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 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 19 */ 20 21#include <linux/kernel.h> 22#include <linux/module.h> 23#include <linux/moduleparam.h> 24#include <linux/delay.h> 25#include <linux/jiffies.h> 26#include <linux/init.h> 27#include <linux/errno.h> 28#include <linux/i2c.h> 29#include <linux/i2c-algo-pca.h> 30 31#define DEB1(fmt, args...) do { if (i2c_debug >= 1) \ 32 printk(KERN_DEBUG fmt, ## args); } while (0) 33#define DEB2(fmt, args...) do { if (i2c_debug >= 2) \ 34 printk(KERN_DEBUG fmt, ## args); } while (0) 35#define DEB3(fmt, args...) do { if (i2c_debug >= 3) \ 36 printk(KERN_DEBUG fmt, ## args); } while (0) 37 38static int i2c_debug; 39 40#define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val) 41#define pca_inw(adap, reg) adap->read_byte(adap->data, reg) 42 43#define pca_status(adap) pca_inw(adap, I2C_PCA_STA) 44#define pca_clock(adap) adap->i2c_clock 45#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val) 46#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON) 47#define pca_wait(adap) adap->wait_for_completion(adap->data) 48#define pca_reset(adap) adap->reset_chip(adap->data) 49 50static void pca9665_reset(void *pd) 51{ 52 struct i2c_algo_pca_data *adap = pd; 53 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET); 54 pca_outw(adap, I2C_PCA_IND, 0xA5); 55 pca_outw(adap, I2C_PCA_IND, 0x5A); 56} 57 58/* 59 * Generate a start condition on the i2c bus. 60 * 61 * returns after the start condition has occurred 62 */ 63static 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 */ 78static 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 */ 97static 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 */ 111static 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 */ 136static 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 */ 154static 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 */ 166static 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 180static 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 -EAGAIN; 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 = -EREMOTEIO; 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 goto out; 263 264 case 0x40: /* SLA+R has been transmitted; ACK has been received */ 265 completed = pca_rx_ack(adap, msg->len > 1); 266 break; 267 268 case 0x50: /* Data bytes has been received; ACK has been returned */ 269 if (numbytes < msg->len) { 270 pca_rx_byte(adap, &msg->buf[numbytes], 1); 271 numbytes++; 272 completed = pca_rx_ack(adap, 273 numbytes < msg->len - 1); 274 break; 275 } 276 curmsg++; numbytes = 0; 277 if (curmsg == num) 278 pca_stop(adap); 279 else 280 completed = pca_repeated_start(adap); 281 break; 282 283 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */ 284 DEB2("NOT ACK received after SLA+R\n"); 285 pca_stop(adap); 286 goto out; 287 288 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */ 289 DEB2("NOT ACK received after data byte\n"); 290 pca_stop(adap); 291 goto out; 292 293 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */ 294 DEB2("Arbitration lost\n"); 295 /* 296 * The PCA9564 data sheet (2006-09-01) says "A 297 * START condition will be transmitted when the 298 * bus becomes free (STOP or SCL and SDA high)" 299 * when the STA bit is set (p. 11). 300 * 301 * In case this won't work, try pca_reset() 302 * instead. 303 */ 304 pca_start(adap); 305 goto out; 306 307 case 0x58: /* Data byte has been received; NOT ACK has been returned */ 308 if (numbytes == msg->len - 1) { 309 pca_rx_byte(adap, &msg->buf[numbytes], 0); 310 curmsg++; numbytes = 0; 311 if (curmsg == num) 312 pca_stop(adap); 313 else 314 completed = pca_repeated_start(adap); 315 } else { 316 DEB2("NOT ACK sent after data byte received. " 317 "Not final byte. numbytes %d. len %d\n", 318 numbytes, msg->len); 319 pca_stop(adap); 320 goto out; 321 } 322 break; 323 case 0x70: /* Bus error - SDA stuck low */ 324 DEB2("BUS ERROR - SDA Stuck low\n"); 325 pca_reset(adap); 326 goto out; 327 case 0x90: /* Bus error - SCL stuck low */ 328 DEB2("BUS ERROR - SCL Stuck low\n"); 329 pca_reset(adap); 330 goto out; 331 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */ 332 DEB2("BUS ERROR - Illegal START or STOP\n"); 333 pca_reset(adap); 334 goto out; 335 default: 336 dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state); 337 break; 338 } 339 340 if (!completed) 341 goto out; 342 } 343 344 ret = curmsg; 345 out: 346 DEB1("}}} transfered %d/%d messages. " 347 "status is %#04x. control is %#04x\n", 348 curmsg, num, pca_status(adap), 349 pca_get_con(adap)); 350 return ret; 351} 352 353static u32 pca_func(struct i2c_adapter *adap) 354{ 355 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 356} 357 358static const struct i2c_algorithm pca_algo = { 359 .master_xfer = pca_xfer, 360 .functionality = pca_func, 361}; 362 363static unsigned int pca_probe_chip(struct i2c_adapter *adap) 364{ 365 struct i2c_algo_pca_data *pca_data = adap->algo_data; 366 /* The trick here is to check if there is an indirect register 367 * available. If there is one, we will read the value we first 368 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value 369 * we wrote on I2C_PCA_ADR 370 */ 371 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR); 372 pca_outw(pca_data, I2C_PCA_IND, 0xAA); 373 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO); 374 pca_outw(pca_data, I2C_PCA_IND, 0x00); 375 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR); 376 if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) { 377 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name); 378 return I2C_PCA_CHIP_9665; 379 } else { 380 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name); 381 return I2C_PCA_CHIP_9564; 382 } 383} 384 385static int pca_init(struct i2c_adapter *adap) 386{ 387 struct i2c_algo_pca_data *pca_data = adap->algo_data; 388 389 adap->algo = &pca_algo; 390 391 if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) { 392 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36}; 393 int clock; 394 395 if (pca_data->i2c_clock > 7) { 396 switch (pca_data->i2c_clock) { 397 case 330000: 398 pca_data->i2c_clock = I2C_PCA_CON_330kHz; 399 break; 400 case 288000: 401 pca_data->i2c_clock = I2C_PCA_CON_288kHz; 402 break; 403 case 217000: 404 pca_data->i2c_clock = I2C_PCA_CON_217kHz; 405 break; 406 case 146000: 407 pca_data->i2c_clock = I2C_PCA_CON_146kHz; 408 break; 409 case 88000: 410 pca_data->i2c_clock = I2C_PCA_CON_88kHz; 411 break; 412 case 59000: 413 pca_data->i2c_clock = I2C_PCA_CON_59kHz; 414 break; 415 case 44000: 416 pca_data->i2c_clock = I2C_PCA_CON_44kHz; 417 break; 418 case 36000: 419 pca_data->i2c_clock = I2C_PCA_CON_36kHz; 420 break; 421 default: 422 printk(KERN_WARNING 423 "%s: Invalid I2C clock speed selected." 424 " Using default 59kHz.\n", adap->name); 425 pca_data->i2c_clock = I2C_PCA_CON_59kHz; 426 } 427 } else { 428 printk(KERN_WARNING "%s: " 429 "Choosing the clock frequency based on " 430 "index is deprecated." 431 " Use the nominal frequency.\n", adap->name); 432 } 433 434 pca_reset(pca_data); 435 436 clock = pca_clock(pca_data); 437 printk(KERN_INFO "%s: Clock frequency is %dkHz\n", 438 adap->name, freqs[clock]); 439 440 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock); 441 } else { 442 int clock; 443 int mode; 444 int tlow, thi; 445 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */ 446 int min_tlow, min_thi; 447 /* These values are the maximum raise and fall values allowed 448 * by the I2C operation mode (Standard, Fast or Fast+) 449 * They are used (added) below to calculate the clock dividers 450 * of PCA9665. Note that they are slightly different of the 451 * real maximum, to allow the change on mode exactly on the 452 * maximum clock rate for each mode 453 */ 454 int raise_fall_time; 455 456 /* Ignore the reset function from the module, 457 * we can use the parallel bus reset 458 */ 459 pca_data->reset_chip = pca9665_reset; 460 461 if (pca_data->i2c_clock > 1265800) { 462 printk(KERN_WARNING "%s: I2C clock speed too high." 463 " Using 1265.8kHz.\n", adap->name); 464 pca_data->i2c_clock = 1265800; 465 } 466 467 if (pca_data->i2c_clock < 60300) { 468 printk(KERN_WARNING "%s: I2C clock speed too low." 469 " Using 60.3kHz.\n", adap->name); 470 pca_data->i2c_clock = 60300; 471 } 472 473 /* To avoid integer overflow, use clock/100 for calculations */ 474 clock = pca_clock(pca_data) / 100; 475 476 if (pca_data->i2c_clock > 10000) { 477 mode = I2C_PCA_MODE_TURBO; 478 min_tlow = 14; 479 min_thi = 5; 480 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */ 481 } else if (pca_data->i2c_clock > 4000) { 482 mode = I2C_PCA_MODE_FASTP; 483 min_tlow = 17; 484 min_thi = 9; 485 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */ 486 } else if (pca_data->i2c_clock > 1000) { 487 mode = I2C_PCA_MODE_FAST; 488 min_tlow = 44; 489 min_thi = 20; 490 raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */ 491 } else { 492 mode = I2C_PCA_MODE_STD; 493 min_tlow = 157; 494 min_thi = 134; 495 raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */ 496 } 497 498 /* The minimum clock that respects the thi/tlow = 134/157 is 499 * 64800 Hz. Below that, we have to fix the tlow to 255 and 500 * calculate the thi factor. 501 */ 502 if (clock < 648) { 503 tlow = 255; 504 thi = 1000000 - clock * raise_fall_time; 505 thi /= (I2C_PCA_OSC_PER * clock) - tlow; 506 } else { 507 tlow = (1000000 - clock * raise_fall_time) * min_tlow; 508 tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow); 509 thi = tlow * min_thi / min_tlow; 510 } 511 512 pca_reset(pca_data); 513 514 printk(KERN_INFO 515 "%s: Clock frequency is %dHz\n", adap->name, clock * 100); 516 517 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE); 518 pca_outw(pca_data, I2C_PCA_IND, mode); 519 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL); 520 pca_outw(pca_data, I2C_PCA_IND, tlow); 521 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH); 522 pca_outw(pca_data, I2C_PCA_IND, thi); 523 524 pca_set_con(pca_data, I2C_PCA_CON_ENSIO); 525 } 526 udelay(500); /* 500 us for oscilator to stabilise */ 527 528 return 0; 529} 530 531/* 532 * registering functions to load algorithms at runtime 533 */ 534int i2c_pca_add_bus(struct i2c_adapter *adap) 535{ 536 int rval; 537 538 rval = pca_init(adap); 539 if (rval) 540 return rval; 541 542 return i2c_add_adapter(adap); 543} 544EXPORT_SYMBOL(i2c_pca_add_bus); 545 546int i2c_pca_add_numbered_bus(struct i2c_adapter *adap) 547{ 548 int rval; 549 550 rval = pca_init(adap); 551 if (rval) 552 return rval; 553 554 return i2c_add_numbered_adapter(adap); 555} 556EXPORT_SYMBOL(i2c_pca_add_numbered_bus); 557 558MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, " 559 "Wolfram Sang <w.sang@pengutronix.de>"); 560MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm"); 561MODULE_LICENSE("GPL"); 562 563module_param(i2c_debug, int, 0); 564