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@hansjkoch.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  * The 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  * Insmod parameters
  45  */
  46
  47 /* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */
  48 static int fan_voltage;
  49 /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
  50 static int prescaler;
  51 /* clock: The clock frequency of the chip the driver should assume */
  52 static int clock = 254000;
  53
  54 module_param(fan_voltage, int, S_IRUGO);
  55 module_param(prescaler, int, S_IRUGO);
  56 module_param(clock, int, S_IRUGO);
  57
  58 /*
  59  * MAX 6650/6651 registers
  60  */
  61
  62 #define MAX6650_REG_SPEED       0x00
  63 #define MAX6650_REG_CONFIG      0x02
  64 #define MAX6650_REG_GPIO_DEF    0x04
  65 #define MAX6650_REG_DAC         0x06
  66 #define MAX6650_REG_ALARM_EN    0x08
  67 #define MAX6650_REG_ALARM       0x0A
  68 #define MAX6650_REG_TACH0       0x0C
  69 #define MAX6650_REG_TACH1       0x0E
  70 #define MAX6650_REG_TACH2       0x10
  71 #define MAX6650_REG_TACH3       0x12
  72 #define MAX6650_REG_GPIO_STAT   0x14
  73 #define MAX6650_REG_COUNT       0x16
  74
  75 /*
  76  * Config register bits
  77  */
  78
  79 #define MAX6650_CFG_V12                 0x08
  80 #define MAX6650_CFG_PRESCALER_MASK      0x07
  81 #define MAX6650_CFG_PRESCALER_2         0x01
  82 #define MAX6650_CFG_PRESCALER_4         0x02
  83 #define MAX6650_CFG_PRESCALER_8         0x03
  84 #define MAX6650_CFG_PRESCALER_16        0x04
  85 #define MAX6650_CFG_MODE_MASK           0x30
  86 #define MAX6650_CFG_MODE_ON             0x00
  87 #define MAX6650_CFG_MODE_OFF            0x10
  88 #define MAX6650_CFG_MODE_CLOSED_LOOP    0x20
  89 #define MAX6650_CFG_MODE_OPEN_LOOP      0x30
  90 #define MAX6650_COUNT_MASK              0x03
  91
  92 /*
  93  * Alarm status register bits
  94  */
  95
  96 #define MAX6650_ALRM_MAX        0x01
  97 #define MAX6650_ALRM_MIN        0x02
  98 #define MAX6650_ALRM_TACH       0x04
  99 #define MAX6650_ALRM_GPIO1      0x08
 100 #define MAX6650_ALRM_GPIO2      0x10
 101
 102 /* Minimum and maximum values of the FAN-RPM */
 103 #define FAN_RPM_MIN 240
 104 #define FAN_RPM_MAX 30000
 105
 106 #define DIV_FROM_REG(reg) (1 << (reg & 7))
 107
 108 static int max6650_probe(struct i2c_client *client,
 109                          const struct i2c_device_id *id);
 110 static int max6650_init_client(struct i2c_client *client);
 111 static int max6650_remove(struct i2c_client *client);
 112 static struct max6650_data *max6650_update_device(struct device *dev);
 113
 114 /*
 115  * Driver data (common to all clients)
 116  */
 117
 118 static const struct i2c_device_id max6650_id[] = {
 119         { "max6650", 1 },
 120         { "max6651", 4 },
 121         { }
 122 };
 123 MODULE_DEVICE_TABLE(i2c, max6650_id);
 124
 125 static struct i2c_driver max6650_driver = {
 126         .driver = {
 127                 .name   = "max6650",
 128         },
 129         .probe          = max6650_probe,
 130         .remove         = max6650_remove,
 131         .id_table       = max6650_id,
 132 };
 133
 134 /*
 135  * Client data (each client gets its own)
 136  */
 137
 138 struct max6650_data
 139 {
 140         struct device *hwmon_dev;
 141         struct mutex update_lock;
 142         int nr_fans;
 143         char valid; /* zero until following fields are valid */
 144         unsigned long last_updated; /* in jiffies */
 145
 146         /* register values */
 147         u8 speed;
 148         u8 config;
 149         u8 tach[4];
 150         u8 count;
 151         u8 dac;
 152         u8 alarm;
 153 };
 154
 155 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
 156                        char *buf)
 157 {
 158         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 159         struct max6650_data *data = max6650_update_device(dev);
 160         int rpm;
 161
 162         /*
 163         * Calculation details:
 164         *
 165         * Each tachometer counts over an interval given by the "count"
 166         * register (0.25, 0.5, 1 or 2 seconds). This module assumes
 167         * that the fans produce two pulses per revolution (this seems
 168         * to be the most common).
 169         */
 170
 171         rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
 172         return sprintf(buf, "%d\n", rpm);
 173 }
 174
 175 /*
 176  * Set the fan speed to the specified RPM (or read back the RPM setting).
 177  * This works in closed loop mode only. Use pwm1 for open loop speed setting.
 178  *
 179  * The MAX6650/1 will automatically control fan speed when in closed loop
 180  * mode.
 181  *
 182  * Assumptions:
 183  *
 184  * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
 185  *    the clock module parameter if you need to fine tune this.
 186  *
 187  * 2) The prescaler (low three bits of the config register) has already
 188  *    been set to an appropriate value. Use the prescaler module parameter
 189  *    if your BIOS doesn't initialize the chip properly.
 190  *
 191  * The relevant equations are given on pages 21 and 22 of the datasheet.
 192  *
 193  * From the datasheet, the relevant equation when in regulation is:
 194  *
 195  *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
 196  *
 197  * where:
 198  *
 199  *    fCLK is the oscillator frequency (either the 254kHz internal
 200  *         oscillator or the externally applied clock)
 201  *
 202  *    KTACH is the value in the speed register
 203  *
 204  *    FanSpeed is the speed of the fan in rps
 205  *
 206  *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)
 207  *
 208  * When reading, we need to solve for FanSpeed. When writing, we need to
 209  * solve for KTACH.
 210  *
 211  * Note: this tachometer is completely separate from the tachometers
 212  * used to measure the fan speeds. Only one fan's speed (fan1) is
 213  * controlled.
 214  */
 215
 216 static ssize_t get_target(struct device *dev, struct device_attribute *devattr,
 217                          char *buf)
 218 {
 219         struct max6650_data *data = max6650_update_device(dev);
 220         int kscale, ktach, rpm;
 221
 222         /*
 223         * Use the datasheet equation:
 224         *
 225         *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
 226         *
 227         * then multiply by 60 to give rpm.
 228         */
 229
 230         kscale = DIV_FROM_REG(data->config);
 231         ktach = data->speed;
 232         rpm = 60 * kscale * clock / (256 * (ktach + 1));
 233         return sprintf(buf, "%d\n", rpm);
 234 }
 235
 236 static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
 237                          const char *buf, size_t count)
 238 {
 239         struct i2c_client *client = to_i2c_client(dev);
 240         struct max6650_data *data = i2c_get_clientdata(client);
 241         int rpm = simple_strtoul(buf, NULL, 10);
 242         int kscale, ktach;
 243
 244         rpm = SENSORS_LIMIT(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
 245
 246         /*
 247         * Divide the required speed by 60 to get from rpm to rps, then
 248         * use the datasheet equation:
 249         *
 250         *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
 251         */
 252
 253         mutex_lock(&data->update_lock);
 254
 255         kscale = DIV_FROM_REG(data->config);
 256         ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
 257         if (ktach < 0)
 258                 ktach = 0;
 259         if (ktach > 255)
 260                 ktach = 255;
 261         data->speed = ktach;
 262
 263         i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);
 264
 265         mutex_unlock(&data->update_lock);
 266
 267         return count;
 268 }
 269
 270 /*
 271  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 272  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 273  * speed. Note that this is done by writing directly to the chip's DAC,
 274  * it won't change the closed loop speed set by fan1_target.
 275  * Also note that due to rounding errors it is possible that you don't read
 276  * back exactly the value you have set.
 277  */
 278
 279 static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,
 280                        char *buf)
 281 {
 282         int pwm;
 283         struct max6650_data *data = max6650_update_device(dev);
 284
 285         /* Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 286            Lower DAC values mean higher speeds. */
 287         if (data->config & MAX6650_CFG_V12)
 288                 pwm = 255 - (255 * (int)data->dac)/180;
 289         else
 290                 pwm = 255 - (255 * (int)data->dac)/76;
 291
 292         if (pwm < 0)
 293                 pwm = 0;
 294
 295         return sprintf(buf, "%d\n", pwm);
 296 }
 297
 298 static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
 299                         const char *buf, size_t count)
 300 {
 301         struct i2c_client *client = to_i2c_client(dev);
 302         struct max6650_data *data = i2c_get_clientdata(client);
 303         int pwm = simple_strtoul(buf, NULL, 10);
 304
 305         pwm = SENSORS_LIMIT(pwm, 0, 255);
 306
 307         mutex_lock(&data->update_lock);
 308
 309         if (data->config & MAX6650_CFG_V12)
 310                 data->dac = 180 - (180 * pwm)/255;
 311         else
 312                 data->dac = 76 - (76 * pwm)/255;
 313
 314         i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 315
 316         mutex_unlock(&data->update_lock);
 317
 318         return count;
 319 }
 320
 321 /*
 322  * Get/Set controller mode:
 323  * Possible values:
 324  * 0 = Fan always on
 325  * 1 = Open loop, Voltage is set according to speed, not regulated.
 326  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 327  */
 328
 329 static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,
 330                           char *buf)
 331 {
 332         struct max6650_data *data = max6650_update_device(dev);
 333         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 334         int sysfs_modes[4] = {0, 1, 2, 1};
 335
 336         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 337 }
 338
 339 static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
 340                           const char *buf, size_t count)
 341 {
 342         struct i2c_client *client = to_i2c_client(dev);
 343         struct max6650_data *data = i2c_get_clientdata(client);
 344         int mode = simple_strtoul(buf, NULL, 10);
 345         int max6650_modes[3] = {0, 3, 2};
 346
 347         if ((mode < 0)||(mode > 2)) {
 348                 dev_err(&client->dev,
 349                         "illegal value for pwm1_enable (%d)\n", mode);
 350                 return -EINVAL;
 351         }
 352
 353         mutex_lock(&data->update_lock);
 354
 355         data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 356         data->config = (data->config & ~MAX6650_CFG_MODE_MASK)
 357                        | (max6650_modes[mode] << 4);
 358
 359         i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);
 360
 361         mutex_unlock(&data->update_lock);
 362
 363         return count;
 364 }
 365
 366 /*
 367  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 368  * divider. We handle this by converting between divider and counttime:
 369  *
 370  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 371  *
 372  * Lower values of k allow to connect a faster fan without the risk of
 373  * counter overflow. The price is lower resolution. You can also set counttime
 374  * using the module parameter. Note that the module parameter "prescaler" also
 375  * influences the behaviour. Unfortunately, there's no sysfs attribute
 376  * defined for that. See the data sheet for details.
 377  */
 378
 379 static ssize_t get_div(struct device *dev, struct device_attribute *devattr,
 380                        char *buf)
 381 {
 382         struct max6650_data *data = max6650_update_device(dev);
 383
 384         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 385 }
 386
 387 static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 388                        const char *buf, size_t count)
 389 {
 390         struct i2c_client *client = to_i2c_client(dev);
 391         struct max6650_data *data = i2c_get_clientdata(client);
 392         int div = simple_strtoul(buf, NULL, 10);
 393
 394         mutex_lock(&data->update_lock);
 395         switch (div) {
 396         case 1:
 397                 data->count = 0;
 398                 break;
 399         case 2:
 400                 data->count = 1;
 401                 break;
 402         case 4:
 403                 data->count = 2;
 404                 break;
 405         case 8:
 406                 data->count = 3;
 407                 break;
 408         default:
 409                 mutex_unlock(&data->update_lock);
 410                 dev_err(&client->dev,
 411                         "illegal value for fan divider (%d)\n", div);
 412                 return -EINVAL;
 413         }
 414
 415         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 416         mutex_unlock(&data->update_lock);
 417
 418         return count;
 419 }
 420
 421 /*
 422  * Get alarm stati:
 423  * Possible values:
 424  * 0 = no alarm
 425  * 1 = alarm
 426  */
 427
 428 static ssize_t get_alarm(struct device *dev, struct device_attribute *devattr,
 429                          char *buf)
 430 {
 431         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 432         struct max6650_data *data = max6650_update_device(dev);
 433         struct i2c_client *client = to_i2c_client(dev);
 434         int alarm = 0;
 435
 436         if (data->alarm & attr->index) {
 437                 mutex_lock(&data->update_lock);
 438                 alarm = 1;
 439                 data->alarm &= ~attr->index;
 440                 data->alarm |= i2c_smbus_read_byte_data(client,
 441                                                         MAX6650_REG_ALARM);
 442                 mutex_unlock(&data->update_lock);
 443         }
 444
 445         return sprintf(buf, "%d\n", alarm);
 446 }
 447
 448 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 449 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 450 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 451 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 452 static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 453 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 454 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 455 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 456 static SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
 457                           MAX6650_ALRM_MAX);
 458 static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
 459                           MAX6650_ALRM_MIN);
 460 static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
 461                           MAX6650_ALRM_TACH);
 462 static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
 463                           MAX6650_ALRM_GPIO1);
 464 static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
 465                           MAX6650_ALRM_GPIO2);
 466
 467 static mode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
 468                                     int n)
 469 {
 470         struct device *dev = container_of(kobj, struct device, kobj);
 471         struct i2c_client *client = to_i2c_client(dev);
 472         u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
 473         struct device_attribute *devattr;
 474
 475         /*
 476          * Hide the alarms that have not been enabled by the firmware
 477          */
 478
 479         devattr = container_of(a, struct device_attribute, attr);
 480         if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
 481          || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
 482          || devattr == &sensor_dev_attr_fan1_fault.dev_attr
 483          || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
 484          || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
 485                 if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
 486                         return 0;
 487         }
 488
 489         return a->mode;
 490 }
 491
 492 static struct attribute *max6650_attrs[] = {
 493         &sensor_dev_attr_fan1_input.dev_attr.attr,
 494         &dev_attr_fan1_target.attr,
 495         &dev_attr_fan1_div.attr,
 496         &dev_attr_pwm1_enable.attr,
 497         &dev_attr_pwm1.attr,
 498         &sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
 499         &sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
 500         &sensor_dev_attr_fan1_fault.dev_attr.attr,
 501         &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
 502         &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
 503         NULL
 504 };
 505
 506 static struct attribute_group max6650_attr_grp = {
 507         .attrs = max6650_attrs,
 508         .is_visible = max6650_attrs_visible,
 509 };
 510
 511 static struct attribute *max6651_attrs[] = {
 512         &sensor_dev_attr_fan2_input.dev_attr.attr,
 513         &sensor_dev_attr_fan3_input.dev_attr.attr,
 514         &sensor_dev_attr_fan4_input.dev_attr.attr,
 515         NULL
 516 };
 517
 518 static const struct attribute_group max6651_attr_grp = {
 519         .attrs = max6651_attrs,
 520 };
 521
 522 /*
 523  * Real code
 524  */
 525
 526 static int max6650_probe(struct i2c_client *client,
 527                          const struct i2c_device_id *id)
 528 {
 529         struct max6650_data *data;
 530         int err;
 531
 532         if (!(data = kzalloc(sizeof(struct max6650_data), GFP_KERNEL))) {
 533                 dev_err(&client->dev, "out of memory.\n");
 534                 return -ENOMEM;
 535         }
 536
 537         i2c_set_clientdata(client, data);
 538         mutex_init(&data->update_lock);
 539         data->nr_fans = id->driver_data;
 540
 541         /*
 542          * Initialize the max6650 chip
 543          */
 544         err = max6650_init_client(client);
 545         if (err)
 546                 goto err_free;
 547
 548         err = sysfs_create_group(&client->dev.kobj, &max6650_attr_grp);
 549         if (err)
 550                 goto err_free;
 551         /* 3 additional fan inputs for the MAX6651 */
 552         if (data->nr_fans == 4) {
 553                 err = sysfs_create_group(&client->dev.kobj, &max6651_attr_grp);
 554                 if (err)
 555                         goto err_remove;
 556         }
 557
 558         data->hwmon_dev = hwmon_device_register(&client->dev);
 559         if (!IS_ERR(data->hwmon_dev))
 560                 return 0;
 561
 562         err = PTR_ERR(data->hwmon_dev);
 563         dev_err(&client->dev, "error registering hwmon device.\n");
 564         if (data->nr_fans == 4)
 565                 sysfs_remove_group(&client->dev.kobj, &max6651_attr_grp);
 566 err_remove:
 567         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 568 err_free:
 569         kfree(data);
 570         return err;
 571 }
 572
 573 static int max6650_remove(struct i2c_client *client)
 574 {
 575         struct max6650_data *data = i2c_get_clientdata(client);
 576
 577         hwmon_device_unregister(data->hwmon_dev);
 578         if (data->nr_fans == 4)
 579                 sysfs_remove_group(&client->dev.kobj, &max6651_attr_grp);
 580         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 581         kfree(data);
 582         return 0;
 583 }
 584
 585 static int max6650_init_client(struct i2c_client *client)
 586 {
 587         struct max6650_data *data = i2c_get_clientdata(client);
 588         int config;
 589         int err = -EIO;
 590
 591         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 592
 593         if (config < 0) {
 594                 dev_err(&client->dev, "Error reading config, aborting.\n");
 595                 return err;
 596         }
 597
 598         switch (fan_voltage) {
 599                 case 0:
 600                         break;
 601                 case 5:
 602                         config &= ~MAX6650_CFG_V12;
 603                         break;
 604                 case 12:
 605                         config |= MAX6650_CFG_V12;
 606                         break;
 607                 default:
 608                         dev_err(&client->dev,
 609                                 "illegal value for fan_voltage (%d)\n",
 610                                 fan_voltage);
 611         }
 612
 613         dev_info(&client->dev, "Fan voltage is set to %dV.\n",
 614                  (config & MAX6650_CFG_V12) ? 12 : 5);
 615
 616         switch (prescaler) {
 617                 case 0:
 618                         break;
 619                 case 1:
 620                         config &= ~MAX6650_CFG_PRESCALER_MASK;
 621                         break;
 622                 case 2:
 623                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 624                                  | MAX6650_CFG_PRESCALER_2;
 625                         break;
 626                 case  4:
 627                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 628                                  | MAX6650_CFG_PRESCALER_4;
 629                         break;
 630                 case  8:
 631                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 632                                  | MAX6650_CFG_PRESCALER_8;
 633                         break;
 634                 case 16:
 635                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 636                                  | MAX6650_CFG_PRESCALER_16;
 637                         break;
 638                 default:
 639                         dev_err(&client->dev,
 640                                 "illegal value for prescaler (%d)\n",
 641                                 prescaler);
 642         }
 643
 644         dev_info(&client->dev, "Prescaler is set to %d.\n",
 645                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 646
 647         /* If mode is set to "full off", we change it to "open loop" and
 648          * set DAC to 255, which has the same effect. We do this because
 649          * there's no "full off" mode defined in hwmon specifcations.
 650          */
 651
 652         if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {
 653                 dev_dbg(&client->dev, "Change mode to open loop, full off.\n");
 654                 config = (config & ~MAX6650_CFG_MODE_MASK)
 655                          | MAX6650_CFG_MODE_OPEN_LOOP;
 656                 if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {
 657                         dev_err(&client->dev, "DAC write error, aborting.\n");
 658                         return err;
 659                 }
 660         }
 661
 662         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 663                 dev_err(&client->dev, "Config write error, aborting.\n");
 664                 return err;
 665         }
 666
 667         data->config = config;
 668         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 669
 670         return 0;
 671 }
 672
 673 static const u8 tach_reg[] = {
 674         MAX6650_REG_TACH0,
 675         MAX6650_REG_TACH1,
 676         MAX6650_REG_TACH2,
 677         MAX6650_REG_TACH3,
 678 };
 679
 680 static struct max6650_data *max6650_update_device(struct device *dev)
 681 {
 682         int i;
 683         struct i2c_client *client = to_i2c_client(dev);
 684         struct max6650_data *data = i2c_get_clientdata(client);
 685
 686         mutex_lock(&data->update_lock);
 687
 688         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 689                 data->speed = i2c_smbus_read_byte_data(client,
 690                                                        MAX6650_REG_SPEED);
 691                 data->config = i2c_smbus_read_byte_data(client,
 692                                                         MAX6650_REG_CONFIG);
 693                 for (i = 0; i < data->nr_fans; i++) {
 694                         data->tach[i] = i2c_smbus_read_byte_data(client,
 695                                                                  tach_reg[i]);
 696                 }
 697                 data->count = i2c_smbus_read_byte_data(client,
 698                                                         MAX6650_REG_COUNT);
 699                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 700
 701                 /* Alarms are cleared on read in case the condition that
 702                  * caused the alarm is removed. Keep the value latched here
 703                  * for providing the register through different alarm files. */
 704                 data->alarm |= i2c_smbus_read_byte_data(client,
 705                                                         MAX6650_REG_ALARM);
 706
 707                 data->last_updated = jiffies;
 708                 data->valid = 1;
 709         }
 710
 711         mutex_unlock(&data->update_lock);
 712
 713         return data;
 714 }
 715
 716 static int __init sensors_max6650_init(void)
 717 {
 718         return i2c_add_driver(&max6650_driver);
 719 }
 720
 721 static void __exit sensors_max6650_exit(void)
 722 {
 723         i2c_del_driver(&max6650_driver);
 724 }
 725
 726 MODULE_AUTHOR("Hans J. Koch");
 727 MODULE_DESCRIPTION("MAX6650 sensor driver");
 728 MODULE_LICENSE("GPL");
 729
 730 module_init(sensors_max6650_init);
 731 module_exit(sensors_max6650_exit);