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 /*
  53  * The LM92 and MAX6635 have 2 two-state pins for address selection,
  54  * resulting in 4 possible addresses.
  55  */
  56 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
  57                                                 I2C_CLIENT_END };
  58
  59 /* The LM92 registers */
  60 #define LM92_REG_CONFIG                 0x01 /* 8-bit, RW */
  61 #define LM92_REG_TEMP                   0x00 /* 16-bit, RO */
  62 #define LM92_REG_TEMP_HYST              0x02 /* 16-bit, RW */
  63 #define LM92_REG_TEMP_CRIT              0x03 /* 16-bit, RW */
  64 #define LM92_REG_TEMP_LOW               0x04 /* 16-bit, RW */
  65 #define LM92_REG_TEMP_HIGH              0x05 /* 16-bit, RW */
  66 #define LM92_REG_MAN_ID                 0x07 /* 16-bit, RO, LM92 only */
  67
  68 /*
  69  * The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius,
  70  * left-justified in 16-bit registers. No rounding is done, with such
  71  * a resolution it's just not worth it. Note that the MAX6635 doesn't
  72  * make use of the 4 lower bits for limits (i.e. effective resolution
  73  * for limits is 1 degree Celsius).
  74  */
  75 static inline int TEMP_FROM_REG(s16 reg)
  76 {
  77         return reg / 8 * 625 / 10;
  78 }
  79
  80 static inline s16 TEMP_TO_REG(int val)
  81 {
  82         if (val <= -60000)
  83                 return -60000 * 10 / 625 * 8;
  84         if (val >= 160000)
  85                 return 160000 * 10 / 625 * 8;
  86         return val * 10 / 625 * 8;
  87 }
  88
  89 /* Alarm flags are stored in the 3 LSB of the temperature register */
  90 static inline u8 ALARMS_FROM_REG(s16 reg)
  91 {
  92         return reg & 0x0007;
  93 }
  94
  95 /* Driver data (common to all clients) */
  96 static struct i2c_driver lm92_driver;
  97
  98 /* Client data (each client gets its own) */
  99 struct lm92_data {
 100         struct device *hwmon_dev;
 101         struct mutex update_lock;
 102         char valid; /* zero until following fields are valid */
 103         unsigned long last_updated; /* in jiffies */
 104
 105         /* registers values */
 106         s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst;
 107 };
 108
 109
 110 /*
 111  * Sysfs attributes and callback functions
 112  */
 113
 114 static struct lm92_data *lm92_update_device(struct device *dev)
 115 {
 116         struct i2c_client *client = to_i2c_client(dev);
 117         struct lm92_data *data = i2c_get_clientdata(client);
 118
 119         mutex_lock(&data->update_lock);
 120
 121         if (time_after(jiffies, data->last_updated + HZ)
 122          || !data->valid) {
 123                 dev_dbg(&client->dev, "Updating lm92 data\n");
 124                 data->temp1_input = i2c_smbus_read_word_swapped(client,
 125                                     LM92_REG_TEMP);
 126                 data->temp1_hyst = i2c_smbus_read_word_swapped(client,
 127                                     LM92_REG_TEMP_HYST);
 128                 data->temp1_crit = i2c_smbus_read_word_swapped(client,
 129                                     LM92_REG_TEMP_CRIT);
 130                 data->temp1_min = i2c_smbus_read_word_swapped(client,
 131                                     LM92_REG_TEMP_LOW);
 132                 data->temp1_max = i2c_smbus_read_word_swapped(client,
 133                                     LM92_REG_TEMP_HIGH);
 134
 135                 data->last_updated = jiffies;
 136                 data->valid = 1;
 137         }
 138
 139         mutex_unlock(&data->update_lock);
 140
 141         return data;
 142 }
 143
 144 #define show_temp(value) \
 145 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, \
 146                             char *buf) \
 147 { \
 148         struct lm92_data *data = lm92_update_device(dev); \
 149         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \
 150 }
 151 show_temp(temp1_input);
 152 show_temp(temp1_crit);
 153 show_temp(temp1_min);
 154 show_temp(temp1_max);
 155
 156 #define set_temp(value, reg) \
 157 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, \
 158                            const char *buf, \
 159         size_t count) \
 160 { \
 161         struct i2c_client *client = to_i2c_client(dev); \
 162         struct lm92_data *data = i2c_get_clientdata(client); \
 163         long val; \
 164         int err = kstrtol(buf, 10, &val); \
 165         if (err) \
 166                 return err; \
 167 \
 168         mutex_lock(&data->update_lock); \
 169         data->value = TEMP_TO_REG(val); \
 170         i2c_smbus_write_word_swapped(client, reg, data->value); \
 171         mutex_unlock(&data->update_lock); \
 172         return count; \
 173 }
 174 set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
 175 set_temp(temp1_min, LM92_REG_TEMP_LOW);
 176 set_temp(temp1_max, LM92_REG_TEMP_HIGH);
 177
 178 static ssize_t show_temp1_crit_hyst(struct device *dev,
 179                                     struct device_attribute *attr, char *buf)
 180 {
 181         struct lm92_data *data = lm92_update_device(dev);
 182         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit)
 183                        - TEMP_FROM_REG(data->temp1_hyst));
 184 }
 185 static ssize_t show_temp1_max_hyst(struct device *dev,
 186                                    struct device_attribute *attr, char *buf)
 187 {
 188         struct lm92_data *data = lm92_update_device(dev);
 189         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max)
 190                        - TEMP_FROM_REG(data->temp1_hyst));
 191 }
 192 static ssize_t show_temp1_min_hyst(struct device *dev,
 193                                    struct device_attribute *attr, char *buf)
 194 {
 195         struct lm92_data *data = lm92_update_device(dev);
 196         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min)
 197                        + TEMP_FROM_REG(data->temp1_hyst));
 198 }
 199
 200 static ssize_t set_temp1_crit_hyst(struct device *dev,
 201                                    struct device_attribute *attr,
 202                                    const char *buf, size_t count)
 203 {
 204         struct i2c_client *client = to_i2c_client(dev);
 205         struct lm92_data *data = i2c_get_clientdata(client);
 206         long val;
 207         int err;
 208
 209         err = kstrtol(buf, 10, &val);
 210         if (err)
 211                 return err;
 212
 213         mutex_lock(&data->update_lock);
 214         data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val;
 215         i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
 216                                      TEMP_TO_REG(data->temp1_hyst));
 217         mutex_unlock(&data->update_lock);
 218         return count;
 219 }
 220
 221 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr,
 222                            char *buf)
 223 {
 224         struct lm92_data *data = lm92_update_device(dev);
 225         return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input));
 226 }
 227
 228 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
 229                           char *buf)
 230 {
 231         int bitnr = to_sensor_dev_attr(attr)->index;
 232         struct lm92_data *data = lm92_update_device(dev);
 233         return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1);
 234 }
 235
 236 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
 237 static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit,
 238         set_temp1_crit);
 239 static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst,
 240         set_temp1_crit_hyst);
 241 static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min,
 242         set_temp1_min);
 243 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
 244 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max,
 245         set_temp1_max);
 246 static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
 247 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 248 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 249 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 250 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
 251
 252
 253 /*
 254  * Detection and registration
 255  */
 256
 257 static void lm92_init_client(struct i2c_client *client)
 258 {
 259         u8 config;
 260
 261         /* Start the conversions if needed */
 262         config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 263         if (config & 0x01)
 264                 i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
 265                                           config & 0xFE);
 266 }
 267
 268 /*
 269  * The MAX6635 has no identification register, so we have to use tricks
 270  * to identify it reliably. This is somewhat slow.
 271  * Note that we do NOT rely on the 2 MSB of the configuration register
 272  * always reading 0, as suggested by the datasheet, because it was once
 273  * reported not to be true.
 274  */
 275 static int max6635_check(struct i2c_client *client)
 276 {
 277         u16 temp_low, temp_high, temp_hyst, temp_crit;
 278         u8 conf;
 279         int i;
 280
 281         /*
 282          * No manufacturer ID register, so a read from this address will
 283          * always return the last read value.
 284          */
 285         temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
 286         if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
 287                 return 0;
 288         temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
 289         if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
 290                 return 0;
 291
 292         /* Limits are stored as integer values (signed, 9-bit). */
 293         if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
 294                 return 0;
 295         temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
 296         temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
 297         if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
 298                 return 0;
 299
 300         /*
 301          * Registers addresses were found to cycle over 16-byte boundaries.
 302          * We don't test all registers with all offsets so as to save some
 303          * reads and time, but this should still be sufficient to dismiss
 304          * non-MAX6635 chips.
 305          */
 306         conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 307         for (i = 16; i < 96; i *= 2) {
 308                 if (temp_hyst != i2c_smbus_read_word_data(client,
 309                                  LM92_REG_TEMP_HYST + i - 16)
 310                  || temp_crit != i2c_smbus_read_word_data(client,
 311                                  LM92_REG_TEMP_CRIT + i)
 312                  || temp_low != i2c_smbus_read_word_data(client,
 313                                 LM92_REG_TEMP_LOW + i + 16)
 314                  || temp_high != i2c_smbus_read_word_data(client,
 315                                  LM92_REG_TEMP_HIGH + i + 32)
 316                  || conf != i2c_smbus_read_byte_data(client,
 317                             LM92_REG_CONFIG + i))
 318                         return 0;
 319         }
 320
 321         return 1;
 322 }
 323
 324 static struct attribute *lm92_attributes[] = {
 325         &dev_attr_temp1_input.attr,
 326         &dev_attr_temp1_crit.attr,
 327         &dev_attr_temp1_crit_hyst.attr,
 328         &dev_attr_temp1_min.attr,
 329         &dev_attr_temp1_min_hyst.attr,
 330         &dev_attr_temp1_max.attr,
 331         &dev_attr_temp1_max_hyst.attr,
 332         &dev_attr_alarms.attr,
 333         &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 334         &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
 335         &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
 336         NULL
 337 };
 338
 339 static const struct attribute_group lm92_group = {
 340         .attrs = lm92_attributes,
 341 };
 342
 343 /* Return 0 if detection is successful, -ENODEV otherwise */
 344 static int lm92_detect(struct i2c_client *new_client,
 345                        struct i2c_board_info *info)
 346 {
 347         struct i2c_adapter *adapter = new_client->adapter;
 348         u8 config;
 349         u16 man_id;
 350
 351         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
 352                                             | I2C_FUNC_SMBUS_WORD_DATA))
 353                 return -ENODEV;
 354
 355         config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
 356         man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);
 357
 358         if ((config & 0xe0) == 0x00 && man_id == 0x0180)
 359                 pr_info("lm92: Found National Semiconductor LM92 chip\n");
 360         else if (max6635_check(new_client))
 361                 pr_info("lm92: Found Maxim MAX6635 chip\n");
 362         else
 363                 return -ENODEV;
 364
 365         strlcpy(info->type, "lm92", I2C_NAME_SIZE);
 366
 367         return 0;
 368 }
 369
 370 static int lm92_probe(struct i2c_client *new_client,
 371                       const struct i2c_device_id *id)
 372 {
 373         struct lm92_data *data;
 374         int err;
 375
 376         data = kzalloc(sizeof(struct lm92_data), GFP_KERNEL);
 377         if (!data) {
 378                 err = -ENOMEM;
 379                 goto exit;
 380         }
 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                 goto exit_free;
 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 exit_free:
 405         kfree(data);
 406 exit:
 407         return err;
 408 }
 409
 410 static int lm92_remove(struct i2c_client *client)
 411 {
 412         struct lm92_data *data = i2c_get_clientdata(client);
 413
 414         hwmon_device_unregister(data->hwmon_dev);
 415         sysfs_remove_group(&client->dev.kobj, &lm92_group);
 416
 417         kfree(data);
 418         return 0;
 419 }
 420
 421
 422 /*
 423  * Module and driver stuff
 424  */
 425
 426 static const struct i2c_device_id lm92_id[] = {
 427         { "lm92", 0 },
 428         /* max6635 could be added here */
 429         { }
 430 };
 431 MODULE_DEVICE_TABLE(i2c, lm92_id);
 432
 433 static struct i2c_driver lm92_driver = {
 434         .class          = I2C_CLASS_HWMON,
 435         .driver = {
 436                 .name   = "lm92",
 437         },
 438         .probe          = lm92_probe,
 439         .remove         = lm92_remove,
 440         .id_table       = lm92_id,
 441         .detect         = lm92_detect,
 442         .address_list   = normal_i2c,
 443 };
 444
 445 module_i2c_driver(lm92_driver);
 446
 447 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 448 MODULE_DESCRIPTION("LM92/MAX6635 driver");
 449 MODULE_LICENSE("GPL");