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 */ 53static 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 */ 72static inline int TEMP_FROM_REG(s16 reg) 73{ 74 return reg / 8 * 625 / 10; 75} 76 77static inline s16 TEMP_TO_REG(long val) 78{ 79 val = clamp_val(val, -60000, 160000); 80 return val * 10 / 625 * 8; 81} 82 83/* Alarm flags are stored in the 3 LSB of the temperature register */ 84static inline u8 ALARMS_FROM_REG(s16 reg) 85{ 86 return reg & 0x0007; 87} 88 89enum temp_index { 90 t_input, 91 t_crit, 92 t_min, 93 t_max, 94 t_hyst, 95 t_num_regs 96}; 97 98static const u8 regs[t_num_regs] = { 99 [t_input] = LM92_REG_TEMP, 100 [t_crit] = LM92_REG_TEMP_CRIT, 101 [t_min] = LM92_REG_TEMP_LOW, 102 [t_max] = LM92_REG_TEMP_HIGH, 103 [t_hyst] = LM92_REG_TEMP_HYST, 104}; 105 106/* Client data (each client gets its own) */ 107struct lm92_data { 108 struct i2c_client *client; 109 struct mutex update_lock; 110 char valid; /* zero until following fields are valid */ 111 unsigned long last_updated; /* in jiffies */ 112 113 /* registers values */ 114 s16 temp[t_num_regs]; /* index with enum temp_index */ 115}; 116 117/* 118 * Sysfs attributes and callback functions 119 */ 120 121static struct lm92_data *lm92_update_device(struct device *dev) 122{ 123 struct lm92_data *data = dev_get_drvdata(dev); 124 struct i2c_client *client = data->client; 125 int i; 126 127 mutex_lock(&data->update_lock); 128 129 if (time_after(jiffies, data->last_updated + HZ) 130 || !data->valid) { 131 dev_dbg(&client->dev, "Updating lm92 data\n"); 132 for (i = 0; i < t_num_regs; i++) { 133 data->temp[i] = 134 i2c_smbus_read_word_swapped(client, regs[i]); 135 } 136 data->last_updated = jiffies; 137 data->valid = 1; 138 } 139 140 mutex_unlock(&data->update_lock); 141 142 return data; 143} 144 145static ssize_t show_temp(struct device *dev, struct device_attribute *devattr, 146 char *buf) 147{ 148 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 149 struct lm92_data *data = lm92_update_device(dev); 150 151 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[attr->index])); 152} 153 154static ssize_t set_temp(struct device *dev, struct device_attribute *devattr, 155 const char *buf, size_t count) 156{ 157 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 158 struct lm92_data *data = dev_get_drvdata(dev); 159 struct i2c_client *client = data->client; 160 int nr = attr->index; 161 long val; 162 int err; 163 164 err = kstrtol(buf, 10, &val); 165 if (err) 166 return err; 167 168 mutex_lock(&data->update_lock); 169 data->temp[nr] = TEMP_TO_REG(val); 170 i2c_smbus_write_word_swapped(client, regs[nr], data->temp[nr]); 171 mutex_unlock(&data->update_lock); 172 return count; 173} 174 175static ssize_t show_temp_hyst(struct device *dev, 176 struct device_attribute *devattr, char *buf) 177{ 178 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 179 struct lm92_data *data = lm92_update_device(dev); 180 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[attr->index]) 181 - TEMP_FROM_REG(data->temp[t_hyst])); 182} 183 184static ssize_t show_temp_min_hyst(struct device *dev, 185 struct device_attribute *attr, char *buf) 186{ 187 struct lm92_data *data = lm92_update_device(dev); 188 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[t_min]) 189 + TEMP_FROM_REG(data->temp[t_hyst])); 190} 191 192static ssize_t set_temp_hyst(struct device *dev, 193 struct device_attribute *devattr, 194 const char *buf, size_t count) 195{ 196 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr); 197 struct lm92_data *data = dev_get_drvdata(dev); 198 struct i2c_client *client = data->client; 199 long val; 200 int err; 201 202 err = kstrtol(buf, 10, &val); 203 if (err) 204 return err; 205 206 val = clamp_val(val, -120000, 220000); 207 mutex_lock(&data->update_lock); 208 data->temp[t_hyst] = 209 TEMP_TO_REG(TEMP_FROM_REG(data->temp[attr->index]) - val); 210 i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST, 211 data->temp[t_hyst]); 212 mutex_unlock(&data->update_lock); 213 return count; 214} 215 216static ssize_t show_alarms(struct device *dev, struct device_attribute *attr, 217 char *buf) 218{ 219 struct lm92_data *data = lm92_update_device(dev); 220 return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp[t_input])); 221} 222 223static ssize_t show_alarm(struct device *dev, struct device_attribute *attr, 224 char *buf) 225{ 226 int bitnr = to_sensor_dev_attr(attr)->index; 227 struct lm92_data *data = lm92_update_device(dev); 228 return sprintf(buf, "%d\n", (data->temp[t_input] >> bitnr) & 1); 229} 230 231static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input); 232static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp, 233 t_crit); 234static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst, 235 set_temp_hyst, t_crit); 236static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp, 237 t_min); 238static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp_min_hyst, NULL); 239static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp, 240 t_max); 241static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max); 242static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL); 243static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2); 244static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0); 245static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1); 246 247/* 248 * Detection and registration 249 */ 250 251static void lm92_init_client(struct i2c_client *client) 252{ 253 u8 config; 254 255 /* Start the conversions if needed */ 256 config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG); 257 if (config & 0x01) 258 i2c_smbus_write_byte_data(client, LM92_REG_CONFIG, 259 config & 0xFE); 260} 261 262/* 263 * The MAX6635 has no identification register, so we have to use tricks 264 * to identify it reliably. This is somewhat slow. 265 * Note that we do NOT rely on the 2 MSB of the configuration register 266 * always reading 0, as suggested by the datasheet, because it was once 267 * reported not to be true. 268 */ 269static int max6635_check(struct i2c_client *client) 270{ 271 u16 temp_low, temp_high, temp_hyst, temp_crit; 272 u8 conf; 273 int i; 274 275 /* 276 * No manufacturer ID register, so a read from this address will 277 * always return the last read value. 278 */ 279 temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW); 280 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low) 281 return 0; 282 temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH); 283 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high) 284 return 0; 285 286 /* Limits are stored as integer values (signed, 9-bit). */ 287 if ((temp_low & 0x7f00) || (temp_high & 0x7f00)) 288 return 0; 289 temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST); 290 temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT); 291 if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00)) 292 return 0; 293 294 /* 295 * Registers addresses were found to cycle over 16-byte boundaries. 296 * We don't test all registers with all offsets so as to save some 297 * reads and time, but this should still be sufficient to dismiss 298 * non-MAX6635 chips. 299 */ 300 conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG); 301 for (i = 16; i < 96; i *= 2) { 302 if (temp_hyst != i2c_smbus_read_word_data(client, 303 LM92_REG_TEMP_HYST + i - 16) 304 || temp_crit != i2c_smbus_read_word_data(client, 305 LM92_REG_TEMP_CRIT + i) 306 || temp_low != i2c_smbus_read_word_data(client, 307 LM92_REG_TEMP_LOW + i + 16) 308 || temp_high != i2c_smbus_read_word_data(client, 309 LM92_REG_TEMP_HIGH + i + 32) 310 || conf != i2c_smbus_read_byte_data(client, 311 LM92_REG_CONFIG + i)) 312 return 0; 313 } 314 315 return 1; 316} 317 318static struct attribute *lm92_attrs[] = { 319 &sensor_dev_attr_temp1_input.dev_attr.attr, 320 &sensor_dev_attr_temp1_crit.dev_attr.attr, 321 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr, 322 &sensor_dev_attr_temp1_min.dev_attr.attr, 323 &dev_attr_temp1_min_hyst.attr, 324 &sensor_dev_attr_temp1_max.dev_attr.attr, 325 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr, 326 &dev_attr_alarms.attr, 327 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr, 328 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr, 329 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr, 330 NULL 331}; 332ATTRIBUTE_GROUPS(lm92); 333 334/* Return 0 if detection is successful, -ENODEV otherwise */ 335static int lm92_detect(struct i2c_client *new_client, 336 struct i2c_board_info *info) 337{ 338 struct i2c_adapter *adapter = new_client->adapter; 339 u8 config; 340 u16 man_id; 341 342 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA 343 | I2C_FUNC_SMBUS_WORD_DATA)) 344 return -ENODEV; 345 346 config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG); 347 man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID); 348 349 if ((config & 0xe0) == 0x00 && man_id == 0x0180) 350 pr_info("lm92: Found National Semiconductor LM92 chip\n"); 351 else if (max6635_check(new_client)) 352 pr_info("lm92: Found Maxim MAX6635 chip\n"); 353 else 354 return -ENODEV; 355 356 strlcpy(info->type, "lm92", I2C_NAME_SIZE); 357 358 return 0; 359} 360 361static int lm92_probe(struct i2c_client *new_client, 362 const struct i2c_device_id *id) 363{ 364 struct device *hwmon_dev; 365 struct lm92_data *data; 366 367 data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data), 368 GFP_KERNEL); 369 if (!data) 370 return -ENOMEM; 371 372 data->client = new_client; 373 mutex_init(&data->update_lock); 374 375 /* Initialize the chipset */ 376 lm92_init_client(new_client); 377 378 hwmon_dev = devm_hwmon_device_register_with_groups(&new_client->dev, 379 new_client->name, 380 data, lm92_groups); 381 return PTR_ERR_OR_ZERO(hwmon_dev); 382} 383 384 385/* 386 * Module and driver stuff 387 */ 388 389static const struct i2c_device_id lm92_id[] = { 390 { "lm92", 0 }, 391 /* max6635 could be added here */ 392 { } 393}; 394MODULE_DEVICE_TABLE(i2c, lm92_id); 395 396static struct i2c_driver lm92_driver = { 397 .class = I2C_CLASS_HWMON, 398 .driver = { 399 .name = "lm92", 400 }, 401 .probe = lm92_probe, 402 .id_table = lm92_id, 403 .detect = lm92_detect, 404 .address_list = normal_i2c, 405}; 406 407module_i2c_driver(lm92_driver); 408 409MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); 410MODULE_DESCRIPTION("LM92/MAX6635 driver"); 411MODULE_LICENSE("GPL"); 412