MULTI_BUS) 74 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0; 75 #endif /* CONFIG_I2C_MULTI_BUS */ 76 77 /*----------------------------------------------------------------------- 78 * Local functions 79 */ 80 #if !defined(CONFIG_SYS_I2C_INIT_BOARD) 81 static void send_reset (void); 82 #endif 83 static void send_start (void); 84 static void send_stop (void); 85 static void send_ack (int); 86 static int write_byte (uchar byte); 87 static uchar read_byte (int); 88 89 #if !defined(CONFIG_SYS_I2C_INIT_BOARD) 90 /*----------------------------------------------------------------------- 91 * Send a reset sequence consisting of 9 clocks with the data signal high 92 * to clock any confused device back into an idle state. Also send a 93 * <stop> at the end of the sequence for belts & suspenders. 94 */ 95 static void send_reset(void) 96 { 97 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 98 int j; 99 100 I2C_SCL(1); 101 I2C_SDA(1); 102 #ifdef I2C_INIT 103 I2C_INIT; 104 #endif 105 I2C_TRISTATE; 106 for(j = 0; j < 9; j++) { 107 I2C_SCL(0); 108 I2C_DELAY; 109 I2C_DELAY; 110 I2C_SCL(1); 111 I2C_DELAY; 112 I2C_DELAY; 113 } 114 send_stop(); 115 I2C_TRISTATE; 116 } 117 #endif 118 119 /*----------------------------------------------------------------------- 120 * START: High -> Low on SDA while SCL is High 121 */ 122 static void send_start(void) 123 { 124 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 125 126 I2C_DELAY; 127 I2C_SDA(1); 128 I2C_ACTIVE; 129 I2C_DELAY; 130 I2C_SCL(1); 131 I2C_DELAY; 132 I2C_SDA(0); 133 I2C_DELAY; 134 } 135 136 /*----------------------------------------------------------------------- 137 * STOP: Low -> High on SDA while SCL is High 138 */ 139 static void send_stop(void) 140 { 141 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 142 143 I2C_SCL(0); 144 I2C_DELAY; 145 I2C_SDA(0); 146 I2C_ACTIVE; 147 I2C_DELAY; 148 I2C_SCL(1); 149 I2C_DELAY; 150 I2C_SDA(1); 151 I2C_DELAY; 152 I2C_TRISTATE; 153 } 154 155 /*----------------------------------------------------------------------- 156 * ack should be I2C_ACK or I2C_NOACK 157 */ 158 static void send_ack(int ack) 159 { 160 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 161 162 I2C_SCL(0); 163 I2C_DELAY; 164 I2C_ACTIVE; 165 I2C_SDA(ack); 166 I2C_DELAY; 167 I2C_SCL(1); 168 I2C_DELAY; 169 I2C_DELAY; 170 I2C_SCL(0); 171 I2C_DELAY; 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 #endif 246 247 /*----------------------------------------------------------------------- 248 * if ack == I2C_ACK, ACK the byte so can continue reading, else 249 * send I2C_NOACK to end the read. 250 */ 251 static uchar read_byte(int ack) 252 { 253 I2C_SOFT_DECLARATIONS /* intentional without ';' */ 254 int data; 255 int j; 256 257 /* 258 * Read 8 bits, MSB first. 259 */ 260 I2C_TRISTATE; 261 I2C_SDA(1); 262 data = 0; 263 for(j = 0; j < 8; j++) { 264 I2C_SCL(0); 265 I2C_DELAY; 266 I2C_SCL(1); 267 I2C_DELAY; 268 data <<= 1; 269 data |= I2C_READ; 270 I2C_DELAY; 271 } 272 send_ack(ack); 273 274 return(data); 275 } 276 277 /*=====================================================================*/ 278 /* Public Functions */ 279 /*=====================================================================*/ 280 281 /*----------------------------------------------------------------------- 282 * Initialization 283 */ 284 void i2c_init (int speed, int slaveaddr) 285 { 286 #if defined(CONFIG_SYS_I2C_INIT_BOARD) 287 /* call board specific i2c bus reset routine before accessing the */ 288 /* environment, which might be in a chip on that bus. For details */ 289 /* about this problem see doc/I2C_Edge_Conditions. */ 290 i2c_init_board(); 291 #else 292 /* 293 * WARNING: Do NOT save speed in a static variable: if the 294 * I2C routines are called before RAM is initialized (to read 295 * the DIMM SPD, for instance), RAM won't be usable and your 296 * system will crash. 297 */ 298 send_reset (); 299 #endif 300 } 301 302 /*----------------------------------------------------------------------- 303 * Probe to see if a chip is present. Also good for checking for the 304 * completion of EEPROM writes since the chip stops responding until 305 * the write completes (typically 10mSec). 306 */ 307 int i2c_probe(uchar addr) 308 { 309 int rc; 310 311 /* 312 * perform 1 byte write transaction with just address byte 313 * (fake write) 314 */ 315 send_start(); 316 rc = write_byte ((addr << 1) | 0); 317 send_stop(); 318 319 return (rc ? 1 : 0); 320 } 321 322 /*----------------------------------------------------------------------- 323 * Read bytes 324 */ 325 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len) 326 { 327 int shift; 328 PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n", 329 chip, addr, alen, buffer, len); 330 331 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW 332 /* 333 * EEPROM chips that implement "address overflow" are ones 334 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of 335 * address and the extra bits end up in the "chip address" 336 * bit slots. This makes a 24WC08 (1Kbyte) chip look like 337 * four 256 byte chips. 338 * 339 * Note that we consider the length of the address field to 340 * still be one byte because the extra address bits are 341 * hidden in the chip address. 342 */ 343 chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW); 344 345 PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n", 346 chip, addr); 347 #endif 348 349 /* 350 * Do the addressing portion of a write cycle to set the 351 * chip's address pointer. If the address length is zero, 352 * don't do the normal write cycle to set the address pointer, 353 * there is no address pointer in this chip. 354 */ 355 send_start(); 356 if(alen > 0) { 357 if(write_byte(chip << 1)) { /* write cycle */ 358 send_stop(); 359 PRINTD("i2c_read, no chip responded %02X\n", chip); 360 return(1); 361 } 362 shift = (alen-1) * 8; 363 while(alen-- > 0) { 364 if(write_byte(addr >> shift)) { 365 PRINTD("i2c_read, address not <ACK>ed\n"); 366 return(1); 367 } 368 shift -= 8; 369 } 370 371 /* Some I2C chips need a stop/start sequence here, 372 * other chips don't work with a full stop and need 373 * only a start. Default behaviour is to send the 374 * stop/start sequence. 375 */ 376 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START 377 send_start(); 378 #else 379 send_stop(); 380 send_start(); 381 #endif 382 } 383 /* 384 * Send the chip address again, this time for a read cycle. 385 * Then read the data. On the last byte, we do a NACK instead 386 * of an ACK(len == 0) to terminate the read. 387 */ 388 write_byte((chip << 1) | 1); /* read cycle */ 389 while(len-- > 0) { 390 *buffer++ = read_byte(len == 0); 391 } 392 send_stop(); 393 return(0); 394 } 395 396 /*----------------------------------------------------------------------- 397 * Write bytes 398 */ 399 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len) 400 { 401 int shift, failures = 0; 402 403 PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n", 404 chip, addr, alen, buffer, len); 405 406 send_start(); 407 if(write_byte(chip << 1)) { /* write cycle */ 408 send_stop(); 409 PRINTD("i2c_write, no chip responded %02X\n", chip); 410 return(1); 411 } 412 shift = (alen-1) * 8; 413 while(alen-- > 0) { 414 if(write_byte(addr >> shift)) { 415 PRINTD("i2c_write, address not <ACK>ed\n"); 416 return(1); 417 } 418 shift -= 8; 419 } 420 421 while(len-- > 0) { 422 if(write_byte(*buffer++)) { 423 failures++; 424 } 425 } 426 send_stop(); 427 return(failures); 428 } 429