drivers/i2c/chips/lm90.c

   1 /*
   2  * lm90.c - Part of lm_sensors, Linux kernel modules for hardware
   3  *          monitoring
   4  * Copyright (C) 2003-2004  Jean Delvare <khali@linux-fr.org>
   5  *
   6  * Based on the lm83 driver. The LM90 is a sensor chip made by National
   7  * Semiconductor. It reports up to two temperatures (its own plus up to
   8  * one external one) with a 0.125 deg resolution (1 deg for local
   9  * temperature) and a 3-4 deg accuracy. Complete datasheet can be
  10  * obtained from National's website at:
  11  *   http://www.national.com/pf/LM/LM90.html
  12  *
  13  * This driver also supports the LM89 and LM99, two other sensor chips
  14  * made by National Semiconductor. Both have an increased remote
  15  * temperature measurement accuracy (1 degree), and the LM99
  16  * additionally shifts remote temperatures (measured and limits) by 16
  17  * degrees, which allows for higher temperatures measurement. The
  18  * driver doesn't handle it since it can be done easily in user-space.
  19  * Complete datasheets can be obtained from National's website at:
  20  *   http://www.national.com/pf/LM/LM89.html
  21  *   http://www.national.com/pf/LM/LM99.html
  22  * Note that there is no way to differenciate between both chips.
  23  *
  24  * This driver also supports the LM86, another sensor chip made by
  25  * National Semiconductor. It is exactly similar to the LM90 except it
  26  * has a higher accuracy.
  27  * Complete datasheet can be obtained from National's website at:
  28  *   http://www.national.com/pf/LM/LM86.html
  29  *
  30  * This driver also supports the ADM1032, a sensor chip made by Analog
  31  * Devices. That chip is similar to the LM90, with a few differences
  32  * that are not handled by this driver. Complete datasheet can be
  33  * obtained from Analog's website at:
  34  *   http://products.analog.com/products/info.asp?product=ADM1032
  35  * Among others, it has a higher accuracy than the LM90, much like the
  36  * LM86 does.
  37  *
  38  * This driver also supports the MAX6657, MAX6658 and MAX6659 sensor
  39  * chips made by Maxim. These chips are similar to the LM86. Complete
  40  * datasheet can be obtained at Maxim's website at:
  41  *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
  42  * Note that there is no easy way to differenciate between the three
  43  * variants. The extra address and features of the MAX6659 are not
  44  * supported by this driver.
  45  *
  46  * This driver also supports the ADT7461 chip from Analog Devices but
  47  * only in its "compatability mode". If an ADT7461 chip is found but
  48  * is configured in non-compatible mode (where its temperature
  49  * register values are decoded differently) it is ignored by this
  50  * driver. Complete datasheet can be obtained from Analog's website
  51  * at:
  52  *   http://products.analog.com/products/info.asp?product=ADT7461
  53  *
  54  * Since the LM90 was the first chipset supported by this driver, most
  55  * comments will refer to this chipset, but are actually general and
  56  * concern all supported chipsets, unless mentioned otherwise.
  57  *
  58  * This program is free software; you can redistribute it and/or modify
  59  * it under the terms of the GNU General Public License as published by
  60  * the Free Software Foundation; either version 2 of the License, or
  61  * (at your option) any later version.
  62  *
  63  * This program is distributed in the hope that it will be useful,
  64  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  65  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  66  * GNU General Public License for more details.
  67  *
  68  * You should have received a copy of the GNU General Public License
  69  * along with this program; if not, write to the Free Software
  70  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  71  */
  72
  73 #include <linux/config.h>
  74 #include <linux/module.h>
  75 #include <linux/init.h>
  76 #include <linux/slab.h>
  77 #include <linux/jiffies.h>
  78 #include <linux/i2c.h>
  79 #include <linux/i2c-sensor.h>
  80
  81 /*
  82  * Addresses to scan
  83  * Address is fully defined internally and cannot be changed except for
  84  * MAX6659.
  85  * LM86, LM89, LM90, LM99, ADM1032, MAX6657 and MAX6658 have address 0x4c.
  86  * LM89-1, and LM99-1 have address 0x4d.
  87  * MAX6659 can have address 0x4c, 0x4d or 0x4e (unsupported).
  88  * ADT7461 always has address 0x4c.
  89  */
  90
  91 static unsigned short normal_i2c[] = { 0x4c, 0x4d, I2C_CLIENT_END };
  92 static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
  93
  94 /*
  95  * Insmod parameters
  96  */
  97
  98 SENSORS_INSMOD_6(lm90, adm1032, lm99, lm86, max6657, adt7461);
  99
 100 /*
 101  * The LM90 registers
 102  */
 103
 104 #define LM90_REG_R_MAN_ID               0xFE
 105 #define LM90_REG_R_CHIP_ID              0xFF
 106 #define LM90_REG_R_CONFIG1              0x03
 107 #define LM90_REG_W_CONFIG1              0x09
 108 #define LM90_REG_R_CONFIG2              0xBF
 109 #define LM90_REG_W_CONFIG2              0xBF
 110 #define LM90_REG_R_CONVRATE             0x04
 111 #define LM90_REG_W_CONVRATE             0x0A
 112 #define LM90_REG_R_STATUS               0x02
 113 #define LM90_REG_R_LOCAL_TEMP           0x00
 114 #define LM90_REG_R_LOCAL_HIGH           0x05
 115 #define LM90_REG_W_LOCAL_HIGH           0x0B
 116 #define LM90_REG_R_LOCAL_LOW            0x06
 117 #define LM90_REG_W_LOCAL_LOW            0x0C
 118 #define LM90_REG_R_LOCAL_CRIT           0x20
 119 #define LM90_REG_W_LOCAL_CRIT           0x20
 120 #define LM90_REG_R_REMOTE_TEMPH         0x01
 121 #define LM90_REG_R_REMOTE_TEMPL         0x10
 122 #define LM90_REG_R_REMOTE_OFFSH         0x11
 123 #define LM90_REG_W_REMOTE_OFFSH         0x11
 124 #define LM90_REG_R_REMOTE_OFFSL         0x12
 125 #define LM90_REG_W_REMOTE_OFFSL         0x12
 126 #define LM90_REG_R_REMOTE_HIGHH         0x07
 127 #define LM90_REG_W_REMOTE_HIGHH         0x0D
 128 #define LM90_REG_R_REMOTE_HIGHL         0x13
 129 #define LM90_REG_W_REMOTE_HIGHL         0x13
 130 #define LM90_REG_R_REMOTE_LOWH          0x08
 131 #define LM90_REG_W_REMOTE_LOWH          0x0E
 132 #define LM90_REG_R_REMOTE_LOWL          0x14
 133 #define LM90_REG_W_REMOTE_LOWL          0x14
 134 #define LM90_REG_R_REMOTE_CRIT          0x19
 135 #define LM90_REG_W_REMOTE_CRIT          0x19
 136 #define LM90_REG_R_TCRIT_HYST           0x21
 137 #define LM90_REG_W_TCRIT_HYST           0x21
 138
 139 /*
 140  * Conversions and various macros
 141  * For local temperatures and limits, critical limits and the hysteresis
 142  * value, the LM90 uses signed 8-bit values with LSB = 1 degree Celcius.
 143  * For remote temperatures and limits, it uses signed 11-bit values with
 144  * LSB = 0.125 degree Celcius, left-justified in 16-bit registers.
 145  */
 146
 147 #define TEMP1_FROM_REG(val)     ((val) * 1000)
 148 #define TEMP1_TO_REG(val)       ((val) <= -128000 ? -128 : \
 149                                  (val) >= 127000 ? 127 : \
 150                                  (val) < 0 ? ((val) - 500) / 1000 : \
 151                                  ((val) + 500) / 1000)
 152 #define TEMP2_FROM_REG(val)     ((val) / 32 * 125)
 153 #define TEMP2_TO_REG(val)       ((val) <= -128000 ? 0x8000 : \
 154                                  (val) >= 127875 ? 0x7FE0 : \
 155                                  (val) < 0 ? ((val) - 62) / 125 * 32 : \
 156                                  ((val) + 62) / 125 * 32)
 157 #define HYST_TO_REG(val)        ((val) <= 0 ? 0 : (val) >= 30500 ? 31 : \
 158                                  ((val) + 500) / 1000)
 159
 160 /*
 161  * ADT7461 is almost identical to LM90 except that attempts to write
 162  * values that are outside the range 0 < temp < 127 are treated as
 163  * the boundary value.
 164  */
 165
 166 #define TEMP1_TO_REG_ADT7461(val) ((val) <= 0 ? 0 : \
 167                                  (val) >= 127000 ? 127 : \
 168                                  ((val) + 500) / 1000)
 169 #define TEMP2_TO_REG_ADT7461(val) ((val) <= 0 ? 0 : \
 170                                  (val) >= 127750 ? 0x7FC0 : \
 171                                  ((val) + 125) / 250 * 64)
 172
 173 /*
 174  * Functions declaration
 175  */
 176
 177 static int lm90_attach_adapter(struct i2c_adapter *adapter);
 178 static int lm90_detect(struct i2c_adapter *adapter, int address,
 179         int kind);
 180 static void lm90_init_client(struct i2c_client *client);
 181 static int lm90_detach_client(struct i2c_client *client);
 182 static struct lm90_data *lm90_update_device(struct device *dev);
 183
 184 /*
 185  * Driver data (common to all clients)
 186  */
 187
 188 static struct i2c_driver lm90_driver = {
 189         .owner          = THIS_MODULE,
 190         .name           = "lm90",
 191         .id             = I2C_DRIVERID_LM90,
 192         .flags          = I2C_DF_NOTIFY,
 193         .attach_adapter = lm90_attach_adapter,
 194         .detach_client  = lm90_detach_client,
 195 };
 196
 197 /*
 198  * Client data (each client gets its own)
 199  */
 200
 201 struct lm90_data {
 202         struct i2c_client client;
 203         struct semaphore update_lock;
 204         char valid; /* zero until following fields are valid */
 205         unsigned long last_updated; /* in jiffies */
 206         int kind;
 207
 208         /* registers values */
 209         s8 temp_input1, temp_low1, temp_high1; /* local */
 210         s16 temp_input2, temp_low2, temp_high2; /* remote, combined */
 211         s8 temp_crit1, temp_crit2;
 212         u8 temp_hyst;
 213         u8 alarms; /* bitvector */
 214 };
 215
 216 /*
 217  * Sysfs stuff
 218  */
 219
 220 #define show_temp(value, converter) \
 221 static ssize_t show_##value(struct device *dev, char *buf) \
 222 { \
 223         struct lm90_data *data = lm90_update_device(dev); \
 224         return sprintf(buf, "%d\n", converter(data->value)); \
 225 }
 226 show_temp(temp_input1, TEMP1_FROM_REG);
 227 show_temp(temp_input2, TEMP2_FROM_REG);
 228 show_temp(temp_low1, TEMP1_FROM_REG);
 229 show_temp(temp_low2, TEMP2_FROM_REG);
 230 show_temp(temp_high1, TEMP1_FROM_REG);
 231 show_temp(temp_high2, TEMP2_FROM_REG);
 232 show_temp(temp_crit1, TEMP1_FROM_REG);
 233 show_temp(temp_crit2, TEMP1_FROM_REG);
 234
 235 #define set_temp1(value, reg) \
 236 static ssize_t set_##value(struct device *dev, const char *buf, \
 237         size_t count) \
 238 { \
 239         struct i2c_client *client = to_i2c_client(dev); \
 240         struct lm90_data *data = i2c_get_clientdata(client); \
 241         long val = simple_strtol(buf, NULL, 10); \
 242  \
 243         down(&data->update_lock); \
 244         if (data->kind == adt7461) \
 245                 data->value = TEMP1_TO_REG_ADT7461(val); \
 246         else \
 247                 data->value = TEMP1_TO_REG(val); \
 248         i2c_smbus_write_byte_data(client, reg, data->value); \
 249         up(&data->update_lock); \
 250         return count; \
 251 }
 252 #define set_temp2(value, regh, regl) \
 253 static ssize_t set_##value(struct device *dev, const char *buf, \
 254         size_t count) \
 255 { \
 256         struct i2c_client *client = to_i2c_client(dev); \
 257         struct lm90_data *data = i2c_get_clientdata(client); \
 258         long val = simple_strtol(buf, NULL, 10); \
 259  \
 260         down(&data->update_lock); \
 261         if (data->kind == adt7461) \
 262                 data->value = TEMP2_TO_REG_ADT7461(val); \
 263         else \
 264                 data->value = TEMP2_TO_REG(val); \
 265         i2c_smbus_write_byte_data(client, regh, data->value >> 8); \
 266         i2c_smbus_write_byte_data(client, regl, data->value & 0xff); \
 267         up(&data->update_lock); \
 268         return count; \
 269 }
 270 set_temp1(temp_low1, LM90_REG_W_LOCAL_LOW);
 271 set_temp2(temp_low2, LM90_REG_W_REMOTE_LOWH, LM90_REG_W_REMOTE_LOWL);
 272 set_temp1(temp_high1, LM90_REG_W_LOCAL_HIGH);
 273 set_temp2(temp_high2, LM90_REG_W_REMOTE_HIGHH, LM90_REG_W_REMOTE_HIGHL);
 274 set_temp1(temp_crit1, LM90_REG_W_LOCAL_CRIT);
 275 set_temp1(temp_crit2, LM90_REG_W_REMOTE_CRIT);
 276
 277 #define show_temp_hyst(value, basereg) \
 278 static ssize_t show_##value(struct device *dev, char *buf) \
 279 { \
 280         struct lm90_data *data = lm90_update_device(dev); \
 281         return sprintf(buf, "%d\n", TEMP1_FROM_REG(data->basereg) \
 282                        - TEMP1_FROM_REG(data->temp_hyst)); \
 283 }
 284 show_temp_hyst(temp_hyst1, temp_crit1);
 285 show_temp_hyst(temp_hyst2, temp_crit2);
 286
 287 static ssize_t set_temp_hyst1(struct device *dev, const char *buf,
 288         size_t count)
 289 {
 290         struct i2c_client *client = to_i2c_client(dev);
 291         struct lm90_data *data = i2c_get_clientdata(client);
 292         long val = simple_strtol(buf, NULL, 10);
 293         long hyst;
 294
 295         down(&data->update_lock);
 296         hyst = TEMP1_FROM_REG(data->temp_crit1) - val;
 297         i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
 298                                   HYST_TO_REG(hyst));
 299         up(&data->update_lock);
 300         return count;
 301 }
 302
 303 static ssize_t show_alarms(struct device *dev, char *buf)
 304 {
 305         struct lm90_data *data = lm90_update_device(dev);
 306         return sprintf(buf, "%d\n", data->alarms);
 307 }
 308
 309 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input1, NULL);
 310 static DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_input2, NULL);
 311 static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp_low1,
 312         set_temp_low1);
 313 static DEVICE_ATTR(temp2_min, S_IWUSR | S_IRUGO, show_temp_low2,
 314         set_temp_low2);
 315 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_high1,
 316         set_temp_high1);
 317 static DEVICE_ATTR(temp2_max, S_IWUSR | S_IRUGO, show_temp_high2,
 318         set_temp_high2);
 319 static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp_crit1,
 320         set_temp_crit1);
 321 static DEVICE_ATTR(temp2_crit, S_IWUSR | S_IRUGO, show_temp_crit2,
 322         set_temp_crit2);
 323 static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst1,
 324         set_temp_hyst1);
 325 static DEVICE_ATTR(temp2_crit_hyst, S_IRUGO, show_temp_hyst2, NULL);
 326 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 327
 328 /*
 329  * Real code
 330  */
 331
 332 static int lm90_attach_adapter(struct i2c_adapter *adapter)
 333 {
 334         if (!(adapter->class & I2C_CLASS_HWMON))
 335                 return 0;
 336         return i2c_detect(adapter, &addr_data, lm90_detect);
 337 }
 338
 339 /*
 340  * The following function does more than just detection. If detection
 341  * succeeds, it also registers the new chip.
 342  */
 343 static int lm90_detect(struct i2c_adapter *adapter, int address, int kind)
 344 {
 345         struct i2c_client *new_client;
 346         struct lm90_data *data;
 347         int err = 0;
 348         const char *name = "";
 349
 350         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 351                 goto exit;
 352
 353         if (!(data = kmalloc(sizeof(struct lm90_data), GFP_KERNEL))) {
 354                 err = -ENOMEM;
 355                 goto exit;
 356         }
 357         memset(data, 0, sizeof(struct lm90_data));
 358
 359         /* The common I2C client data is placed right before the
 360            LM90-specific data. */
 361         new_client = &data->client;
 362         i2c_set_clientdata(new_client, data);
 363         new_client->addr = address;
 364         new_client->adapter = adapter;
 365         new_client->driver = &lm90_driver;
 366         new_client->flags = 0;
 367
 368         /*
 369          * Now we do the remaining detection. A negative kind means that
 370          * the driver was loaded with no force parameter (default), so we
 371          * must both detect and identify the chip. A zero kind means that
 372          * the driver was loaded with the force parameter, the detection
 373          * step shall be skipped. A positive kind means that the driver
 374          * was loaded with the force parameter and a given kind of chip is
 375          * requested, so both the detection and the identification steps
 376          * are skipped.
 377          */
 378
 379         /* Default to an LM90 if forced */
 380         if (kind == 0)
 381                 kind = lm90;
 382
 383         if (kind < 0) { /* detection and identification */
 384                 u8 man_id, chip_id, reg_config1, reg_convrate;
 385
 386                 man_id = i2c_smbus_read_byte_data(new_client,
 387                          LM90_REG_R_MAN_ID);
 388                 chip_id = i2c_smbus_read_byte_data(new_client,
 389                           LM90_REG_R_CHIP_ID);
 390                 reg_config1 = i2c_smbus_read_byte_data(new_client,
 391                               LM90_REG_R_CONFIG1);
 392                 reg_convrate = i2c_smbus_read_byte_data(new_client,
 393                                LM90_REG_R_CONVRATE);
 394
 395                 if (man_id == 0x01) { /* National Semiconductor */
 396                         u8 reg_config2;
 397
 398                         reg_config2 = i2c_smbus_read_byte_data(new_client,
 399                                       LM90_REG_R_CONFIG2);
 400
 401                         if ((reg_config1 & 0x2A) == 0x00
 402                          && (reg_config2 & 0xF8) == 0x00
 403                          && reg_convrate <= 0x09) {
 404                                 if (address == 0x4C
 405                                  && (chip_id & 0xF0) == 0x20) { /* LM90 */
 406                                         kind = lm90;
 407                                 } else
 408                                 if ((chip_id & 0xF0) == 0x30) { /* LM89/LM99 */
 409                                         kind = lm99;
 410                                 } else
 411                                 if (address == 0x4C
 412                                  && (chip_id & 0xF0) == 0x10) { /* LM86 */
 413                                         kind = lm86;
 414                                 }
 415                         }
 416                 } else
 417                 if (man_id == 0x41) { /* Analog Devices */
 418                         if (address == 0x4C
 419                          && (chip_id & 0xF0) == 0x40 /* ADM1032 */
 420                          && (reg_config1 & 0x3F) == 0x00
 421                          && reg_convrate <= 0x0A) {
 422                                 kind = adm1032;
 423                         } else
 424                         if (address == 0x4c
 425                          && chip_id == 0x51 /* ADT7461 */
 426                          && (reg_config1 & 0x1F) == 0x00 /* check compat mode */
 427                          && reg_convrate <= 0x0A) {
 428                                 kind = adt7461;
 429                         }
 430                 } else
 431                 if (man_id == 0x4D) { /* Maxim */
 432                         /*
 433                          * The Maxim variants do NOT have a chip_id register.
 434                          * Reading from that address will return the last read
 435                          * value, which in our case is those of the man_id
 436                          * register. Likewise, the config1 register seems to
 437                          * lack a low nibble, so the value will be those of the
 438                          * previous read, so in our case those of the man_id
 439                          * register.
 440                          */
 441                         if (chip_id == man_id
 442                          && (reg_config1 & 0x1F) == (man_id & 0x0F)
 443                          && reg_convrate <= 0x09) {
 444                                 kind = max6657;
 445                         }
 446                 }
 447
 448                 if (kind <= 0) { /* identification failed */
 449                         dev_info(&adapter->dev,
 450                             "Unsupported chip (man_id=0x%02X, "
 451                             "chip_id=0x%02X).\n", man_id, chip_id);
 452                         goto exit_free;
 453                 }
 454         }
 455
 456         if (kind == lm90) {
 457                 name = "lm90";
 458         } else if (kind == adm1032) {
 459                 name = "adm1032";
 460         } else if (kind == lm99) {
 461                 name = "lm99";
 462         } else if (kind == lm86) {
 463                 name = "lm86";
 464         } else if (kind == max6657) {
 465                 name = "max6657";
 466         } else if (kind == adt7461) {
 467                 name = "adt7461";
 468         }
 469
 470         /* We can fill in the remaining client fields */
 471         strlcpy(new_client->name, name, I2C_NAME_SIZE);
 472         data->valid = 0;
 473         data->kind = kind;
 474         init_MUTEX(&data->update_lock);
 475
 476         /* Tell the I2C layer a new client has arrived */
 477         if ((err = i2c_attach_client(new_client)))
 478                 goto exit_free;
 479
 480         /* Initialize the LM90 chip */
 481         lm90_init_client(new_client);
 482
 483         /* Register sysfs hooks */
 484         device_create_file(&new_client->dev, &dev_attr_temp1_input);
 485         device_create_file(&new_client->dev, &dev_attr_temp2_input);
 486         device_create_file(&new_client->dev, &dev_attr_temp1_min);
 487         device_create_file(&new_client->dev, &dev_attr_temp2_min);
 488         device_create_file(&new_client->dev, &dev_attr_temp1_max);
 489         device_create_file(&new_client->dev, &dev_attr_temp2_max);
 490         device_create_file(&new_client->dev, &dev_attr_temp1_crit);
 491         device_create_file(&new_client->dev, &dev_attr_temp2_crit);
 492         device_create_file(&new_client->dev, &dev_attr_temp1_crit_hyst);
 493         device_create_file(&new_client->dev, &dev_attr_temp2_crit_hyst);
 494         device_create_file(&new_client->dev, &dev_attr_alarms);
 495
 496         return 0;
 497
 498 exit_free:
 499         kfree(data);
 500 exit:
 501         return err;
 502 }
 503
 504 static void lm90_init_client(struct i2c_client *client)
 505 {
 506         u8 config;
 507
 508         /*
 509          * Start the conversions.
 510          */
 511         i2c_smbus_write_byte_data(client, LM90_REG_W_CONVRATE,
 512                                   5); /* 2 Hz */
 513         config = i2c_smbus_read_byte_data(client, LM90_REG_R_CONFIG1);
 514         if (config & 0x40)
 515                 i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1,
 516                                           config & 0xBF); /* run */
 517 }
 518
 519 static int lm90_detach_client(struct i2c_client *client)
 520 {
 521         int err;
 522
 523         if ((err = i2c_detach_client(client))) {
 524                 dev_err(&client->dev, "Client deregistration failed, "
 525                         "client not detached.\n");
 526                 return err;
 527         }
 528
 529         kfree(i2c_get_clientdata(client));
 530         return 0;
 531 }
 532
 533 static struct lm90_data *lm90_update_device(struct device *dev)
 534 {
 535         struct i2c_client *client = to_i2c_client(dev);
 536         struct lm90_data *data = i2c_get_clientdata(client);
 537
 538         down(&data->update_lock);
 539
 540         if (time_after(jiffies, data->last_updated + HZ * 2) || !data->valid) {
 541                 u8 oldh, newh;
 542
 543                 dev_dbg(&client->dev, "Updating lm90 data.\n");
 544                 data->temp_input1 = i2c_smbus_read_byte_data(client,
 545                                     LM90_REG_R_LOCAL_TEMP);
 546                 data->temp_high1 = i2c_smbus_read_byte_data(client,
 547                                    LM90_REG_R_LOCAL_HIGH);
 548                 data->temp_low1 = i2c_smbus_read_byte_data(client,
 549                                   LM90_REG_R_LOCAL_LOW);
 550                 data->temp_crit1 = i2c_smbus_read_byte_data(client,
 551                                    LM90_REG_R_LOCAL_CRIT);
 552                 data->temp_crit2 = i2c_smbus_read_byte_data(client,
 553                                    LM90_REG_R_REMOTE_CRIT);
 554                 data->temp_hyst = i2c_smbus_read_byte_data(client,
 555                                   LM90_REG_R_TCRIT_HYST);
 556
 557                 /*
 558                  * There is a trick here. We have to read two registers to
 559                  * have the remote sensor temperature, but we have to beware
 560                  * a conversion could occur inbetween the readings. The
 561                  * datasheet says we should either use the one-shot
 562                  * conversion register, which we don't want to do (disables
 563                  * hardware monitoring) or monitor the busy bit, which is
 564                  * impossible (we can't read the values and monitor that bit
 565                  * at the exact same time). So the solution used here is to
 566                  * read the high byte once, then the low byte, then the high
 567                  * byte again. If the new high byte matches the old one,
 568                  * then we have a valid reading. Else we have to read the low
 569                  * byte again, and now we believe we have a correct reading.
 570                  */
 571                 oldh = i2c_smbus_read_byte_data(client,
 572                        LM90_REG_R_REMOTE_TEMPH);
 573                 data->temp_input2 = i2c_smbus_read_byte_data(client,
 574                                     LM90_REG_R_REMOTE_TEMPL);
 575                 newh = i2c_smbus_read_byte_data(client,
 576                        LM90_REG_R_REMOTE_TEMPH);
 577                 if (newh != oldh) {
 578                         data->temp_input2 = i2c_smbus_read_byte_data(client,
 579                                             LM90_REG_R_REMOTE_TEMPL);
 580 #ifdef DEBUG
 581                         oldh = i2c_smbus_read_byte_data(client,
 582                                LM90_REG_R_REMOTE_TEMPH);
 583                         /* oldh is actually newer */
 584                         if (newh != oldh)
 585                                 dev_warn(&client->dev, "Remote temperature may be "
 586                                          "wrong.\n");
 587 #endif
 588                 }
 589                 data->temp_input2 |= (newh << 8);
 590
 591                 data->temp_high2 = (i2c_smbus_read_byte_data(client,
 592                                    LM90_REG_R_REMOTE_HIGHH) << 8) +
 593                                    i2c_smbus_read_byte_data(client,
 594                                    LM90_REG_R_REMOTE_HIGHL);
 595                 data->temp_low2 = (i2c_smbus_read_byte_data(client,
 596                                   LM90_REG_R_REMOTE_LOWH) << 8) +
 597                                   i2c_smbus_read_byte_data(client,
 598                                   LM90_REG_R_REMOTE_LOWL);
 599                 data->alarms = i2c_smbus_read_byte_data(client,
 600                                LM90_REG_R_STATUS);
 601
 602                 data->last_updated = jiffies;
 603                 data->valid = 1;
 604         }
 605
 606         up(&data->update_lock);
 607
 608         return data;
 609 }
 610
 611 static int __init sensors_lm90_init(void)
 612 {
 613         return i2c_add_driver(&lm90_driver);
 614 }
 615
 616 static void __exit sensors_lm90_exit(void)
 617 {
 618         i2c_del_driver(&lm90_driver);
 619 }
 620
 621 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 622 MODULE_DESCRIPTION("LM90/ADM1032 driver");
 623 MODULE_LICENSE("GPL");
 624
 625 module_init(sensors_lm90_init);
 626 module_exit(sensors_lm90_exit);