drivers/hwmon/lm92.c

   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  * 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 /* Client data (each client gets its own) */
  97 struct lm92_data {
  98         struct device *hwmon_dev;
  99         struct mutex update_lock;
 100         char valid; /* zero until following fields are valid */
 101         unsigned long last_updated; /* in jiffies */
 102
 103         /* registers values */
 104         s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst;
 105 };
 106
 107
 108 /*
 109  * Sysfs attributes and callback functions
 110  */
 111
 112 static struct lm92_data *lm92_update_device(struct device *dev)
 113 {
 114         struct i2c_client *client = to_i2c_client(dev);
 115         struct lm92_data *data = i2c_get_clientdata(client);
 116
 117         mutex_lock(&data->update_lock);
 118
 119         if (time_after(jiffies, data->last_updated + HZ)
 120          || !data->valid) {
 121                 dev_dbg(&client->dev, "Updating lm92 data\n");
 122                 data->temp1_input = i2c_smbus_read_word_swapped(client,
 123                                     LM92_REG_TEMP);
 124                 data->temp1_hyst = i2c_smbus_read_word_swapped(client,
 125                                     LM92_REG_TEMP_HYST);
 126                 data->temp1_crit = i2c_smbus_read_word_swapped(client,
 127                                     LM92_REG_TEMP_CRIT);
 128                 data->temp1_min = i2c_smbus_read_word_swapped(client,
 129                                     LM92_REG_TEMP_LOW);
 130                 data->temp1_max = i2c_smbus_read_word_swapped(client,
 131                                     LM92_REG_TEMP_HIGH);
 132
 133                 data->last_updated = jiffies;
 134                 data->valid = 1;
 135         }
 136
 137         mutex_unlock(&data->update_lock);
 138
 139         return data;
 140 }
 141
 142 #define show_temp(value) \
 143 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, \
 144                             char *buf) \
 145 { \
 146         struct lm92_data *data = lm92_update_device(dev); \
 147         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \
 148 }
 149 show_temp(temp1_input);
 150 show_temp(temp1_crit);
 151 show_temp(temp1_min);
 152 show_temp(temp1_max);
 153
 154 #define set_temp(value, reg) \
 155 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, \
 156                            const char *buf, \
 157         size_t count) \
 158 { \
 159         struct i2c_client *client = to_i2c_client(dev); \
 160         struct lm92_data *data = i2c_get_clientdata(client); \
 161         long val; \
 162         int err = kstrtol(buf, 10, &val); \
 163         if (err) \
 164                 return err; \
 165 \
 166         mutex_lock(&data->update_lock); \
 167         data->value = TEMP_TO_REG(val); \
 168         i2c_smbus_write_word_swapped(client, reg, data->value); \
 169         mutex_unlock(&data->update_lock); \
 170         return count; \
 171 }
 172 set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
 173 set_temp(temp1_min, LM92_REG_TEMP_LOW);
 174 set_temp(temp1_max, LM92_REG_TEMP_HIGH);
 175
 176 static ssize_t show_temp1_crit_hyst(struct device *dev,
 177                                     struct device_attribute *attr, char *buf)
 178 {
 179         struct lm92_data *data = lm92_update_device(dev);
 180         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit)
 181                        - TEMP_FROM_REG(data->temp1_hyst));
 182 }
 183 static ssize_t show_temp1_max_hyst(struct device *dev,
 184                                    struct device_attribute *attr, char *buf)
 185 {
 186         struct lm92_data *data = lm92_update_device(dev);
 187         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max)
 188                        - TEMP_FROM_REG(data->temp1_hyst));
 189 }
 190 static ssize_t show_temp1_min_hyst(struct device *dev,
 191                                    struct device_attribute *attr, char *buf)
 192 {
 193         struct lm92_data *data = lm92_update_device(dev);
 194         return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min)
 195                        + TEMP_FROM_REG(data->temp1_hyst));
 196 }
 197
 198 static ssize_t set_temp1_crit_hyst(struct device *dev,
 199                                    struct device_attribute *attr,
 200                                    const char *buf, size_t count)
 201 {
 202         struct i2c_client *client = to_i2c_client(dev);
 203         struct lm92_data *data = i2c_get_clientdata(client);
 204         long val;
 205         int err;
 206
 207         err = kstrtol(buf, 10, &val);
 208         if (err)
 209                 return err;
 210
 211         mutex_lock(&data->update_lock);
 212         data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val;
 213         i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
 214                                      TEMP_TO_REG(data->temp1_hyst));
 215         mutex_unlock(&data->update_lock);
 216         return count;
 217 }
 218
 219 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr,
 220                            char *buf)
 221 {
 222         struct lm92_data *data = lm92_update_device(dev);
 223         return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input));
 224 }
 225
 226 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
 227                           char *buf)
 228 {
 229         int bitnr = to_sensor_dev_attr(attr)->index;
 230         struct lm92_data *data = lm92_update_device(dev);
 231         return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1);
 232 }
 233
 234 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
 235 static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit,
 236         set_temp1_crit);
 237 static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst,
 238         set_temp1_crit_hyst);
 239 static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min,
 240         set_temp1_min);
 241 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
 242 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max,
 243         set_temp1_max);
 244 static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
 245 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 246 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 247 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 248 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
 249
 250
 251 /*
 252  * Detection and registration
 253  */
 254
 255 static void lm92_init_client(struct i2c_client *client)
 256 {
 257         u8 config;
 258
 259         /* Start the conversions if needed */
 260         config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 261         if (config & 0x01)
 262                 i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
 263                                           config & 0xFE);
 264 }
 265
 266 /*
 267  * The MAX6635 has no identification register, so we have to use tricks
 268  * to identify it reliably. This is somewhat slow.
 269  * Note that we do NOT rely on the 2 MSB of the configuration register
 270  * always reading 0, as suggested by the datasheet, because it was once
 271  * reported not to be true.
 272  */
 273 static int max6635_check(struct i2c_client *client)
 274 {
 275         u16 temp_low, temp_high, temp_hyst, temp_crit;
 276         u8 conf;
 277         int i;
 278
 279         /*
 280          * No manufacturer ID register, so a read from this address will
 281          * always return the last read value.
 282          */
 283         temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
 284         if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
 285                 return 0;
 286         temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
 287         if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
 288                 return 0;
 289
 290         /* Limits are stored as integer values (signed, 9-bit). */
 291         if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
 292                 return 0;
 293         temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
 294         temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
 295         if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
 296                 return 0;
 297
 298         /*
 299          * Registers addresses were found to cycle over 16-byte boundaries.
 300          * We don't test all registers with all offsets so as to save some
 301          * reads and time, but this should still be sufficient to dismiss
 302          * non-MAX6635 chips.
 303          */
 304         conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 305         for (i = 16; i < 96; i *= 2) {
 306                 if (temp_hyst != i2c_smbus_read_word_data(client,
 307                                  LM92_REG_TEMP_HYST + i - 16)
 308                  || temp_crit != i2c_smbus_read_word_data(client,
 309                                  LM92_REG_TEMP_CRIT + i)
 310                  || temp_low != i2c_smbus_read_word_data(client,
 311                                 LM92_REG_TEMP_LOW + i + 16)
 312                  || temp_high != i2c_smbus_read_word_data(client,
 313                                  LM92_REG_TEMP_HIGH + i + 32)
 314                  || conf != i2c_smbus_read_byte_data(client,
 315                             LM92_REG_CONFIG + i))
 316                         return 0;
 317         }
 318
 319         return 1;
 320 }
 321
 322 static struct attribute *lm92_attributes[] = {
 323         &dev_attr_temp1_input.attr,
 324         &dev_attr_temp1_crit.attr,
 325         &dev_attr_temp1_crit_hyst.attr,
 326         &dev_attr_temp1_min.attr,
 327         &dev_attr_temp1_min_hyst.attr,
 328         &dev_attr_temp1_max.attr,
 329         &dev_attr_temp1_max_hyst.attr,
 330         &dev_attr_alarms.attr,
 331         &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 332         &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
 333         &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
 334         NULL
 335 };
 336
 337 static const struct attribute_group lm92_group = {
 338         .attrs = lm92_attributes,
 339 };
 340
 341 /* Return 0 if detection is successful, -ENODEV otherwise */
 342 static int lm92_detect(struct i2c_client *new_client,
 343                        struct i2c_board_info *info)
 344 {
 345         struct i2c_adapter *adapter = new_client->adapter;
 346         u8 config;
 347         u16 man_id;
 348
 349         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
 350                                             | I2C_FUNC_SMBUS_WORD_DATA))
 351                 return -ENODEV;
 352
 353         config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
 354         man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);
 355
 356         if ((config & 0xe0) == 0x00 && man_id == 0x0180)
 357                 pr_info("lm92: Found National Semiconductor LM92 chip\n");
 358         else if (max6635_check(new_client))
 359                 pr_info("lm92: Found Maxim MAX6635 chip\n");
 360         else
 361                 return -ENODEV;
 362
 363         strlcpy(info->type, "lm92", I2C_NAME_SIZE);
 364
 365         return 0;
 366 }
 367
 368 static int lm92_probe(struct i2c_client *new_client,
 369                       const struct i2c_device_id *id)
 370 {
 371         struct lm92_data *data;
 372         int err;
 373
 374         data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data),
 375                             GFP_KERNEL);
 376         if (!data)
 377                 return -ENOMEM;
 378
 379         i2c_set_clientdata(new_client, data);
 380         mutex_init(&data->update_lock);
 381
 382         /* Initialize the chipset */
 383         lm92_init_client(new_client);
 384
 385         /* Register sysfs hooks */
 386         err = sysfs_create_group(&new_client->dev.kobj, &lm92_group);
 387         if (err)
 388                 return err;
 389
 390         data->hwmon_dev = hwmon_device_register(&new_client->dev);
 391         if (IS_ERR(data->hwmon_dev)) {
 392                 err = PTR_ERR(data->hwmon_dev);
 393                 goto exit_remove;
 394         }
 395
 396         return 0;
 397
 398 exit_remove:
 399         sysfs_remove_group(&new_client->dev.kobj, &lm92_group);
 400         return err;
 401 }
 402
 403 static int lm92_remove(struct i2c_client *client)
 404 {
 405         struct lm92_data *data = i2c_get_clientdata(client);
 406
 407         hwmon_device_unregister(data->hwmon_dev);
 408         sysfs_remove_group(&client->dev.kobj, &lm92_group);
 409
 410         return 0;
 411 }
 412
 413
 414 /*
 415  * Module and driver stuff
 416  */
 417
 418 static const struct i2c_device_id lm92_id[] = {
 419         { "lm92", 0 },
 420         /* max6635 could be added here */
 421         { }
 422 };
 423 MODULE_DEVICE_TABLE(i2c, lm92_id);
 424
 425 static struct i2c_driver lm92_driver = {
 426         .class          = I2C_CLASS_HWMON,
 427         .driver = {
 428                 .name   = "lm92",
 429         },
 430         .probe          = lm92_probe,
 431         .remove         = lm92_remove,
 432         .id_table       = lm92_id,
 433         .detect         = lm92_detect,
 434         .address_list   = normal_i2c,
 435 };
 436
 437 module_i2c_driver(lm92_driver);
 438
 439 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 440 MODULE_DESCRIPTION("LM92/MAX6635 driver");
 441 MODULE_LICENSE("GPL");