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
  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");