1 /* 2 * sht15.c - support for the SHT15 Temperature and Humidity Sensor 3 * 4 * Portions Copyright (c) 2010-2011 Savoir-faire Linux Inc. 5 * Jerome Oufella <jerome.oufella@savoirfairelinux.com> 6 * Vivien Didelot <vivien.didelot@savoirfairelinux.com> 7 * 8 * Copyright (c) 2009 Jonathan Cameron 9 * 10 * Copyright (c) 2007 Wouter Horre 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License version 2 as 14 * published by the Free Software Foundation. 15 * 16 * For further information, see the Documentation/hwmon/sht15 file. 17 */ 18 19 #include <linux/interrupt.h> 20 #include <linux/irq.h> 21 #include <linux/gpio.h> 22 #include <linux/module.h> 23 #include <linux/init.h> 24 #include <linux/hwmon.h> 25 #include <linux/hwmon-sysfs.h> 26 #include <linux/mutex.h> 27 #include <linux/platform_device.h> 28 #include <linux/sched.h> 29 #include <linux/delay.h> 30 #include <linux/jiffies.h> 31 #include <linux/err.h> 32 #include <linux/sht15.h> 33 #include <linux/regulator/consumer.h> 34 #include <linux/slab.h> 35 #include <linux/atomic.h> 36 37 /* Commands */ 38 #define SHT15_MEASURE_TEMP 0x03 39 #define SHT15_MEASURE_RH 0x05 40 #define SHT15_WRITE_STATUS 0x06 41 #define SHT15_READ_STATUS 0x07 42 #define SHT15_SOFT_RESET 0x1E 43 44 /* Min timings */ 45 #define SHT15_TSCKL 100 /* (nsecs) clock low */ 46 #define SHT15_TSCKH 100 /* (nsecs) clock high */ 47 #define SHT15_TSU 150 /* (nsecs) data setup time */ 48 #define SHT15_TSRST 11 /* (msecs) soft reset time */ 49 50 /* Status Register Bits */ 51 #define SHT15_STATUS_LOW_RESOLUTION 0x01 52 #define SHT15_STATUS_NO_OTP_RELOAD 0x02 53 #define SHT15_STATUS_HEATER 0x04 54 #define SHT15_STATUS_LOW_BATTERY 0x40 55 56 /* Actions the driver may be doing */ 57 enum sht15_state { 58 SHT15_READING_NOTHING, 59 SHT15_READING_TEMP, 60 SHT15_READING_HUMID 61 }; 62 63 /** 64 * struct sht15_temppair - elements of voltage dependent temp calc 65 * @vdd: supply voltage in microvolts 66 * @d1: see data sheet 67 */ 68 struct sht15_temppair { 69 int vdd; /* microvolts */ 70 int d1; 71 }; 72 73 /* Table 9 from datasheet - relates temperature calculation to supply voltage */ 74 static const struct sht15_temppair temppoints[] = { 75 { 2500000, -39400 }, 76 { 3000000, -39600 }, 77 { 3500000, -39700 }, 78 { 4000000, -39800 }, 79 { 5000000, -40100 }, 80 }; 81 82 /* Table from CRC datasheet, section 2.4 */ 83 static const u8 sht15_crc8_table[] = { 84 0, 49, 98, 83, 196, 245, 166, 151, 85 185, 136, 219, 234, 125, 76, 31, 46, 86 67, 114, 33, 16, 135, 182, 229, 212, 87 250, 203, 152, 169, 62, 15, 92, 109, 88 134, 183, 228, 213, 66, 115, 32, 17, 89 63, 14, 93, 108, 251, 202, 153, 168, 90 197, 244, 167, 150, 1, 48, 99, 82, 91 124, 77, 30, 47, 184, 137, 218, 235, 92 61, 12, 95, 110, 249, 200, 155, 170, 93 132, 181, 230, 215, 64, 113, 34, 19, 94 126, 79, 28, 45, 186, 139, 216, 233, 95 199, 246, 165, 148, 3, 50, 97, 80, 96 187, 138, 217, 232, 127, 78, 29, 44, 97 2, 51, 96, 81, 198, 247, 164, 149, 98 248, 201, 154, 171, 60, 13, 94, 111, 99 65, 112, 35, 18, 133, 180, 231, 214, 100 122, 75, 24, 41, 190, 143, 220, 237, 101 195, 242, 161, 144, 7, 54, 101, 84, 102 57, 8, 91, 106, 253, 204, 159, 174, 103 128, 177, 226, 211, 68, 117, 38, 23, 104 252, 205, 158, 175, 56, 9, 90, 107, 105 69, 116, 39, 22, 129, 176, 227, 210, 106 191, 142, 221, 236, 123, 74, 25, 40, 107 6, 55, 100, 85, 194, 243, 160, 145, 108 71, 118, 37, 20, 131, 178, 225, 208, 109 254, 207, 156, 173, 58, 11, 88, 105, 110 4, 53, 102, 87, 192, 241, 162, 147, 111 189, 140, 223, 238, 121, 72, 27, 42, 112 193, 240, 163, 146, 5, 52, 103, 86, 113 120, 73, 26, 43, 188, 141, 222, 239, 114 130, 179, 224, 209, 70, 119, 36, 21, 115 59, 10, 89, 104, 255, 206, 157, 172 116 }; 117 118 /** 119 * struct sht15_data - device instance specific data 120 * @pdata: platform data (gpio's etc). 121 * @read_work: bh of interrupt handler. 122 * @wait_queue: wait queue for getting values from device. 123 * @val_temp: last temperature value read from device. 124 * @val_humid: last humidity value read from device. 125 * @val_status: last status register value read from device. 126 * @checksum_ok: last value read from the device passed CRC validation. 127 * @checksumming: flag used to enable the data validation with CRC. 128 * @state: state identifying the action the driver is doing. 129 * @measurements_valid: are the current stored measures valid (start condition). 130 * @status_valid: is the current stored status valid (start condition). 131 * @last_measurement: time of last measure. 132 * @last_status: time of last status reading. 133 * @read_lock: mutex to ensure only one read in progress at a time. 134 * @dev: associate device structure. 135 * @hwmon_dev: device associated with hwmon subsystem. 136 * @reg: associated regulator (if specified). 137 * @nb: notifier block to handle notifications of voltage 138 * changes. 139 * @supply_uV: local copy of supply voltage used to allow use of 140 * regulator consumer if available. 141 * @supply_uV_valid: indicates that an updated value has not yet been 142 * obtained from the regulator and so any calculations 143 * based upon it will be invalid. 144 * @update_supply_work: work struct that is used to update the supply_uV. 145 * @interrupt_handled: flag used to indicate a handler has been scheduled. 146 */ 147 struct sht15_data { 148 struct sht15_platform_data *pdata; 149 struct work_struct read_work; 150 wait_queue_head_t wait_queue; 151 uint16_t val_temp; 152 uint16_t val_humid; 153 u8 val_status; 154 bool checksum_ok; 155 bool checksumming; 156 enum sht15_state state; 157 bool measurements_valid; 158 bool status_valid; 159 unsigned long last_measurement; 160 unsigned long last_status; 161 struct mutex read_lock; 162 struct device *dev; 163 struct device *hwmon_dev; 164 struct regulator *reg; 165 struct notifier_block nb; 166 int supply_uV; 167 bool supply_uV_valid; 168 struct work_struct update_supply_work; 169 atomic_t interrupt_handled; 170 }; 171 172 /** 173 * sht15_reverse() - reverse a byte 174 * @byte: byte to reverse. 175 */ 176 static u8 sht15_reverse(u8 byte) 177 { 178 u8 i, c; 179 180 for (c = 0, i = 0; i < 8; i++) 181 c |= (!!(byte & (1 << i))) << (7 - i); 182 return c; 183 } 184 185 /** 186 * sht15_crc8() - compute crc8 187 * @data: sht15 specific data. 188 * @value: sht15 retrieved data. 189 * 190 * This implements section 2 of the CRC datasheet. 191 */ 192 static u8 sht15_crc8(struct sht15_data *data, 193 const u8 *value, 194 int len) 195 { 196 u8 crc = sht15_reverse(data->val_status & 0x0F); 197 198 while (len--) { 199 crc = sht15_crc8_table[*value ^ crc]; 200 value++; 201 } 202 203 return crc; 204 } 205 206 /** 207 * sht15_connection_reset() - reset the comms interface 208 * @data: sht15 specific data 209 * 210 * This implements section 3.4 of the data sheet 211 */ 212 static void sht15_connection_reset(struct sht15_data *data) 213 { 214 int i; 215 216 gpio_direction_output(data->pdata->gpio_data, 1); 217 ndelay(SHT15_TSCKL); 218 gpio_set_value(data->pdata->gpio_sck, 0); 219 ndelay(SHT15_TSCKL); 220 for (i = 0; i < 9; ++i) { 221 gpio_set_value(data->pdata->gpio_sck, 1); 222 ndelay(SHT15_TSCKH); 223 gpio_set_value(data->pdata->gpio_sck, 0); 224 ndelay(SHT15_TSCKL); 225 } 226 } 227 228 /** 229 * sht15_send_bit() - send an individual bit to the device 230 * @data: device state data 231 * @val: value of bit to be sent 232 */ 233 static inline void sht15_send_bit(struct sht15_data *data, int val) 234 { 235 gpio_set_value(data->pdata->gpio_data, val); 236 ndelay(SHT15_TSU); 237 gpio_set_value(data->pdata->gpio_sck, 1); 238 ndelay(SHT15_TSCKH); 239 gpio_set_value(data->pdata->gpio_sck, 0); 240 ndelay(SHT15_TSCKL); /* clock low time */ 241 } 242 243 /** 244 * sht15_transmission_start() - specific sequence for new transmission 245 * @data: device state data 246 * 247 * Timings for this are not documented on the data sheet, so very 248 * conservative ones used in implementation. This implements 249 * figure 12 on the data sheet. 250 */ 251 static void sht15_transmission_start(struct sht15_data *data) 252 { 253 /* ensure data is high and output */ 254 gpio_direction_output(data->pdata->gpio_data, 1); 255 ndelay(SHT15_TSU); 256 gpio_set_value(data->pdata->gpio_sck, 0); 257 ndelay(SHT15_TSCKL); 258 gpio_set_value(data->pdata->gpio_sck, 1); 259 ndelay(SHT15_TSCKH); 260 gpio_set_value(data->pdata->gpio_data, 0); 261 ndelay(SHT15_TSU); 262 gpio_set_value(data->pdata->gpio_sck, 0); 263 ndelay(SHT15_TSCKL); 264 gpio_set_value(data->pdata->gpio_sck, 1); 265 ndelay(SHT15_TSCKH); 266 gpio_set_value(data->pdata->gpio_data, 1); 267 ndelay(SHT15_TSU); 268 gpio_set_value(data->pdata->gpio_sck, 0); 269 ndelay(SHT15_TSCKL); 270 } 271 272 /** 273 * sht15_send_byte() - send a single byte to the device 274 * @data: device state 275 * @byte: value to be sent 276 */ 277 static void sht15_send_byte(struct sht15_data *data, u8 byte) 278 { 279 int i; 280 281 for (i = 0; i < 8; i++) { 282 sht15_send_bit(data, !!(byte & 0x80)); 283 byte <<= 1; 284 } 285 } 286 287 /** 288 * sht15_wait_for_response() - checks for ack from device 289 * @data: device state 290 */ 291 static int sht15_wait_for_response(struct sht15_data *data) 292 { 293 gpio_direction_input(data->pdata->gpio_data); 294 gpio_set_value(data->pdata->gpio_sck, 1); 295 ndelay(SHT15_TSCKH); 296 if (gpio_get_value(data->pdata->gpio_data)) { 297 gpio_set_value(data->pdata->gpio_sck, 0); 298 dev_err(data->dev, "Command not acknowledged\n"); 299 sht15_connection_reset(data); 300 return -EIO; 301 } 302 gpio_set_value(data->pdata->gpio_sck, 0); 303 ndelay(SHT15_TSCKL); 304 return 0; 305 } 306 307 /** 308 * sht15_send_cmd() - Sends a command to the device. 309 * @data: device state 310 * @cmd: command byte to be sent 311 * 312 * On entry, sck is output low, data is output pull high 313 * and the interrupt disabled. 314 */ 315 static int sht15_send_cmd(struct sht15_data *data, u8 cmd) 316 { 317 int ret = 0; 318 319 sht15_transmission_start(data); 320 sht15_send_byte(data, cmd); 321 ret = sht15_wait_for_response(data); 322 return ret; 323 } 324 325 /** 326 * sht15_soft_reset() - send a soft reset command 327 * @data: sht15 specific data. 328 * 329 * As described in section 3.2 of the datasheet. 330 */ 331 static int sht15_soft_reset(struct sht15_data *data) 332 { 333 int ret; 334 335 ret = sht15_send_cmd(data, SHT15_SOFT_RESET); 336 if (ret) 337 return ret; 338 msleep(SHT15_TSRST); 339 /* device resets default hardware status register value */ 340 data->val_status = 0; 341 342 return ret; 343 } 344 345 /** 346 * sht15_ack() - send a ack 347 * @data: sht15 specific data. 348 * 349 * Each byte of data is acknowledged by pulling the data line 350 * low for one clock pulse. 351 */ 352 static void sht15_ack(struct sht15_data *data) 353 { 354 gpio_direction_output(data->pdata->gpio_data, 0); 355 ndelay(SHT15_TSU); 356 gpio_set_value(data->pdata->gpio_sck, 1); 357 ndelay(SHT15_TSU); 358 gpio_set_value(data->pdata->gpio_sck, 0); 359 ndelay(SHT15_TSU); 360 gpio_set_value(data->pdata->gpio_data, 1); 361 362 gpio_direction_input(data->pdata->gpio_data); 363 } 364 365 /** 366 * sht15_end_transmission() - notify device of end of transmission 367 * @data: device state. 368 * 369 * This is basically a NAK (single clock pulse, data high). 370 */ 371 static void sht15_end_transmission(struct sht15_data *data) 372 { 373 gpio_direction_output(data->pdata->gpio_data, 1); 374 ndelay(SHT15_TSU); 375 gpio_set_value(data->pdata->gpio_sck, 1); 376 ndelay(SHT15_TSCKH); 377 gpio_set_value(data->pdata->gpio_sck, 0); 378 ndelay(SHT15_TSCKL); 379 } 380 381 /** 382 * sht15_read_byte() - Read a byte back from the device 383 * @data: device state. 384 */ 385 static u8 sht15_read_byte(struct sht15_data *data) 386 { 387 int i; 388 u8 byte = 0; 389 390 for (i = 0; i < 8; ++i) { 391 byte <<= 1; 392 gpio_set_value(data->pdata->gpio_sck, 1); 393 ndelay(SHT15_TSCKH); 394 byte |= !!gpio_get_value(data->pdata->gpio_data); 395 gpio_set_value(data->pdata->gpio_sck, 0); 396 ndelay(SHT15_TSCKL); 397 } 398 return byte; 399 } 400 401 /** 402 * sht15_send_status() - write the status register byte 403 * @data: sht15 specific data. 404 * @status: the byte to set the status register with. 405 * 406 * As described in figure 14 and table 5 of the datasheet. 407 */ 408 static int sht15_send_status(struct sht15_data *data, u8 status) 409 { 410 int ret; 411 412 ret = sht15_send_cmd(data, SHT15_WRITE_STATUS); 413 if (ret) 414 return ret; 415 gpio_direction_output(data->pdata->gpio_data, 1); 416 ndelay(SHT15_TSU); 417 sht15_send_byte(data, status); 418 ret = sht15_wait_for_response(data); 419 if (ret) 420 return ret; 421 422 data->val_status = status; 423 return 0; 424 } 425 426 /** 427 * sht15_update_status() - get updated status register from device if too old 428 * @data: device instance specific data. 429 * 430 * As described in figure 15 and table 5 of the datasheet. 431 */ 432 static int sht15_update_status(struct sht15_data *data) 433 { 434 int ret = 0; 435 u8 status; 436 u8 previous_config; 437 u8 dev_checksum = 0; 438 u8 checksum_vals[2]; 439 int timeout = HZ; 440 441 mutex_lock(&data->read_lock); 442 if (time_after(jiffies, data->last_status + timeout) 443 || !data->status_valid) { 444 ret = sht15_send_cmd(data, SHT15_READ_STATUS); 445 if (ret) 446 goto error_ret; 447 status = sht15_read_byte(data); 448 449 if (data->checksumming) { 450 sht15_ack(data); 451 dev_checksum = sht15_reverse(sht15_read_byte(data)); 452 checksum_vals[0] = SHT15_READ_STATUS; 453 checksum_vals[1] = status; 454 data->checksum_ok = (sht15_crc8(data, checksum_vals, 2) 455 == dev_checksum); 456 } 457 458 sht15_end_transmission(data); 459 460 /* 461 * Perform checksum validation on the received data. 462 * Specification mentions that in case a checksum verification 463 * fails, a soft reset command must be sent to the device. 464 */ 465 if (data->checksumming && !data->checksum_ok) { 466 previous_config = data->val_status & 0x07; 467 ret = sht15_soft_reset(data); 468 if (ret) 469 goto error_ret; 470 if (previous_config) { 471 ret = sht15_send_status(data, previous_config); 472 if (ret) { 473 dev_err(data->dev, 474 "CRC validation failed, unable " 475 "to restore device settings\n"); 476 goto error_ret; 477 } 478 } 479 ret = -EAGAIN; 480 goto error_ret; 481 } 482 483 data->val_status = status; 484 data->status_valid = true; 485 data->last_status = jiffies; 486 } 487 error_ret: 488 mutex_unlock(&data->read_lock); 489 490 return ret; 491 } 492 493 /** 494 * sht15_measurement() - get a new value from device 495 * @data: device instance specific data 496 * @command: command sent to request value 497 * @timeout_msecs: timeout after which comms are assumed 498 * to have failed are reset. 499 */ 500 static int sht15_measurement(struct sht15_data *data, 501 int command, 502 int timeout_msecs) 503 { 504 int ret; 505 u8 previous_config; 506 507 ret = sht15_send_cmd(data, command); 508 if (ret) 509 return ret; 510 511 gpio_direction_input(data->pdata->gpio_data); 512 atomic_set(&data->interrupt_handled, 0); 513 514 enable_irq(gpio_to_irq(data->pdata->gpio_data)); 515 if (gpio_get_value(data->pdata->gpio_data) == 0) { 516 disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data)); 517 /* Only relevant if the interrupt hasn't occurred. */ 518 if (!atomic_read(&data->interrupt_handled)) 519 schedule_work(&data->read_work); 520 } 521 ret = wait_event_timeout(data->wait_queue, 522 (data->state == SHT15_READING_NOTHING), 523 msecs_to_jiffies(timeout_msecs)); 524 if (ret == 0) {/* timeout occurred */ 525 disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data)); 526 sht15_connection_reset(data); 527 return -ETIME; 528 } 529 530 /* 531 * Perform checksum validation on the received data. 532 * Specification mentions that in case a checksum verification fails, 533 * a soft reset command must be sent to the device. 534 */ 535 if (data->checksumming && !data->checksum_ok) { 536 previous_config = data->val_status & 0x07; 537 ret = sht15_soft_reset(data); 538 if (ret) 539 return ret; 540 if (previous_config) { 541 ret = sht15_send_status(data, previous_config); 542 if (ret) { 543 dev_err(data->dev, 544 "CRC validation failed, unable " 545 "to restore device settings\n"); 546 return ret; 547 } 548 } 549 return -EAGAIN; 550 } 551 552 return 0; 553 } 554 555 /** 556 * sht15_update_measurements() - get updated measures from device if too old 557 * @data: device state 558 */ 559 static int sht15_update_measurements(struct sht15_data *data) 560 { 561 int ret = 0; 562 int timeout = HZ; 563 564 mutex_lock(&data->read_lock); 565 if (time_after(jiffies, data->last_measurement + timeout) 566 || !data->measurements_valid) { 567 data->state = SHT15_READING_HUMID; 568 ret = sht15_measurement(data, SHT15_MEASURE_RH, 160); 569 if (ret) 570 goto error_ret; 571 data->state = SHT15_READING_TEMP; 572 ret = sht15_measurement(data, SHT15_MEASURE_TEMP, 400); 573 if (ret) 574 goto error_ret; 575 data->measurements_valid = true; 576 data->last_measurement = jiffies; 577 } 578 error_ret: 579 mutex_unlock(&data->read_lock); 580 581 return ret; 582 } 583 584 /** 585 * sht15_calc_temp() - convert the raw reading to a temperature 586 * @data: device state 587 * 588 * As per section 4.3 of the data sheet. 589 */ 590 static inline int sht15_calc_temp(struct sht15_data *data) 591 { 592 int d1 = temppoints[0].d1; 593 int d2 = (data->val_status & SHT15_STATUS_LOW_RESOLUTION) ? 40 : 10; 594 int i; 595 596 for (i = ARRAY_SIZE(temppoints) - 1; i > 0; i--) 597 /* Find pointer to interpolate */ 598 if (data->supply_uV > temppoints[i - 1].vdd) { 599 d1 = (data->supply_uV - temppoints[i - 1].vdd) 600 * (temppoints[i].d1 - temppoints[i - 1].d1) 601 / (temppoints[i].vdd - temppoints[i - 1].vdd) 602 + temppoints[i - 1].d1; 603 break; 604 } 605 606 return data->val_temp * d2 + d1; 607 } 608 609 /** 610 * sht15_calc_humid() - using last temperature convert raw to humid 611 * @data: device state 612 * 613 * This is the temperature compensated version as per section 4.2 of 614 * the data sheet. 615 * 616 * The sensor is assumed to be V3, which is compatible with V4. 617 * Humidity conversion coefficients are shown in table 7 of the datasheet. 618 */ 619 static inline int sht15_calc_humid(struct sht15_data *data) 620 { 621 int rh_linear; /* milli percent */ 622 int temp = sht15_calc_temp(data); 623 int c2, c3; 624 int t2; 625 const int c1 = -4; 626 627 if (data->val_status & SHT15_STATUS_LOW_RESOLUTION) { 628 c2 = 648000; /* x 10 ^ -6 */ 629 c3 = -7200; /* x 10 ^ -7 */ 630 t2 = 1280; 631 } else { 632 c2 = 40500; /* x 10 ^ -6 */ 633 c3 = -28; /* x 10 ^ -7 */ 634 t2 = 80; 635 } 636 637 rh_linear = c1 * 1000 638 + c2 * data->val_humid / 1000 639 + (data->val_humid * data->val_humid * c3) / 10000; 640 return (temp - 25000) * (10000 + t2 * data->val_humid) 641 / 1000000 + rh_linear; 642 } 643 644 /** 645 * sht15_show_status() - show status information in sysfs 646 * @dev: device. 647 * @attr: device attribute. 648 * @buf: sysfs buffer where information is written to. 649 * 650 * Will be called on read access to temp1_fault, humidity1_fault 651 * and heater_enable sysfs attributes. 652 * Returns number of bytes written into buffer, negative errno on error. 653 */ 654 static ssize_t sht15_show_status(struct device *dev, 655 struct device_attribute *attr, 656 char *buf) 657 { 658 int ret; 659 struct sht15_data *data = dev_get_drvdata(dev); 660 u8 bit = to_sensor_dev_attr(attr)->index; 661 662 ret = sht15_update_status(data); 663 664 return ret ? ret : sprintf(buf, "%d\n", !!(data->val_status & bit)); 665 } 666 667 /** 668 * sht15_store_heater() - change heater state via sysfs 669 * @dev: device. 670 * @attr: device attribute. 671 * @buf: sysfs buffer to read the new heater state from. 672 * @count: length of the data. 673 * 674 * Will be called on write access to heater_enable sysfs attribute. 675 * Returns number of bytes actually decoded, negative errno on error. 676 */ 677 static ssize_t sht15_store_heater(struct device *dev, 678 struct device_attribute *attr, 679 const char *buf, size_t count) 680 { 681 int ret; 682 struct sht15_data *data = dev_get_drvdata(dev); 683 long value; 684 u8 status; 685 686 if (strict_strtol(buf, 10, &value)) 687 return -EINVAL; 688 689 mutex_lock(&data->read_lock); 690 status = data->val_status & 0x07; 691 if (!!value) 692 status |= SHT15_STATUS_HEATER; 693 else 694 status &= ~SHT15_STATUS_HEATER; 695 696 ret = sht15_send_status(data, status); 697 mutex_unlock(&data->read_lock); 698 699 return ret ? ret : count; 700 } 701 702 /** 703 * sht15_show_temp() - show temperature measurement value in sysfs 704 * @dev: device. 705 * @attr: device attribute. 706 * @buf: sysfs buffer where measurement values are written to. 707 * 708 * Will be called on read access to temp1_input sysfs attribute. 709 * Returns number of bytes written into buffer, negative errno on error. 710 */ 711 static ssize_t sht15_show_temp(struct device *dev, 712 struct device_attribute *attr, 713 char *buf) 714 { 715 int ret; 716 struct sht15_data *data = dev_get_drvdata(dev); 717 718 /* Technically no need to read humidity as well */ 719 ret = sht15_update_measurements(data); 720 721 return ret ? ret : sprintf(buf, "%d\n", 722 sht15_calc_temp(data)); 723 } 724 725 /** 726 * sht15_show_humidity() - show humidity measurement value in sysfs 727 * @dev: device. 728 * @attr: device attribute. 729 * @buf: sysfs buffer where measurement values are written to. 730 * 731 * Will be called on read access to humidity1_input sysfs attribute. 732 * Returns number of bytes written into buffer, negative errno on error. 733 */ 734 static ssize_t sht15_show_humidity(struct device *dev, 735 struct device_attribute *attr, 736 char *buf) 737 { 738 int ret; 739 struct sht15_data *data = dev_get_drvdata(dev); 740 741 ret = sht15_update_measurements(data); 742 743 return ret ? ret : sprintf(buf, "%d\n", sht15_calc_humid(data)); 744 } 745 746 static ssize_t show_name(struct device *dev, 747 struct device_attribute *attr, 748 char *buf) 749 { 750 struct platform_device *pdev = to_platform_device(dev); 751 return sprintf(buf, "%s\n", pdev->name); 752 } 753 754 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, 755 sht15_show_temp, NULL, 0); 756 static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, 757 sht15_show_humidity, NULL, 0); 758 static SENSOR_DEVICE_ATTR(temp1_fault, S_IRUGO, sht15_show_status, NULL, 759 SHT15_STATUS_LOW_BATTERY); 760 static SENSOR_DEVICE_ATTR(humidity1_fault, S_IRUGO, sht15_show_status, NULL, 761 SHT15_STATUS_LOW_BATTERY); 762 static SENSOR_DEVICE_ATTR(heater_enable, S_IRUGO | S_IWUSR, sht15_show_status, 763 sht15_store_heater, SHT15_STATUS_HEATER); 764 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL); 765 static struct attribute *sht15_attrs[] = { 766 &sensor_dev_attr_temp1_input.dev_attr.attr, 767 &sensor_dev_attr_humidity1_input.dev_attr.attr, 768 &sensor_dev_attr_temp1_fault.dev_attr.attr, 769 &sensor_dev_attr_humidity1_fault.dev_attr.attr, 770 &sensor_dev_attr_heater_enable.dev_attr.attr, 771 &dev_attr_name.attr, 772 NULL, 773 }; 774 775 static const struct attribute_group sht15_attr_group = { 776 .attrs = sht15_attrs, 777 }; 778 779 static irqreturn_t sht15_interrupt_fired(int irq, void *d) 780 { 781 struct sht15_data *data = d; 782 783 /* First disable the interrupt */ 784 disable_irq_nosync(irq); 785 atomic_inc(&data->interrupt_handled); 786 /* Then schedule a reading work struct */ 787 if (data->state != SHT15_READING_NOTHING) 788 schedule_work(&data->read_work); 789 return IRQ_HANDLED; 790 } 791 792 static void sht15_bh_read_data(struct work_struct *work_s) 793 { 794 uint16_t val = 0; 795 u8 dev_checksum = 0; 796 u8 checksum_vals[3]; 797 struct sht15_data *data 798 = container_of(work_s, struct sht15_data, 799 read_work); 800 801 /* Firstly, verify the line is low */ 802 if (gpio_get_value(data->pdata->gpio_data)) { 803 /* 804 * If not, then start the interrupt again - care here as could 805 * have gone low in meantime so verify it hasn't! 806 */ 807 atomic_set(&data->interrupt_handled, 0); 808 enable_irq(gpio_to_irq(data->pdata->gpio_data)); 809 /* If still not occurred or another handler has been scheduled */ 810 if (gpio_get_value(data->pdata->gpio_data) 811 || atomic_read(&data->interrupt_handled)) 812 return; 813 } 814 815 /* Read the data back from the device */ 816 val = sht15_read_byte(data); 817 val <<= 8; 818 sht15_ack(data); 819 val |= sht15_read_byte(data); 820 821 if (data->checksumming) { 822 /* 823 * Ask the device for a checksum and read it back. 824 * Note: the device sends the checksum byte reversed. 825 */ 826 sht15_ack(data); 827 dev_checksum = sht15_reverse(sht15_read_byte(data)); 828 checksum_vals[0] = (data->state == SHT15_READING_TEMP) ? 829 SHT15_MEASURE_TEMP : SHT15_MEASURE_RH; 830 checksum_vals[1] = (u8) (val >> 8); 831 checksum_vals[2] = (u8) val; 832 data->checksum_ok 833 = (sht15_crc8(data, checksum_vals, 3) == dev_checksum); 834 } 835 836 /* Tell the device we are done */ 837 sht15_end_transmission(data); 838 839 switch (data->state) { 840 case SHT15_READING_TEMP: 841 data->val_temp = val; 842 break; 843 case SHT15_READING_HUMID: 844 data->val_humid = val; 845 break; 846 default: 847 break; 848 } 849 850 data->state = SHT15_READING_NOTHING; 851 wake_up(&data->wait_queue); 852 } 853 854 static void sht15_update_voltage(struct work_struct *work_s) 855 { 856 struct sht15_data *data 857 = container_of(work_s, struct sht15_data, 858 update_supply_work); 859 data->supply_uV = regulator_get_voltage(data->reg); 860 } 861 862 /** 863 * sht15_invalidate_voltage() - mark supply voltage invalid when notified by reg 864 * @nb: associated notification structure 865 * @event: voltage regulator state change event code 866 * @ignored: function parameter - ignored here 867 * 868 * Note that as the notification code holds the regulator lock, we have 869 * to schedule an update of the supply voltage rather than getting it directly. 870 */ 871 static int sht15_invalidate_voltage(struct notifier_block *nb, 872 unsigned long event, 873 void *ignored) 874 { 875 struct sht15_data *data = container_of(nb, struct sht15_data, nb); 876 877 if (event == REGULATOR_EVENT_VOLTAGE_CHANGE) 878 data->supply_uV_valid = false; 879 schedule_work(&data->update_supply_work); 880 881 return NOTIFY_OK; 882 } 883 884 static int __devinit sht15_probe(struct platform_device *pdev) 885 { 886 int ret = 0; 887 struct sht15_data *data = kzalloc(sizeof(*data), GFP_KERNEL); 888 u8 status = 0; 889 890 if (!data) { 891 ret = -ENOMEM; 892 dev_err(&pdev->dev, "kzalloc failed\n"); 893 goto error_ret; 894 } 895 896 INIT_WORK(&data->read_work, sht15_bh_read_data); 897 INIT_WORK(&data->update_supply_work, sht15_update_voltage); 898 platform_set_drvdata(pdev, data); 899 mutex_init(&data->read_lock); 900 data->dev = &pdev->dev; 901 init_waitqueue_head(&data->wait_queue); 902 903 if (pdev->dev.platform_data == NULL) { 904 dev_err(&pdev->dev, "no platform data supplied\n"); 905 goto err_free_data; 906 } 907 data->pdata = pdev->dev.platform_data; 908 data->supply_uV = data->pdata->supply_mv * 1000; 909 if (data->pdata->checksum) 910 data->checksumming = true; 911 if (data->pdata->no_otp_reload) 912 status |= SHT15_STATUS_NO_OTP_RELOAD; 913 if (data->pdata->low_resolution) 914 status |= SHT15_STATUS_LOW_RESOLUTION; 915 916 /* 917 * If a regulator is available, 918 * query what the supply voltage actually is! 919 */ 920 data->reg = regulator_get(data->dev, "vcc"); 921 if (!IS_ERR(data->reg)) { 922 int voltage; 923 924 voltage = regulator_get_voltage(data->reg); 925 if (voltage) 926 data->supply_uV = voltage; 927 928 regulator_enable(data->reg); 929 /* 930 * Setup a notifier block to update this if another device 931 * causes the voltage to change 932 */ 933 data->nb.notifier_call = &sht15_invalidate_voltage; 934 ret = regulator_register_notifier(data->reg, &data->nb); 935 if (ret) { 936 dev_err(&pdev->dev, 937 "regulator notifier request failed\n"); 938 regulator_disable(data->reg); 939 regulator_put(data->reg); 940 goto err_free_data; 941 } 942 } 943 944 /* Try requesting the GPIOs */ 945 ret = gpio_request(data->pdata->gpio_sck, "SHT15 sck"); 946 if (ret) { 947 dev_err(&pdev->dev, "gpio request failed\n"); 948 goto err_release_reg; 949 } 950 gpio_direction_output(data->pdata->gpio_sck, 0); 951 952 ret = gpio_request(data->pdata->gpio_data, "SHT15 data"); 953 if (ret) { 954 dev_err(&pdev->dev, "gpio request failed\n"); 955 goto err_release_gpio_sck; 956 } 957 958 ret = request_irq(gpio_to_irq(data->pdata->gpio_data), 959 sht15_interrupt_fired, 960 IRQF_TRIGGER_FALLING, 961 "sht15 data", 962 data); 963 if (ret) { 964 dev_err(&pdev->dev, "failed to get irq for data line\n"); 965 goto err_release_gpio_data; 966 } 967 disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data)); 968 sht15_connection_reset(data); 969 ret = sht15_soft_reset(data); 970 if (ret) 971 goto err_release_irq; 972 973 /* write status with platform data options */ 974 if (status) { 975 ret = sht15_send_status(data, status); 976 if (ret) 977 goto err_release_irq; 978 } 979 980 ret = sysfs_create_group(&pdev->dev.kobj, &sht15_attr_group); 981 if (ret) { 982 dev_err(&pdev->dev, "sysfs create failed\n"); 983 goto err_release_irq; 984 } 985 986 data->hwmon_dev = hwmon_device_register(data->dev); 987 if (IS_ERR(data->hwmon_dev)) { 988 ret = PTR_ERR(data->hwmon_dev); 989 goto err_release_sysfs_group; 990 } 991 992 return 0; 993 994 err_release_sysfs_group: 995 sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group); 996 err_release_irq: 997 free_irq(gpio_to_irq(data->pdata->gpio_data), data); 998 err_release_gpio_data: 999 gpio_free(data->pdata->gpio_data); 1000 err_release_gpio_sck: 1001 gpio_free(data->pdata->gpio_sck); 1002 err_release_reg: 1003 if (!IS_ERR(data->reg)) { 1004 regulator_unregister_notifier(data->reg, &data->nb); 1005 regulator_disable(data->reg); 1006 regulator_put(data->reg); 1007 } 1008 err_free_data: 1009 kfree(data); 1010 error_ret: 1011 return ret; 1012 } 1013 1014 static int __devexit sht15_remove(struct platform_device *pdev) 1015 { 1016 struct sht15_data *data = platform_get_drvdata(pdev); 1017 1018 /* 1019 * Make sure any reads from the device are done and 1020 * prevent new ones beginning 1021 */ 1022 mutex_lock(&data->read_lock); 1023 if (sht15_soft_reset(data)) { 1024 mutex_unlock(&data->read_lock); 1025 return -EFAULT; 1026 } 1027 hwmon_device_unregister(data->hwmon_dev); 1028 sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group); 1029 if (!IS_ERR(data->reg)) { 1030 regulator_unregister_notifier(data->reg, &data->nb); 1031 regulator_disable(data->reg); 1032 regulator_put(data->reg); 1033 } 1034 1035 free_irq(gpio_to_irq(data->pdata->gpio_data), data); 1036 gpio_free(data->pdata->gpio_data); 1037 gpio_free(data->pdata->gpio_sck); 1038 mutex_unlock(&data->read_lock); 1039 kfree(data); 1040 1041 return 0; 1042 } 1043 1044 /* 1045 * sht_drivers simultaneously refers to __devinit and __devexit function 1046 * which causes spurious section mismatch warning. So use __refdata to 1047 * get rid from this. 1048 */ 1049 static struct platform_driver __refdata sht_drivers[] = { 1050 { 1051 .driver = { 1052 .name = "sht10", 1053 .owner = THIS_MODULE, 1054 }, 1055 .probe = sht15_probe, 1056 .remove = __devexit_p(sht15_remove), 1057 }, { 1058 .driver = { 1059 .name = "sht11", 1060 .owner = THIS_MODULE, 1061 }, 1062 .probe = sht15_probe, 1063 .remove = __devexit_p(sht15_remove), 1064 }, { 1065 .driver = { 1066 .name = "sht15", 1067 .owner = THIS_MODULE, 1068 }, 1069 .probe = sht15_probe, 1070 .remove = __devexit_p(sht15_remove), 1071 }, { 1072 .driver = { 1073 .name = "sht71", 1074 .owner = THIS_MODULE, 1075 }, 1076 .probe = sht15_probe, 1077 .remove = __devexit_p(sht15_remove), 1078 }, { 1079 .driver = { 1080 .name = "sht75", 1081 .owner = THIS_MODULE, 1082 }, 1083 .probe = sht15_probe, 1084 .remove = __devexit_p(sht15_remove), 1085 }, 1086 }; 1087 1088 static int __init sht15_init(void) 1089 { 1090 int ret; 1091 int i; 1092 1093 for (i = 0; i < ARRAY_SIZE(sht_drivers); i++) { 1094 ret = platform_driver_register(&sht_drivers[i]); 1095 if (ret) 1096 goto error_unreg; 1097 } 1098 1099 return 0; 1100 1101 error_unreg: 1102 while (--i >= 0) 1103 platform_driver_unregister(&sht_drivers[i]); 1104 1105 return ret; 1106 } 1107 module_init(sht15_init); 1108 1109 static void __exit sht15_exit(void) 1110 { 1111 int i; 1112 for (i = ARRAY_SIZE(sht_drivers) - 1; i >= 0; i--) 1113 platform_driver_unregister(&sht_drivers[i]); 1114 } 1115 module_exit(sht15_exit); 1116 1117 MODULE_LICENSE("GPL"); 1118