1 /* 2 * lm92 - Hardware monitoring driver 3 * Copyright (C) 2005-2008 Jean Delvare <jdelvare@suse.de> 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 39 #include <linux/module.h> 40 #include <linux/init.h> 41 #include <linux/slab.h> 42 #include <linux/i2c.h> 43 #include <linux/hwmon.h> 44 #include <linux/hwmon-sysfs.h> 45 #include <linux/err.h> 46 #include <linux/mutex.h> 47 #include <linux/jiffies.h> 48 49 /* 50 * The LM92 and MAX6635 have 2 two-state pins for address selection, 51 * resulting in 4 possible addresses. 52 */ 53 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 54 I2C_CLIENT_END }; 55 56 /* The LM92 registers */ 57 #define LM92_REG_CONFIG 0x01 /* 8-bit, RW */ 58 #define LM92_REG_TEMP 0x00 /* 16-bit, RO */ 59 #define LM92_REG_TEMP_HYST 0x02 /* 16-bit, RW */ 60 #define LM92_REG_TEMP_CRIT 0x03 /* 16-bit, RW */ 61 #define LM92_REG_TEMP_LOW 0x04 /* 16-bit, RW */ 62 #define LM92_REG_TEMP_HIGH 0x05 /* 16-bit, RW */ 63 #define LM92_REG_MAN_ID 0x07 /* 16-bit, RO, LM92 only */ 64 65 /* 66 * The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius, 67 * left-justified in 16-bit registers. No rounding is done, with such 68 * a resolution it's just not worth it. Note that the MAX6635 doesn't 69 * make use of the 4 lower bits for limits (i.e. effective resolution 70 * for limits is 1 degree Celsius). 71 */ 72 static inline int TEMP_FROM_REG(s16 reg) 73 { 74 return reg / 8 * 625 / 10; 75 } 76 77 static inline s16 TEMP_TO_REG(int val) 78 { 79 if (val <= -60000) 80 return -60000 * 10 / 625 * 8; 81 if (val >= 160000) 82 return 160000 * 10 / 625 * 8; 83 return val * 10 / 625 * 8; 84 } 85 86 /* Alarm flags are stored in the 3 LSB of the temperature register */ 87 static inline u8 ALARMS_FROM_REG(s16 reg) 88 { 89 return reg & 0x0007; 90 } 91 92 enum temp_index { 93 t_input, 94 t_crit, 95 t_min, 96 t_max, 97 t_hyst, 98 t_num_regs 99 }; 100 101 static const u8 regs[t_num_regs] = { 102 [t_input] = LM92_REG_TEMP, 103 [t_crit] = LM92_REG_TEMP_CRIT, 104 [t_min] = LM92_REG_TEMP_LOW, 105 [t_max] = LM92_REG_TEMP_HIGH, 106 [t_hyst] = LM92_REG_TEMP_HYST, 107 }; 108 109 /* Client data (each client gets its own) */ 110 struct lm92_data { 111 struct i2c_client *client; 112 struct mutex update_lock; 113 char valid; /* zero until following fields are valid */ 114 unsigned long last_updated; /* in jiffies */ 115 116 /* registers values */ 117 s16 temp[t_num_regs]; /* index with enum temp_index */ 118 }; 119 120 /* 121 * Sysfs attributes and callback functions 122 */ 123 124 static struct lm92_data *lm92_update_device(struct device *dev) 125 { 126 struct lm92_data *data = dev_get_drvdata(dev); 127 struct i2c_client *client = data->client; 128 int i; 129 130 mutex_lock(&data->update_lock); 131 132 if (time_after(jiffies, data->last_updated + HZ) 133 || !data->valid) { 134 dev_dbg(&client->dev, "Updating lm92 data\n"); 135 for (i = 0; i < t_num_regs; i++) { 136 data->temp[i] = 137 i2c_smbus_read_word_swapped(client, regs[i]); 138 } 139 data->last_updated = jiffies; 140 data->valid = 1; 141 } 142 143 mutex_unlock(&data->update_lock); 144 145 return data; 146 } 147 148 static ssize_t show_temp(struct device *dev, struct device_attribute *devattr, 149 char *buf) 150 { 151 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 152 struct lm92_data *data = lm92_update_device(dev); 153 154 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[attr->index])); 155 } 156 157 static ssize_t set_temp(struct device *dev, struct device_attribute *devattr, 158 const char *buf, size_t count) 159 { 160 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 161 struct lm92_data *data = dev_get_drvdata(dev); 162 struct i2c_client *client = data->client; 163 int nr = attr->index; 164 long val; 165 int err; 166 167 err = kstrtol(buf, 10, &val); 168 if (err) 169 return err; 170 171 mutex_lock(&data->update_lock); 172 data->temp[nr] = TEMP_TO_REG(val); 173 i2c_smbus_write_word_swapped(client, regs[nr], data->temp[nr]); 174 mutex_unlock(&data->update_lock); 175 return count; 176 } 177 178 static ssize_t show_temp_hyst(struct device *dev, 179 struct device_attribute *devattr, char *buf) 180 { 181 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 182 struct lm92_data *data = lm92_update_device(dev); 183 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[attr->index]) 184 - TEMP_FROM_REG(data->temp[t_hyst])); 185 } 186 187 static ssize_t show_temp_min_hyst(struct device *dev, 188 struct device_attribute *attr, char *buf) 189 { 190 struct lm92_data *data = lm92_update_device(dev); 191 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[t_min]) 192 + TEMP_FROM_REG(data->temp[t_hyst])); 193 } 194 195 static ssize_t set_temp_hyst(struct device *dev, 196 struct device_attribute *devattr, 197 const char *buf, size_t count) 198 { 199 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 200 struct lm92_data *data = dev_get_drvdata(dev); 201 struct i2c_client *client = data->client; 202 long val; 203 int err; 204 205 err = kstrtol(buf, 10, &val); 206 if (err) 207 return err; 208 209 mutex_lock(&data->update_lock); 210 data->temp[t_hyst] = TEMP_FROM_REG(data->temp[attr->index]) - val; 211 i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST, 212 TEMP_TO_REG(data->temp[t_hyst])); 213 mutex_unlock(&data->update_lock); 214 return count; 215 } 216 217 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr, 218 char *buf) 219 { 220 struct lm92_data *data = lm92_update_device(dev); 221 return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp[t_input])); 222 } 223 224 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr, 225 char *buf) 226 { 227 int bitnr = to_sensor_dev_attr(attr)->index; 228 struct lm92_data *data = lm92_update_device(dev); 229 return sprintf(buf, "%d\n", (data->temp[t_input] >> bitnr) & 1); 230 } 231 232 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input); 233 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp, 234 t_crit); 235 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst, 236 set_temp_hyst, t_crit); 237 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp, 238 t_min); 239 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp_min_hyst, NULL); 240 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp, 241 t_max); 242 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max); 243 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL); 244 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2); 245 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0); 246 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1); 247 248 /* 249 * Detection and registration 250 */ 251 252 static void lm92_init_client(struct i2c_client *client) 253 { 254 u8 config; 255 256 /* Start the conversions if needed */ 257 config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG); 258 if (config & 0x01) 259 i2c_smbus_write_byte_data(client, LM92_REG_CONFIG, 260 config & 0xFE); 261 } 262 263 /* 264 * The MAX6635 has no identification register, so we have to use tricks 265 * to identify it reliably. This is somewhat slow. 266 * Note that we do NOT rely on the 2 MSB of the configuration register 267 * always reading 0, as suggested by the datasheet, because it was once 268 * reported not to be true. 269 */ 270 static int max6635_check(struct i2c_client *client) 271 { 272 u16 temp_low, temp_high, temp_hyst, temp_crit; 273 u8 conf; 274 int i; 275 276 /* 277 * No manufacturer ID register, so a read from this address will 278 * always return the last read value. 279 */ 280 temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW); 281 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low) 282 return 0; 283 temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH); 284 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high) 285 return 0; 286 287 /* Limits are stored as integer values (signed, 9-bit). */ 288 if ((temp_low & 0x7f00) || (temp_high & 0x7f00)) 289 return 0; 290 temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST); 291 temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT); 292 if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00)) 293 return 0; 294 295 /* 296 * Registers addresses were found to cycle over 16-byte boundaries. 297 * We don't test all registers with all offsets so as to save some 298 * reads and time, but this should still be sufficient to dismiss 299 * non-MAX6635 chips. 300 */ 301 conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG); 302 for (i = 16; i < 96; i *= 2) { 303 if (temp_hyst != i2c_smbus_read_word_data(client, 304 LM92_REG_TEMP_HYST + i - 16) 305 || temp_crit != i2c_smbus_read_word_data(client, 306 LM92_REG_TEMP_CRIT + i) 307 || temp_low != i2c_smbus_read_word_data(client, 308 LM92_REG_TEMP_LOW + i + 16) 309 || temp_high != i2c_smbus_read_word_data(client, 310 LM92_REG_TEMP_HIGH + i + 32) 311 || conf != i2c_smbus_read_byte_data(client, 312 LM92_REG_CONFIG + i)) 313 return 0; 314 } 315 316 return 1; 317 } 318 319 static struct attribute *lm92_attrs[] = { 320 &sensor_dev_attr_temp1_input.dev_attr.attr, 321 &sensor_dev_attr_temp1_crit.dev_attr.attr, 322 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr, 323 &sensor_dev_attr_temp1_min.dev_attr.attr, 324 &dev_attr_temp1_min_hyst.attr, 325 &sensor_dev_attr_temp1_max.dev_attr.attr, 326 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr, 327 &dev_attr_alarms.attr, 328 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr, 329 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr, 330 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr, 331 NULL 332 }; 333 ATTRIBUTE_GROUPS(lm92); 334 335 /* Return 0 if detection is successful, -ENODEV otherwise */ 336 static int lm92_detect(struct i2c_client *new_client, 337 struct i2c_board_info *info) 338 { 339 struct i2c_adapter *adapter = new_client->adapter; 340 u8 config; 341 u16 man_id; 342 343 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA 344 | I2C_FUNC_SMBUS_WORD_DATA)) 345 return -ENODEV; 346 347 config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG); 348 man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID); 349 350 if ((config & 0xe0) == 0x00 && man_id == 0x0180) 351 pr_info("lm92: Found National Semiconductor LM92 chip\n"); 352 else if (max6635_check(new_client)) 353 pr_info("lm92: Found Maxim MAX6635 chip\n"); 354 else 355 return -ENODEV; 356 357 strlcpy(info->type, "lm92", I2C_NAME_SIZE); 358 359 return 0; 360 } 361 362 static int lm92_probe(struct i2c_client *new_client, 363 const struct i2c_device_id *id) 364 { 365 struct device *hwmon_dev; 366 struct lm92_data *data; 367 368 data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data), 369 GFP_KERNEL); 370 if (!data) 371 return -ENOMEM; 372 373 data->client = new_client; 374 mutex_init(&data->update_lock); 375 376 /* Initialize the chipset */ 377 lm92_init_client(new_client); 378 379 hwmon_dev = devm_hwmon_device_register_with_groups(&new_client->dev, 380 new_client->name, 381 data, lm92_groups); 382 return PTR_ERR_OR_ZERO(hwmon_dev); 383 } 384 385 386 /* 387 * Module and driver stuff 388 */ 389 390 static const struct i2c_device_id lm92_id[] = { 391 { "lm92", 0 }, 392 /* max6635 could be added here */ 393 { } 394 }; 395 MODULE_DEVICE_TABLE(i2c, lm92_id); 396 397 static struct i2c_driver lm92_driver = { 398 .class = I2C_CLASS_HWMON, 399 .driver = { 400 .name = "lm92", 401 }, 402 .probe = lm92_probe, 403 .id_table = lm92_id, 404 .detect = lm92_detect, 405 .address_list = normal_i2c, 406 }; 407 408 module_i2c_driver(lm92_driver); 409 410 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); 411 MODULE_DESCRIPTION("LM92/MAX6635 driver"); 412 MODULE_LICENSE("GPL"); 413