1 /* 2 * lm90.c - Part of lm_sensors, Linux kernel modules for hardware 3 * monitoring 4 * Copyright (C) 2003-2005 Jean Delvare <khali@linux-fr.org> 5 * 6 * Based on the lm83 driver. The LM90 is a sensor chip made by National 7 * Semiconductor. It reports up to two temperatures (its own plus up to 8 * one external one) with a 0.125 deg resolution (1 deg for local 9 * temperature) and a 3-4 deg accuracy. Complete datasheet can be 10 * obtained from National's website at: 11 * http://www.national.com/pf/LM/LM90.html 12 * 13 * This driver also supports the LM89 and LM99, two other sensor chips 14 * made by National Semiconductor. Both have an increased remote 15 * temperature measurement accuracy (1 degree), and the LM99 16 * additionally shifts remote temperatures (measured and limits) by 16 17 * degrees, which allows for higher temperatures measurement. The 18 * driver doesn't handle it since it can be done easily in user-space. 19 * Complete datasheets can be obtained from National's website at: 20 * http://www.national.com/pf/LM/LM89.html 21 * http://www.national.com/pf/LM/LM99.html 22 * Note that there is no way to differentiate between both chips. 23 * 24 * This driver also supports the LM86, another sensor chip made by 25 * National Semiconductor. It is exactly similar to the LM90 except it 26 * has a higher accuracy. 27 * Complete datasheet can be obtained from National's website at: 28 * http://www.national.com/pf/LM/LM86.html 29 * 30 * This driver also supports the ADM1032, a sensor chip made by Analog 31 * Devices. That chip is similar to the LM90, with a few differences 32 * that are not handled by this driver. Complete datasheet can be 33 * obtained from Analog's website at: 34 * http://products.analog.com/products/info.asp?product=ADM1032 35 * Among others, it has a higher accuracy than the LM90, much like the 36 * LM86 does. 37 * 38 * This driver also supports the MAX6657, MAX6658 and MAX6659 sensor 39 * chips made by Maxim. These chips are similar to the LM86. Complete 40 * datasheet can be obtained at Maxim's website at: 41 * http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 42 * Note that there is no easy way to differentiate between the three 43 * variants. The extra address and features of the MAX6659 are not 44 * supported by this driver. 45 * 46 * This driver also supports the ADT7461 chip from Analog Devices but 47 * only in its "compatability mode". If an ADT7461 chip is found but 48 * is configured in non-compatible mode (where its temperature 49 * register values are decoded differently) it is ignored by this 50 * driver. Complete datasheet can be obtained from Analog's website 51 * at: 52 * http://products.analog.com/products/info.asp?product=ADT7461 53 * 54 * Since the LM90 was the first chipset supported by this driver, most 55 * comments will refer to this chipset, but are actually general and 56 * concern all supported chipsets, unless mentioned otherwise. 57 * 58 * This program is free software; you can redistribute it and/or modify 59 * it under the terms of the GNU General Public License as published by 60 * the Free Software Foundation; either version 2 of the License, or 61 * (at your option) any later version. 62 * 63 * This program is distributed in the hope that it will be useful, 64 * but WITHOUT ANY WARRANTY; without even the implied warranty of 65 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 66 * GNU General Public License for more details. 67 * 68 * You should have received a copy of the GNU General Public License 69 * along with this program; if not, write to the Free Software 70 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 71 */ 72 73 #include <linux/module.h> 74 #include <linux/init.h> 75 #include <linux/slab.h> 76 #include <linux/jiffies.h> 77 #include <linux/i2c.h> 78 #include <linux/i2c-sensor.h> 79 #include <linux/hwmon-sysfs.h> 80 81 /* 82 * Addresses to scan 83 * Address is fully defined internally and cannot be changed except for 84 * MAX6659. 85 * LM86, LM89, LM90, LM99, ADM1032, MAX6657 and MAX6658 have address 0x4c. 86 * LM89-1, and LM99-1 have address 0x4d. 87 * MAX6659 can have address 0x4c, 0x4d or 0x4e (unsupported). 88 * ADT7461 always has address 0x4c. 89 */ 90 91 static unsigned short normal_i2c[] = { 0x4c, 0x4d, I2C_CLIENT_END }; 92 static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END }; 93 94 /* 95 * Insmod parameters 96 */ 97 98 SENSORS_INSMOD_6(lm90, adm1032, lm99, lm86, max6657, adt7461); 99 100 /* 101 * The LM90 registers 102 */ 103 104 #define LM90_REG_R_MAN_ID 0xFE 105 #define LM90_REG_R_CHIP_ID 0xFF 106 #define LM90_REG_R_CONFIG1 0x03 107 #define LM90_REG_W_CONFIG1 0x09 108 #define LM90_REG_R_CONFIG2 0xBF 109 #define LM90_REG_W_CONFIG2 0xBF 110 #define LM90_REG_R_CONVRATE 0x04 111 #define LM90_REG_W_CONVRATE 0x0A 112 #define LM90_REG_R_STATUS 0x02 113 #define LM90_REG_R_LOCAL_TEMP 0x00 114 #define LM90_REG_R_LOCAL_HIGH 0x05 115 #define LM90_REG_W_LOCAL_HIGH 0x0B 116 #define LM90_REG_R_LOCAL_LOW 0x06 117 #define LM90_REG_W_LOCAL_LOW 0x0C 118 #define LM90_REG_R_LOCAL_CRIT 0x20 119 #define LM90_REG_W_LOCAL_CRIT 0x20 120 #define LM90_REG_R_REMOTE_TEMPH 0x01 121 #define LM90_REG_R_REMOTE_TEMPL 0x10 122 #define LM90_REG_R_REMOTE_OFFSH 0x11 123 #define LM90_REG_W_REMOTE_OFFSH 0x11 124 #define LM90_REG_R_REMOTE_OFFSL 0x12 125 #define LM90_REG_W_REMOTE_OFFSL 0x12 126 #define LM90_REG_R_REMOTE_HIGHH 0x07 127 #define LM90_REG_W_REMOTE_HIGHH 0x0D 128 #define LM90_REG_R_REMOTE_HIGHL 0x13 129 #define LM90_REG_W_REMOTE_HIGHL 0x13 130 #define LM90_REG_R_REMOTE_LOWH 0x08 131 #define LM90_REG_W_REMOTE_LOWH 0x0E 132 #define LM90_REG_R_REMOTE_LOWL 0x14 133 #define LM90_REG_W_REMOTE_LOWL 0x14 134 #define LM90_REG_R_REMOTE_CRIT 0x19 135 #define LM90_REG_W_REMOTE_CRIT 0x19 136 #define LM90_REG_R_TCRIT_HYST 0x21 137 #define LM90_REG_W_TCRIT_HYST 0x21 138 139 /* 140 * Conversions and various macros 141 * For local temperatures and limits, critical limits and the hysteresis 142 * value, the LM90 uses signed 8-bit values with LSB = 1 degree Celsius. 143 * For remote temperatures and limits, it uses signed 11-bit values with 144 * LSB = 0.125 degree Celsius, left-justified in 16-bit registers. 145 */ 146 147 #define TEMP1_FROM_REG(val) ((val) * 1000) 148 #define TEMP1_TO_REG(val) ((val) <= -128000 ? -128 : \ 149 (val) >= 127000 ? 127 : \ 150 (val) < 0 ? ((val) - 500) / 1000 : \ 151 ((val) + 500) / 1000) 152 #define TEMP2_FROM_REG(val) ((val) / 32 * 125) 153 #define TEMP2_TO_REG(val) ((val) <= -128000 ? 0x8000 : \ 154 (val) >= 127875 ? 0x7FE0 : \ 155 (val) < 0 ? ((val) - 62) / 125 * 32 : \ 156 ((val) + 62) / 125 * 32) 157 #define HYST_TO_REG(val) ((val) <= 0 ? 0 : (val) >= 30500 ? 31 : \ 158 ((val) + 500) / 1000) 159 160 /* 161 * ADT7461 is almost identical to LM90 except that attempts to write 162 * values that are outside the range 0 < temp < 127 are treated as 163 * the boundary value. 164 */ 165 166 #define TEMP1_TO_REG_ADT7461(val) ((val) <= 0 ? 0 : \ 167 (val) >= 127000 ? 127 : \ 168 ((val) + 500) / 1000) 169 #define TEMP2_TO_REG_ADT7461(val) ((val) <= 0 ? 0 : \ 170 (val) >= 127750 ? 0x7FC0 : \ 171 ((val) + 125) / 250 * 64) 172 173 /* 174 * Functions declaration 175 */ 176 177 static int lm90_attach_adapter(struct i2c_adapter *adapter); 178 static int lm90_detect(struct i2c_adapter *adapter, int address, 179 int kind); 180 static void lm90_init_client(struct i2c_client *client); 181 static int lm90_detach_client(struct i2c_client *client); 182 static struct lm90_data *lm90_update_device(struct device *dev); 183 184 /* 185 * Driver data (common to all clients) 186 */ 187 188 static struct i2c_driver lm90_driver = { 189 .owner = THIS_MODULE, 190 .name = "lm90", 191 .id = I2C_DRIVERID_LM90, 192 .flags = I2C_DF_NOTIFY, 193 .attach_adapter = lm90_attach_adapter, 194 .detach_client = lm90_detach_client, 195 }; 196 197 /* 198 * Client data (each client gets its own) 199 */ 200 201 struct lm90_data { 202 struct i2c_client client; 203 struct semaphore update_lock; 204 char valid; /* zero until following fields are valid */ 205 unsigned long last_updated; /* in jiffies */ 206 int kind; 207 208 /* registers values */ 209 s8 temp8[5]; /* 0: local input 210 1: local low limit 211 2: local high limit 212 3: local critical limit 213 4: remote critical limit */ 214 s16 temp11[3]; /* 0: remote input 215 1: remote low limit 216 2: remote high limit */ 217 u8 temp_hyst; 218 u8 alarms; /* bitvector */ 219 }; 220 221 /* 222 * Sysfs stuff 223 */ 224 225 static ssize_t show_temp8(struct device *dev, struct device_attribute *devattr, 226 char *buf) 227 { 228 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 229 struct lm90_data *data = lm90_update_device(dev); 230 return sprintf(buf, "%d\n", TEMP1_FROM_REG(data->temp8[attr->index])); 231 } 232 233 static ssize_t set_temp8(struct device *dev, struct device_attribute *devattr, 234 const char *buf, size_t count) 235 { 236 static const u8 reg[4] = { 237 LM90_REG_W_LOCAL_LOW, 238 LM90_REG_W_LOCAL_HIGH, 239 LM90_REG_W_LOCAL_CRIT, 240 LM90_REG_W_REMOTE_CRIT, 241 }; 242 243 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 244 struct i2c_client *client = to_i2c_client(dev); 245 struct lm90_data *data = i2c_get_clientdata(client); 246 long val = simple_strtol(buf, NULL, 10); 247 int nr = attr->index; 248 249 down(&data->update_lock); 250 if (data->kind == adt7461) 251 data->temp8[nr] = TEMP1_TO_REG_ADT7461(val); 252 else 253 data->temp8[nr] = TEMP1_TO_REG(val); 254 i2c_smbus_write_byte_data(client, reg[nr - 1], data->temp8[nr]); 255 up(&data->update_lock); 256 return count; 257 } 258 259 static ssize_t show_temp11(struct device *dev, struct device_attribute *devattr, 260 char *buf) 261 { 262 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 263 struct lm90_data *data = lm90_update_device(dev); 264 return sprintf(buf, "%d\n", TEMP2_FROM_REG(data->temp11[attr->index])); 265 } 266 267 static ssize_t set_temp11(struct device *dev, struct device_attribute *devattr, 268 const char *buf, size_t count) 269 { 270 static const u8 reg[4] = { 271 LM90_REG_W_REMOTE_LOWH, 272 LM90_REG_W_REMOTE_LOWL, 273 LM90_REG_W_REMOTE_HIGHH, 274 LM90_REG_W_REMOTE_HIGHL, 275 }; 276 277 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 278 struct i2c_client *client = to_i2c_client(dev); 279 struct lm90_data *data = i2c_get_clientdata(client); 280 long val = simple_strtol(buf, NULL, 10); 281 int nr = attr->index; 282 283 down(&data->update_lock); 284 if (data->kind == adt7461) 285 data->temp11[nr] = TEMP2_TO_REG_ADT7461(val); 286 else 287 data->temp11[nr] = TEMP2_TO_REG(val); 288 i2c_smbus_write_byte_data(client, reg[(nr - 1) * 2], 289 data->temp11[nr] >> 8); 290 i2c_smbus_write_byte_data(client, reg[(nr - 1) * 2 + 1], 291 data->temp11[nr] & 0xff); 292 up(&data->update_lock); 293 return count; 294 } 295 296 static ssize_t show_temphyst(struct device *dev, struct device_attribute *devattr, 297 char *buf) 298 { 299 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 300 struct lm90_data *data = lm90_update_device(dev); 301 return sprintf(buf, "%d\n", TEMP1_FROM_REG(data->temp8[attr->index]) 302 - TEMP1_FROM_REG(data->temp_hyst)); 303 } 304 305 static ssize_t set_temphyst(struct device *dev, struct device_attribute *dummy, 306 const char *buf, size_t count) 307 { 308 struct i2c_client *client = to_i2c_client(dev); 309 struct lm90_data *data = i2c_get_clientdata(client); 310 long val = simple_strtol(buf, NULL, 10); 311 long hyst; 312 313 down(&data->update_lock); 314 hyst = TEMP1_FROM_REG(data->temp8[3]) - val; 315 i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST, 316 HYST_TO_REG(hyst)); 317 up(&data->update_lock); 318 return count; 319 } 320 321 static ssize_t show_alarms(struct device *dev, struct device_attribute *dummy, 322 char *buf) 323 { 324 struct lm90_data *data = lm90_update_device(dev); 325 return sprintf(buf, "%d\n", data->alarms); 326 } 327 328 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp8, NULL, 0); 329 static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp11, NULL, 0); 330 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp8, 331 set_temp8, 1); 332 static SENSOR_DEVICE_ATTR(temp2_min, S_IWUSR | S_IRUGO, show_temp11, 333 set_temp11, 1); 334 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp8, 335 set_temp8, 2); 336 static SENSOR_DEVICE_ATTR(temp2_max, S_IWUSR | S_IRUGO, show_temp11, 337 set_temp11, 2); 338 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp8, 339 set_temp8, 3); 340 static SENSOR_DEVICE_ATTR(temp2_crit, S_IWUSR | S_IRUGO, show_temp8, 341 set_temp8, 4); 342 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temphyst, 343 set_temphyst, 3); 344 static SENSOR_DEVICE_ATTR(temp2_crit_hyst, S_IRUGO, show_temphyst, NULL, 4); 345 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL); 346 347 /* 348 * Real code 349 */ 350 351 static int lm90_attach_adapter(struct i2c_adapter *adapter) 352 { 353 if (!(adapter->class & I2C_CLASS_HWMON)) 354 return 0; 355 return i2c_detect(adapter, &addr_data, lm90_detect); 356 } 357 358 /* 359 * The following function does more than just detection. If detection 360 * succeeds, it also registers the new chip. 361 */ 362 static int lm90_detect(struct i2c_adapter *adapter, int address, int kind) 363 { 364 struct i2c_client *new_client; 365 struct lm90_data *data; 366 int err = 0; 367 const char *name = ""; 368 369 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 370 goto exit; 371 372 if (!(data = kmalloc(sizeof(struct lm90_data), GFP_KERNEL))) { 373 err = -ENOMEM; 374 goto exit; 375 } 376 memset(data, 0, sizeof(struct lm90_data)); 377 378 /* The common I2C client data is placed right before the 379 LM90-specific data. */ 380 new_client = &data->client; 381 i2c_set_clientdata(new_client, data); 382 new_client->addr = address; 383 new_client->adapter = adapter; 384 new_client->driver = &lm90_driver; 385 new_client->flags = 0; 386 387 /* 388 * Now we do the remaining detection. A negative kind means that 389 * the driver was loaded with no force parameter (default), so we 390 * must both detect and identify the chip. A zero kind means that 391 * the driver was loaded with the force parameter, the detection 392 * step shall be skipped. A positive kind means that the driver 393 * was loaded with the force parameter and a given kind of chip is 394 * requested, so both the detection and the identification steps 395 * are skipped. 396 */ 397 398 /* Default to an LM90 if forced */ 399 if (kind == 0) 400 kind = lm90; 401 402 if (kind < 0) { /* detection and identification */ 403 u8 man_id, chip_id, reg_config1, reg_convrate; 404 405 man_id = i2c_smbus_read_byte_data(new_client, 406 LM90_REG_R_MAN_ID); 407 chip_id = i2c_smbus_read_byte_data(new_client, 408 LM90_REG_R_CHIP_ID); 409 reg_config1 = i2c_smbus_read_byte_data(new_client, 410 LM90_REG_R_CONFIG1); 411 reg_convrate = i2c_smbus_read_byte_data(new_client, 412 LM90_REG_R_CONVRATE); 413 414 if (man_id == 0x01) { /* National Semiconductor */ 415 u8 reg_config2; 416 417 reg_config2 = i2c_smbus_read_byte_data(new_client, 418 LM90_REG_R_CONFIG2); 419 420 if ((reg_config1 & 0x2A) == 0x00 421 && (reg_config2 & 0xF8) == 0x00 422 && reg_convrate <= 0x09) { 423 if (address == 0x4C 424 && (chip_id & 0xF0) == 0x20) { /* LM90 */ 425 kind = lm90; 426 } else 427 if ((chip_id & 0xF0) == 0x30) { /* LM89/LM99 */ 428 kind = lm99; 429 } else 430 if (address == 0x4C 431 && (chip_id & 0xF0) == 0x10) { /* LM86 */ 432 kind = lm86; 433 } 434 } 435 } else 436 if (man_id == 0x41) { /* Analog Devices */ 437 if (address == 0x4C 438 && (chip_id & 0xF0) == 0x40 /* ADM1032 */ 439 && (reg_config1 & 0x3F) == 0x00 440 && reg_convrate <= 0x0A) { 441 kind = adm1032; 442 } else 443 if (address == 0x4c 444 && chip_id == 0x51 /* ADT7461 */ 445 && (reg_config1 & 0x1F) == 0x00 /* check compat mode */ 446 && reg_convrate <= 0x0A) { 447 kind = adt7461; 448 } 449 } else 450 if (man_id == 0x4D) { /* Maxim */ 451 /* 452 * The Maxim variants do NOT have a chip_id register. 453 * Reading from that address will return the last read 454 * value, which in our case is those of the man_id 455 * register. Likewise, the config1 register seems to 456 * lack a low nibble, so the value will be those of the 457 * previous read, so in our case those of the man_id 458 * register. 459 */ 460 if (chip_id == man_id 461 && (reg_config1 & 0x1F) == (man_id & 0x0F) 462 && reg_convrate <= 0x09) { 463 kind = max6657; 464 } 465 } 466 467 if (kind <= 0) { /* identification failed */ 468 dev_info(&adapter->dev, 469 "Unsupported chip (man_id=0x%02X, " 470 "chip_id=0x%02X).\n", man_id, chip_id); 471 goto exit_free; 472 } 473 } 474 475 if (kind == lm90) { 476 name = "lm90"; 477 } else if (kind == adm1032) { 478 name = "adm1032"; 479 } else if (kind == lm99) { 480 name = "lm99"; 481 } else if (kind == lm86) { 482 name = "lm86"; 483 } else if (kind == max6657) { 484 name = "max6657"; 485 } else if (kind == adt7461) { 486 name = "adt7461"; 487 } 488 489 /* We can fill in the remaining client fields */ 490 strlcpy(new_client->name, name, I2C_NAME_SIZE); 491 data->valid = 0; 492 data->kind = kind; 493 init_MUTEX(&data->update_lock); 494 495 /* Tell the I2C layer a new client has arrived */ 496 if ((err = i2c_attach_client(new_client))) 497 goto exit_free; 498 499 /* Initialize the LM90 chip */ 500 lm90_init_client(new_client); 501 502 /* Register sysfs hooks */ 503 device_create_file(&new_client->dev, 504 &sensor_dev_attr_temp1_input.dev_attr); 505 device_create_file(&new_client->dev, 506 &sensor_dev_attr_temp2_input.dev_attr); 507 device_create_file(&new_client->dev, 508 &sensor_dev_attr_temp1_min.dev_attr); 509 device_create_file(&new_client->dev, 510 &sensor_dev_attr_temp2_min.dev_attr); 511 device_create_file(&new_client->dev, 512 &sensor_dev_attr_temp1_max.dev_attr); 513 device_create_file(&new_client->dev, 514 &sensor_dev_attr_temp2_max.dev_attr); 515 device_create_file(&new_client->dev, 516 &sensor_dev_attr_temp1_crit.dev_attr); 517 device_create_file(&new_client->dev, 518 &sensor_dev_attr_temp2_crit.dev_attr); 519 device_create_file(&new_client->dev, 520 &sensor_dev_attr_temp1_crit_hyst.dev_attr); 521 device_create_file(&new_client->dev, 522 &sensor_dev_attr_temp2_crit_hyst.dev_attr); 523 device_create_file(&new_client->dev, &dev_attr_alarms); 524 525 return 0; 526 527 exit_free: 528 kfree(data); 529 exit: 530 return err; 531 } 532 533 static void lm90_init_client(struct i2c_client *client) 534 { 535 u8 config; 536 537 /* 538 * Start the conversions. 539 */ 540 i2c_smbus_write_byte_data(client, LM90_REG_W_CONVRATE, 541 5); /* 2 Hz */ 542 config = i2c_smbus_read_byte_data(client, LM90_REG_R_CONFIG1); 543 if (config & 0x40) 544 i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1, 545 config & 0xBF); /* run */ 546 } 547 548 static int lm90_detach_client(struct i2c_client *client) 549 { 550 int err; 551 552 if ((err = i2c_detach_client(client))) { 553 dev_err(&client->dev, "Client deregistration failed, " 554 "client not detached.\n"); 555 return err; 556 } 557 558 kfree(i2c_get_clientdata(client)); 559 return 0; 560 } 561 562 static struct lm90_data *lm90_update_device(struct device *dev) 563 { 564 struct i2c_client *client = to_i2c_client(dev); 565 struct lm90_data *data = i2c_get_clientdata(client); 566 567 down(&data->update_lock); 568 569 if (time_after(jiffies, data->last_updated + HZ * 2) || !data->valid) { 570 u8 oldh, newh; 571 572 dev_dbg(&client->dev, "Updating lm90 data.\n"); 573 data->temp8[0] = i2c_smbus_read_byte_data(client, 574 LM90_REG_R_LOCAL_TEMP); 575 data->temp8[1] = i2c_smbus_read_byte_data(client, 576 LM90_REG_R_LOCAL_LOW); 577 data->temp8[2] = i2c_smbus_read_byte_data(client, 578 LM90_REG_R_LOCAL_HIGH); 579 data->temp8[3] = i2c_smbus_read_byte_data(client, 580 LM90_REG_R_LOCAL_CRIT); 581 data->temp8[4] = i2c_smbus_read_byte_data(client, 582 LM90_REG_R_REMOTE_CRIT); 583 data->temp_hyst = i2c_smbus_read_byte_data(client, 584 LM90_REG_R_TCRIT_HYST); 585 586 /* 587 * There is a trick here. We have to read two registers to 588 * have the remote sensor temperature, but we have to beware 589 * a conversion could occur inbetween the readings. The 590 * datasheet says we should either use the one-shot 591 * conversion register, which we don't want to do (disables 592 * hardware monitoring) or monitor the busy bit, which is 593 * impossible (we can't read the values and monitor that bit 594 * at the exact same time). So the solution used here is to 595 * read the high byte once, then the low byte, then the high 596 * byte again. If the new high byte matches the old one, 597 * then we have a valid reading. Else we have to read the low 598 * byte again, and now we believe we have a correct reading. 599 */ 600 oldh = i2c_smbus_read_byte_data(client, 601 LM90_REG_R_REMOTE_TEMPH); 602 data->temp11[0] = i2c_smbus_read_byte_data(client, 603 LM90_REG_R_REMOTE_TEMPL); 604 newh = i2c_smbus_read_byte_data(client, 605 LM90_REG_R_REMOTE_TEMPH); 606 if (newh != oldh) { 607 data->temp11[0] = i2c_smbus_read_byte_data(client, 608 LM90_REG_R_REMOTE_TEMPL); 609 #ifdef DEBUG 610 oldh = i2c_smbus_read_byte_data(client, 611 LM90_REG_R_REMOTE_TEMPH); 612 /* oldh is actually newer */ 613 if (newh != oldh) 614 dev_warn(&client->dev, "Remote temperature may be " 615 "wrong.\n"); 616 #endif 617 } 618 data->temp11[0] |= (newh << 8); 619 620 data->temp11[1] = (i2c_smbus_read_byte_data(client, 621 LM90_REG_R_REMOTE_LOWH) << 8) + 622 i2c_smbus_read_byte_data(client, 623 LM90_REG_R_REMOTE_LOWL); 624 data->temp11[2] = (i2c_smbus_read_byte_data(client, 625 LM90_REG_R_REMOTE_HIGHH) << 8) + 626 i2c_smbus_read_byte_data(client, 627 LM90_REG_R_REMOTE_HIGHL); 628 data->alarms = i2c_smbus_read_byte_data(client, 629 LM90_REG_R_STATUS); 630 631 data->last_updated = jiffies; 632 data->valid = 1; 633 } 634 635 up(&data->update_lock); 636 637 return data; 638 } 639 640 static int __init sensors_lm90_init(void) 641 { 642 return i2c_add_driver(&lm90_driver); 643 } 644 645 static void __exit sensors_lm90_exit(void) 646 { 647 i2c_del_driver(&lm90_driver); 648 } 649 650 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); 651 MODULE_DESCRIPTION("LM90/ADM1032 driver"); 652 MODULE_LICENSE("GPL"); 653 654 module_init(sensors_lm90_init); 655 module_exit(sensors_lm90_exit); 656