1 /* 2 * lm92 - Hardware monitoring driver 3 * Copyright (C) 2005-2008 Jean Delvare <khali@linux-fr.org> 4 * 5 * Based on the lm90 driver, with some ideas taken from the lm_sensors 6 * lm92 driver as well. 7 * 8 * The LM92 is a sensor chip made by National Semiconductor. It reports 9 * its own temperature with a 0.0625 deg resolution and a 0.33 deg 10 * accuracy. Complete datasheet can be obtained from National's website 11 * at: 12 * http://www.national.com/pf/LM/LM92.html 13 * 14 * This driver also supports the MAX6635 sensor chip made by Maxim. 15 * This chip is compatible with the LM92, but has a lesser accuracy 16 * (1.0 deg). Complete datasheet can be obtained from Maxim's website 17 * at: 18 * http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3074 19 * 20 * Since the LM92 was the first chipset supported by this driver, most 21 * comments will refer to this chipset, but are actually general and 22 * concern all supported chipsets, unless mentioned otherwise. 23 * 24 * Support could easily be added for the National Semiconductor LM76 25 * and Maxim MAX6633 and MAX6634 chips, which are mostly compatible 26 * with the LM92. 27 * 28 * This program is free software; you can redistribute it and/or modify 29 * it under the terms of the GNU General Public License as published by 30 * the Free Software Foundation; either version 2 of the License, or 31 * (at your option) any later version. 32 * 33 * This program is distributed in the hope that it will be useful, 34 * but WITHOUT ANY WARRANTY; without even the implied warranty of 35 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 36 * GNU General Public License for more details. 37 * 38 * You should have received a copy of the GNU General Public License 39 * along with this program; if not, write to the Free Software 40 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 41 */ 42 43 #include <linux/module.h> 44 #include <linux/init.h> 45 #include <linux/slab.h> 46 #include <linux/i2c.h> 47 #include <linux/hwmon.h> 48 #include <linux/hwmon-sysfs.h> 49 #include <linux/err.h> 50 #include <linux/mutex.h> 51 #include <linux/jiffies.h> 52 53 /* 54 * The LM92 and MAX6635 have 2 two-state pins for address selection, 55 * resulting in 4 possible addresses. 56 */ 57 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 58 I2C_CLIENT_END }; 59 60 /* The LM92 registers */ 61 #define LM92_REG_CONFIG 0x01 /* 8-bit, RW */ 62 #define LM92_REG_TEMP 0x00 /* 16-bit, RO */ 63 #define LM92_REG_TEMP_HYST 0x02 /* 16-bit, RW */ 64 #define LM92_REG_TEMP_CRIT 0x03 /* 16-bit, RW */ 65 #define LM92_REG_TEMP_LOW 0x04 /* 16-bit, RW */ 66 #define LM92_REG_TEMP_HIGH 0x05 /* 16-bit, RW */ 67 #define LM92_REG_MAN_ID 0x07 /* 16-bit, RO, LM92 only */ 68 69 /* 70 * The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius, 71 * left-justified in 16-bit registers. No rounding is done, with such 72 * a resolution it's just not worth it. Note that the MAX6635 doesn't 73 * make use of the 4 lower bits for limits (i.e. effective resolution 74 * for limits is 1 degree Celsius). 75 */ 76 static inline int TEMP_FROM_REG(s16 reg) 77 { 78 return reg / 8 * 625 / 10; 79 } 80 81 static inline s16 TEMP_TO_REG(int val) 82 { 83 if (val <= -60000) 84 return -60000 * 10 / 625 * 8; 85 if (val >= 160000) 86 return 160000 * 10 / 625 * 8; 87 return val * 10 / 625 * 8; 88 } 89 90 /* Alarm flags are stored in the 3 LSB of the temperature register */ 91 static inline u8 ALARMS_FROM_REG(s16 reg) 92 { 93 return reg & 0x0007; 94 } 95 96 /* Driver data (common to all clients) */ 97 static struct i2c_driver lm92_driver; 98 99 /* Client data (each client gets its own) */ 100 struct lm92_data { 101 struct device *hwmon_dev; 102 struct mutex update_lock; 103 char valid; /* zero until following fields are valid */ 104 unsigned long last_updated; /* in jiffies */ 105 106 /* registers values */ 107 s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst; 108 }; 109 110 111 /* 112 * Sysfs attributes and callback functions 113 */ 114 115 static struct lm92_data *lm92_update_device(struct device *dev) 116 { 117 struct i2c_client *client = to_i2c_client(dev); 118 struct lm92_data *data = i2c_get_clientdata(client); 119 120 mutex_lock(&data->update_lock); 121 122 if (time_after(jiffies, data->last_updated + HZ) 123 || !data->valid) { 124 dev_dbg(&client->dev, "Updating lm92 data\n"); 125 data->temp1_input = i2c_smbus_read_word_swapped(client, 126 LM92_REG_TEMP); 127 data->temp1_hyst = i2c_smbus_read_word_swapped(client, 128 LM92_REG_TEMP_HYST); 129 data->temp1_crit = i2c_smbus_read_word_swapped(client, 130 LM92_REG_TEMP_CRIT); 131 data->temp1_min = i2c_smbus_read_word_swapped(client, 132 LM92_REG_TEMP_LOW); 133 data->temp1_max = i2c_smbus_read_word_swapped(client, 134 LM92_REG_TEMP_HIGH); 135 136 data->last_updated = jiffies; 137 data->valid = 1; 138 } 139 140 mutex_unlock(&data->update_lock); 141 142 return data; 143 } 144 145 #define show_temp(value) \ 146 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, \ 147 char *buf) \ 148 { \ 149 struct lm92_data *data = lm92_update_device(dev); \ 150 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \ 151 } 152 show_temp(temp1_input); 153 show_temp(temp1_crit); 154 show_temp(temp1_min); 155 show_temp(temp1_max); 156 157 #define set_temp(value, reg) \ 158 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, \ 159 const char *buf, \ 160 size_t count) \ 161 { \ 162 struct i2c_client *client = to_i2c_client(dev); \ 163 struct lm92_data *data = i2c_get_clientdata(client); \ 164 long val; \ 165 int err = kstrtol(buf, 10, &val); \ 166 if (err) \ 167 return err; \ 168 \ 169 mutex_lock(&data->update_lock); \ 170 data->value = TEMP_TO_REG(val); \ 171 i2c_smbus_write_word_swapped(client, reg, data->value); \ 172 mutex_unlock(&data->update_lock); \ 173 return count; \ 174 } 175 set_temp(temp1_crit, LM92_REG_TEMP_CRIT); 176 set_temp(temp1_min, LM92_REG_TEMP_LOW); 177 set_temp(temp1_max, LM92_REG_TEMP_HIGH); 178 179 static ssize_t show_temp1_crit_hyst(struct device *dev, 180 struct device_attribute *attr, char *buf) 181 { 182 struct lm92_data *data = lm92_update_device(dev); 183 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit) 184 - TEMP_FROM_REG(data->temp1_hyst)); 185 } 186 static ssize_t show_temp1_max_hyst(struct device *dev, 187 struct device_attribute *attr, char *buf) 188 { 189 struct lm92_data *data = lm92_update_device(dev); 190 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max) 191 - TEMP_FROM_REG(data->temp1_hyst)); 192 } 193 static ssize_t show_temp1_min_hyst(struct device *dev, 194 struct device_attribute *attr, char *buf) 195 { 196 struct lm92_data *data = lm92_update_device(dev); 197 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min) 198 + TEMP_FROM_REG(data->temp1_hyst)); 199 } 200 201 static ssize_t set_temp1_crit_hyst(struct device *dev, 202 struct device_attribute *attr, 203 const char *buf, size_t count) 204 { 205 struct i2c_client *client = to_i2c_client(dev); 206 struct lm92_data *data = i2c_get_clientdata(client); 207 long val; 208 int err; 209 210 err = kstrtol(buf, 10, &val); 211 if (err) 212 return err; 213 214 mutex_lock(&data->update_lock); 215 data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val; 216 i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST, 217 TEMP_TO_REG(data->temp1_hyst)); 218 mutex_unlock(&data->update_lock); 219 return count; 220 } 221 222 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr, 223 char *buf) 224 { 225 struct lm92_data *data = lm92_update_device(dev); 226 return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input)); 227 } 228 229 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr, 230 char *buf) 231 { 232 int bitnr = to_sensor_dev_attr(attr)->index; 233 struct lm92_data *data = lm92_update_device(dev); 234 return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1); 235 } 236 237 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL); 238 static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit, 239 set_temp1_crit); 240 static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst, 241 set_temp1_crit_hyst); 242 static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min, 243 set_temp1_min); 244 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL); 245 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max, 246 set_temp1_max); 247 static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL); 248 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL); 249 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2); 250 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0); 251 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1); 252 253 254 /* 255 * Detection and registration 256 */ 257 258 static void lm92_init_client(struct i2c_client *client) 259 { 260 u8 config; 261 262 /* Start the conversions if needed */ 263 config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG); 264 if (config & 0x01) 265 i2c_smbus_write_byte_data(client, LM92_REG_CONFIG, 266 config & 0xFE); 267 } 268 269 /* 270 * The MAX6635 has no identification register, so we have to use tricks 271 * to identify it reliably. This is somewhat slow. 272 * Note that we do NOT rely on the 2 MSB of the configuration register 273 * always reading 0, as suggested by the datasheet, because it was once 274 * reported not to be true. 275 */ 276 static int max6635_check(struct i2c_client *client) 277 { 278 u16 temp_low, temp_high, temp_hyst, temp_crit; 279 u8 conf; 280 int i; 281 282 /* 283 * No manufacturer ID register, so a read from this address will 284 * always return the last read value. 285 */ 286 temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW); 287 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low) 288 return 0; 289 temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH); 290 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high) 291 return 0; 292 293 /* Limits are stored as integer values (signed, 9-bit). */ 294 if ((temp_low & 0x7f00) || (temp_high & 0x7f00)) 295 return 0; 296 temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST); 297 temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT); 298 if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00)) 299 return 0; 300 301 /* 302 * Registers addresses were found to cycle over 16-byte boundaries. 303 * We don't test all registers with all offsets so as to save some 304 * reads and time, but this should still be sufficient to dismiss 305 * non-MAX6635 chips. 306 */ 307 conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG); 308 for (i = 16; i < 96; i *= 2) { 309 if (temp_hyst != i2c_smbus_read_word_data(client, 310 LM92_REG_TEMP_HYST + i - 16) 311 || temp_crit != i2c_smbus_read_word_data(client, 312 LM92_REG_TEMP_CRIT + i) 313 || temp_low != i2c_smbus_read_word_data(client, 314 LM92_REG_TEMP_LOW + i + 16) 315 || temp_high != i2c_smbus_read_word_data(client, 316 LM92_REG_TEMP_HIGH + i + 32) 317 || conf != i2c_smbus_read_byte_data(client, 318 LM92_REG_CONFIG + i)) 319 return 0; 320 } 321 322 return 1; 323 } 324 325 static struct attribute *lm92_attributes[] = { 326 &dev_attr_temp1_input.attr, 327 &dev_attr_temp1_crit.attr, 328 &dev_attr_temp1_crit_hyst.attr, 329 &dev_attr_temp1_min.attr, 330 &dev_attr_temp1_min_hyst.attr, 331 &dev_attr_temp1_max.attr, 332 &dev_attr_temp1_max_hyst.attr, 333 &dev_attr_alarms.attr, 334 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr, 335 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr, 336 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr, 337 NULL 338 }; 339 340 static const struct attribute_group lm92_group = { 341 .attrs = lm92_attributes, 342 }; 343 344 /* Return 0 if detection is successful, -ENODEV otherwise */ 345 static int lm92_detect(struct i2c_client *new_client, 346 struct i2c_board_info *info) 347 { 348 struct i2c_adapter *adapter = new_client->adapter; 349 u8 config; 350 u16 man_id; 351 352 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA 353 | I2C_FUNC_SMBUS_WORD_DATA)) 354 return -ENODEV; 355 356 config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG); 357 man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID); 358 359 if ((config & 0xe0) == 0x00 && man_id == 0x0180) 360 pr_info("lm92: Found National Semiconductor LM92 chip\n"); 361 else if (max6635_check(new_client)) 362 pr_info("lm92: Found Maxim MAX6635 chip\n"); 363 else 364 return -ENODEV; 365 366 strlcpy(info->type, "lm92", I2C_NAME_SIZE); 367 368 return 0; 369 } 370 371 static int lm92_probe(struct i2c_client *new_client, 372 const struct i2c_device_id *id) 373 { 374 struct lm92_data *data; 375 int err; 376 377 data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data), 378 GFP_KERNEL); 379 if (!data) 380 return -ENOMEM; 381 382 i2c_set_clientdata(new_client, data); 383 data->valid = 0; 384 mutex_init(&data->update_lock); 385 386 /* Initialize the chipset */ 387 lm92_init_client(new_client); 388 389 /* Register sysfs hooks */ 390 err = sysfs_create_group(&new_client->dev.kobj, &lm92_group); 391 if (err) 392 return err; 393 394 data->hwmon_dev = hwmon_device_register(&new_client->dev); 395 if (IS_ERR(data->hwmon_dev)) { 396 err = PTR_ERR(data->hwmon_dev); 397 goto exit_remove; 398 } 399 400 return 0; 401 402 exit_remove: 403 sysfs_remove_group(&new_client->dev.kobj, &lm92_group); 404 return err; 405 } 406 407 static int lm92_remove(struct i2c_client *client) 408 { 409 struct lm92_data *data = i2c_get_clientdata(client); 410 411 hwmon_device_unregister(data->hwmon_dev); 412 sysfs_remove_group(&client->dev.kobj, &lm92_group); 413 414 return 0; 415 } 416 417 418 /* 419 * Module and driver stuff 420 */ 421 422 static const struct i2c_device_id lm92_id[] = { 423 { "lm92", 0 }, 424 /* max6635 could be added here */ 425 { } 426 }; 427 MODULE_DEVICE_TABLE(i2c, lm92_id); 428 429 static struct i2c_driver lm92_driver = { 430 .class = I2C_CLASS_HWMON, 431 .driver = { 432 .name = "lm92", 433 }, 434 .probe = lm92_probe, 435 .remove = lm92_remove, 436 .id_table = lm92_id, 437 .detect = lm92_detect, 438 .address_list = normal_i2c, 439 }; 440 441 module_i2c_driver(lm92_driver); 442 443 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); 444 MODULE_DESCRIPTION("LM92/MAX6635 driver"); 445 MODULE_LICENSE("GPL"); 446