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 /*----------------------------------------------------------------------- 72 * Local functions 73 */ 74 static void send_reset (void); 75 static void send_start (void); 76 static void send_stop (void); 77 static void send_ack (int); 78 static int write_byte (uchar byte); 79 static uchar read_byte (int); 80 81 82 /*----------------------------------------------------------------------- 83 * Send a reset sequence consisting of 9 clocks with the data signal high 84 * to clock any confused device back into an idle state. Also send a 85 * <stop> at the end of the sequence for belts & suspenders. 86 */ 87 static void send_reset(void) 88 { 89 #ifdef CONFIG_MPC8260 90 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 91 #endif 92 #ifdef CONFIG_8xx 93 volatile immap_t *immr = (immap_t *)CFG_IMMR; 94 #endif 95 int j; 96 97 I2C_SCL(1); 98 I2C_SDA(1); 99 #ifdef I2C_INIT 100 I2C_INIT; 101 #endif 102 I2C_TRISTATE; 103 for(j = 0; j < 9; j++) { 104 I2C_SCL(0); 105 I2C_DELAY; 106 I2C_DELAY; 107 I2C_SCL(1); 108 I2C_DELAY; 109 I2C_DELAY; 110 } 111 send_stop(); 112 I2C_TRISTATE; 113 } 114 115 /*----------------------------------------------------------------------- 116 * START: High -> Low on SDA while SCL is High 117 */ 118 static void send_start(void) 119 { 120 #ifdef CONFIG_MPC8260 121 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 122 #endif 123 #ifdef CONFIG_8xx 124 volatile immap_t *immr = (immap_t *)CFG_IMMR; 125 #endif 126 127 I2C_DELAY; 128 I2C_SDA(1); 129 I2C_ACTIVE; 130 I2C_DELAY; 131 I2C_SCL(1); 132 I2C_DELAY; 133 I2C_SDA(0); 134 I2C_DELAY; 135 } 136 137 /*----------------------------------------------------------------------- 138 * STOP: Low -> High on SDA while SCL is High 139 */ 140 static void send_stop(void) 141 { 142 #ifdef CONFIG_MPC8260 143 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 144 #endif 145 #ifdef CONFIG_8xx 146 volatile immap_t *immr = (immap_t *)CFG_IMMR; 147 #endif 148 149 I2C_SCL(0); 150 I2C_DELAY; 151 I2C_SDA(0); 152 I2C_ACTIVE; 153 I2C_DELAY; 154 I2C_SCL(1); 155 I2C_DELAY; 156 I2C_SDA(1); 157 I2C_DELAY; 158 I2C_TRISTATE; 159 } 160 161 162 /*----------------------------------------------------------------------- 163 * ack should be I2C_ACK or I2C_NOACK 164 */ 165 static void send_ack(int ack) 166 { 167 #ifdef CONFIG_MPC8260 168 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 169 #endif 170 #ifdef CONFIG_8xx 171 volatile immap_t *immr = (immap_t *)CFG_IMMR; 172 #endif 173 174 I2C_SCL(0); 175 I2C_DELAY; 176 I2C_ACTIVE; 177 I2C_SDA(ack); 178 I2C_DELAY; 179 I2C_SCL(1); 180 I2C_DELAY; 181 I2C_DELAY; 182 I2C_SCL(0); 183 I2C_DELAY; 184 } 185 186 187 /*----------------------------------------------------------------------- 188 * Send 8 bits and look for an acknowledgement. 189 */ 190 static int write_byte(uchar data) 191 { 192 #ifdef CONFIG_MPC8260 193 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 194 #endif 195 #ifdef CONFIG_8xx 196 volatile immap_t *immr = (immap_t *)CFG_IMMR; 197 #endif 198 int j; 199 int nack; 200 201 I2C_ACTIVE; 202 for(j = 0; j < 8; j++) { 203 I2C_SCL(0); 204 I2C_DELAY; 205 I2C_SDA(data & 0x80); 206 I2C_DELAY; 207 I2C_SCL(1); 208 I2C_DELAY; 209 I2C_DELAY; 210 211 data <<= 1; 212 } 213 214 /* 215 * Look for an <ACK>(negative logic) and return it. 216 */ 217 I2C_SCL(0); 218 I2C_DELAY; 219 I2C_SDA(1); 220 I2C_TRISTATE; 221 I2C_DELAY; 222 I2C_SCL(1); 223 I2C_DELAY; 224 I2C_DELAY; 225 nack = I2C_READ; 226 I2C_SCL(0); 227 I2C_DELAY; 228 I2C_ACTIVE; 229 230 return(nack); /* not a nack is an ack */ 231 } 232 233 234 /*----------------------------------------------------------------------- 235 * if ack == I2C_ACK, ACK the byte so can continue reading, else 236 * send I2C_NOACK to end the read. 237 */ 238 static uchar read_byte(int ack) 239 { 240 #ifdef CONFIG_MPC8260 241 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); 242 #endif 243 #ifdef CONFIG_8xx 244 volatile immap_t *immr = (immap_t *)CFG_IMMR; 245 #endif 246 int data; 247 int j; 248 249 /* 250 * Read 8 bits, MSB first. 251 */ 252 I2C_TRISTATE; 253 I2C_SDA(1); 254 data = 0; 255 for(j = 0; j < 8; j++) { 256 I2C_SCL(0); 257 I2C_DELAY; 258 I2C_SCL(1); 259 I2C_DELAY; 260 data <<= 1; 261 data |= I2C_READ; 262 I2C_DELAY; 263 } 264 send_ack(ack); 265 266 return(data); 267 } 268 269 /*=====================================================================*/ 270 /* Public Functions */ 271 /*=====================================================================*/ 272 273 /*----------------------------------------------------------------------- 274 * Initialization 275 */ 276 void i2c_init (int speed, int slaveaddr) 277 { 278 /* 279 * WARNING: Do NOT save speed in a static variable: if the 280 * I2C routines are called before RAM is initialized (to read 281 * the DIMM SPD, for instance), RAM won't be usable and your 282 * system will crash. 283 */ 284 send_reset (); 285 } 286 287 /*----------------------------------------------------------------------- 288 * Probe to see if a chip is present. Also good for checking for the 289 * completion of EEPROM writes since the chip stops responding until 290 * the write completes (typically 10mSec). 291 */ 292 int i2c_probe(uchar addr) 293 { 294 int rc; 295 296 /* 297 * perform 1 byte write transaction with just address byte 298 * (fake write) 299 */ 300 send_start(); 301 rc = write_byte ((addr << 1) | 0); 302 send_stop(); 303 304 return (rc ? 1 : 0); 305 } 306 307 /*----------------------------------------------------------------------- 308 * Read bytes 309 */ 310 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len) 311 { 312 int shift; 313 PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n", 314 chip, addr, alen, buffer, len); 315 316 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW 317 /* 318 * EEPROM chips that implement "address overflow" are ones 319 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of 320 * address and the extra bits end up in the "chip address" 321 * bit slots. This makes a 24WC08 (1Kbyte) chip look like 322 * four 256 byte chips. 323 * 324 * Note that we consider the length of the address field to 325 * still be one byte because the extra address bits are 326 * hidden in the chip address. 327 */ 328 chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW); 329 330 PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n", 331 chip, addr); 332 #endif 333 334 /* 335 * Do the addressing portion of a write cycle to set the 336 * chip's address pointer. If the address length is zero, 337 * don't do the normal write cycle to set the address pointer, 338 * there is no address pointer in this chip. 339 */ 340 send_start(); 341 if(alen > 0) { 342 if(write_byte(chip << 1)) { /* write cycle */ 343 send_stop(); 344 PRINTD("i2c_read, no chip responded %02X\n", chip); 345 return(1); 346 } 347 shift = (alen-1) * 8; 348 while(alen-- > 0) { 349 if(write_byte(addr >> shift)) { 350 PRINTD("i2c_read, address not <ACK>ed\n"); 351 return(1); 352 } 353 shift -= 8; 354 } 355 send_stop(); /* reportedly some chips need a full stop */ 356 send_start(); 357 } 358 /* 359 * Send the chip address again, this time for a read cycle. 360 * Then read the data. On the last byte, we do a NACK instead 361 * of an ACK(len == 0) to terminate the read. 362 */ 363 write_byte((chip << 1) | 1); /* read cycle */ 364 while(len-- > 0) { 365 *buffer++ = read_byte(len == 0); 366 } 367 send_stop(); 368 return(0); 369 } 370 371 /*----------------------------------------------------------------------- 372 * Write bytes 373 */ 374 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len) 375 { 376 int shift, failures = 0; 377 378 PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n", 379 chip, addr, alen, buffer, len); 380 381 send_start(); 382 if(write_byte(chip << 1)) { /* write cycle */ 383 send_stop(); 384 PRINTD("i2c_write, no chip responded %02X\n", chip); 385 return(1); 386 } 387 shift = (alen-1) * 8; 388 while(alen-- > 0) { 389 if(write_byte(addr >> shift)) { 390 PRINTD("i2c_write, address not <ACK>ed\n"); 391 return(1); 392 } 393 shift -= 8; 394 } 395 396 while(len-- > 0) { 397 if(write_byte(*buffer++)) { 398 failures++; 399 } 400 } 401 send_stop(); 402 return(failures); 403 } 404 405 /*----------------------------------------------------------------------- 406 * Read a register 407 */ 408 uchar i2c_reg_read(uchar i2c_addr, uchar reg) 409 { 410 uchar buf; 411 412 i2c_read(i2c_addr, reg, 1, &buf, 1); 413 414 return(buf); 415 } 416 417 /*----------------------------------------------------------------------- 418 * Write a register 419 */ 420 void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val) 421 { 422 i2c_write(i2c_addr, reg, 1, &val, 1); 423 } 424