1 /* 2 * i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters 3 * Copyright (C) 2004 Arcom Control Systems 4 * Copyright (C) 2008 Pengutronix 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 */ 16 17 #include <linux/kernel.h> 18 #include <linux/module.h> 19 #include <linux/moduleparam.h> 20 #include <linux/delay.h> 21 #include <linux/jiffies.h> 22 #include <linux/errno.h> 23 #include <linux/i2c.h> 24 #include <linux/i2c-algo-pca.h> 25 26 #define DEB1(fmt, args...) do { if (i2c_debug >= 1) \ 27 printk(KERN_DEBUG fmt, ## args); } while (0) 28 #define DEB2(fmt, args...) do { if (i2c_debug >= 2) \ 29 printk(KERN_DEBUG fmt, ## args); } while (0) 30 #define DEB3(fmt, args...) do { if (i2c_debug >= 3) \ 31 printk(KERN_DEBUG fmt, ## args); } while (0) 32 33 static int i2c_debug; 34 35 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val) 36 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg) 37 38 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA) 39 #define pca_clock(adap) adap->i2c_clock 40 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val) 41 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON) 42 #define pca_wait(adap) adap->wait_for_completion(adap->data) 43 44 static void pca_reset(struct i2c_algo_pca_data *adap) 45 { 46 if (adap->chip == I2C_PCA_CHIP_9665) { 47 /* Ignore the reset function from the module, 48 * we can use the parallel bus reset. 49 */ 50 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET); 51 pca_outw(adap, I2C_PCA_IND, 0xA5); 52 pca_outw(adap, I2C_PCA_IND, 0x5A); 53 } else { 54 adap->reset_chip(adap->data); 55 } 56 } 57 58 /* 59 * Generate a start condition on the i2c bus. 60 * 61 * returns after the start condition has occurred 62 */ 63 static int pca_start(struct i2c_algo_pca_data *adap) 64 { 65 int sta = pca_get_con(adap); 66 DEB2("=== START\n"); 67 sta |= I2C_PCA_CON_STA; 68 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI); 69 pca_set_con(adap, sta); 70 return pca_wait(adap); 71 } 72 73 /* 74 * Generate a repeated start condition on the i2c bus 75 * 76 * return after the repeated start condition has occurred 77 */ 78 static int pca_repeated_start(struct i2c_algo_pca_data *adap) 79 { 80 int sta = pca_get_con(adap); 81 DEB2("=== REPEATED START\n"); 82 sta |= I2C_PCA_CON_STA; 83 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI); 84 pca_set_con(adap, sta); 85 return pca_wait(adap); 86 } 87 88 /* 89 * Generate a stop condition on the i2c bus 90 * 91 * returns after the stop condition has been generated 92 * 93 * STOPs do not generate an interrupt or set the SI flag, since the 94 * part returns the idle state (0xf8). Hence we don't need to 95 * pca_wait here. 96 */ 97 static void pca_stop(struct i2c_algo_pca_data *adap) 98 { 99 int sta = pca_get_con(adap); 100 DEB2("=== STOP\n"); 101 sta |= I2C_PCA_CON_STO; 102 sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI); 103 pca_set_con(adap, sta); 104 } 105 106 /* 107 * Send the slave address and R/W bit 108 * 109 * returns after the address has been sent 110 */ 111 static int pca_address(struct i2c_algo_pca_data *adap, 112 struct i2c_msg *msg) 113 { 114 int sta = pca_get_con(adap); 115 int addr; 116 117 addr = ((0x7f & msg->addr) << 1); 118 if (msg->flags & I2C_M_RD) 119 addr |= 1; 120 DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n", 121 msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr); 122 123 pca_outw(adap, I2C_PCA_DAT, addr); 124 125 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI); 126 pca_set_con(adap, sta); 127 128 return pca_wait(adap); 129 } 130 131 /* 132 * Transmit a byte. 133 * 134 * Returns after the byte has been transmitted 135 */ 136 static int pca_tx_byte(struct i2c_algo_pca_data *adap, 137 __u8 b) 138 { 139 int sta = pca_get_con(adap); 140 DEB2("=== WRITE %#04x\n", b); 141 pca_outw(adap, I2C_PCA_DAT, b); 142 143 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI); 144 pca_set_con(adap, sta); 145 146 return pca_wait(adap); 147 } 148 149 /* 150 * Receive a byte 151 * 152 * returns immediately. 153 */ 154 static void pca_rx_byte(struct i2c_algo_pca_data *adap, 155 __u8 *b, int ack) 156 { 157 *b = pca_inw(adap, I2C_PCA_DAT); 158 DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK"); 159 } 160 161 /* 162 * Setup ACK or NACK for next received byte and wait for it to arrive. 163 * 164 * Returns after next byte has arrived. 165 */ 166 static int pca_rx_ack(struct i2c_algo_pca_data *adap, 167 int ack) 168 { 169 int sta = pca_get_con(adap); 170 171 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA); 172 173 if (ack) 174 sta |= I2C_PCA_CON_AA; 175 176 pca_set_con(adap, sta); 177 return pca_wait(adap); 178 } 179 180 static int pca_xfer(struct i2c_adapter *i2c_adap, 181 struct i2c_msg *msgs, 182 int num) 183 { 184 struct i2c_algo_pca_data *adap = i2c_adap->algo_data; 185 struct i2c_msg *msg = NULL; 186 int curmsg; 187 int numbytes = 0; 188 int state; 189 int ret; 190 int completed = 1; 191 unsigned long timeout = jiffies + i2c_adap->timeout; 192 193 while ((state = pca_status(adap)) != 0xf8) { 194 if (time_before(jiffies, timeout)) { 195 msleep(10); 196 } else { 197 dev_dbg(&i2c_adap->dev, "bus is not idle. status is " 198 "%#04x\n", state); 199 return -EBUSY; 200 } 201 } 202 203 DEB1("{{{ XFER %d messages\n", num); 204 205 if (i2c_debug >= 2) { 206 for (curmsg = 0; curmsg < num; curmsg++) { 207 int addr, i; 208 msg = &msgs[curmsg]; 209 210 addr = (0x7f & msg->addr) ; 211 212 if (msg->flags & I2C_M_RD) 213 printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n", 214 curmsg, msg->len, addr, (addr << 1) | 1); 215 else { 216 printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s", 217 curmsg, msg->len, addr, addr << 1, 218 msg->len == 0 ? "" : ", "); 219 for (i = 0; i < msg->len; i++) 220 printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", "); 221 printk("]\n"); 222 } 223 } 224 } 225 226 curmsg = 0; 227 ret = -EIO; 228 while (curmsg < num) { 229 state = pca_status(adap); 230 231 DEB3("STATE is 0x%02x\n", state); 232 msg = &msgs[curmsg]; 233 234 switch (state) { 235 case 0xf8: /* On reset or stop the bus is idle */ 236 completed = pca_start(adap); 237 break; 238 239 case 0x08: /* A START condition has been transmitted */ 240 case 0x10: /* A repeated start condition has been transmitted */ 241 completed = pca_address(adap, msg); 242 break; 243 244 case 0x18: /* SLA+W has been transmitted; ACK has been received */ 245 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */ 246 if (numbytes < msg->len) { 247 completed = pca_tx_byte(adap, 248 msg->buf[numbytes]); 249 numbytes++; 250 break; 251 } 252 curmsg++; numbytes = 0; 253 if (curmsg == num) 254 pca_stop(adap); 255 else 256 completed = pca_repeated_start(adap); 257 break; 258 259 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */ 260 DEB2("NOT ACK received after SLA+W\n"); 261 pca_stop(adap); 262 ret = -ENXIO; 263 goto out; 264 265 case 0x40: /* SLA+R has been transmitted; ACK has been received */ 266 completed = pca_rx_ack(adap, msg->len > 1); 267 break; 268 269 case 0x50: /* Data bytes has been received; ACK has been returned */ 270 if (numbytes < msg->len) { 271 pca_rx_byte(adap, &msg->buf[numbytes], 1); 272 numbytes++; 273 completed = pca_rx_ack(adap, 274 numbytes < msg->len - 1); 275 break; 276 } 277 curmsg++; numbytes = 0; 278 if (curmsg == num) 279 pca_stop(adap); 280 else 281 completed = pca_repeated_start(adap); 282 break; 283 284 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */ 285 DEB2("NOT ACK received after SLA+R\n"); 286 pca_stop(adap); 287 ret = -ENXIO; 288 goto out; 289 290 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */ 291 DEB2("NOT ACK received after data byte\n"); 292 pca_stop(adap); 293 goto out; 294 295 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */ 296 DEB2("Arbitration lost\n"); 297 /* 298 * The PCA9564 data sheet (2006-09-01) says "A 299 * START condition will be transmitted when the 300 * bus becomes free (STOP or SCL and SDA high)" 301 * when the STA bit is set (p. 11). 302 * 303 * In case this won't work, try pca_reset() 304 * instead. 305 */ 306 pca_start(adap); 307 goto out; 308 309 case 0x58: /* Data byte has been received; NOT ACK has been returned */ 310 if (numbytes == msg->len - 1) { 311 pca_rx_byte(adap, &msg->buf[numbytes], 0); 312 curmsg++; numbytes = 0; 313 if (curmsg == num) 314 pca_stop(adap); 315 else 316 completed = pca_repeated_start(adap); 317 } else { 318 DEB2("NOT ACK sent after data byte received. " 319 "Not final byte. numbytes %d. len %d\n", 320 numbytes, msg->len); 321 pca_stop(adap); 322 goto out; 323 } 324 break; 325 case 0x70: /* Bus error - SDA stuck low */ 326 DEB2("BUS ERROR - SDA Stuck low\n"); 327 pca_reset(adap); 328 goto out; 329 case 0x90: /* Bus error - SCL stuck low */ 330 DEB2("BUS ERROR - SCL Stuck low\n"); 331 pca_reset(adap); 332 goto out; 333 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */ 334 DEB2("BUS ERROR - Illegal START or STOP\n"); 335 pca_reset(adap); 336 goto out; 337 default: 338 dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state); 339 break; 340 } 341 342 if (!completed) 343 goto out; 344 } 345 346 ret = curmsg; 347 out: 348 DEB1("}}} transferred %d/%d messages. " 349 "status is %#04x. control is %#04x\n", 350 curmsg, num, pca_status(adap), 351 pca_get_con(adap)); 352 return ret; 353 } 354 355 static u32 pca_func(struct i2c_adapter *adap) 356 { 357 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 358 } 359 360 static const struct i2c_algorithm pca_algo = { 361 .master_xfer = pca_xfer, 362 .functionality = pca_func, 363 }; 364 365 static unsigned int pca_probe_chip(struct i2c_adapter *adap) 366 { 367 struct i2c_algo_pca_data *pca_data = adap->algo_data; 368 /* The trick here is to check if there is an indirect register 369 * available. If there is one, we will read the value we first 370 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value 371 * we wrote on I2C_PCA_ADR 372 */ 373 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR); 374 pca_outw(pca_data, I2C_PCA_IND, 0xAA); 375 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO); 376 pca_outw(pca_data, I2C_PCA_IND, 0x00); 377 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR); 378 if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) { 379 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name); 380 pca_data->chip = I2C_PCA_CHIP_9665; 381 } else { 382 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name); 383 pca_data->chip = I2C_PCA_CHIP_9564; 384 } 385 return pca_data->chip; 386 } 387 388 static int pca_init(struct i2c_adapter *adap) 389 { 390 struct i2c_algo_pca_data *pca_data = adap->algo_data; 391 392 adap->algo = &pca_algo; 393 394 if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) { 395 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36}; 396 int clock; 397 398 if (pca_data->i2c_clock > 7) { 399 switch (pca_data->i2c_clock) { 400 case 330000: 401 pca_data->i2c_clock = I2C_PCA_CON_330kHz; 402 break; 403 case 288000: 404 pca_data->i2c_clock = I2C_PCA_CON_288kHz; 405 break; 406 case 217000: 407 pca_data->i2c_clock = I2C_PCA_CON_217kHz; 408 break; 409 case 146000: 410 pca_data->i2c_clock = I2C_PCA_CON_146kHz; 411 break; 412 case 88000: 413 pca_data->i2c_clock = I2C_PCA_CON_88kHz; 414 break; 415 case 59000: 416 pca_data->i2c_clock = I2C_PCA_CON_59kHz; 417 break; 418 case 44000: 419 pca_data->i2c_clock = I2C_PCA_CON_44kHz; 420 break; 421 case 36000: 422 pca_data->i2c_clock = I2C_PCA_CON_36kHz; 423 break; 424 default: 425 printk(KERN_WARNING 426 "%s: Invalid I2C clock speed selected." 427 " Using default 59kHz.\n", adap->name); 428 pca_data->i2c_clock = I2C_PCA_CON_59kHz; 429 } 430 } else { 431 printk(KERN_WARNING "%s: " 432 "Choosing the clock frequency based on " 433 "index is deprecated." 434 " Use the nominal frequency.\n", adap->name); 435 } 436 437 pca_reset(pca_data); 438 439 clock = pca_clock(pca_data); 440 printk(KERN_INFO "%s: Clock frequency is %dkHz\n", 441 adap->name, freqs[clock]); 442 443 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock); 444 } else { 445 int clock; 446 int mode; 447 int tlow, thi; 448 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */ 449 int min_tlow, min_thi; 450 /* These values are the maximum raise and fall values allowed 451 * by the I2C operation mode (Standard, Fast or Fast+) 452 * They are used (added) below to calculate the clock dividers 453 * of PCA9665. Note that they are slightly different of the 454 * real maximum, to allow the change on mode exactly on the 455 * maximum clock rate for each mode 456 */ 457 int raise_fall_time; 458 459 if (pca_data->i2c_clock > 1265800) { 460 printk(KERN_WARNING "%s: I2C clock speed too high." 461 " Using 1265.8kHz.\n", adap->name); 462 pca_data->i2c_clock = 1265800; 463 } 464 465 if (pca_data->i2c_clock < 60300) { 466 printk(KERN_WARNING "%s: I2C clock speed too low." 467 " Using 60.3kHz.\n", adap->name); 468 pca_data->i2c_clock = 60300; 469 } 470 471 /* To avoid integer overflow, use clock/100 for calculations */ 472 clock = pca_clock(pca_data) / 100; 473 474 if (pca_data->i2c_clock > 1000000) { 475 mode = I2C_PCA_MODE_TURBO; 476 min_tlow = 14; 477 min_thi = 5; 478 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */ 479 } else if (pca_data->i2c_clock > 400000) { 480 mode = I2C_PCA_MODE_FASTP; 481 min_tlow = 17; 482 min_thi = 9; 483 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */ 484 } else if (pca_data->i2c_clock > 100000) { 485 mode = I2C_PCA_MODE_FAST; 486 min_tlow = 44; 487 min_thi = 20; 488 raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */ 489 } else { 490 mode = I2C_PCA_MODE_STD; 491 min_tlow = 157; 492 min_thi = 134; 493 raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */ 494 } 495 496 /* The minimum clock that respects the thi/tlow = 134/157 is 497 * 64800 Hz. Below that, we have to fix the tlow to 255 and 498 * calculate the thi factor. 499 */ 500 if (clock < 648) { 501 tlow = 255; 502 thi = 1000000 - clock * raise_fall_time; 503 thi /= (I2C_PCA_OSC_PER * clock) - tlow; 504 } else { 505 tlow = (1000000 - clock * raise_fall_time) * min_tlow; 506 tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow); 507 thi = tlow * min_thi / min_tlow; 508 } 509 510 pca_reset(pca_data); 511 512 printk(KERN_INFO 513 "%s: Clock frequency is %dHz\n", adap->name, clock * 100); 514 515 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE); 516 pca_outw(pca_data, I2C_PCA_IND, mode); 517 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL); 518 pca_outw(pca_data, I2C_PCA_IND, tlow); 519 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH); 520 pca_outw(pca_data, I2C_PCA_IND, thi); 521 522 pca_set_con(pca_data, I2C_PCA_CON_ENSIO); 523 } 524 udelay(500); /* 500 us for oscilator to stabilise */ 525 526 return 0; 527 } 528 529 /* 530 * registering functions to load algorithms at runtime 531 */ 532 int i2c_pca_add_bus(struct i2c_adapter *adap) 533 { 534 int rval; 535 536 rval = pca_init(adap); 537 if (rval) 538 return rval; 539 540 return i2c_add_adapter(adap); 541 } 542 EXPORT_SYMBOL(i2c_pca_add_bus); 543 544 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap) 545 { 546 int rval; 547 548 rval = pca_init(adap); 549 if (rval) 550 return rval; 551 552 return i2c_add_numbered_adapter(adap); 553 } 554 EXPORT_SYMBOL(i2c_pca_add_numbered_bus); 555 556 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, " 557 "Wolfram Sang <w.sang@pengutronix.de>"); 558 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm"); 559 MODULE_LICENSE("GPL"); 560 561 module_param(i2c_debug, int, 0); 562