drivers/hwmon/lm92.c

   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
  52 /* The LM92 and MAX6635 have 2 two-state pins for address selection,
  53    resulting in 4 possible addresses. */
  54 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
  55                                                 I2C_CLIENT_END };
  56
  57 /* The LM92 registers */
  58 #define LM92_REG_CONFIG                 0x01 /* 8-bit, RW */
  59 #define LM92_REG_TEMP                   0x00 /* 16-bit, RO */
  60 #define LM92_REG_TEMP_HYST              0x02 /* 16-bit, RW */
  61 #define LM92_REG_TEMP_CRIT              0x03 /* 16-bit, RW */
  62 #define LM92_REG_TEMP_LOW               0x04 /* 16-bit, RW */
  63 #define LM92_REG_TEMP_HIGH              0x05 /* 16-bit, RW */
  64 #define LM92_REG_MAN_ID                 0x07 /* 16-bit, RO, LM92 only */
  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 static inline int TEMP_FROM_REG(s16 reg)
  72 {
  73         return reg / 8 * 625 / 10;
  74 }
  75
  76 static inline s16 TEMP_TO_REG(int val)
  77 {
  78         if (val <= -60000)
  79                 return -60000 * 10 / 625 * 8;
  80         if (val >= 160000)
  81                 return 160000 * 10 / 625 * 8;
  82         return val * 10 / 625 * 8;
  83 }
  84
  85 /* Alarm flags are stored in the 3 LSB of the temperature register */
  86 static inline u8 ALARMS_FROM_REG(s16 reg)
  87 {
  88         return reg & 0x0007;
  89 }
  90
  91 /* Driver data (common to all clients) */
  92 static struct i2c_driver lm92_driver;
  93
  94 /* Client data (each client gets its own) */
  95 struct lm92_data {
  96         struct device *hwmon_dev;
  97         struct mutex update_lock;
  98         char valid; /* zero until following fields are valid */
  99         unsigned long last_updated; /* in jiffies */
 100
 101         /* registers values */
 102         s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst;
 103 };
 104
 105
 106 /*
 107  * Sysfs attributes and callback functions
 108  */
 109
 110 static struct lm92_data *lm92_update_device(struct device *dev)
 111 {
 112         struct i2c_client *client = to_i2c_client(dev);
 113         struct lm92_data *data = i2c_get_clientdata(client);
 114
 115         mutex_lock(&data->update_lock);
 116
 117         if (time_after(jiffies, data->last_updated + HZ)
 118          || !data->valid) {
 119                 dev_dbg(&client->dev, "Updating lm92 data\n");
 120                 data->temp1_input = swab16(i2c_smbus_read_word_data(client,
 121                                     LM92_REG_TEMP));
 122                 data->temp1_hyst = swab16(i2c_smbus_read_word_data(client,
 123                                     LM92_REG_TEMP_HYST));
 124                 data->temp1_crit = swab16(i2c_smbus_read_word_data(client,
 125                                     LM92_REG_TEMP_CRIT));
 126                 data->temp1_min = swab16(i2c_smbus_read_word_data(client,
 127                                     LM92_REG_TEMP_LOW));
 128                 data->temp1_max = swab16(i2c_smbus_read_word_data(client,
 129                                     LM92_REG_TEMP_HIGH));
 130
 131                 data->last_updated = jiffies;
 132                 data->valid = 1;
 133         }
 134
 135         mutex_unlock(&data->update_lock);
 136
 137         return data;
 138 }
 139
 140 #define show_temp(value) \
 141 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf) \
 142 { \
 143         struct lm92_data *data = lm92_update_device(dev); \
 144         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \
 145 }
 146 show_temp(temp1_input);
 147 show_temp(temp1_crit);
 148 show_temp(temp1_min);
 149 show_temp(temp1_max);
 150
 151 #define set_temp(value, reg) \
 152 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, \
 153         size_t count) \
 154 { \
 155         struct i2c_client *client = to_i2c_client(dev); \
 156         struct lm92_data *data = i2c_get_clientdata(client); \
 157         long val = simple_strtol(buf, NULL, 10); \
 158  \
 159         mutex_lock(&data->update_lock); \
 160         data->value = TEMP_TO_REG(val); \
 161         i2c_smbus_write_word_data(client, reg, swab16(data->value)); \
 162         mutex_unlock(&data->update_lock); \
 163         return count; \
 164 }
 165 set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
 166 set_temp(temp1_min, LM92_REG_TEMP_LOW);
 167 set_temp(temp1_max, LM92_REG_TEMP_HIGH);
 168
 169 static ssize_t show_temp1_crit_hyst(struct device *dev, struct device_attribute *attr, char *buf)
 170 {
 171         struct lm92_data *data = lm92_update_device(dev);
 172         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit)
 173                        - TEMP_FROM_REG(data->temp1_hyst));
 174 }
 175 static ssize_t show_temp1_max_hyst(struct device *dev, struct device_attribute *attr, char *buf)
 176 {
 177         struct lm92_data *data = lm92_update_device(dev);
 178         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max)
 179                        - TEMP_FROM_REG(data->temp1_hyst));
 180 }
 181 static ssize_t show_temp1_min_hyst(struct device *dev, struct device_attribute *attr, char *buf)
 182 {
 183         struct lm92_data *data = lm92_update_device(dev);
 184         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min)
 185                        + TEMP_FROM_REG(data->temp1_hyst));
 186 }
 187
 188 static ssize_t set_temp1_crit_hyst(struct device *dev, struct device_attribute *attr, const char *buf,
 189         size_t count)
 190 {
 191         struct i2c_client *client = to_i2c_client(dev);
 192         struct lm92_data *data = i2c_get_clientdata(client);
 193         long val = simple_strtol(buf, NULL, 10);
 194
 195         mutex_lock(&data->update_lock);
 196         data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val;
 197         i2c_smbus_write_word_data(client, LM92_REG_TEMP_HYST,
 198                                   swab16(TEMP_TO_REG(data->temp1_hyst)));
 199         mutex_unlock(&data->update_lock);
 200         return count;
 201 }
 202
 203 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr, char *buf)
 204 {
 205         struct lm92_data *data = lm92_update_device(dev);
 206         return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input));
 207 }
 208
 209 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
 210                           char *buf)
 211 {
 212         int bitnr = to_sensor_dev_attr(attr)->index;
 213         struct lm92_data *data = lm92_update_device(dev);
 214         return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1);
 215 }
 216
 217 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
 218 static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit,
 219         set_temp1_crit);
 220 static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst,
 221         set_temp1_crit_hyst);
 222 static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min,
 223         set_temp1_min);
 224 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
 225 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max,
 226         set_temp1_max);
 227 static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
 228 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 229 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 230 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 231 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
 232
 233
 234 /*
 235  * Detection and registration
 236  */
 237
 238 static void lm92_init_client(struct i2c_client *client)
 239 {
 240         u8 config;
 241
 242         /* Start the conversions if needed */
 243         config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 244         if (config & 0x01)
 245                 i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
 246                                           config & 0xFE);
 247 }
 248
 249 /* The MAX6635 has no identification register, so we have to use tricks
 250    to identify it reliably. This is somewhat slow.
 251    Note that we do NOT rely on the 2 MSB of the configuration register
 252    always reading 0, as suggested by the datasheet, because it was once
 253    reported not to be true. */
 254 static int max6635_check(struct i2c_client *client)
 255 {
 256         u16 temp_low, temp_high, temp_hyst, temp_crit;
 257         u8 conf;
 258         int i;
 259
 260         /* No manufacturer ID register, so a read from this address will
 261            always return the last read value. */
 262         temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
 263         if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
 264                 return 0;
 265         temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
 266         if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
 267                 return 0;
 268
 269         /* Limits are stored as integer values (signed, 9-bit). */
 270         if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
 271                 return 0;
 272         temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
 273         temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
 274         if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
 275                 return 0;
 276
 277         /* Registers addresses were found to cycle over 16-byte boundaries.
 278            We don't test all registers with all offsets so as to save some
 279            reads and time, but this should still be sufficient to dismiss
 280            non-MAX6635 chips. */
 281         conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 282         for (i=16; i<96; i*=2) {
 283                 if (temp_hyst != i2c_smbus_read_word_data(client,
 284                                  LM92_REG_TEMP_HYST + i - 16)
 285                  || temp_crit != i2c_smbus_read_word_data(client,
 286                                  LM92_REG_TEMP_CRIT + i)
 287                  || temp_low != i2c_smbus_read_word_data(client,
 288                                 LM92_REG_TEMP_LOW + i + 16)
 289                  || temp_high != i2c_smbus_read_word_data(client,
 290                                  LM92_REG_TEMP_HIGH + i + 32)
 291                  || conf != i2c_smbus_read_byte_data(client,
 292                             LM92_REG_CONFIG + i))
 293                         return 0;
 294         }
 295
 296         return 1;
 297 }
 298
 299 static struct attribute *lm92_attributes[] = {
 300         &dev_attr_temp1_input.attr,
 301         &dev_attr_temp1_crit.attr,
 302         &dev_attr_temp1_crit_hyst.attr,
 303         &dev_attr_temp1_min.attr,
 304         &dev_attr_temp1_min_hyst.attr,
 305         &dev_attr_temp1_max.attr,
 306         &dev_attr_temp1_max_hyst.attr,
 307         &dev_attr_alarms.attr,
 308         &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 309         &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
 310         &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
 311         NULL
 312 };
 313
 314 static const struct attribute_group lm92_group = {
 315         .attrs = lm92_attributes,
 316 };
 317
 318 /* Return 0 if detection is successful, -ENODEV otherwise */
 319 static int lm92_detect(struct i2c_client *new_client,
 320                        struct i2c_board_info *info)
 321 {
 322         struct i2c_adapter *adapter = new_client->adapter;
 323         u8 config;
 324         u16 man_id;
 325
 326         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
 327                                             | I2C_FUNC_SMBUS_WORD_DATA))
 328                 return -ENODEV;
 329
 330         config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
 331         man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);
 332
 333         if ((config & 0xe0) == 0x00 && man_id == 0x0180)
 334                 pr_info("lm92: Found National Semiconductor LM92 chip\n");
 335         else if (max6635_check(new_client))
 336                 pr_info("lm92: Found Maxim MAX6635 chip\n");
 337         else
 338                 return -ENODEV;
 339
 340         strlcpy(info->type, "lm92", I2C_NAME_SIZE);
 341
 342         return 0;
 343 }
 344
 345 static int lm92_probe(struct i2c_client *new_client,
 346                       const struct i2c_device_id *id)
 347 {
 348         struct lm92_data *data;
 349         int err;
 350
 351         data = kzalloc(sizeof(struct lm92_data), GFP_KERNEL);
 352         if (!data) {
 353                 err = -ENOMEM;
 354                 goto exit;
 355         }
 356
 357         i2c_set_clientdata(new_client, data);
 358         data->valid = 0;
 359         mutex_init(&data->update_lock);
 360
 361         /* Initialize the chipset */
 362         lm92_init_client(new_client);
 363
 364         /* Register sysfs hooks */
 365         if ((err = sysfs_create_group(&new_client->dev.kobj, &lm92_group)))
 366                 goto exit_free;
 367
 368         data->hwmon_dev = hwmon_device_register(&new_client->dev);
 369         if (IS_ERR(data->hwmon_dev)) {
 370                 err = PTR_ERR(data->hwmon_dev);
 371                 goto exit_remove;
 372         }
 373
 374         return 0;
 375
 376 exit_remove:
 377         sysfs_remove_group(&new_client->dev.kobj, &lm92_group);
 378 exit_free:
 379         kfree(data);
 380 exit:
 381         return err;
 382 }
 383
 384 static int lm92_remove(struct i2c_client *client)
 385 {
 386         struct lm92_data *data = i2c_get_clientdata(client);
 387
 388         hwmon_device_unregister(data->hwmon_dev);
 389         sysfs_remove_group(&client->dev.kobj, &lm92_group);
 390
 391         kfree(data);
 392         return 0;
 393 }
 394
 395
 396 /*
 397  * Module and driver stuff
 398  */
 399
 400 static const struct i2c_device_id lm92_id[] = {
 401         { "lm92", 0 },
 402         /* max6635 could be added here */
 403         { }
 404 };
 405 MODULE_DEVICE_TABLE(i2c, lm92_id);
 406
 407 static struct i2c_driver lm92_driver = {
 408         .class          = I2C_CLASS_HWMON,
 409         .driver = {
 410                 .name   = "lm92",
 411         },
 412         .probe          = lm92_probe,
 413         .remove         = lm92_remove,
 414         .id_table       = lm92_id,
 415         .detect         = lm92_detect,
 416         .address_list   = normal_i2c,
 417 };
 418
 419 static int __init sensors_lm92_init(void)
 420 {
 421         return i2c_add_driver(&lm92_driver);
 422 }
 423
 424 static void __exit sensors_lm92_exit(void)
 425 {
 426         i2c_del_driver(&lm92_driver);
 427 }
 428
 429 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 430 MODULE_DESCRIPTION("LM92/MAX6635 driver");
 431 MODULE_LICENSE("GPL");
 432
 433 module_init(sensors_lm92_init);
 434 module_exit(sensors_lm92_exit);