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  * 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  * 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 /*
 102  * Alarm status register bits
 103  */
 104
 105 #define MAX6650_ALRM_MAX        0x01
 106 #define MAX6650_ALRM_MIN        0x02
 107 #define MAX6650_ALRM_TACH       0x04
 108 #define MAX6650_ALRM_GPIO1      0x08
 109 #define MAX6650_ALRM_GPIO2      0x10
 110
 111 /* Minimum and maximum values of the FAN-RPM */
 112 #define FAN_RPM_MIN 240
 113 #define FAN_RPM_MAX 30000
 114
 115 #define DIV_FROM_REG(reg) (1 << (reg & 7))
 116
 117 static int max6650_probe(struct i2c_client *client,
 118                          const struct i2c_device_id *id);
 119 static int max6650_detect(struct i2c_client *client, int kind,
 120                           struct i2c_board_info *info);
 121 static int max6650_init_client(struct i2c_client *client);
 122 static int max6650_remove(struct i2c_client *client);
 123 static struct max6650_data *max6650_update_device(struct device *dev);
 124
 125 /*
 126  * Driver data (common to all clients)
 127  */
 128
 129 static const struct i2c_device_id max6650_id[] = {
 130         { "max6650", max6650 },
 131         { }
 132 };
 133 MODULE_DEVICE_TABLE(i2c, max6650_id);
 134
 135 static struct i2c_driver max6650_driver = {
 136         .class          = I2C_CLASS_HWMON,
 137         .driver = {
 138                 .name   = "max6650",
 139         },
 140         .probe          = max6650_probe,
 141         .remove         = max6650_remove,
 142         .id_table       = max6650_id,
 143         .detect         = max6650_detect,
 144         .address_data   = &addr_data,
 145 };
 146
 147 /*
 148  * Client data (each client gets its own)
 149  */
 150
 151 struct max6650_data
 152 {
 153         struct device *hwmon_dev;
 154         struct mutex update_lock;
 155         char valid; /* zero until following fields are valid */
 156         unsigned long last_updated; /* in jiffies */
 157
 158         /* register values */
 159         u8 speed;
 160         u8 config;
 161         u8 tach[4];
 162         u8 count;
 163         u8 dac;
 164         u8 alarm;
 165 };
 166
 167 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
 168                        char *buf)
 169 {
 170         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 171         struct max6650_data *data = max6650_update_device(dev);
 172         int rpm;
 173
 174         /*
 175         * Calculation details:
 176         *
 177         * Each tachometer counts over an interval given by the "count"
 178         * register (0.25, 0.5, 1 or 2 seconds). This module assumes
 179         * that the fans produce two pulses per revolution (this seems
 180         * to be the most common).
 181         */
 182
 183         rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
 184         return sprintf(buf, "%d\n", rpm);
 185 }
 186
 187 /*
 188  * Set the fan speed to the specified RPM (or read back the RPM setting).
 189  * This works in closed loop mode only. Use pwm1 for open loop speed setting.
 190  *
 191  * The MAX6650/1 will automatically control fan speed when in closed loop
 192  * mode.
 193  *
 194  * Assumptions:
 195  *
 196  * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
 197  *    the clock module parameter if you need to fine tune this.
 198  *
 199  * 2) The prescaler (low three bits of the config register) has already
 200  *    been set to an appropriate value. Use the prescaler module parameter
 201  *    if your BIOS doesn't initialize the chip properly.
 202  *
 203  * The relevant equations are given on pages 21 and 22 of the datasheet.
 204  *
 205  * From the datasheet, the relevant equation when in regulation is:
 206  *
 207  *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
 208  *
 209  * where:
 210  *
 211  *    fCLK is the oscillator frequency (either the 254kHz internal
 212  *         oscillator or the externally applied clock)
 213  *
 214  *    KTACH is the value in the speed register
 215  *
 216  *    FanSpeed is the speed of the fan in rps
 217  *
 218  *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)
 219  *
 220  * When reading, we need to solve for FanSpeed. When writing, we need to
 221  * solve for KTACH.
 222  *
 223  * Note: this tachometer is completely separate from the tachometers
 224  * used to measure the fan speeds. Only one fan's speed (fan1) is
 225  * controlled.
 226  */
 227
 228 static ssize_t get_target(struct device *dev, struct device_attribute *devattr,
 229                          char *buf)
 230 {
 231         struct max6650_data *data = max6650_update_device(dev);
 232         int kscale, ktach, rpm;
 233
 234         /*
 235         * Use the datasheet equation:
 236         *
 237         *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
 238         *
 239         * then multiply by 60 to give rpm.
 240         */
 241
 242         kscale = DIV_FROM_REG(data->config);
 243         ktach = data->speed;
 244         rpm = 60 * kscale * clock / (256 * (ktach + 1));
 245         return sprintf(buf, "%d\n", rpm);
 246 }
 247
 248 static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
 249                          const char *buf, size_t count)
 250 {
 251         struct i2c_client *client = to_i2c_client(dev);
 252         struct max6650_data *data = i2c_get_clientdata(client);
 253         int rpm = simple_strtoul(buf, NULL, 10);
 254         int kscale, ktach;
 255
 256         rpm = SENSORS_LIMIT(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
 257
 258         /*
 259         * Divide the required speed by 60 to get from rpm to rps, then
 260         * use the datasheet equation:
 261         *
 262         *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
 263         */
 264
 265         mutex_lock(&data->update_lock);
 266
 267         kscale = DIV_FROM_REG(data->config);
 268         ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
 269         if (ktach < 0)
 270                 ktach = 0;
 271         if (ktach > 255)
 272                 ktach = 255;
 273         data->speed = ktach;
 274
 275         i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);
 276
 277         mutex_unlock(&data->update_lock);
 278
 279         return count;
 280 }
 281
 282 /*
 283  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 284  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 285  * speed. Note that this is done by writing directly to the chip's DAC,
 286  * it won't change the closed loop speed set by fan1_target.
 287  * Also note that due to rounding errors it is possible that you don't read
 288  * back exactly the value you have set.
 289  */
 290
 291 static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,
 292                        char *buf)
 293 {
 294         int pwm;
 295         struct max6650_data *data = max6650_update_device(dev);
 296
 297         /* Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 298            Lower DAC values mean higher speeds. */
 299         if (data->config & MAX6650_CFG_V12)
 300                 pwm = 255 - (255 * (int)data->dac)/180;
 301         else
 302                 pwm = 255 - (255 * (int)data->dac)/76;
 303
 304         if (pwm < 0)
 305                 pwm = 0;
 306
 307         return sprintf(buf, "%d\n", pwm);
 308 }
 309
 310 static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
 311                         const char *buf, size_t count)
 312 {
 313         struct i2c_client *client = to_i2c_client(dev);
 314         struct max6650_data *data = i2c_get_clientdata(client);
 315         int pwm = simple_strtoul(buf, NULL, 10);
 316
 317         pwm = SENSORS_LIMIT(pwm, 0, 255);
 318
 319         mutex_lock(&data->update_lock);
 320
 321         if (data->config & MAX6650_CFG_V12)
 322                 data->dac = 180 - (180 * pwm)/255;
 323         else
 324                 data->dac = 76 - (76 * pwm)/255;
 325
 326         i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 327
 328         mutex_unlock(&data->update_lock);
 329
 330         return count;
 331 }
 332
 333 /*
 334  * Get/Set controller mode:
 335  * Possible values:
 336  * 0 = Fan always on
 337  * 1 = Open loop, Voltage is set according to speed, not regulated.
 338  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 339  */
 340
 341 static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,
 342                           char *buf)
 343 {
 344         struct max6650_data *data = max6650_update_device(dev);
 345         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 346         int sysfs_modes[4] = {0, 1, 2, 1};
 347
 348         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 349 }
 350
 351 static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
 352                           const char *buf, size_t count)
 353 {
 354         struct i2c_client *client = to_i2c_client(dev);
 355         struct max6650_data *data = i2c_get_clientdata(client);
 356         int mode = simple_strtoul(buf, NULL, 10);
 357         int max6650_modes[3] = {0, 3, 2};
 358
 359         if ((mode < 0)||(mode > 2)) {
 360                 dev_err(&client->dev,
 361                         "illegal value for pwm1_enable (%d)\n", mode);
 362                 return -EINVAL;
 363         }
 364
 365         mutex_lock(&data->update_lock);
 366
 367         data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 368         data->config = (data->config & ~MAX6650_CFG_MODE_MASK)
 369                        | (max6650_modes[mode] << 4);
 370
 371         i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);
 372
 373         mutex_unlock(&data->update_lock);
 374
 375         return count;
 376 }
 377
 378 /*
 379  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 380  * divider. We handle this by converting between divider and counttime:
 381  *
 382  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 383  *
 384  * Lower values of k allow to connect a faster fan without the risk of
 385  * counter overflow. The price is lower resolution. You can also set counttime
 386  * using the module parameter. Note that the module parameter "prescaler" also
 387  * influences the behaviour. Unfortunately, there's no sysfs attribute
 388  * defined for that. See the data sheet for details.
 389  */
 390
 391 static ssize_t get_div(struct device *dev, struct device_attribute *devattr,
 392                        char *buf)
 393 {
 394         struct max6650_data *data = max6650_update_device(dev);
 395
 396         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 397 }
 398
 399 static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 400                        const char *buf, size_t count)
 401 {
 402         struct i2c_client *client = to_i2c_client(dev);
 403         struct max6650_data *data = i2c_get_clientdata(client);
 404         int div = simple_strtoul(buf, NULL, 10);
 405
 406         mutex_lock(&data->update_lock);
 407         switch (div) {
 408         case 1:
 409                 data->count = 0;
 410                 break;
 411         case 2:
 412                 data->count = 1;
 413                 break;
 414         case 4:
 415                 data->count = 2;
 416                 break;
 417         case 8:
 418                 data->count = 3;
 419                 break;
 420         default:
 421                 mutex_unlock(&data->update_lock);
 422                 dev_err(&client->dev,
 423                         "illegal value for fan divider (%d)\n", div);
 424                 return -EINVAL;
 425         }
 426
 427         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 428         mutex_unlock(&data->update_lock);
 429
 430         return count;
 431 }
 432
 433 /*
 434  * Get alarm stati:
 435  * Possible values:
 436  * 0 = no alarm
 437  * 1 = alarm
 438  */
 439
 440 static ssize_t get_alarm(struct device *dev, struct device_attribute *devattr,
 441                          char *buf)
 442 {
 443         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 444         struct max6650_data *data = max6650_update_device(dev);
 445         struct i2c_client *client = to_i2c_client(dev);
 446         int alarm = 0;
 447
 448         if (data->alarm & attr->index) {
 449                 mutex_lock(&data->update_lock);
 450                 alarm = 1;
 451                 data->alarm &= ~attr->index;
 452                 data->alarm |= i2c_smbus_read_byte_data(client,
 453                                                         MAX6650_REG_ALARM);
 454                 mutex_unlock(&data->update_lock);
 455         }
 456
 457         return sprintf(buf, "%d\n", alarm);
 458 }
 459
 460 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 461 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 462 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 463 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 464 static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 465 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 466 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 467 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 468 static SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
 469                           MAX6650_ALRM_MAX);
 470 static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
 471                           MAX6650_ALRM_MIN);
 472 static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
 473                           MAX6650_ALRM_TACH);
 474 static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
 475                           MAX6650_ALRM_GPIO1);
 476 static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
 477                           MAX6650_ALRM_GPIO2);
 478
 479 static mode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
 480                                     int n)
 481 {
 482         struct device *dev = container_of(kobj, struct device, kobj);
 483         struct i2c_client *client = to_i2c_client(dev);
 484         u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
 485         struct device_attribute *devattr;
 486
 487         /*
 488          * Hide the alarms that have not been enabled by the firmware
 489          */
 490
 491         devattr = container_of(a, struct device_attribute, attr);
 492         if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
 493          || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
 494          || devattr == &sensor_dev_attr_fan1_fault.dev_attr
 495          || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
 496          || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
 497                 if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
 498                         return 0;
 499         }
 500
 501         return a->mode;
 502 }
 503
 504 static struct attribute *max6650_attrs[] = {
 505         &sensor_dev_attr_fan1_input.dev_attr.attr,
 506         &sensor_dev_attr_fan2_input.dev_attr.attr,
 507         &sensor_dev_attr_fan3_input.dev_attr.attr,
 508         &sensor_dev_attr_fan4_input.dev_attr.attr,
 509         &dev_attr_fan1_target.attr,
 510         &dev_attr_fan1_div.attr,
 511         &dev_attr_pwm1_enable.attr,
 512         &dev_attr_pwm1.attr,
 513         &sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
 514         &sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
 515         &sensor_dev_attr_fan1_fault.dev_attr.attr,
 516         &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
 517         &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
 518         NULL
 519 };
 520
 521 static struct attribute_group max6650_attr_grp = {
 522         .attrs = max6650_attrs,
 523         .is_visible = max6650_attrs_visible,
 524 };
 525
 526 /*
 527  * Real code
 528  */
 529
 530 /* Return 0 if detection is successful, -ENODEV otherwise */
 531 static int max6650_detect(struct i2c_client *client, int kind,
 532                           struct i2c_board_info *info)
 533 {
 534         struct i2c_adapter *adapter = client->adapter;
 535         int address = client->addr;
 536
 537         dev_dbg(&adapter->dev, "max6650_detect called, kind = %d\n", kind);
 538
 539         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
 540                 dev_dbg(&adapter->dev, "max6650: I2C bus doesn't support "
 541                                         "byte read mode, skipping.\n");
 542                 return -ENODEV;
 543         }
 544
 545         /*
 546          * Now we do the remaining detection. A negative kind means that
 547          * the driver was loaded with no force parameter (default), so we
 548          * must both detect and identify the chip (actually there is only
 549          * one possible kind of chip for now, max6650). A zero kind means that
 550          * the driver was loaded with the force parameter, the detection
 551          * step shall be skipped. A positive kind means that the driver
 552          * was loaded with the force parameter and a given kind of chip is
 553          * requested, so both the detection and the identification steps
 554          * are skipped.
 555          *
 556          * Currently I can find no way to distinguish between a MAX6650 and
 557          * a MAX6651. This driver has only been tried on the former.
 558          */
 559
 560         if ((kind < 0) &&
 561            (  (i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG) & 0xC0)
 562             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_GPIO_STAT) & 0xE0)
 563             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN) & 0xE0)
 564             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM) & 0xE0)
 565             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT) & 0xFC))) {
 566                 dev_dbg(&adapter->dev,
 567                         "max6650: detection failed at 0x%02x.\n", address);
 568                 return -ENODEV;
 569         }
 570
 571         dev_info(&adapter->dev, "max6650: chip found at 0x%02x.\n", address);
 572
 573         strlcpy(info->type, "max6650", I2C_NAME_SIZE);
 574
 575         return 0;
 576 }
 577
 578 static int max6650_probe(struct i2c_client *client,
 579                          const struct i2c_device_id *id)
 580 {
 581         struct max6650_data *data;
 582         int err;
 583
 584         if (!(data = kzalloc(sizeof(struct max6650_data), GFP_KERNEL))) {
 585                 dev_err(&client->dev, "out of memory.\n");
 586                 return -ENOMEM;
 587         }
 588
 589         i2c_set_clientdata(client, data);
 590         mutex_init(&data->update_lock);
 591
 592         /*
 593          * Initialize the max6650 chip
 594          */
 595         err = max6650_init_client(client);
 596         if (err)
 597                 goto err_free;
 598
 599         err = sysfs_create_group(&client->dev.kobj, &max6650_attr_grp);
 600         if (err)
 601                 goto err_free;
 602
 603         data->hwmon_dev = hwmon_device_register(&client->dev);
 604         if (!IS_ERR(data->hwmon_dev))
 605                 return 0;
 606
 607         err = PTR_ERR(data->hwmon_dev);
 608         dev_err(&client->dev, "error registering hwmon device.\n");
 609         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 610 err_free:
 611         kfree(data);
 612         return err;
 613 }
 614
 615 static int max6650_remove(struct i2c_client *client)
 616 {
 617         struct max6650_data *data = i2c_get_clientdata(client);
 618
 619         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 620         hwmon_device_unregister(data->hwmon_dev);
 621         kfree(data);
 622         return 0;
 623 }
 624
 625 static int max6650_init_client(struct i2c_client *client)
 626 {
 627         struct max6650_data *data = i2c_get_clientdata(client);
 628         int config;
 629         int err = -EIO;
 630
 631         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 632
 633         if (config < 0) {
 634                 dev_err(&client->dev, "Error reading config, aborting.\n");
 635                 return err;
 636         }
 637
 638         switch (fan_voltage) {
 639                 case 0:
 640                         break;
 641                 case 5:
 642                         config &= ~MAX6650_CFG_V12;
 643                         break;
 644                 case 12:
 645                         config |= MAX6650_CFG_V12;
 646                         break;
 647                 default:
 648                         dev_err(&client->dev,
 649                                 "illegal value for fan_voltage (%d)\n",
 650                                 fan_voltage);
 651         }
 652
 653         dev_info(&client->dev, "Fan voltage is set to %dV.\n",
 654                  (config & MAX6650_CFG_V12) ? 12 : 5);
 655
 656         switch (prescaler) {
 657                 case 0:
 658                         break;
 659                 case 1:
 660                         config &= ~MAX6650_CFG_PRESCALER_MASK;
 661                         break;
 662                 case 2:
 663                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 664                                  | MAX6650_CFG_PRESCALER_2;
 665                         break;
 666                 case  4:
 667                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 668                                  | MAX6650_CFG_PRESCALER_4;
 669                         break;
 670                 case  8:
 671                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 672                                  | MAX6650_CFG_PRESCALER_8;
 673                         break;
 674                 case 16:
 675                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 676                                  | MAX6650_CFG_PRESCALER_16;
 677                         break;
 678                 default:
 679                         dev_err(&client->dev,
 680                                 "illegal value for prescaler (%d)\n",
 681                                 prescaler);
 682         }
 683
 684         dev_info(&client->dev, "Prescaler is set to %d.\n",
 685                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 686
 687         /* If mode is set to "full off", we change it to "open loop" and
 688          * set DAC to 255, which has the same effect. We do this because
 689          * there's no "full off" mode defined in hwmon specifcations.
 690          */
 691
 692         if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {
 693                 dev_dbg(&client->dev, "Change mode to open loop, full off.\n");
 694                 config = (config & ~MAX6650_CFG_MODE_MASK)
 695                          | MAX6650_CFG_MODE_OPEN_LOOP;
 696                 if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {
 697                         dev_err(&client->dev, "DAC write error, aborting.\n");
 698                         return err;
 699                 }
 700         }
 701
 702         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 703                 dev_err(&client->dev, "Config write error, aborting.\n");
 704                 return err;
 705         }
 706
 707         data->config = config;
 708         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 709
 710         return 0;
 711 }
 712
 713 static const u8 tach_reg[] = {
 714         MAX6650_REG_TACH0,
 715         MAX6650_REG_TACH1,
 716         MAX6650_REG_TACH2,
 717         MAX6650_REG_TACH3,
 718 };
 719
 720 static struct max6650_data *max6650_update_device(struct device *dev)
 721 {
 722         int i;
 723         struct i2c_client *client = to_i2c_client(dev);
 724         struct max6650_data *data = i2c_get_clientdata(client);
 725
 726         mutex_lock(&data->update_lock);
 727
 728         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 729                 data->speed = i2c_smbus_read_byte_data(client,
 730                                                        MAX6650_REG_SPEED);
 731                 data->config = i2c_smbus_read_byte_data(client,
 732                                                         MAX6650_REG_CONFIG);
 733                 for (i = 0; i < 4; i++) {
 734                         data->tach[i] = i2c_smbus_read_byte_data(client,
 735                                                                  tach_reg[i]);
 736                 }
 737                 data->count = i2c_smbus_read_byte_data(client,
 738                                                         MAX6650_REG_COUNT);
 739                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 740
 741                 /* Alarms are cleared on read in case the condition that
 742                  * caused the alarm is removed. Keep the value latched here
 743                  * for providing the register through different alarm files. */
 744                 data->alarm |= i2c_smbus_read_byte_data(client,
 745                                                         MAX6650_REG_ALARM);
 746
 747                 data->last_updated = jiffies;
 748                 data->valid = 1;
 749         }
 750
 751         mutex_unlock(&data->update_lock);
 752
 753         return data;
 754 }
 755
 756 static int __init sensors_max6650_init(void)
 757 {
 758         return i2c_add_driver(&max6650_driver);
 759 }
 760
 761 static void __exit sensors_max6650_exit(void)
 762 {
 763         i2c_del_driver(&max6650_driver);
 764 }
 765
 766 MODULE_AUTHOR("Hans J. Koch");
 767 MODULE_DESCRIPTION("MAX6650 sensor driver");
 768 MODULE_LICENSE("GPL");
 769
 770 module_init(sensors_max6650_init);
 771 module_exit(sensors_max6650_exit);