drivers/hwmon/lm75.c

   1 /*
   2  * lm75.c - Part of lm_sensors, Linux kernel modules for hardware
   3  *       monitoring
   4  * Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/slab.h>
  24 #include <linux/jiffies.h>
  25 #include <linux/i2c.h>
  26 #include <linux/hwmon.h>
  27 #include <linux/hwmon-sysfs.h>
  28 #include <linux/err.h>
  29 #include <linux/mutex.h>
  30 #include "lm75.h"
  31
  32
  33 /*
  34  * This driver handles the LM75 and compatible digital temperature sensors.
  35  */
  36
  37 enum lm75_type {                /* keep sorted in alphabetical order */
  38         adt75,
  39         ds1775,
  40         ds75,
  41         lm75,
  42         lm75a,
  43         max6625,
  44         max6626,
  45         mcp980x,
  46         stds75,
  47         tcn75,
  48         tmp100,
  49         tmp101,
  50         tmp105,
  51         tmp175,
  52         tmp275,
  53         tmp75,
  54 };
  55
  56 /* Addresses scanned */
  57 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
  58                                         0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
  59
  60
  61 /* The LM75 registers */
  62 #define LM75_REG_CONF           0x01
  63 static const u8 LM75_REG_TEMP[3] = {
  64         0x00,           /* input */
  65         0x03,           /* max */
  66         0x02,           /* hyst */
  67 };
  68
  69 /* Each client has this additional data */
  70 struct lm75_data {
  71         struct device           *hwmon_dev;
  72         struct mutex            update_lock;
  73         u8                      orig_conf;
  74         char                    valid;          /* !=0 if registers are valid */
  75         unsigned long           last_updated;   /* In jiffies */
  76         u16                     temp[3];        /* Register values,
  77                                                    0 = input
  78                                                    1 = max
  79                                                    2 = hyst */
  80 };
  81
  82 static int lm75_read_value(struct i2c_client *client, u8 reg);
  83 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
  84 static struct lm75_data *lm75_update_device(struct device *dev);
  85
  86
  87 /*-----------------------------------------------------------------------*/
  88
  89 /* sysfs attributes for hwmon */
  90
  91 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
  92                          char *buf)
  93 {
  94         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  95         struct lm75_data *data = lm75_update_device(dev);
  96
  97         if (IS_ERR(data))
  98                 return PTR_ERR(data);
  99
 100         return sprintf(buf, "%d\n",
 101                        LM75_TEMP_FROM_REG(data->temp[attr->index]));
 102 }
 103
 104 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
 105                         const char *buf, size_t count)
 106 {
 107         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 108         struct i2c_client *client = to_i2c_client(dev);
 109         struct lm75_data *data = i2c_get_clientdata(client);
 110         int nr = attr->index;
 111         long temp;
 112         int error;
 113
 114         error = kstrtol(buf, 10, &temp);
 115         if (error)
 116                 return error;
 117
 118         mutex_lock(&data->update_lock);
 119         data->temp[nr] = LM75_TEMP_TO_REG(temp);
 120         lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
 121         mutex_unlock(&data->update_lock);
 122         return count;
 123 }
 124
 125 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
 126                         show_temp, set_temp, 1);
 127 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
 128                         show_temp, set_temp, 2);
 129 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
 130
 131 static struct attribute *lm75_attributes[] = {
 132         &sensor_dev_attr_temp1_input.dev_attr.attr,
 133         &sensor_dev_attr_temp1_max.dev_attr.attr,
 134         &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
 135
 136         NULL
 137 };
 138
 139 static const struct attribute_group lm75_group = {
 140         .attrs = lm75_attributes,
 141 };
 142
 143 /*-----------------------------------------------------------------------*/
 144
 145 /* device probe and removal */
 146
 147 static int
 148 lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 149 {
 150         struct lm75_data *data;
 151         int status;
 152         u8 set_mask, clr_mask;
 153         int new;
 154
 155         if (!i2c_check_functionality(client->adapter,
 156                         I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
 157                 return -EIO;
 158
 159         data = devm_kzalloc(&client->dev, sizeof(struct lm75_data), GFP_KERNEL);
 160         if (!data)
 161                 return -ENOMEM;
 162
 163         i2c_set_clientdata(client, data);
 164         mutex_init(&data->update_lock);
 165
 166         /* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
 167          * Then tweak to be more precise when appropriate.
 168          */
 169         set_mask = 0;
 170         clr_mask = (1 << 0)                     /* continuous conversions */
 171                 | (1 << 6) | (1 << 5);          /* 9-bit mode */
 172
 173         /* configure as specified */
 174         status = lm75_read_value(client, LM75_REG_CONF);
 175         if (status < 0) {
 176                 dev_dbg(&client->dev, "Can't read config? %d\n", status);
 177                 return status;
 178         }
 179         data->orig_conf = status;
 180         new = status & ~clr_mask;
 181         new |= set_mask;
 182         if (status != new)
 183                 lm75_write_value(client, LM75_REG_CONF, new);
 184         dev_dbg(&client->dev, "Config %02x\n", new);
 185
 186         /* Register sysfs hooks */
 187         status = sysfs_create_group(&client->dev.kobj, &lm75_group);
 188         if (status)
 189                 return status;
 190
 191         data->hwmon_dev = hwmon_device_register(&client->dev);
 192         if (IS_ERR(data->hwmon_dev)) {
 193                 status = PTR_ERR(data->hwmon_dev);
 194                 goto exit_remove;
 195         }
 196
 197         dev_info(&client->dev, "%s: sensor '%s'\n",
 198                  dev_name(data->hwmon_dev), client->name);
 199
 200         return 0;
 201
 202 exit_remove:
 203         sysfs_remove_group(&client->dev.kobj, &lm75_group);
 204         return status;
 205 }
 206
 207 static int lm75_remove(struct i2c_client *client)
 208 {
 209         struct lm75_data *data = i2c_get_clientdata(client);
 210
 211         hwmon_device_unregister(data->hwmon_dev);
 212         sysfs_remove_group(&client->dev.kobj, &lm75_group);
 213         lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
 214         return 0;
 215 }
 216
 217 static const struct i2c_device_id lm75_ids[] = {
 218         { "adt75", adt75, },
 219         { "ds1775", ds1775, },
 220         { "ds75", ds75, },
 221         { "lm75", lm75, },
 222         { "lm75a", lm75a, },
 223         { "max6625", max6625, },
 224         { "max6626", max6626, },
 225         { "mcp980x", mcp980x, },
 226         { "stds75", stds75, },
 227         { "tcn75", tcn75, },
 228         { "tmp100", tmp100, },
 229         { "tmp101", tmp101, },
 230         { "tmp105", tmp105, },
 231         { "tmp175", tmp175, },
 232         { "tmp275", tmp275, },
 233         { "tmp75", tmp75, },
 234         { /* LIST END */ }
 235 };
 236 MODULE_DEVICE_TABLE(i2c, lm75_ids);
 237
 238 #define LM75A_ID 0xA1
 239
 240 /* Return 0 if detection is successful, -ENODEV otherwise */
 241 static int lm75_detect(struct i2c_client *new_client,
 242                        struct i2c_board_info *info)
 243 {
 244         struct i2c_adapter *adapter = new_client->adapter;
 245         int i;
 246         int conf, hyst, os;
 247         bool is_lm75a = 0;
 248
 249         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 250                                      I2C_FUNC_SMBUS_WORD_DATA))
 251                 return -ENODEV;
 252
 253         /*
 254          * Now, we do the remaining detection. There is no identification-
 255          * dedicated register so we have to rely on several tricks:
 256          * unused bits, registers cycling over 8-address boundaries,
 257          * addresses 0x04-0x07 returning the last read value.
 258          * The cycling+unused addresses combination is not tested,
 259          * since it would significantly slow the detection down and would
 260          * hardly add any value.
 261          *
 262          * The National Semiconductor LM75A is different than earlier
 263          * LM75s.  It has an ID byte of 0xaX (where X is the chip
 264          * revision, with 1 being the only revision in existence) in
 265          * register 7, and unused registers return 0xff rather than the
 266          * last read value.
 267          *
 268          * Note that this function only detects the original National
 269          * Semiconductor LM75 and the LM75A. Clones from other vendors
 270          * aren't detected, on purpose, because they are typically never
 271          * found on PC hardware. They are found on embedded designs where
 272          * they can be instantiated explicitly so detection is not needed.
 273          * The absence of identification registers on all these clones
 274          * would make their exhaustive detection very difficult and weak,
 275          * and odds are that the driver would bind to unsupported devices.
 276          */
 277
 278         /* Unused bits */
 279         conf = i2c_smbus_read_byte_data(new_client, 1);
 280         if (conf & 0xe0)
 281                 return -ENODEV;
 282
 283         /* First check for LM75A */
 284         if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
 285                 /* LM75A returns 0xff on unused registers so
 286                    just to be sure we check for that too. */
 287                 if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
 288                  || i2c_smbus_read_byte_data(new_client, 5) != 0xff
 289                  || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
 290                         return -ENODEV;
 291                 is_lm75a = 1;
 292                 hyst = i2c_smbus_read_byte_data(new_client, 2);
 293                 os = i2c_smbus_read_byte_data(new_client, 3);
 294         } else { /* Traditional style LM75 detection */
 295                 /* Unused addresses */
 296                 hyst = i2c_smbus_read_byte_data(new_client, 2);
 297                 if (i2c_smbus_read_byte_data(new_client, 4) != hyst
 298                  || i2c_smbus_read_byte_data(new_client, 5) != hyst
 299                  || i2c_smbus_read_byte_data(new_client, 6) != hyst
 300                  || i2c_smbus_read_byte_data(new_client, 7) != hyst)
 301                         return -ENODEV;
 302                 os = i2c_smbus_read_byte_data(new_client, 3);
 303                 if (i2c_smbus_read_byte_data(new_client, 4) != os
 304                  || i2c_smbus_read_byte_data(new_client, 5) != os
 305                  || i2c_smbus_read_byte_data(new_client, 6) != os
 306                  || i2c_smbus_read_byte_data(new_client, 7) != os)
 307                         return -ENODEV;
 308         }
 309
 310         /* Addresses cycling */
 311         for (i = 8; i <= 248; i += 40) {
 312                 if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
 313                  || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
 314                  || i2c_smbus_read_byte_data(new_client, i + 3) != os)
 315                         return -ENODEV;
 316                 if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
 317                                 != LM75A_ID)
 318                         return -ENODEV;
 319         }
 320
 321         strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);
 322
 323         return 0;
 324 }
 325
 326 #ifdef CONFIG_PM
 327 static int lm75_suspend(struct device *dev)
 328 {
 329         int status;
 330         struct i2c_client *client = to_i2c_client(dev);
 331         status = lm75_read_value(client, LM75_REG_CONF);
 332         if (status < 0) {
 333                 dev_dbg(&client->dev, "Can't read config? %d\n", status);
 334                 return status;
 335         }
 336         status = status | LM75_SHUTDOWN;
 337         lm75_write_value(client, LM75_REG_CONF, status);
 338         return 0;
 339 }
 340
 341 static int lm75_resume(struct device *dev)
 342 {
 343         int status;
 344         struct i2c_client *client = to_i2c_client(dev);
 345         status = lm75_read_value(client, LM75_REG_CONF);
 346         if (status < 0) {
 347                 dev_dbg(&client->dev, "Can't read config? %d\n", status);
 348                 return status;
 349         }
 350         status = status & ~LM75_SHUTDOWN;
 351         lm75_write_value(client, LM75_REG_CONF, status);
 352         return 0;
 353 }
 354
 355 static const struct dev_pm_ops lm75_dev_pm_ops = {
 356         .suspend        = lm75_suspend,
 357         .resume         = lm75_resume,
 358 };
 359 #define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
 360 #else
 361 #define LM75_DEV_PM_OPS NULL
 362 #endif /* CONFIG_PM */
 363
 364 static struct i2c_driver lm75_driver = {
 365         .class          = I2C_CLASS_HWMON,
 366         .driver = {
 367                 .name   = "lm75",
 368                 .pm     = LM75_DEV_PM_OPS,
 369         },
 370         .probe          = lm75_probe,
 371         .remove         = lm75_remove,
 372         .id_table       = lm75_ids,
 373         .detect         = lm75_detect,
 374         .address_list   = normal_i2c,
 375 };
 376
 377 /*-----------------------------------------------------------------------*/
 378
 379 /* register access */
 380
 381 /*
 382  * All registers are word-sized, except for the configuration register.
 383  * LM75 uses a high-byte first convention, which is exactly opposite to
 384  * the SMBus standard.
 385  */
 386 static int lm75_read_value(struct i2c_client *client, u8 reg)
 387 {
 388         if (reg == LM75_REG_CONF)
 389                 return i2c_smbus_read_byte_data(client, reg);
 390         else
 391                 return i2c_smbus_read_word_swapped(client, reg);
 392 }
 393
 394 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
 395 {
 396         if (reg == LM75_REG_CONF)
 397                 return i2c_smbus_write_byte_data(client, reg, value);
 398         else
 399                 return i2c_smbus_write_word_swapped(client, reg, value);
 400 }
 401
 402 static struct lm75_data *lm75_update_device(struct device *dev)
 403 {
 404         struct i2c_client *client = to_i2c_client(dev);
 405         struct lm75_data *data = i2c_get_clientdata(client);
 406         struct lm75_data *ret = data;
 407
 408         mutex_lock(&data->update_lock);
 409
 410         if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 411             || !data->valid) {
 412                 int i;
 413                 dev_dbg(&client->dev, "Starting lm75 update\n");
 414
 415                 for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
 416                         int status;
 417
 418                         status = lm75_read_value(client, LM75_REG_TEMP[i]);
 419                         if (unlikely(status < 0)) {
 420                                 dev_dbg(dev,
 421                                         "LM75: Failed to read value: reg %d, error %d\n",
 422                                         LM75_REG_TEMP[i], status);
 423                                 ret = ERR_PTR(status);
 424                                 data->valid = 0;
 425                                 goto abort;
 426                         }
 427                         data->temp[i] = status;
 428                 }
 429                 data->last_updated = jiffies;
 430                 data->valid = 1;
 431         }
 432
 433 abort:
 434         mutex_unlock(&data->update_lock);
 435         return ret;
 436 }
 437
 438 module_i2c_driver(lm75_driver);
 439
 440 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
 441 MODULE_DESCRIPTION("LM75 driver");
 442 MODULE_LICENSE("GPL");