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(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 */
  84 static inline u8 ALARMS_FROM_REG(s16 reg)
  85 {
  86         return reg & 0x0007;
  87 }
  88
  89 enum temp_index {
  90         t_input,
  91         t_crit,
  92         t_min,
  93         t_max,
  94         t_hyst,
  95         t_num_regs
  96 };
  97
  98 static 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) */
 107 struct 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
 121 static 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
 145 static 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
 154 static 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
 175 static 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
 184 static ssize_t temp1_min_hyst_show(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
 192 static 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
 216 static ssize_t alarms_show(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
 223 static 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
 231 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input);
 232 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp,
 233                           t_crit);
 234 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst,
 235                           set_temp_hyst, t_crit);
 236 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp,
 237                           t_min);
 238 static DEVICE_ATTR_RO(temp1_min_hyst);
 239 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp,
 240                           t_max);
 241 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max);
 242 static DEVICE_ATTR_RO(alarms);
 243 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 244 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 245 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
 246
 247 /*
 248  * Detection and registration
 249  */
 250
 251 static 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  */
 269 static 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
 318 static 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 };
 332 ATTRIBUTE_GROUPS(lm92);
 333
 334 /* Return 0 if detection is successful, -ENODEV otherwise */
 335 static 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
 361 static 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
 389 static const struct i2c_device_id lm92_id[] = {
 390         { "lm92", 0 },
 391         /* max6635 could be added here */
 392         { }
 393 };
 394 MODULE_DEVICE_TABLE(i2c, lm92_id);
 395
 396 static 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
 407 module_i2c_driver(lm92_driver);
 408
 409 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 410 MODULE_DESCRIPTION("LM92/MAX6635 driver");
 411 MODULE_LICENSE("GPL");