drivers/hwmon/max6650.c

   1 /*
   2  * max6650.c - Part of lm_sensors, Linux kernel modules for hardware
   3  *             monitoring.
   4  *
   5  * (C) 2007 by Hans J. Koch <hjk@linutronix.de>
   6  *
   7  * based on code written by John Morris <john.morris@spirentcom.com>
   8  * Copyright (c) 2003 Spirent Communications
   9  * and Claus Gindhart <claus.gindhart@kontron.com>
  10  *
  11  * This module has only been tested with the MAX6650 chip. It should
  12  * also work with the MAX6651. It does not distinguish max6650 and max6651
  13  * chips.
  14  *
  15  * Tha datasheet was last seen at:
  16  *
  17  *        http://pdfserv.maxim-ic.com/en/ds/MAX6650-MAX6651.pdf
  18  *
  19  * This program is free software; you can redistribute it and/or modify
  20  * it under the terms of the GNU General Public License as published by
  21  * the Free Software Foundation; either version 2 of the License, or
  22  * (at your option) any later version.
  23  *
  24  * This program is distributed in the hope that it will be useful,
  25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27  * GNU General Public License for more details.
  28  *
  29  * You should have received a copy of the GNU General Public License
  30  * along with this program; if not, write to the Free Software
  31  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  32  */
  33
  34 #include <linux/module.h>
  35 #include <linux/init.h>
  36 #include <linux/slab.h>
  37 #include <linux/jiffies.h>
  38 #include <linux/i2c.h>
  39 #include <linux/hwmon.h>
  40 #include <linux/hwmon-sysfs.h>
  41 #include <linux/err.h>
  42
  43 /*
  44  * Addresses to scan. There are four disjoint possibilities, by pin config.
  45  */
  46
  47 static const unsigned short normal_i2c[] = {0x1b, 0x1f, 0x48, 0x4b,
  48                                                 I2C_CLIENT_END};
  49
  50 /*
  51  * Insmod parameters
  52  */
  53
  54 /* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */
  55 static int fan_voltage;
  56 /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
  57 static int prescaler;
  58 /* clock: The clock frequency of the chip the driver should assume */
  59 static int clock = 254000;
  60
  61 module_param(fan_voltage, int, S_IRUGO);
  62 module_param(prescaler, int, S_IRUGO);
  63 module_param(clock, int, S_IRUGO);
  64
  65 I2C_CLIENT_INSMOD_1(max6650);
  66
  67 /*
  68  * MAX 6650/6651 registers
  69  */
  70
  71 #define MAX6650_REG_SPEED       0x00
  72 #define MAX6650_REG_CONFIG      0x02
  73 #define MAX6650_REG_GPIO_DEF    0x04
  74 #define MAX6650_REG_DAC         0x06
  75 #define MAX6650_REG_ALARM_EN    0x08
  76 #define MAX6650_REG_ALARM       0x0A
  77 #define MAX6650_REG_TACH0       0x0C
  78 #define MAX6650_REG_TACH1       0x0E
  79 #define MAX6650_REG_TACH2       0x10
  80 #define MAX6650_REG_TACH3       0x12
  81 #define MAX6650_REG_GPIO_STAT   0x14
  82 #define MAX6650_REG_COUNT       0x16
  83
  84 /*
  85  * Config register bits
  86  */
  87
  88 #define MAX6650_CFG_V12                 0x08
  89 #define MAX6650_CFG_PRESCALER_MASK      0x07
  90 #define MAX6650_CFG_PRESCALER_2         0x01
  91 #define MAX6650_CFG_PRESCALER_4         0x02
  92 #define MAX6650_CFG_PRESCALER_8         0x03
  93 #define MAX6650_CFG_PRESCALER_16        0x04
  94 #define MAX6650_CFG_MODE_MASK           0x30
  95 #define MAX6650_CFG_MODE_ON             0x00
  96 #define MAX6650_CFG_MODE_OFF            0x10
  97 #define MAX6650_CFG_MODE_CLOSED_LOOP    0x20
  98 #define MAX6650_CFG_MODE_OPEN_LOOP      0x30
  99 #define MAX6650_COUNT_MASK              0x03
 100
 101 /* Minimum and maximum values of the FAN-RPM */
 102 #define FAN_RPM_MIN 240
 103 #define FAN_RPM_MAX 30000
 104
 105 #define DIV_FROM_REG(reg) (1 << (reg & 7))
 106
 107 static int max6650_probe(struct i2c_client *client,
 108                          const struct i2c_device_id *id);
 109 static int max6650_detect(struct i2c_client *client, int kind,
 110                           struct i2c_board_info *info);
 111 static int max6650_init_client(struct i2c_client *client);
 112 static int max6650_remove(struct i2c_client *client);
 113 static struct max6650_data *max6650_update_device(struct device *dev);
 114
 115 /*
 116  * Driver data (common to all clients)
 117  */
 118
 119 static const struct i2c_device_id max6650_id[] = {
 120         { "max6650", max6650 },
 121         { }
 122 };
 123 MODULE_DEVICE_TABLE(i2c, max6650_id);
 124
 125 static struct i2c_driver max6650_driver = {
 126         .class          = I2C_CLASS_HWMON,
 127         .driver = {
 128                 .name   = "max6650",
 129         },
 130         .probe          = max6650_probe,
 131         .remove         = max6650_remove,
 132         .id_table       = max6650_id,
 133         .detect         = max6650_detect,
 134         .address_data   = &addr_data,
 135 };
 136
 137 /*
 138  * Client data (each client gets its own)
 139  */
 140
 141 struct max6650_data
 142 {
 143         struct device *hwmon_dev;
 144         struct mutex update_lock;
 145         char valid; /* zero until following fields are valid */
 146         unsigned long last_updated; /* in jiffies */
 147
 148         /* register values */
 149         u8 speed;
 150         u8 config;
 151         u8 tach[4];
 152         u8 count;
 153         u8 dac;
 154 };
 155
 156 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
 157                        char *buf)
 158 {
 159         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 160         struct max6650_data *data = max6650_update_device(dev);
 161         int rpm;
 162
 163         /*
 164         * Calculation details:
 165         *
 166         * Each tachometer counts over an interval given by the "count"
 167         * register (0.25, 0.5, 1 or 2 seconds). This module assumes
 168         * that the fans produce two pulses per revolution (this seems
 169         * to be the most common).
 170         */
 171
 172         rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
 173         return sprintf(buf, "%d\n", rpm);
 174 }
 175
 176 /*
 177  * Set the fan speed to the specified RPM (or read back the RPM setting).
 178  * This works in closed loop mode only. Use pwm1 for open loop speed setting.
 179  *
 180  * The MAX6650/1 will automatically control fan speed when in closed loop
 181  * mode.
 182  *
 183  * Assumptions:
 184  *
 185  * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
 186  *    the clock module parameter if you need to fine tune this.
 187  *
 188  * 2) The prescaler (low three bits of the config register) has already
 189  *    been set to an appropriate value. Use the prescaler module parameter
 190  *    if your BIOS doesn't initialize the chip properly.
 191  *
 192  * The relevant equations are given on pages 21 and 22 of the datasheet.
 193  *
 194  * From the datasheet, the relevant equation when in regulation is:
 195  *
 196  *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
 197  *
 198  * where:
 199  *
 200  *    fCLK is the oscillator frequency (either the 254kHz internal
 201  *         oscillator or the externally applied clock)
 202  *
 203  *    KTACH is the value in the speed register
 204  *
 205  *    FanSpeed is the speed of the fan in rps
 206  *
 207  *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)
 208  *
 209  * When reading, we need to solve for FanSpeed. When writing, we need to
 210  * solve for KTACH.
 211  *
 212  * Note: this tachometer is completely separate from the tachometers
 213  * used to measure the fan speeds. Only one fan's speed (fan1) is
 214  * controlled.
 215  */
 216
 217 static ssize_t get_target(struct device *dev, struct device_attribute *devattr,
 218                          char *buf)
 219 {
 220         struct max6650_data *data = max6650_update_device(dev);
 221         int kscale, ktach, rpm;
 222
 223         /*
 224         * Use the datasheet equation:
 225         *
 226         *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
 227         *
 228         * then multiply by 60 to give rpm.
 229         */
 230
 231         kscale = DIV_FROM_REG(data->config);
 232         ktach = data->speed;
 233         rpm = 60 * kscale * clock / (256 * (ktach + 1));
 234         return sprintf(buf, "%d\n", rpm);
 235 }
 236
 237 static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
 238                          const char *buf, size_t count)
 239 {
 240         struct i2c_client *client = to_i2c_client(dev);
 241         struct max6650_data *data = i2c_get_clientdata(client);
 242         int rpm = simple_strtoul(buf, NULL, 10);
 243         int kscale, ktach;
 244
 245         rpm = SENSORS_LIMIT(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
 246
 247         /*
 248         * Divide the required speed by 60 to get from rpm to rps, then
 249         * use the datasheet equation:
 250         *
 251         *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
 252         */
 253
 254         mutex_lock(&data->update_lock);
 255
 256         kscale = DIV_FROM_REG(data->config);
 257         ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
 258         if (ktach < 0)
 259                 ktach = 0;
 260         if (ktach > 255)
 261                 ktach = 255;
 262         data->speed = ktach;
 263
 264         i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);
 265
 266         mutex_unlock(&data->update_lock);
 267
 268         return count;
 269 }
 270
 271 /*
 272  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 273  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 274  * speed. Note that this is done by writing directly to the chip's DAC,
 275  * it won't change the closed loop speed set by fan1_target.
 276  * Also note that due to rounding errors it is possible that you don't read
 277  * back exactly the value you have set.
 278  */
 279
 280 static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,
 281                        char *buf)
 282 {
 283         int pwm;
 284         struct max6650_data *data = max6650_update_device(dev);
 285
 286         /* Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 287            Lower DAC values mean higher speeds. */
 288         if (data->config & MAX6650_CFG_V12)
 289                 pwm = 255 - (255 * (int)data->dac)/180;
 290         else
 291                 pwm = 255 - (255 * (int)data->dac)/76;
 292
 293         if (pwm < 0)
 294                 pwm = 0;
 295
 296         return sprintf(buf, "%d\n", pwm);
 297 }
 298
 299 static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
 300                         const char *buf, size_t count)
 301 {
 302         struct i2c_client *client = to_i2c_client(dev);
 303         struct max6650_data *data = i2c_get_clientdata(client);
 304         int pwm = simple_strtoul(buf, NULL, 10);
 305
 306         pwm = SENSORS_LIMIT(pwm, 0, 255);
 307
 308         mutex_lock(&data->update_lock);
 309
 310         if (data->config & MAX6650_CFG_V12)
 311                 data->dac = 180 - (180 * pwm)/255;
 312         else
 313                 data->dac = 76 - (76 * pwm)/255;
 314
 315         i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 316
 317         mutex_unlock(&data->update_lock);
 318
 319         return count;
 320 }
 321
 322 /*
 323  * Get/Set controller mode:
 324  * Possible values:
 325  * 0 = Fan always on
 326  * 1 = Open loop, Voltage is set according to speed, not regulated.
 327  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 328  */
 329
 330 static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,
 331                           char *buf)
 332 {
 333         struct max6650_data *data = max6650_update_device(dev);
 334         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 335         int sysfs_modes[4] = {0, 1, 2, 1};
 336
 337         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 338 }
 339
 340 static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
 341                           const char *buf, size_t count)
 342 {
 343         struct i2c_client *client = to_i2c_client(dev);
 344         struct max6650_data *data = i2c_get_clientdata(client);
 345         int mode = simple_strtoul(buf, NULL, 10);
 346         int max6650_modes[3] = {0, 3, 2};
 347
 348         if ((mode < 0)||(mode > 2)) {
 349                 dev_err(&client->dev,
 350                         "illegal value for pwm1_enable (%d)\n", mode);
 351                 return -EINVAL;
 352         }
 353
 354         mutex_lock(&data->update_lock);
 355
 356         data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 357         data->config = (data->config & ~MAX6650_CFG_MODE_MASK)
 358                        | (max6650_modes[mode] << 4);
 359
 360         i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);
 361
 362         mutex_unlock(&data->update_lock);
 363
 364         return count;
 365 }
 366
 367 /*
 368  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 369  * divider. We handle this by converting between divider and counttime:
 370  *
 371  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 372  *
 373  * Lower values of k allow to connect a faster fan without the risk of
 374  * counter overflow. The price is lower resolution. You can also set counttime
 375  * using the module parameter. Note that the module parameter "prescaler" also
 376  * influences the behaviour. Unfortunately, there's no sysfs attribute
 377  * defined for that. See the data sheet for details.
 378  */
 379
 380 static ssize_t get_div(struct device *dev, struct device_attribute *devattr,
 381                        char *buf)
 382 {
 383         struct max6650_data *data = max6650_update_device(dev);
 384
 385         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 386 }
 387
 388 static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 389                        const char *buf, size_t count)
 390 {
 391         struct i2c_client *client = to_i2c_client(dev);
 392         struct max6650_data *data = i2c_get_clientdata(client);
 393         int div = simple_strtoul(buf, NULL, 10);
 394
 395         mutex_lock(&data->update_lock);
 396         switch (div) {
 397         case 1:
 398                 data->count = 0;
 399                 break;
 400         case 2:
 401                 data->count = 1;
 402                 break;
 403         case 4:
 404                 data->count = 2;
 405                 break;
 406         case 8:
 407                 data->count = 3;
 408                 break;
 409         default:
 410                 mutex_unlock(&data->update_lock);
 411                 dev_err(&client->dev,
 412                         "illegal value for fan divider (%d)\n", div);
 413                 return -EINVAL;
 414         }
 415
 416         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 417         mutex_unlock(&data->update_lock);
 418
 419         return count;
 420 }
 421
 422 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 423 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 424 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 425 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 426 static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 427 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 428 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 429 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 430
 431
 432 static struct attribute *max6650_attrs[] = {
 433         &sensor_dev_attr_fan1_input.dev_attr.attr,
 434         &sensor_dev_attr_fan2_input.dev_attr.attr,
 435         &sensor_dev_attr_fan3_input.dev_attr.attr,
 436         &sensor_dev_attr_fan4_input.dev_attr.attr,
 437         &dev_attr_fan1_target.attr,
 438         &dev_attr_fan1_div.attr,
 439         &dev_attr_pwm1_enable.attr,
 440         &dev_attr_pwm1.attr,
 441         NULL
 442 };
 443
 444 static struct attribute_group max6650_attr_grp = {
 445         .attrs = max6650_attrs,
 446 };
 447
 448 /*
 449  * Real code
 450  */
 451
 452 /* Return 0 if detection is successful, -ENODEV otherwise */
 453 static int max6650_detect(struct i2c_client *client, int kind,
 454                           struct i2c_board_info *info)
 455 {
 456         struct i2c_adapter *adapter = client->adapter;
 457         int address = client->addr;
 458
 459         dev_dbg(&adapter->dev, "max6650_detect called, kind = %d\n", kind);
 460
 461         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
 462                 dev_dbg(&adapter->dev, "max6650: I2C bus doesn't support "
 463                                         "byte read mode, skipping.\n");
 464                 return -ENODEV;
 465         }
 466
 467         /*
 468          * Now we do the remaining detection. A negative kind means that
 469          * the driver was loaded with no force parameter (default), so we
 470          * must both detect and identify the chip (actually there is only
 471          * one possible kind of chip for now, max6650). A zero kind means that
 472          * the driver was loaded with the force parameter, the detection
 473          * step shall be skipped. A positive kind means that the driver
 474          * was loaded with the force parameter and a given kind of chip is
 475          * requested, so both the detection and the identification steps
 476          * are skipped.
 477          *
 478          * Currently I can find no way to distinguish between a MAX6650 and
 479          * a MAX6651. This driver has only been tried on the former.
 480          */
 481
 482         if ((kind < 0) &&
 483            (  (i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG) & 0xC0)
 484             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_GPIO_STAT) & 0xE0)
 485             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN) & 0xE0)
 486             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM) & 0xE0)
 487             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT) & 0xFC))) {
 488                 dev_dbg(&adapter->dev,
 489                         "max6650: detection failed at 0x%02x.\n", address);
 490                 return -ENODEV;
 491         }
 492
 493         dev_info(&adapter->dev, "max6650: chip found at 0x%02x.\n", address);
 494
 495         strlcpy(info->type, "max6650", I2C_NAME_SIZE);
 496
 497         return 0;
 498 }
 499
 500 static int max6650_probe(struct i2c_client *client,
 501                          const struct i2c_device_id *id)
 502 {
 503         struct max6650_data *data;
 504         int err;
 505
 506         if (!(data = kzalloc(sizeof(struct max6650_data), GFP_KERNEL))) {
 507                 dev_err(&client->dev, "out of memory.\n");
 508                 return -ENOMEM;
 509         }
 510
 511         i2c_set_clientdata(client, data);
 512         mutex_init(&data->update_lock);
 513
 514         /*
 515          * Initialize the max6650 chip
 516          */
 517         err = max6650_init_client(client);
 518         if (err)
 519                 goto err_free;
 520
 521         err = sysfs_create_group(&client->dev.kobj, &max6650_attr_grp);
 522         if (err)
 523                 goto err_free;
 524
 525         data->hwmon_dev = hwmon_device_register(&client->dev);
 526         if (!IS_ERR(data->hwmon_dev))
 527                 return 0;
 528
 529         err = PTR_ERR(data->hwmon_dev);
 530         dev_err(&client->dev, "error registering hwmon device.\n");
 531         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 532 err_free:
 533         kfree(data);
 534         return err;
 535 }
 536
 537 static int max6650_remove(struct i2c_client *client)
 538 {
 539         struct max6650_data *data = i2c_get_clientdata(client);
 540
 541         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 542         hwmon_device_unregister(data->hwmon_dev);
 543         kfree(data);
 544         return 0;
 545 }
 546
 547 static int max6650_init_client(struct i2c_client *client)
 548 {
 549         struct max6650_data *data = i2c_get_clientdata(client);
 550         int config;
 551         int err = -EIO;
 552
 553         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 554
 555         if (config < 0) {
 556                 dev_err(&client->dev, "Error reading config, aborting.\n");
 557                 return err;
 558         }
 559
 560         switch (fan_voltage) {
 561                 case 0:
 562                         break;
 563                 case 5:
 564                         config &= ~MAX6650_CFG_V12;
 565                         break;
 566                 case 12:
 567                         config |= MAX6650_CFG_V12;
 568                         break;
 569                 default:
 570                         dev_err(&client->dev,
 571                                 "illegal value for fan_voltage (%d)\n",
 572                                 fan_voltage);
 573         }
 574
 575         dev_info(&client->dev, "Fan voltage is set to %dV.\n",
 576                  (config & MAX6650_CFG_V12) ? 12 : 5);
 577
 578         switch (prescaler) {
 579                 case 0:
 580                         break;
 581                 case 1:
 582                         config &= ~MAX6650_CFG_PRESCALER_MASK;
 583                         break;
 584                 case 2:
 585                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 586                                  | MAX6650_CFG_PRESCALER_2;
 587                         break;
 588                 case  4:
 589                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 590                                  | MAX6650_CFG_PRESCALER_4;
 591                         break;
 592                 case  8:
 593                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 594                                  | MAX6650_CFG_PRESCALER_8;
 595                         break;
 596                 case 16:
 597                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 598                                  | MAX6650_CFG_PRESCALER_16;
 599                         break;
 600                 default:
 601                         dev_err(&client->dev,
 602                                 "illegal value for prescaler (%d)\n",
 603                                 prescaler);
 604         }
 605
 606         dev_info(&client->dev, "Prescaler is set to %d.\n",
 607                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 608
 609         /* If mode is set to "full off", we change it to "open loop" and
 610          * set DAC to 255, which has the same effect. We do this because
 611          * there's no "full off" mode defined in hwmon specifcations.
 612          */
 613
 614         if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {
 615                 dev_dbg(&client->dev, "Change mode to open loop, full off.\n");
 616                 config = (config & ~MAX6650_CFG_MODE_MASK)
 617                          | MAX6650_CFG_MODE_OPEN_LOOP;
 618                 if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {
 619                         dev_err(&client->dev, "DAC write error, aborting.\n");
 620                         return err;
 621                 }
 622         }
 623
 624         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 625                 dev_err(&client->dev, "Config write error, aborting.\n");
 626                 return err;
 627         }
 628
 629         data->config = config;
 630         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 631
 632         return 0;
 633 }
 634
 635 static const u8 tach_reg[] = {
 636         MAX6650_REG_TACH0,
 637         MAX6650_REG_TACH1,
 638         MAX6650_REG_TACH2,
 639         MAX6650_REG_TACH3,
 640 };
 641
 642 static struct max6650_data *max6650_update_device(struct device *dev)
 643 {
 644         int i;
 645         struct i2c_client *client = to_i2c_client(dev);
 646         struct max6650_data *data = i2c_get_clientdata(client);
 647
 648         mutex_lock(&data->update_lock);
 649
 650         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 651                 data->speed = i2c_smbus_read_byte_data(client,
 652                                                        MAX6650_REG_SPEED);
 653                 data->config = i2c_smbus_read_byte_data(client,
 654                                                         MAX6650_REG_CONFIG);
 655                 for (i = 0; i < 4; i++) {
 656                         data->tach[i] = i2c_smbus_read_byte_data(client,
 657                                                                  tach_reg[i]);
 658                 }
 659                 data->count = i2c_smbus_read_byte_data(client,
 660                                                         MAX6650_REG_COUNT);
 661                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 662
 663                 data->last_updated = jiffies;
 664                 data->valid = 1;
 665         }
 666
 667         mutex_unlock(&data->update_lock);
 668
 669         return data;
 670 }
 671
 672 static int __init sensors_max6650_init(void)
 673 {
 674         return i2c_add_driver(&max6650_driver);
 675 }
 676
 677 static void __exit sensors_max6650_exit(void)
 678 {
 679         i2c_del_driver(&max6650_driver);
 680 }
 681
 682 MODULE_AUTHOR("Hans J. Koch");
 683 MODULE_DESCRIPTION("MAX6650 sensor driver");
 684 MODULE_LICENSE("GPL");
 685
 686 module_init(sensors_max6650_init);
 687 module_exit(sensors_max6650_exit);