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
  52/*
  53 * The LM92 and MAX6635 have 2 two-state pins for address selection,
  54 * resulting in 4 possible addresses.
  55 */
  56static 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 */
  75static inline int TEMP_FROM_REG(s16 reg)
  76{
  77        return reg / 8 * 625 / 10;
  78}
  79
  80static 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 */
  90static inline u8 ALARMS_FROM_REG(s16 reg)
  91{
  92        return reg & 0x0007;
  93}
  94
  95/* Driver data (common to all clients) */
  96static struct i2c_driver lm92_driver;
  97
  98/* Client data (each client gets its own) */
  99struct 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
 114static 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) \
 145static 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}
 151show_temp(temp1_input);
 152show_temp(temp1_crit);
 153show_temp(temp1_min);
 154show_temp(temp1_max);
 155
 156#define set_temp(value, reg) \
 157static 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}
 174set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
 175set_temp(temp1_min, LM92_REG_TEMP_LOW);
 176set_temp(temp1_max, LM92_REG_TEMP_HIGH);
 177
 178static 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}
 185static 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}
 192static 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
 200static 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
 221static 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
 228static 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
 236static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
 237static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit,
 238        set_temp1_crit);
 239static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst,
 240        set_temp1_crit_hyst);
 241static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min,
 242        set_temp1_min);
 243static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
 244static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max,
 245        set_temp1_max);
 246static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
 247static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 248static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 249static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 250static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
 251
 252
 253/*
 254 * Detection and registration
 255 */
 256
 257static 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 */
 275static 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
 324static 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
 339static const struct attribute_group lm92_group = {
 340        .attrs = lm92_attributes,
 341};
 342
 343/* Return 0 if detection is successful, -ENODEV otherwise */
 344static 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
 370static 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 = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data),
 377                            GFP_KERNEL);
 378        if (!data)
 379                return -ENOMEM;
 380
 381        i2c_set_clientdata(new_client, data);
 382        data->valid = 0;
 383        mutex_init(&data->update_lock);
 384
 385        /* Initialize the chipset */
 386        lm92_init_client(new_client);
 387
 388        /* Register sysfs hooks */
 389        err = sysfs_create_group(&new_client->dev.kobj, &lm92_group);
 390        if (err)
 391                return err;
 392
 393        data->hwmon_dev = hwmon_device_register(&new_client->dev);
 394        if (IS_ERR(data->hwmon_dev)) {
 395                err = PTR_ERR(data->hwmon_dev);
 396                goto exit_remove;
 397        }
 398
 399        return 0;
 400
 401exit_remove:
 402        sysfs_remove_group(&new_client->dev.kobj, &lm92_group);
 403        return err;
 404}
 405
 406static int lm92_remove(struct i2c_client *client)
 407{
 408        struct lm92_data *data = i2c_get_clientdata(client);
 409
 410        hwmon_device_unregister(data->hwmon_dev);
 411        sysfs_remove_group(&client->dev.kobj, &lm92_group);
 412
 413        return 0;
 414}
 415
 416
 417/*
 418 * Module and driver stuff
 419 */
 420
 421static const struct i2c_device_id lm92_id[] = {
 422        { "lm92", 0 },
 423        /* max6635 could be added here */
 424        { }
 425};
 426MODULE_DEVICE_TABLE(i2c, lm92_id);
 427
 428static struct i2c_driver lm92_driver = {
 429        .class          = I2C_CLASS_HWMON,
 430        .driver = {
 431                .name   = "lm92",
 432        },
 433        .probe          = lm92_probe,
 434        .remove         = lm92_remove,
 435        .id_table       = lm92_id,
 436        .detect         = lm92_detect,
 437        .address_list   = normal_i2c,
 438};
 439
 440module_i2c_driver(lm92_driver);
 441
 442MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 443MODULE_DESCRIPTION("LM92/MAX6635 driver");
 444MODULE_LICENSE("GPL");
 445
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