1/** 2 * ds2482.c - provides i2c to w1-master bridge(s) 3 * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com> 4 * 5 * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim). 6 * It is a I2C to 1-wire bridge. 7 * There are two variations: -100 and -800, which have 1 or 8 1-wire ports. 8 * The complete datasheet can be obtained from MAXIM's website at: 9 * http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382 10 * 11 * This program is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License as published by 13 * the Free Software Foundation; version 2 of the License. 14 */ 15 16#include <linux/module.h> 17#include <linux/init.h> 18#include <linux/slab.h> 19#include <linux/i2c.h> 20#include <linux/delay.h> 21#include <linux/gpio.h> 22#include <linux/platform_data/ds2482.h> 23#include <asm/delay.h> 24 25#include "../w1.h" 26#include "../w1_int.h" 27 28/** 29 * The DS2482 registers - there are 3 registers that are addressed by a read 30 * pointer. The read pointer is set by the last command executed. 31 * 32 * To read the data, issue a register read for any address 33 */ 34#define DS2482_CMD_RESET 0xF0 /* No param */ 35#define DS2482_CMD_SET_READ_PTR 0xE1 /* Param: DS2482_PTR_CODE_xxx */ 36#define DS2482_CMD_CHANNEL_SELECT 0xC3 /* Param: Channel byte - DS2482-800 only */ 37#define DS2482_CMD_WRITE_CONFIG 0xD2 /* Param: Config byte */ 38#define DS2482_CMD_1WIRE_RESET 0xB4 /* Param: None */ 39#define DS2482_CMD_1WIRE_SINGLE_BIT 0x87 /* Param: Bit byte (bit7) */ 40#define DS2482_CMD_1WIRE_WRITE_BYTE 0xA5 /* Param: Data byte */ 41#define DS2482_CMD_1WIRE_READ_BYTE 0x96 /* Param: None */ 42/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */ 43#define DS2482_CMD_1WIRE_TRIPLET 0x78 /* Param: Dir byte (bit7) */ 44 45/* Values for DS2482_CMD_SET_READ_PTR */ 46#define DS2482_PTR_CODE_STATUS 0xF0 47#define DS2482_PTR_CODE_DATA 0xE1 48#define DS2482_PTR_CODE_CHANNEL 0xD2 /* DS2482-800 only */ 49#define DS2482_PTR_CODE_CONFIG 0xC3 50 51/** 52 * Configure Register bit definitions 53 * The top 4 bits always read 0. 54 * To write, the top nibble must be the 1's compl. of the low nibble. 55 */ 56#define DS2482_REG_CFG_1WS 0x08 /* 1-wire speed */ 57#define DS2482_REG_CFG_SPU 0x04 /* strong pull-up */ 58#define DS2482_REG_CFG_PPM 0x02 /* presence pulse masking */ 59#define DS2482_REG_CFG_APU 0x01 /* active pull-up */ 60 61 62/** 63 * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only). 64 * To set the channel, write the value at the index of the channel. 65 * Read and compare against the corresponding value to verify the change. 66 */ 67static const u8 ds2482_chan_wr[8] = 68 { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 }; 69static const u8 ds2482_chan_rd[8] = 70 { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 }; 71 72 73/** 74 * Status Register bit definitions (read only) 75 */ 76#define DS2482_REG_STS_DIR 0x80 77#define DS2482_REG_STS_TSB 0x40 78#define DS2482_REG_STS_SBR 0x20 79#define DS2482_REG_STS_RST 0x10 80#define DS2482_REG_STS_LL 0x08 81#define DS2482_REG_STS_SD 0x04 82#define DS2482_REG_STS_PPD 0x02 83#define DS2482_REG_STS_1WB 0x01 84 85 86static int ds2482_probe(struct i2c_client *client, 87 const struct i2c_device_id *id); 88static int ds2482_remove(struct i2c_client *client); 89static int ds2482_suspend(struct device *dev); 90static int ds2482_resume(struct device *dev); 91 92/** 93 * Driver data (common to all clients) 94 */ 95static const struct i2c_device_id ds2482_id[] = { 96 { "ds2482", 0 }, 97 { } 98}; 99 100static const struct dev_pm_ops ds2482_pm_ops = { 101 .suspend = ds2482_suspend, 102 .resume = ds2482_resume, 103}; 104 105static struct i2c_driver ds2482_driver = { 106 .driver = { 107 .owner = THIS_MODULE, 108 .name = "ds2482", 109 .pm = &ds2482_pm_ops, 110 }, 111 .probe = ds2482_probe, 112 .remove = ds2482_remove, 113 .id_table = ds2482_id, 114}; 115 116/* 117 * Client data (each client gets its own) 118 */ 119 120struct ds2482_data; 121 122struct ds2482_w1_chan { 123 struct ds2482_data *pdev; 124 u8 channel; 125 struct w1_bus_master w1_bm; 126}; 127 128struct ds2482_data { 129 struct i2c_client *client; 130 struct mutex access_lock; 131 int slpz_gpio; 132 133 /* 1-wire interface(s) */ 134 int w1_count; /* 1 or 8 */ 135 struct ds2482_w1_chan w1_ch[8]; 136 137 /* per-device values */ 138 u8 channel; 139 u8 read_prt; /* see DS2482_PTR_CODE_xxx */ 140 u8 reg_config; 141}; 142 143 144/** 145 * Helper to calculate values for configuration register 146 * @param conf the raw config value 147 * @return the value w/ complements that can be written to register 148 */ 149static inline u8 ds2482_calculate_config(u8 conf) 150{ 151 return conf | ((~conf & 0x0f) << 4); 152} 153 154 155/** 156 * Sets the read pointer. 157 * @param pdev The ds2482 client pointer 158 * @param read_ptr see DS2482_PTR_CODE_xxx above 159 * @return -1 on failure, 0 on success 160 */ 161static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr) 162{ 163 if (pdev->read_prt != read_ptr) { 164 if (i2c_smbus_write_byte_data(pdev->client, 165 DS2482_CMD_SET_READ_PTR, 166 read_ptr) < 0) 167 return -1; 168 169 pdev->read_prt = read_ptr; 170 } 171 return 0; 172} 173 174/** 175 * Sends a command without a parameter 176 * @param pdev The ds2482 client pointer 177 * @param cmd DS2482_CMD_RESET, 178 * DS2482_CMD_1WIRE_RESET, 179 * DS2482_CMD_1WIRE_READ_BYTE 180 * @return -1 on failure, 0 on success 181 */ 182static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd) 183{ 184 if (i2c_smbus_write_byte(pdev->client, cmd) < 0) 185 return -1; 186 187 pdev->read_prt = DS2482_PTR_CODE_STATUS; 188 return 0; 189} 190 191/** 192 * Sends a command with a parameter 193 * @param pdev The ds2482 client pointer 194 * @param cmd DS2482_CMD_WRITE_CONFIG, 195 * DS2482_CMD_1WIRE_SINGLE_BIT, 196 * DS2482_CMD_1WIRE_WRITE_BYTE, 197 * DS2482_CMD_1WIRE_TRIPLET 198 * @param byte The data to send 199 * @return -1 on failure, 0 on success 200 */ 201static inline int ds2482_send_cmd_data(struct ds2482_data *pdev, 202 u8 cmd, u8 byte) 203{ 204 if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0) 205 return -1; 206 207 /* all cmds leave in STATUS, except CONFIG */ 208 pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ? 209 DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG; 210 return 0; 211} 212 213 214/* 215 * 1-Wire interface code 216 */ 217 218#define DS2482_WAIT_IDLE_TIMEOUT 100 219 220/** 221 * Waits until the 1-wire interface is idle (not busy) 222 * 223 * @param pdev Pointer to the device structure 224 * @return the last value read from status or -1 (failure) 225 */ 226static int ds2482_wait_1wire_idle(struct ds2482_data *pdev) 227{ 228 int temp = -1; 229 int retries = 0; 230 231 if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) { 232 do { 233 temp = i2c_smbus_read_byte(pdev->client); 234 } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) && 235 (++retries < DS2482_WAIT_IDLE_TIMEOUT)); 236 } 237 238 if (retries >= DS2482_WAIT_IDLE_TIMEOUT) 239 pr_err("%s: timeout on channel %d\n", 240 __func__, pdev->channel); 241 242 return temp; 243} 244 245/** 246 * Selects a w1 channel. 247 * The 1-wire interface must be idle before calling this function. 248 * 249 * @param pdev The ds2482 client pointer 250 * @param channel 0-7 251 * @return -1 (failure) or 0 (success) 252 */ 253static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel) 254{ 255 if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT, 256 ds2482_chan_wr[channel]) < 0) 257 return -1; 258 259 pdev->read_prt = DS2482_PTR_CODE_CHANNEL; 260 pdev->channel = -1; 261 if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) { 262 pdev->channel = channel; 263 return 0; 264 } 265 return -1; 266} 267 268 269/** 270 * Performs the touch-bit function, which writes a 0 or 1 and reads the level. 271 * 272 * @param data The ds2482 channel pointer 273 * @param bit The level to write: 0 or non-zero 274 * @return The level read: 0 or 1 275 */ 276static u8 ds2482_w1_touch_bit(void *data, u8 bit) 277{ 278 struct ds2482_w1_chan *pchan = data; 279 struct ds2482_data *pdev = pchan->pdev; 280 int status = -1; 281 282 mutex_lock(&pdev->access_lock); 283 284 /* Select the channel */ 285 ds2482_wait_1wire_idle(pdev); 286 if (pdev->w1_count > 1) 287 ds2482_set_channel(pdev, pchan->channel); 288 289 /* Send the touch command, wait until 1WB == 0, return the status */ 290 if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT, 291 bit ? 0xFF : 0)) 292 status = ds2482_wait_1wire_idle(pdev); 293 294 mutex_unlock(&pdev->access_lock); 295 296 return (status & DS2482_REG_STS_SBR) ? 1 : 0; 297} 298 299/** 300 * Performs the triplet function, which reads two bits and writes a bit. 301 * The bit written is determined by the two reads: 302 * 00 => dbit, 01 => 0, 10 => 1 303 * 304 * @param data The ds2482 channel pointer 305 * @param dbit The direction to choose if both branches are valid 306 * @return b0=read1 b1=read2 b3=bit written 307 */ 308static u8 ds2482_w1_triplet(void *data, u8 dbit) 309{ 310 struct ds2482_w1_chan *pchan = data; 311 struct ds2482_data *pdev = pchan->pdev; 312 int status = (3 << 5); 313 314 mutex_lock(&pdev->access_lock); 315 316 /* Select the channel */ 317 ds2482_wait_1wire_idle(pdev); 318 if (pdev->w1_count > 1) 319 ds2482_set_channel(pdev, pchan->channel); 320 321 /* Send the triplet command, wait until 1WB == 0, return the status */ 322 if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET, 323 dbit ? 0xFF : 0)) 324 status = ds2482_wait_1wire_idle(pdev); 325 326 mutex_unlock(&pdev->access_lock); 327 328 /* Decode the status */ 329 return (status >> 5); 330} 331 332/** 333 * Performs the write byte function. 334 * 335 * @param data The ds2482 channel pointer 336 * @param byte The value to write 337 */ 338static void ds2482_w1_write_byte(void *data, u8 byte) 339{ 340 struct ds2482_w1_chan *pchan = data; 341 struct ds2482_data *pdev = pchan->pdev; 342 343 mutex_lock(&pdev->access_lock); 344 345 /* Select the channel */ 346 ds2482_wait_1wire_idle(pdev); 347 if (pdev->w1_count > 1) 348 ds2482_set_channel(pdev, pchan->channel); 349 350 /* Send the write byte command */ 351 ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte); 352 353 mutex_unlock(&pdev->access_lock); 354} 355 356/** 357 * Performs the read byte function. 358 * 359 * @param data The ds2482 channel pointer 360 * @return The value read 361 */ 362static u8 ds2482_w1_read_byte(void *data) 363{ 364 struct ds2482_w1_chan *pchan = data; 365 struct ds2482_data *pdev = pchan->pdev; 366 int result; 367 368 mutex_lock(&pdev->access_lock); 369 370 /* Select the channel */ 371 ds2482_wait_1wire_idle(pdev); 372 if (pdev->w1_count > 1) 373 ds2482_set_channel(pdev, pchan->channel); 374 375 /* Send the read byte command */ 376 ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE); 377 378 /* Wait until 1WB == 0 */ 379 ds2482_wait_1wire_idle(pdev); 380 381 /* Select the data register */ 382 ds2482_select_register(pdev, DS2482_PTR_CODE_DATA); 383 384 /* Read the data byte */ 385 result = i2c_smbus_read_byte(pdev->client); 386 387 mutex_unlock(&pdev->access_lock); 388 389 return result; 390} 391 392 393/** 394 * Sends a reset on the 1-wire interface 395 * 396 * @param data The ds2482 channel pointer 397 * @return 0=Device present, 1=No device present or error 398 */ 399static u8 ds2482_w1_reset_bus(void *data) 400{ 401 struct ds2482_w1_chan *pchan = data; 402 struct ds2482_data *pdev = pchan->pdev; 403 int err; 404 u8 retval = 1; 405 406 mutex_lock(&pdev->access_lock); 407 408 /* Select the channel */ 409 ds2482_wait_1wire_idle(pdev); 410 if (pdev->w1_count > 1) 411 ds2482_set_channel(pdev, pchan->channel); 412 413 /* Send the reset command */ 414 err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET); 415 if (err >= 0) { 416 /* Wait until the reset is complete */ 417 err = ds2482_wait_1wire_idle(pdev); 418 retval = !(err & DS2482_REG_STS_PPD); 419 420 /* If the chip did reset since detect, re-config it */ 421 if (err & DS2482_REG_STS_RST) 422 ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG, 423 ds2482_calculate_config(0x00)); 424 } 425 426 mutex_unlock(&pdev->access_lock); 427 428 return retval; 429} 430 431static u8 ds2482_w1_set_pullup(void *data, int delay) 432{ 433 struct ds2482_w1_chan *pchan = data; 434 struct ds2482_data *pdev = pchan->pdev; 435 u8 retval = 1; 436 437 /* if delay is non-zero activate the pullup, 438 * the strong pullup will be automatically deactivated 439 * by the master, so do not explicitly deactive it 440 */ 441 if (delay) { 442 /* both waits are crucial, otherwise devices might not be 443 * powered long enough, causing e.g. a w1_therm sensor to 444 * provide wrong conversion results 445 */ 446 ds2482_wait_1wire_idle(pdev); 447 /* note: it seems like both SPU and APU have to be set! */ 448 retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG, 449 ds2482_calculate_config(DS2482_REG_CFG_SPU | 450 DS2482_REG_CFG_APU)); 451 ds2482_wait_1wire_idle(pdev); 452 } 453 454 return retval; 455} 456 457static int ds2482_suspend(struct device *dev) 458{ 459 struct i2c_client *client = to_i2c_client(dev); 460 struct ds2482_data *data = i2c_get_clientdata(client); 461 462 if (data->slpz_gpio >= 0) 463 gpio_set_value(data->slpz_gpio, 0); 464 return 0; 465} 466 467static int ds2482_resume(struct device *dev) 468{ 469 struct i2c_client *client = to_i2c_client(dev); 470 struct ds2482_data *data = i2c_get_clientdata(client); 471 472 if (data->slpz_gpio >= 0) 473 gpio_set_value(data->slpz_gpio, 1); 474 return 0; 475} 476 477static int ds2482_probe(struct i2c_client *client, 478 const struct i2c_device_id *id) 479{ 480 struct ds2482_data *data; 481 struct ds2482_platform_data *pdata; 482 int err = -ENODEV; 483 int temp1; 484 int idx; 485 486 if (!i2c_check_functionality(client->adapter, 487 I2C_FUNC_SMBUS_WRITE_BYTE_DATA | 488 I2C_FUNC_SMBUS_BYTE)) 489 return -ENODEV; 490 491 if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) { 492 err = -ENOMEM; 493 goto exit; 494 } 495 496 data->client = client; 497 i2c_set_clientdata(client, data); 498 499 /* Reset the device (sets the read_ptr to status) */ 500 if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) { 501 dev_warn(&client->dev, "DS2482 reset failed.\n"); 502 goto exit_free; 503 } 504 505 /* Sleep at least 525ns to allow the reset to complete */ 506 ndelay(525); 507 508 /* Read the status byte - only reset bit and line should be set */ 509 temp1 = i2c_smbus_read_byte(client); 510 if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) { 511 dev_warn(&client->dev, "DS2482 reset status " 512 "0x%02X - not a DS2482\n", temp1); 513 goto exit_free; 514 } 515 516 /* Detect the 8-port version */ 517 data->w1_count = 1; 518 if (ds2482_set_channel(data, 7) == 0) 519 data->w1_count = 8; 520 521 /* Set all config items to 0 (off) */ 522 ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 523 ds2482_calculate_config(0x00)); 524 525 mutex_init(&data->access_lock); 526 527 /* Register 1-wire interface(s) */ 528 for (idx = 0; idx < data->w1_count; idx++) { 529 data->w1_ch[idx].pdev = data; 530 data->w1_ch[idx].channel = idx; 531 532 /* Populate all the w1 bus master stuff */ 533 data->w1_ch[idx].w1_bm.data = &data->w1_ch[idx]; 534 data->w1_ch[idx].w1_bm.read_byte = ds2482_w1_read_byte; 535 data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte; 536 data->w1_ch[idx].w1_bm.touch_bit = ds2482_w1_touch_bit; 537 data->w1_ch[idx].w1_bm.triplet = ds2482_w1_triplet; 538 data->w1_ch[idx].w1_bm.reset_bus = ds2482_w1_reset_bus; 539 data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup; 540 541 err = w1_add_master_device(&data->w1_ch[idx].w1_bm); 542 if (err) { 543 data->w1_ch[idx].pdev = NULL; 544 goto exit_w1_remove; 545 } 546 } 547 548 pdata = client->dev.platform_data; 549 data->slpz_gpio = pdata ? pdata->slpz_gpio : -1; 550 551 if (data->slpz_gpio >= 0) { 552 err = gpio_request_one(data->slpz_gpio, GPIOF_OUT_INIT_HIGH, 553 "ds2482.slpz"); 554 if (err < 0) 555 goto exit_w1_remove; 556 } 557 558 return 0; 559 560exit_w1_remove: 561 for (idx = 0; idx < data->w1_count; idx++) { 562 if (data->w1_ch[idx].pdev != NULL) 563 w1_remove_master_device(&data->w1_ch[idx].w1_bm); 564 } 565exit_free: 566 kfree(data); 567exit: 568 return err; 569} 570 571static int ds2482_remove(struct i2c_client *client) 572{ 573 struct ds2482_data *data = i2c_get_clientdata(client); 574 int idx; 575 576 /* Unregister the 1-wire bridge(s) */ 577 for (idx = 0; idx < data->w1_count; idx++) { 578 if (data->w1_ch[idx].pdev != NULL) 579 w1_remove_master_device(&data->w1_ch[idx].w1_bm); 580 } 581 582 if (data->slpz_gpio >= 0) { 583 gpio_set_value(data->slpz_gpio, 0); 584 gpio_free(data->slpz_gpio); 585 } 586 587 /* Free the memory */ 588 kfree(data); 589 return 0; 590} 591 592module_i2c_driver(ds2482_driver); 593 594MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); 595MODULE_DESCRIPTION("DS2482 driver"); 596MODULE_LICENSE("GPL"); 597