1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters 4 * Copyright (C) 2004 Arcom Control Systems 5 * Copyright (C) 2008 Pengutronix 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/moduleparam.h> 11 #include <linux/delay.h> 12 #include <linux/jiffies.h> 13 #include <linux/errno.h> 14 #include <linux/i2c.h> 15 #include <linux/i2c-algo-pca.h> 16 17 #define DEB1(fmt, args...) do { if (i2c_debug >= 1) \ 18 printk(KERN_DEBUG fmt, ## args); } while (0) 19 #define DEB2(fmt, args...) do { if (i2c_debug >= 2) \ 20 printk(KERN_DEBUG fmt, ## args); } while (0) 21 #define DEB3(fmt, args...) do { if (i2c_debug >= 3) \ 22 printk(KERN_DEBUG fmt, ## args); } while (0) 23 24 static int i2c_debug; 25 26 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val) 27 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg) 28 29 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA) 30 #define pca_clock(adap) adap->i2c_clock 31 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val) 32 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON) 33 #define pca_wait(adap) adap->wait_for_completion(adap->data) 34 35 static void pca_reset(struct i2c_algo_pca_data *adap) 36 { 37 if (adap->chip == I2C_PCA_CHIP_9665) { 38 /* Ignore the reset function from the module, 39 * we can use the parallel bus reset. 40 */ 41 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET); 42 pca_outw(adap, I2C_PCA_IND, 0xA5); 43 pca_outw(adap, I2C_PCA_IND, 0x5A); 44 } else { 45 adap->reset_chip(adap->data); 46 } 47 } 48 49 /* 50 * Generate a start condition on the i2c bus. 51 * 52 * returns after the start condition has occurred 53 */ 54 static int pca_start(struct i2c_algo_pca_data *adap) 55 { 56 int sta = pca_get_con(adap); 57 DEB2("=== START\n"); 58 sta |= I2C_PCA_CON_STA; 59 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI); 60 pca_set_con(adap, sta); 61 return pca_wait(adap); 62 } 63 64 /* 65 * Generate a repeated start condition on the i2c bus 66 * 67 * return after the repeated start condition has occurred 68 */ 69 static int pca_repeated_start(struct i2c_algo_pca_data *adap) 70 { 71 int sta = pca_get_con(adap); 72 DEB2("=== REPEATED START\n"); 73 sta |= I2C_PCA_CON_STA; 74 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI); 75 pca_set_con(adap, sta); 76 return pca_wait(adap); 77 } 78 79 /* 80 * Generate a stop condition on the i2c bus 81 * 82 * returns after the stop condition has been generated 83 * 84 * STOPs do not generate an interrupt or set the SI flag, since the 85 * part returns the idle state (0xf8). Hence we don't need to 86 * pca_wait here. 87 */ 88 static void pca_stop(struct i2c_algo_pca_data *adap) 89 { 90 int sta = pca_get_con(adap); 91 DEB2("=== STOP\n"); 92 sta |= I2C_PCA_CON_STO; 93 sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI); 94 pca_set_con(adap, sta); 95 } 96 97 /* 98 * Send the slave address and R/W bit 99 * 100 * returns after the address has been sent 101 */ 102 static int pca_address(struct i2c_algo_pca_data *adap, 103 struct i2c_msg *msg) 104 { 105 int sta = pca_get_con(adap); 106 int addr = i2c_8bit_addr_from_msg(msg); 107 108 DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n", 109 msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr); 110 111 pca_outw(adap, I2C_PCA_DAT, addr); 112 113 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI); 114 pca_set_con(adap, sta); 115 116 return pca_wait(adap); 117 } 118 119 /* 120 * Transmit a byte. 121 * 122 * Returns after the byte has been transmitted 123 */ 124 static int pca_tx_byte(struct i2c_algo_pca_data *adap, 125 __u8 b) 126 { 127 int sta = pca_get_con(adap); 128 DEB2("=== WRITE %#04x\n", b); 129 pca_outw(adap, I2C_PCA_DAT, b); 130 131 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI); 132 pca_set_con(adap, sta); 133 134 return pca_wait(adap); 135 } 136 137 /* 138 * Receive a byte 139 * 140 * returns immediately. 141 */ 142 static void pca_rx_byte(struct i2c_algo_pca_data *adap, 143 __u8 *b, int ack) 144 { 145 *b = pca_inw(adap, I2C_PCA_DAT); 146 DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK"); 147 } 148 149 /* 150 * Setup ACK or NACK for next received byte and wait for it to arrive. 151 * 152 * Returns after next byte has arrived. 153 */ 154 static int pca_rx_ack(struct i2c_algo_pca_data *adap, 155 int ack) 156 { 157 int sta = pca_get_con(adap); 158 159 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA); 160 161 if (ack) 162 sta |= I2C_PCA_CON_AA; 163 164 pca_set_con(adap, sta); 165 return pca_wait(adap); 166 } 167 168 static int pca_xfer(struct i2c_adapter *i2c_adap, 169 struct i2c_msg *msgs, 170 int num) 171 { 172 struct i2c_algo_pca_data *adap = i2c_adap->algo_data; 173 struct i2c_msg *msg = NULL; 174 int curmsg; 175 int numbytes = 0; 176 int state; 177 int ret; 178 int completed = 1; 179 unsigned long timeout = jiffies + i2c_adap->timeout; 180 181 while ((state = pca_status(adap)) != 0xf8) { 182 if (time_before(jiffies, timeout)) { 183 msleep(10); 184 } else { 185 dev_dbg(&i2c_adap->dev, "bus is not idle. status is " 186 "%#04x\n", state); 187 return -EBUSY; 188 } 189 } 190 191 DEB1("{{{ XFER %d messages\n", num); 192 193 if (i2c_debug >= 2) { 194 for (curmsg = 0; curmsg < num; curmsg++) { 195 int addr, i; 196 msg = &msgs[curmsg]; 197 198 addr = (0x7f & msg->addr) ; 199 200 if (msg->flags & I2C_M_RD) 201 printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n", 202 curmsg, msg->len, addr, (addr << 1) | 1); 203 else { 204 printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s", 205 curmsg, msg->len, addr, addr << 1, 206 msg->len == 0 ? "" : ", "); 207 for (i = 0; i < msg->len; i++) 208 printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", "); 209 printk("]\n"); 210 } 211 } 212 } 213 214 curmsg = 0; 215 ret = -EIO; 216 while (curmsg < num) { 217 state = pca_status(adap); 218 219 DEB3("STATE is 0x%02x\n", state); 220 msg = &msgs[curmsg]; 221 222 switch (state) { 223 case 0xf8: /* On reset or stop the bus is idle */ 224 completed = pca_start(adap); 225 break; 226 227 case 0x08: /* A START condition has been transmitted */ 228 case 0x10: /* A repeated start condition has been transmitted */ 229 completed = pca_address(adap, msg); 230 break; 231 232 case 0x18: /* SLA+W has been transmitted; ACK has been received */ 233 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */ 234 if (numbytes < msg->len) { 235 completed = pca_tx_byte(adap, 236 msg->buf[numbytes]); 237 numbytes++; 238 break; 239 } 240 curmsg++; numbytes = 0; 241 if (curmsg == num) 242 pca_stop(adap); 243 else 244 completed = pca_repeated_start(adap); 245 break; 246 247 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */ 248 DEB2("NOT ACK received after SLA+W\n"); 249 pca_stop(adap); 250 ret = -ENXIO; 251 goto out; 252 253 case 0x40: /* SLA+R has been transmitted; ACK has been received */ 254 completed = pca_rx_ack(adap, msg->len > 1); 255 break; 256 257 case 0x50: /* Data bytes has been received; ACK has been returned */ 258 if (numbytes < msg->len) { 259 pca_rx_byte(adap, &msg->buf[numbytes], 1); 260 numbytes++; 261 completed = pca_rx_ack(adap, 262 numbytes < msg->len - 1); 263 break; 264 } 265 curmsg++; numbytes = 0; 266 if (curmsg == num) 267 pca_stop(adap); 268 else 269 completed = pca_repeated_start(adap); 270 break; 271 272 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */ 273 DEB2("NOT ACK received after SLA+R\n"); 274 pca_stop(adap); 275 ret = -ENXIO; 276 goto out; 277 278 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */ 279 DEB2("NOT ACK received after data byte\n"); 280 pca_stop(adap); 281 goto out; 282 283 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */ 284 DEB2("Arbitration lost\n"); 285 /* 286 * The PCA9564 data sheet (2006-09-01) says "A 287 * START condition will be transmitted when the 288 * bus becomes free (STOP or SCL and SDA high)" 289 * when the STA bit is set (p. 11). 290 * 291 * In case this won't work, try pca_reset() 292 * instead. 293 */ 294 pca_start(adap); 295 goto out; 296 297 case 0x58: /* Data byte has been received; NOT ACK has been returned */ 298 if (numbytes == msg->len - 1) { 299 pca_rx_byte(adap, &msg->buf[numbytes], 0); 300 curmsg++; numbytes = 0; 301 if (curmsg == num) 302 pca_stop(adap); 303 else 304 completed = pca_repeated_start(adap); 305 } else { 306 DEB2("NOT ACK sent after data byte received. " 307 "Not final byte. numbytes %d. len %d\n", 308 numbytes, msg->len); 309 pca_stop(adap); 310 goto out; 311 } 312 break; 313 case 0x70: /* Bus error - SDA stuck low */ 314 DEB2("BUS ERROR - SDA Stuck low\n"); 315 pca_reset(adap); 316 goto out; 317 case 0x78: /* Bus error - SCL stuck low (PCA9665) */ 318 case 0x90: /* Bus error - SCL stuck low (PCA9564) */ 319 DEB2("BUS ERROR - SCL Stuck low\n"); 320 pca_reset(adap); 321 goto out; 322 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */ 323 DEB2("BUS ERROR - Illegal START or STOP\n"); 324 pca_reset(adap); 325 goto out; 326 default: 327 dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state); 328 break; 329 } 330 331 if (!completed) 332 goto out; 333 } 334 335 ret = curmsg; 336 out: 337 DEB1("}}} transferred %d/%d messages. " 338 "status is %#04x. control is %#04x\n", 339 curmsg, num, pca_status(adap), 340 pca_get_con(adap)); 341 return ret; 342 } 343 344 static u32 pca_func(struct i2c_adapter *adap) 345 { 346 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 347 } 348 349 static const struct i2c_algorithm pca_algo = { 350 .master_xfer = pca_xfer, 351 .functionality = pca_func, 352 }; 353 354 static unsigned int pca_probe_chip(struct i2c_adapter *adap) 355 { 356 struct i2c_algo_pca_data *pca_data = adap->algo_data; 357 /* The trick here is to check if there is an indirect register 358 * available. If there is one, we will read the value we first 359 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value 360 * we wrote on I2C_PCA_ADR 361 */ 362 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR); 363 pca_outw(pca_data, I2C_PCA_IND, 0xAA); 364 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO); 365 pca_outw(pca_data, I2C_PCA_IND, 0x00); 366 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR); 367 if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) { 368 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name); 369 pca_data->chip = I2C_PCA_CHIP_9665; 370 } else { 371 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name); 372 pca_data->chip = I2C_PCA_CHIP_9564; 373 } 374 return pca_data->chip; 375 } 376 377 static int pca_init(struct i2c_adapter *adap) 378 { 379 struct i2c_algo_pca_data *pca_data = adap->algo_data; 380 381 adap->algo = &pca_algo; 382 383 if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) { 384 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36}; 385 int clock; 386 387 if (pca_data->i2c_clock > 7) { 388 switch (pca_data->i2c_clock) { 389 case 330000: 390 pca_data->i2c_clock = I2C_PCA_CON_330kHz; 391 break; 392 case 288000: 393 pca_data->i2c_clock = I2C_PCA_CON_288kHz; 394 break; 395 case 217000: 396 pca_data->i2c_clock = I2C_PCA_CON_217kHz; 397 break; 398 case 146000: 399 pca_data->i2c_clock = I2C_PCA_CON_146kHz; 400 break; 401 case 88000: 402 pca_data->i2c_clock = I2C_PCA_CON_88kHz; 403 break; 404 case 59000: 405 pca_data->i2c_clock = I2C_PCA_CON_59kHz; 406 break; 407 case 44000: 408 pca_data->i2c_clock = I2C_PCA_CON_44kHz; 409 break; 410 case 36000: 411 pca_data->i2c_clock = I2C_PCA_CON_36kHz; 412 break; 413 default: 414 printk(KERN_WARNING 415 "%s: Invalid I2C clock speed selected." 416 " Using default 59kHz.\n", adap->name); 417 pca_data->i2c_clock = I2C_PCA_CON_59kHz; 418 } 419 } else { 420 printk(KERN_WARNING "%s: " 421 "Choosing the clock frequency based on " 422 "index is deprecated." 423 " Use the nominal frequency.\n", adap->name); 424 } 425 426 pca_reset(pca_data); 427 428 clock = pca_clock(pca_data); 429 printk(KERN_INFO "%s: Clock frequency is %dkHz\n", 430 adap->name, freqs[clock]); 431 432 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock); 433 } else { 434 int clock; 435 int mode; 436 int tlow, thi; 437 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */ 438 int min_tlow, min_thi; 439 /* These values are the maximum raise and fall values allowed 440 * by the I2C operation mode (Standard, Fast or Fast+) 441 * They are used (added) below to calculate the clock dividers 442 * of PCA9665. Note that they are slightly different of the 443 * real maximum, to allow the change on mode exactly on the 444 * maximum clock rate for each mode 445 */ 446 int raise_fall_time; 447 448 if (pca_data->i2c_clock > 1265800) { 449 printk(KERN_WARNING "%s: I2C clock speed too high." 450 " Using 1265.8kHz.\n", adap->name); 451 pca_data->i2c_clock = 1265800; 452 } 453 454 if (pca_data->i2c_clock < 60300) { 455 printk(KERN_WARNING "%s: I2C clock speed too low." 456 " Using 60.3kHz.\n", adap->name); 457 pca_data->i2c_clock = 60300; 458 } 459 460 /* To avoid integer overflow, use clock/100 for calculations */ 461 clock = pca_clock(pca_data) / 100; 462 463 if (pca_data->i2c_clock > I2C_MAX_FAST_MODE_PLUS_FREQ) { 464 mode = I2C_PCA_MODE_TURBO; 465 min_tlow = 14; 466 min_thi = 5; 467 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */ 468 } else if (pca_data->i2c_clock > I2C_MAX_FAST_MODE_FREQ) { 469 mode = I2C_PCA_MODE_FASTP; 470 min_tlow = 17; 471 min_thi = 9; 472 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */ 473 } else if (pca_data->i2c_clock > I2C_MAX_STANDARD_MODE_FREQ) { 474 mode = I2C_PCA_MODE_FAST; 475 min_tlow = 44; 476 min_thi = 20; 477 raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */ 478 } else { 479 mode = I2C_PCA_MODE_STD; 480 min_tlow = 157; 481 min_thi = 134; 482 raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */ 483 } 484 485 /* The minimum clock that respects the thi/tlow = 134/157 is 486 * 64800 Hz. Below that, we have to fix the tlow to 255 and 487 * calculate the thi factor. 488 */ 489 if (clock < 648) { 490 tlow = 255; 491 thi = 1000000 - clock * raise_fall_time; 492 thi /= (I2C_PCA_OSC_PER * clock) - tlow; 493 } else { 494 tlow = (1000000 - clock * raise_fall_time) * min_tlow; 495 tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow); 496 thi = tlow * min_thi / min_tlow; 497 } 498 499 pca_reset(pca_data); 500 501 printk(KERN_INFO 502 "%s: Clock frequency is %dHz\n", adap->name, clock * 100); 503 504 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE); 505 pca_outw(pca_data, I2C_PCA_IND, mode); 506 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL); 507 pca_outw(pca_data, I2C_PCA_IND, tlow); 508 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH); 509 pca_outw(pca_data, I2C_PCA_IND, thi); 510 511 pca_set_con(pca_data, I2C_PCA_CON_ENSIO); 512 } 513 udelay(500); /* 500 us for oscillator to stabilise */ 514 515 return 0; 516 } 517 518 /* 519 * registering functions to load algorithms at runtime 520 */ 521 int i2c_pca_add_bus(struct i2c_adapter *adap) 522 { 523 int rval; 524 525 rval = pca_init(adap); 526 if (rval) 527 return rval; 528 529 return i2c_add_adapter(adap); 530 } 531 EXPORT_SYMBOL(i2c_pca_add_bus); 532 533 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap) 534 { 535 int rval; 536 537 rval = pca_init(adap); 538 if (rval) 539 return rval; 540 541 return i2c_add_numbered_adapter(adap); 542 } 543 EXPORT_SYMBOL(i2c_pca_add_numbered_bus); 544 545 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>"); 546 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>"); 547 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm"); 548 MODULE_LICENSE("GPL"); 549 550 module_param(i2c_debug, int, 0); 551