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 <<<<<<< HEAD:drivers/hwmon/max6650.c
  48 static unsigned short normal_i2c[] = {0x1b, 0x1f, 0x48, 0x4b, I2C_CLIENT_END};
  49 =======
  50 static const unsigned short normal_i2c[] = {0x1b, 0x1f, 0x48, 0x4b,
  51                                                 I2C_CLIENT_END};
  52 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:drivers/hwmon/max6650.c
  53
  54 /*
  55  * Insmod parameters
  56  */
  57
  58 /* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */
  59 static int fan_voltage;
  60 /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
  61 static int prescaler;
  62 /* clock: The clock frequency of the chip the driver should assume */
  63 static int clock = 254000;
  64
  65 module_param(fan_voltage, int, S_IRUGO);
  66 module_param(prescaler, int, S_IRUGO);
  67 module_param(clock, int, S_IRUGO);
  68
  69 I2C_CLIENT_INSMOD_1(max6650);
  70
  71 /*
  72  * MAX 6650/6651 registers
  73  */
  74
  75 #define MAX6650_REG_SPEED       0x00
  76 #define MAX6650_REG_CONFIG      0x02
  77 #define MAX6650_REG_GPIO_DEF    0x04
  78 #define MAX6650_REG_DAC         0x06
  79 #define MAX6650_REG_ALARM_EN    0x08
  80 #define MAX6650_REG_ALARM       0x0A
  81 #define MAX6650_REG_TACH0       0x0C
  82 #define MAX6650_REG_TACH1       0x0E
  83 #define MAX6650_REG_TACH2       0x10
  84 #define MAX6650_REG_TACH3       0x12
  85 #define MAX6650_REG_GPIO_STAT   0x14
  86 #define MAX6650_REG_COUNT       0x16
  87
  88 /*
  89  * Config register bits
  90  */
  91
  92 #define MAX6650_CFG_V12                 0x08
  93 #define MAX6650_CFG_PRESCALER_MASK      0x07
  94 #define MAX6650_CFG_PRESCALER_2         0x01
  95 #define MAX6650_CFG_PRESCALER_4         0x02
  96 #define MAX6650_CFG_PRESCALER_8         0x03
  97 #define MAX6650_CFG_PRESCALER_16        0x04
  98 #define MAX6650_CFG_MODE_MASK           0x30
  99 #define MAX6650_CFG_MODE_ON             0x00
 100 #define MAX6650_CFG_MODE_OFF            0x10
 101 #define MAX6650_CFG_MODE_CLOSED_LOOP    0x20
 102 #define MAX6650_CFG_MODE_OPEN_LOOP      0x30
 103 #define MAX6650_COUNT_MASK              0x03
 104
 105 /* Minimum and maximum values of the FAN-RPM */
 106 #define FAN_RPM_MIN 240
 107 #define FAN_RPM_MAX 30000
 108
 109 #define DIV_FROM_REG(reg) (1 << (reg & 7))
 110
 111 static int max6650_attach_adapter(struct i2c_adapter *adapter);
 112 static int max6650_detect(struct i2c_adapter *adapter, int address, int kind);
 113 static int max6650_init_client(struct i2c_client *client);
 114 static int max6650_detach_client(struct i2c_client *client);
 115 static struct max6650_data *max6650_update_device(struct device *dev);
 116
 117 /*
 118  * Driver data (common to all clients)
 119  */
 120
 121 static struct i2c_driver max6650_driver = {
 122         .driver = {
 123                 .name   = "max6650",
 124         },
 125         .attach_adapter = max6650_attach_adapter,
 126         .detach_client  = max6650_detach_client,
 127 };
 128
 129 /*
 130  * Client data (each client gets its own)
 131  */
 132
 133 struct max6650_data
 134 {
 135         struct i2c_client client;
 136         struct device *hwmon_dev;
 137         struct mutex update_lock;
 138         char valid; /* zero until following fields are valid */
 139         unsigned long last_updated; /* in jiffies */
 140
 141         /* register values */
 142         u8 speed;
 143         u8 config;
 144         u8 tach[4];
 145         u8 count;
 146         u8 dac;
 147 };
 148
 149 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
 150                        char *buf)
 151 {
 152         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 153         struct max6650_data *data = max6650_update_device(dev);
 154         int rpm;
 155
 156         /*
 157         * Calculation details:
 158         *
 159         * Each tachometer counts over an interval given by the "count"
 160         * register (0.25, 0.5, 1 or 2 seconds). This module assumes
 161         * that the fans produce two pulses per revolution (this seems
 162         * to be the most common).
 163         */
 164
 165         rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
 166         return sprintf(buf, "%d\n", rpm);
 167 }
 168
 169 /*
 170  * Set the fan speed to the specified RPM (or read back the RPM setting).
 171  * This works in closed loop mode only. Use pwm1 for open loop speed setting.
 172  *
 173  * The MAX6650/1 will automatically control fan speed when in closed loop
 174  * mode.
 175  *
 176  * Assumptions:
 177  *
 178  * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
 179  *    the clock module parameter if you need to fine tune this.
 180  *
 181  * 2) The prescaler (low three bits of the config register) has already
 182  *    been set to an appropriate value. Use the prescaler module parameter
 183  *    if your BIOS doesn't initialize the chip properly.
 184  *
 185  * The relevant equations are given on pages 21 and 22 of the datasheet.
 186  *
 187  * From the datasheet, the relevant equation when in regulation is:
 188  *
 189  *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
 190  *
 191  * where:
 192  *
 193  *    fCLK is the oscillator frequency (either the 254kHz internal
 194  *         oscillator or the externally applied clock)
 195  *
 196  *    KTACH is the value in the speed register
 197  *
 198  *    FanSpeed is the speed of the fan in rps
 199  *
 200  *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)
 201  *
 202  * When reading, we need to solve for FanSpeed. When writing, we need to
 203  * solve for KTACH.
 204  *
 205  * Note: this tachometer is completely separate from the tachometers
 206  * used to measure the fan speeds. Only one fan's speed (fan1) is
 207  * controlled.
 208  */
 209
 210 static ssize_t get_target(struct device *dev, struct device_attribute *devattr,
 211                          char *buf)
 212 {
 213         struct max6650_data *data = max6650_update_device(dev);
 214         int kscale, ktach, rpm;
 215
 216         /*
 217         * Use the datasheet equation:
 218         *
 219         *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
 220         *
 221         * then multiply by 60 to give rpm.
 222         */
 223
 224         kscale = DIV_FROM_REG(data->config);
 225         ktach = data->speed;
 226         rpm = 60 * kscale * clock / (256 * (ktach + 1));
 227         return sprintf(buf, "%d\n", rpm);
 228 }
 229
 230 static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
 231                          const char *buf, size_t count)
 232 {
 233         struct i2c_client *client = to_i2c_client(dev);
 234         struct max6650_data *data = i2c_get_clientdata(client);
 235         int rpm = simple_strtoul(buf, NULL, 10);
 236         int kscale, ktach;
 237
 238         rpm = SENSORS_LIMIT(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
 239
 240         /*
 241         * Divide the required speed by 60 to get from rpm to rps, then
 242         * use the datasheet equation:
 243         *
 244         *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
 245         */
 246
 247         mutex_lock(&data->update_lock);
 248
 249         kscale = DIV_FROM_REG(data->config);
 250         ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
 251         if (ktach < 0)
 252                 ktach = 0;
 253         if (ktach > 255)
 254                 ktach = 255;
 255         data->speed = ktach;
 256
 257         i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);
 258
 259         mutex_unlock(&data->update_lock);
 260
 261         return count;
 262 }
 263
 264 /*
 265  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 266  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 267  * speed. Note that this is done by writing directly to the chip's DAC,
 268  * it won't change the closed loop speed set by fan1_target.
 269  * Also note that due to rounding errors it is possible that you don't read
 270  * back exactly the value you have set.
 271  */
 272
 273 static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,
 274                        char *buf)
 275 {
 276         int pwm;
 277         struct max6650_data *data = max6650_update_device(dev);
 278
 279         /* Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 280            Lower DAC values mean higher speeds. */
 281         if (data->config & MAX6650_CFG_V12)
 282                 pwm = 255 - (255 * (int)data->dac)/180;
 283         else
 284                 pwm = 255 - (255 * (int)data->dac)/76;
 285
 286         if (pwm < 0)
 287                 pwm = 0;
 288
 289         return sprintf(buf, "%d\n", pwm);
 290 }
 291
 292 static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
 293                         const char *buf, size_t count)
 294 {
 295         struct i2c_client *client = to_i2c_client(dev);
 296         struct max6650_data *data = i2c_get_clientdata(client);
 297         int pwm = simple_strtoul(buf, NULL, 10);
 298
 299         pwm = SENSORS_LIMIT(pwm, 0, 255);
 300
 301         mutex_lock(&data->update_lock);
 302
 303         if (data->config & MAX6650_CFG_V12)
 304                 data->dac = 180 - (180 * pwm)/255;
 305         else
 306                 data->dac = 76 - (76 * pwm)/255;
 307
 308         i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 309
 310         mutex_unlock(&data->update_lock);
 311
 312         return count;
 313 }
 314
 315 /*
 316  * Get/Set controller mode:
 317  * Possible values:
 318  * 0 = Fan always on
 319  * 1 = Open loop, Voltage is set according to speed, not regulated.
 320  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 321  */
 322
 323 static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,
 324                           char *buf)
 325 {
 326         struct max6650_data *data = max6650_update_device(dev);
 327         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 328         int sysfs_modes[4] = {0, 1, 2, 1};
 329
 330         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 331 }
 332
 333 static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
 334                           const char *buf, size_t count)
 335 {
 336         struct i2c_client *client = to_i2c_client(dev);
 337         struct max6650_data *data = i2c_get_clientdata(client);
 338         int mode = simple_strtoul(buf, NULL, 10);
 339         int max6650_modes[3] = {0, 3, 2};
 340
 341         if ((mode < 0)||(mode > 2)) {
 342                 dev_err(&client->dev,
 343                         "illegal value for pwm1_enable (%d)\n", mode);
 344                 return -EINVAL;
 345         }
 346
 347         mutex_lock(&data->update_lock);
 348
 349         data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 350         data->config = (data->config & ~MAX6650_CFG_MODE_MASK)
 351                        | (max6650_modes[mode] << 4);
 352
 353         i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);
 354
 355         mutex_unlock(&data->update_lock);
 356
 357         return count;
 358 }
 359
 360 /*
 361  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 362  * divider. We handle this by converting between divider and counttime:
 363  *
 364  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 365  *
 366  * Lower values of k allow to connect a faster fan without the risk of
 367  * counter overflow. The price is lower resolution. You can also set counttime
 368  * using the module parameter. Note that the module parameter "prescaler" also
 369  * influences the behaviour. Unfortunately, there's no sysfs attribute
 370  * defined for that. See the data sheet for details.
 371  */
 372
 373 static ssize_t get_div(struct device *dev, struct device_attribute *devattr,
 374                        char *buf)
 375 {
 376         struct max6650_data *data = max6650_update_device(dev);
 377
 378         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 379 }
 380
 381 static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 382                        const char *buf, size_t count)
 383 {
 384         struct i2c_client *client = to_i2c_client(dev);
 385         struct max6650_data *data = i2c_get_clientdata(client);
 386         int div = simple_strtoul(buf, NULL, 10);
 387
 388         mutex_lock(&data->update_lock);
 389         switch (div) {
 390         case 1:
 391                 data->count = 0;
 392                 break;
 393         case 2:
 394                 data->count = 1;
 395                 break;
 396         case 4:
 397                 data->count = 2;
 398                 break;
 399         case 8:
 400                 data->count = 3;
 401                 break;
 402         default:
 403                 dev_err(&client->dev,
 404                         "illegal value for fan divider (%d)\n", div);
 405                 return -EINVAL;
 406         }
 407
 408         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 409         mutex_unlock(&data->update_lock);
 410
 411         return count;
 412 }
 413
 414 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 415 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 416 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 417 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 418 static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 419 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 420 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 421 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 422
 423
 424 static struct attribute *max6650_attrs[] = {
 425         &sensor_dev_attr_fan1_input.dev_attr.attr,
 426         &sensor_dev_attr_fan2_input.dev_attr.attr,
 427         &sensor_dev_attr_fan3_input.dev_attr.attr,
 428         &sensor_dev_attr_fan4_input.dev_attr.attr,
 429         &dev_attr_fan1_target.attr,
 430         &dev_attr_fan1_div.attr,
 431         &dev_attr_pwm1_enable.attr,
 432         &dev_attr_pwm1.attr,
 433         NULL
 434 };
 435
 436 static struct attribute_group max6650_attr_grp = {
 437         .attrs = max6650_attrs,
 438 };
 439
 440 /*
 441  * Real code
 442  */
 443
 444 static int max6650_attach_adapter(struct i2c_adapter *adapter)
 445 {
 446         if (!(adapter->class & I2C_CLASS_HWMON)) {
 447                 dev_dbg(&adapter->dev,
 448                         "FATAL: max6650_attach_adapter class HWMON not set\n");
 449                 return 0;
 450         }
 451
 452         return i2c_probe(adapter, &addr_data, max6650_detect);
 453 }
 454
 455 /*
 456  * The following function does more than just detection. If detection
 457  * succeeds, it also registers the new chip.
 458  */
 459
 460 static int max6650_detect(struct i2c_adapter *adapter, int address, int kind)
 461 {
 462         struct i2c_client *client;
 463         struct max6650_data *data;
 464         int err = -ENODEV;
 465
 466         dev_dbg(&adapter->dev, "max6650_detect called, kind = %d\n", kind);
 467
 468         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
 469                 dev_dbg(&adapter->dev, "max6650: I2C bus doesn't support "
 470                                         "byte read mode, skipping.\n");
 471                 return 0;
 472         }
 473
 474         if (!(data = kzalloc(sizeof(struct max6650_data), GFP_KERNEL))) {
 475                 dev_err(&adapter->dev, "max6650: out of memory.\n");
 476                 return -ENOMEM;
 477         }
 478
 479         client = &data->client;
 480         i2c_set_clientdata(client, data);
 481         client->addr = address;
 482         client->adapter = adapter;
 483         client->driver = &max6650_driver;
 484
 485         /*
 486          * Now we do the remaining detection. A negative kind means that
 487          * the driver was loaded with no force parameter (default), so we
 488          * must both detect and identify the chip (actually there is only
 489          * one possible kind of chip for now, max6650). A zero kind means that
 490          * the driver was loaded with the force parameter, the detection
 491          * step shall be skipped. A positive kind means that the driver
 492          * was loaded with the force parameter and a given kind of chip is
 493          * requested, so both the detection and the identification steps
 494          * are skipped.
 495          *
 496          * Currently I can find no way to distinguish between a MAX6650 and
 497          * a MAX6651. This driver has only been tried on the former.
 498          */
 499
 500         if ((kind < 0) &&
 501            (  (i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG) & 0xC0)
 502             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_GPIO_STAT) & 0xE0)
 503             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN) & 0xE0)
 504             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM) & 0xE0)
 505             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT) & 0xFC))) {
 506                 dev_dbg(&adapter->dev,
 507                         "max6650: detection failed at 0x%02x.\n", address);
 508                 goto err_free;
 509         }
 510
 511         dev_info(&adapter->dev, "max6650: chip found at 0x%02x.\n", address);
 512
 513         strlcpy(client->name, "max6650", I2C_NAME_SIZE);
 514         mutex_init(&data->update_lock);
 515
 516         if ((err = i2c_attach_client(client))) {
 517                 dev_err(&adapter->dev, "max6650: failed to attach client.\n");
 518                 goto err_free;
 519         }
 520
 521         /*
 522          * Initialize the max6650 chip
 523          */
 524         if (max6650_init_client(client))
 525                 goto err_detach;
 526
 527         err = sysfs_create_group(&client->dev.kobj, &max6650_attr_grp);
 528         if (err)
 529                 goto err_detach;
 530
 531         data->hwmon_dev = hwmon_device_register(&client->dev);
 532         if (!IS_ERR(data->hwmon_dev))
 533                 return 0;
 534
 535         err = PTR_ERR(data->hwmon_dev);
 536         dev_err(&client->dev, "error registering hwmon device.\n");
 537         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 538 err_detach:
 539         i2c_detach_client(client);
 540 err_free:
 541         kfree(data);
 542         return err;
 543 }
 544
 545 static int max6650_detach_client(struct i2c_client *client)
 546 {
 547         struct max6650_data *data = i2c_get_clientdata(client);
 548         int err;
 549
 550         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 551         hwmon_device_unregister(data->hwmon_dev);
 552         err = i2c_detach_client(client);
 553         if (!err)
 554                 kfree(data);
 555         return err;
 556 }
 557
 558 static int max6650_init_client(struct i2c_client *client)
 559 {
 560         struct max6650_data *data = i2c_get_clientdata(client);
 561         int config;
 562         int err = -EIO;
 563
 564         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 565
 566         if (config < 0) {
 567                 dev_err(&client->dev, "Error reading config, aborting.\n");
 568                 return err;
 569         }
 570
 571         switch (fan_voltage) {
 572                 case 0:
 573                         break;
 574                 case 5:
 575                         config &= ~MAX6650_CFG_V12;
 576                         break;
 577                 case 12:
 578                         config |= MAX6650_CFG_V12;
 579                         break;
 580                 default:
 581                         dev_err(&client->dev,
 582                                 "illegal value for fan_voltage (%d)\n",
 583                                 fan_voltage);
 584         }
 585
 586         dev_info(&client->dev, "Fan voltage is set to %dV.\n",
 587                  (config & MAX6650_CFG_V12) ? 12 : 5);
 588
 589         switch (prescaler) {
 590                 case 0:
 591                         break;
 592                 case 1:
 593                         config &= ~MAX6650_CFG_PRESCALER_MASK;
 594                         break;
 595                 case 2:
 596                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 597                                  | MAX6650_CFG_PRESCALER_2;
 598                         break;
 599                 case  4:
 600                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 601                                  | MAX6650_CFG_PRESCALER_4;
 602                         break;
 603                 case  8:
 604                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 605                                  | MAX6650_CFG_PRESCALER_8;
 606                         break;
 607                 case 16:
 608                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 609                                  | MAX6650_CFG_PRESCALER_16;
 610                         break;
 611                 default:
 612                         dev_err(&client->dev,
 613                                 "illegal value for prescaler (%d)\n",
 614                                 prescaler);
 615         }
 616
 617         dev_info(&client->dev, "Prescaler is set to %d.\n",
 618                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 619
 620         /* If mode is set to "full off", we change it to "open loop" and
 621          * set DAC to 255, which has the same effect. We do this because
 622          * there's no "full off" mode defined in hwmon specifcations.
 623          */
 624
 625         if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {
 626                 dev_dbg(&client->dev, "Change mode to open loop, full off.\n");
 627                 config = (config & ~MAX6650_CFG_MODE_MASK)
 628                          | MAX6650_CFG_MODE_OPEN_LOOP;
 629                 if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {
 630                         dev_err(&client->dev, "DAC write error, aborting.\n");
 631                         return err;
 632                 }
 633         }
 634
 635         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 636                 dev_err(&client->dev, "Config write error, aborting.\n");
 637                 return err;
 638         }
 639
 640         data->config = config;
 641         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 642
 643         return 0;
 644 }
 645
 646 static const u8 tach_reg[] = {
 647         MAX6650_REG_TACH0,
 648         MAX6650_REG_TACH1,
 649         MAX6650_REG_TACH2,
 650         MAX6650_REG_TACH3,
 651 };
 652
 653 static struct max6650_data *max6650_update_device(struct device *dev)
 654 {
 655         int i;
 656         struct i2c_client *client = to_i2c_client(dev);
 657         struct max6650_data *data = i2c_get_clientdata(client);
 658
 659         mutex_lock(&data->update_lock);
 660
 661         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 662                 data->speed = i2c_smbus_read_byte_data(client,
 663                                                        MAX6650_REG_SPEED);
 664                 data->config = i2c_smbus_read_byte_data(client,
 665                                                         MAX6650_REG_CONFIG);
 666                 for (i = 0; i < 4; i++) {
 667                         data->tach[i] = i2c_smbus_read_byte_data(client,
 668                                                                  tach_reg[i]);
 669                 }
 670                 data->count = i2c_smbus_read_byte_data(client,
 671                                                         MAX6650_REG_COUNT);
 672                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 673
 674                 data->last_updated = jiffies;
 675                 data->valid = 1;
 676         }
 677
 678         mutex_unlock(&data->update_lock);
 679
 680         return data;
 681 }
 682
 683 static int __init sensors_max6650_init(void)
 684 {
 685         return i2c_add_driver(&max6650_driver);
 686 }
 687
 688 static void __exit sensors_max6650_exit(void)
 689 {
 690         i2c_del_driver(&max6650_driver);
 691 }
 692
 693 MODULE_AUTHOR("Hans J. Koch");
 694 MODULE_DESCRIPTION("MAX6650 sensor driver");
 695 MODULE_LICENSE("GPL");
 696
 697 module_init(sensors_max6650_init);
 698 module_exit(sensors_max6650_exit);