linux/drivers/hwmon/lm92.c
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   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#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 */
  57static 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 */
  76static inline int TEMP_FROM_REG(s16 reg)
  77{
  78        return reg / 8 * 625 / 10;
  79}
  80
  81static 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 */
  91static inline u8 ALARMS_FROM_REG(s16 reg)
  92{
  93        return reg & 0x0007;
  94}
  95
  96/* Driver data (common to all clients) */
  97static struct i2c_driver lm92_driver;
  98
  99/* Client data (each client gets its own) */
 100struct lm92_data {
 101        struct device *hwmon_dev;
 102        struct mutex update_lock;
 103        char valid; /* zero until following fields are valid */
 104        unsigned long last_updated; /* in jiffies */
 105
 106        /* registers values */
 107        s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst;
 108};
 109
 110
 111/*
 112 * Sysfs attributes and callback functions
 113 */
 114
 115static struct lm92_data *lm92_update_device(struct device *dev)
 116{
 117        struct i2c_client *client = to_i2c_client(dev);
 118        struct lm92_data *data = i2c_get_clientdata(client);
 119
 120        mutex_lock(&data->update_lock);
 121
 122        if (time_after(jiffies, data->last_updated + HZ)
 123         || !data->valid) {
 124                dev_dbg(&client->dev, "Updating lm92 data\n");
 125                data->temp1_input = i2c_smbus_read_word_swapped(client,
 126                                    LM92_REG_TEMP);
 127                data->temp1_hyst = i2c_smbus_read_word_swapped(client,
 128                                    LM92_REG_TEMP_HYST);
 129                data->temp1_crit = i2c_smbus_read_word_swapped(client,
 130                                    LM92_REG_TEMP_CRIT);
 131                data->temp1_min = i2c_smbus_read_word_swapped(client,
 132                                    LM92_REG_TEMP_LOW);
 133                data->temp1_max = i2c_smbus_read_word_swapped(client,
 134                                    LM92_REG_TEMP_HIGH);
 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#define show_temp(value) \
 146static ssize_t show_##value(struct device *dev, struct device_attribute *attr, \
 147                            char *buf) \
 148{ \
 149        struct lm92_data *data = lm92_update_device(dev); \
 150        return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \
 151}
 152show_temp(temp1_input);
 153show_temp(temp1_crit);
 154show_temp(temp1_min);
 155show_temp(temp1_max);
 156
 157#define set_temp(value, reg) \
 158static ssize_t set_##value(struct device *dev, struct device_attribute *attr, \
 159                           const char *buf, \
 160        size_t count) \
 161{ \
 162        struct i2c_client *client = to_i2c_client(dev); \
 163        struct lm92_data *data = i2c_get_clientdata(client); \
 164        long val; \
 165        int err = kstrtol(buf, 10, &val); \
 166        if (err) \
 167                return err; \
 168\
 169        mutex_lock(&data->update_lock); \
 170        data->value = TEMP_TO_REG(val); \
 171        i2c_smbus_write_word_swapped(client, reg, data->value); \
 172        mutex_unlock(&data->update_lock); \
 173        return count; \
 174}
 175set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
 176set_temp(temp1_min, LM92_REG_TEMP_LOW);
 177set_temp(temp1_max, LM92_REG_TEMP_HIGH);
 178
 179static ssize_t show_temp1_crit_hyst(struct device *dev,
 180                                    struct device_attribute *attr, char *buf)
 181{
 182        struct lm92_data *data = lm92_update_device(dev);
 183        return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit)
 184                       - TEMP_FROM_REG(data->temp1_hyst));
 185}
 186static ssize_t show_temp1_max_hyst(struct device *dev,
 187                                   struct device_attribute *attr, char *buf)
 188{
 189        struct lm92_data *data = lm92_update_device(dev);
 190        return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max)
 191                       - TEMP_FROM_REG(data->temp1_hyst));
 192}
 193static ssize_t show_temp1_min_hyst(struct device *dev,
 194                                   struct device_attribute *attr, char *buf)
 195{
 196        struct lm92_data *data = lm92_update_device(dev);
 197        return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min)
 198                       + TEMP_FROM_REG(data->temp1_hyst));
 199}
 200
 201static ssize_t set_temp1_crit_hyst(struct device *dev,
 202                                   struct device_attribute *attr,
 203                                   const char *buf, size_t count)
 204{
 205        struct i2c_client *client = to_i2c_client(dev);
 206        struct lm92_data *data = i2c_get_clientdata(client);
 207        long val;
 208        int err;
 209
 210        err = kstrtol(buf, 10, &val);
 211        if (err)
 212                return err;
 213
 214        mutex_lock(&data->update_lock);
 215        data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val;
 216        i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
 217                                     TEMP_TO_REG(data->temp1_hyst));
 218        mutex_unlock(&data->update_lock);
 219        return count;
 220}
 221
 222static ssize_t show_alarms(struct device *dev, struct device_attribute *attr,
 223                           char *buf)
 224{
 225        struct lm92_data *data = lm92_update_device(dev);
 226        return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input));
 227}
 228
 229static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
 230                          char *buf)
 231{
 232        int bitnr = to_sensor_dev_attr(attr)->index;
 233        struct lm92_data *data = lm92_update_device(dev);
 234        return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1);
 235}
 236
 237static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
 238static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit,
 239        set_temp1_crit);
 240static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst,
 241        set_temp1_crit_hyst);
 242static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min,
 243        set_temp1_min);
 244static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
 245static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max,
 246        set_temp1_max);
 247static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
 248static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 249static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 250static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 251static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
 252
 253
 254/*
 255 * Detection and registration
 256 */
 257
 258static void lm92_init_client(struct i2c_client *client)
 259{
 260        u8 config;
 261
 262        /* Start the conversions if needed */
 263        config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 264        if (config & 0x01)
 265                i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
 266                                          config & 0xFE);
 267}
 268
 269/*
 270 * The MAX6635 has no identification register, so we have to use tricks
 271 * to identify it reliably. This is somewhat slow.
 272 * Note that we do NOT rely on the 2 MSB of the configuration register
 273 * always reading 0, as suggested by the datasheet, because it was once
 274 * reported not to be true.
 275 */
 276static int max6635_check(struct i2c_client *client)
 277{
 278        u16 temp_low, temp_high, temp_hyst, temp_crit;
 279        u8 conf;
 280        int i;
 281
 282        /*
 283         * No manufacturer ID register, so a read from this address will
 284         * always return the last read value.
 285         */
 286        temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
 287        if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
 288                return 0;
 289        temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
 290        if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
 291                return 0;
 292
 293        /* Limits are stored as integer values (signed, 9-bit). */
 294        if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
 295                return 0;
 296        temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
 297        temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
 298        if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
 299                return 0;
 300
 301        /*
 302         * Registers addresses were found to cycle over 16-byte boundaries.
 303         * We don't test all registers with all offsets so as to save some
 304         * reads and time, but this should still be sufficient to dismiss
 305         * non-MAX6635 chips.
 306         */
 307        conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 308        for (i = 16; i < 96; i *= 2) {
 309                if (temp_hyst != i2c_smbus_read_word_data(client,
 310                                 LM92_REG_TEMP_HYST + i - 16)
 311                 || temp_crit != i2c_smbus_read_word_data(client,
 312                                 LM92_REG_TEMP_CRIT + i)
 313                 || temp_low != i2c_smbus_read_word_data(client,
 314                                LM92_REG_TEMP_LOW + i + 16)
 315                 || temp_high != i2c_smbus_read_word_data(client,
 316                                 LM92_REG_TEMP_HIGH + i + 32)
 317                 || conf != i2c_smbus_read_byte_data(client,
 318                            LM92_REG_CONFIG + i))
 319                        return 0;
 320        }
 321
 322        return 1;
 323}
 324
 325static struct attribute *lm92_attributes[] = {
 326        &dev_attr_temp1_input.attr,
 327        &dev_attr_temp1_crit.attr,
 328        &dev_attr_temp1_crit_hyst.attr,
 329        &dev_attr_temp1_min.attr,
 330        &dev_attr_temp1_min_hyst.attr,
 331        &dev_attr_temp1_max.attr,
 332        &dev_attr_temp1_max_hyst.attr,
 333        &dev_attr_alarms.attr,
 334        &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 335        &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
 336        &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
 337        NULL
 338};
 339
 340static const struct attribute_group lm92_group = {
 341        .attrs = lm92_attributes,
 342};
 343
 344/* Return 0 if detection is successful, -ENODEV otherwise */
 345static int lm92_detect(struct i2c_client *new_client,
 346                       struct i2c_board_info *info)
 347{
 348        struct i2c_adapter *adapter = new_client->adapter;
 349        u8 config;
 350        u16 man_id;
 351
 352        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
 353                                            | I2C_FUNC_SMBUS_WORD_DATA))
 354                return -ENODEV;
 355
 356        config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
 357        man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);
 358
 359        if ((config & 0xe0) == 0x00 && man_id == 0x0180)
 360                pr_info("lm92: Found National Semiconductor LM92 chip\n");
 361        else if (max6635_check(new_client))
 362                pr_info("lm92: Found Maxim MAX6635 chip\n");
 363        else
 364                return -ENODEV;
 365
 366        strlcpy(info->type, "lm92", I2C_NAME_SIZE);
 367
 368        return 0;
 369}
 370
 371static int lm92_probe(struct i2c_client *new_client,
 372                      const struct i2c_device_id *id)
 373{
 374        struct lm92_data *data;
 375        int err;
 376
 377        data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data),
 378                            GFP_KERNEL);
 379        if (!data)
 380                return -ENOMEM;
 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                return err;
 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
 402exit_remove:
 403        sysfs_remove_group(&new_client->dev.kobj, &lm92_group);
 404        return err;
 405}
 406
 407static int lm92_remove(struct i2c_client *client)
 408{
 409        struct lm92_data *data = i2c_get_clientdata(client);
 410
 411        hwmon_device_unregister(data->hwmon_dev);
 412        sysfs_remove_group(&client->dev.kobj, &lm92_group);
 413
 414        return 0;
 415}
 416
 417
 418/*
 419 * Module and driver stuff
 420 */
 421
 422static const struct i2c_device_id lm92_id[] = {
 423        { "lm92", 0 },
 424        /* max6635 could be added here */
 425        { }
 426};
 427MODULE_DEVICE_TABLE(i2c, lm92_id);
 428
 429static struct i2c_driver lm92_driver = {
 430        .class          = I2C_CLASS_HWMON,
 431        .driver = {
 432                .name   = "lm92",
 433        },
 434        .probe          = lm92_probe,
 435        .remove         = lm92_remove,
 436        .id_table       = lm92_id,
 437        .detect         = lm92_detect,
 438        .address_list   = normal_i2c,
 439};
 440
 441module_i2c_driver(lm92_driver);
 442
 443MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 444MODULE_DESCRIPTION("LM92/MAX6635 driver");
 445MODULE_LICENSE("GPL");
 446
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