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 #include <linux/of_device.h>
  43
  44 /*
  45  * Insmod parameters
  46  */
  47
  48 /* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */
  49 static int fan_voltage;
  50 /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
  51 static int prescaler;
  52 /* clock: The clock frequency of the chip (max6651 can be clocked externally) */
  53 static int clock = 254000;
  54
  55 module_param(fan_voltage, int, S_IRUGO);
  56 module_param(prescaler, int, S_IRUGO);
  57 module_param(clock, int, S_IRUGO);
  58
  59 /*
  60  * MAX 6650/6651 registers
  61  */
  62
  63 #define MAX6650_REG_SPEED       0x00
  64 #define MAX6650_REG_CONFIG      0x02
  65 #define MAX6650_REG_GPIO_DEF    0x04
  66 #define MAX6650_REG_DAC         0x06
  67 #define MAX6650_REG_ALARM_EN    0x08
  68 #define MAX6650_REG_ALARM       0x0A
  69 #define MAX6650_REG_TACH0       0x0C
  70 #define MAX6650_REG_TACH1       0x0E
  71 #define MAX6650_REG_TACH2       0x10
  72 #define MAX6650_REG_TACH3       0x12
  73 #define MAX6650_REG_GPIO_STAT   0x14
  74 #define MAX6650_REG_COUNT       0x16
  75
  76 /*
  77  * Config register bits
  78  */
  79
  80 #define MAX6650_CFG_V12                 0x08
  81 #define MAX6650_CFG_PRESCALER_MASK      0x07
  82 #define MAX6650_CFG_PRESCALER_2         0x01
  83 #define MAX6650_CFG_PRESCALER_4         0x02
  84 #define MAX6650_CFG_PRESCALER_8         0x03
  85 #define MAX6650_CFG_PRESCALER_16        0x04
  86 #define MAX6650_CFG_MODE_MASK           0x30
  87 #define MAX6650_CFG_MODE_ON             0x00
  88 #define MAX6650_CFG_MODE_OFF            0x10
  89 #define MAX6650_CFG_MODE_CLOSED_LOOP    0x20
  90 #define MAX6650_CFG_MODE_OPEN_LOOP      0x30
  91 #define MAX6650_COUNT_MASK              0x03
  92
  93 /*
  94  * Alarm status register bits
  95  */
  96
  97 #define MAX6650_ALRM_MAX        0x01
  98 #define MAX6650_ALRM_MIN        0x02
  99 #define MAX6650_ALRM_TACH       0x04
 100 #define MAX6650_ALRM_GPIO1      0x08
 101 #define MAX6650_ALRM_GPIO2      0x10
 102
 103 /* Minimum and maximum values of the FAN-RPM */
 104 #define FAN_RPM_MIN 240
 105 #define FAN_RPM_MAX 30000
 106
 107 #define DIV_FROM_REG(reg) (1 << (reg & 7))
 108
 109 /*
 110  * Client data (each client gets its own)
 111  */
 112
 113 struct max6650_data {
 114         struct i2c_client *client;
 115         const struct attribute_group *groups[3];
 116         struct mutex update_lock;
 117         int nr_fans;
 118         char valid; /* zero until following fields are valid */
 119         unsigned long last_updated; /* in jiffies */
 120
 121         /* register values */
 122         u8 speed;
 123         u8 config;
 124         u8 tach[4];
 125         u8 count;
 126         u8 dac;
 127         u8 alarm;
 128 };
 129
 130 static const u8 tach_reg[] = {
 131         MAX6650_REG_TACH0,
 132         MAX6650_REG_TACH1,
 133         MAX6650_REG_TACH2,
 134         MAX6650_REG_TACH3,
 135 };
 136
 137 static const struct of_device_id max6650_dt_match[] = {
 138         {
 139                 .compatible = "maxim,max6650",
 140                 .data = (void *)1
 141         },
 142         {
 143                 .compatible = "maxim,max6651",
 144                 .data = (void *)4
 145         },
 146         { },
 147 };
 148 MODULE_DEVICE_TABLE(of, max6650_dt_match);
 149
 150 static struct max6650_data *max6650_update_device(struct device *dev)
 151 {
 152         struct max6650_data *data = dev_get_drvdata(dev);
 153         struct i2c_client *client = data->client;
 154         int i;
 155
 156         mutex_lock(&data->update_lock);
 157
 158         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 159                 data->speed = i2c_smbus_read_byte_data(client,
 160                                                        MAX6650_REG_SPEED);
 161                 data->config = i2c_smbus_read_byte_data(client,
 162                                                         MAX6650_REG_CONFIG);
 163                 for (i = 0; i < data->nr_fans; i++) {
 164                         data->tach[i] = i2c_smbus_read_byte_data(client,
 165                                                                  tach_reg[i]);
 166                 }
 167                 data->count = i2c_smbus_read_byte_data(client,
 168                                                         MAX6650_REG_COUNT);
 169                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 170
 171                 /*
 172                  * Alarms are cleared on read in case the condition that
 173                  * caused the alarm is removed. Keep the value latched here
 174                  * for providing the register through different alarm files.
 175                  */
 176                 data->alarm |= i2c_smbus_read_byte_data(client,
 177                                                         MAX6650_REG_ALARM);
 178
 179                 data->last_updated = jiffies;
 180                 data->valid = 1;
 181         }
 182
 183         mutex_unlock(&data->update_lock);
 184
 185         return data;
 186 }
 187
 188 /*
 189  * Change the operating mode of the chip (if needed).
 190  * mode is one of the MAX6650_CFG_MODE_* values.
 191  */
 192 static int max6650_set_operating_mode(struct max6650_data *data, u8 mode)
 193 {
 194         int result;
 195         u8 config = data->config;
 196
 197         if (mode == (config & MAX6650_CFG_MODE_MASK))
 198                 return 0;
 199
 200         config = (config & ~MAX6650_CFG_MODE_MASK) | mode;
 201
 202         result = i2c_smbus_write_byte_data(data->client, MAX6650_REG_CONFIG,
 203                                            config);
 204         if (result < 0)
 205                 return result;
 206
 207         data->config = config;
 208
 209         return 0;
 210 }
 211
 212 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
 213                        char *buf)
 214 {
 215         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 216         struct max6650_data *data = max6650_update_device(dev);
 217         int rpm;
 218
 219         /*
 220          * Calculation details:
 221          *
 222          * Each tachometer counts over an interval given by the "count"
 223          * register (0.25, 0.5, 1 or 2 seconds). This module assumes
 224          * that the fans produce two pulses per revolution (this seems
 225          * to be the most common).
 226          */
 227
 228         rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
 229         return sprintf(buf, "%d\n", rpm);
 230 }
 231
 232 /*
 233  * Set the fan speed to the specified RPM (or read back the RPM setting).
 234  * This works in closed loop mode only. Use pwm1 for open loop speed setting.
 235  *
 236  * The MAX6650/1 will automatically control fan speed when in closed loop
 237  * mode.
 238  *
 239  * Assumptions:
 240  *
 241  * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
 242  *    the clock module parameter if you need to fine tune this.
 243  *
 244  * 2) The prescaler (low three bits of the config register) has already
 245  *    been set to an appropriate value. Use the prescaler module parameter
 246  *    if your BIOS doesn't initialize the chip properly.
 247  *
 248  * The relevant equations are given on pages 21 and 22 of the datasheet.
 249  *
 250  * From the datasheet, the relevant equation when in regulation is:
 251  *
 252  *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
 253  *
 254  * where:
 255  *
 256  *    fCLK is the oscillator frequency (either the 254kHz internal
 257  *         oscillator or the externally applied clock)
 258  *
 259  *    KTACH is the value in the speed register
 260  *
 261  *    FanSpeed is the speed of the fan in rps
 262  *
 263  *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)
 264  *
 265  * When reading, we need to solve for FanSpeed. When writing, we need to
 266  * solve for KTACH.
 267  *
 268  * Note: this tachometer is completely separate from the tachometers
 269  * used to measure the fan speeds. Only one fan's speed (fan1) is
 270  * controlled.
 271  */
 272
 273 static ssize_t get_target(struct device *dev, struct device_attribute *devattr,
 274                          char *buf)
 275 {
 276         struct max6650_data *data = max6650_update_device(dev);
 277         int kscale, ktach, rpm;
 278
 279         /*
 280          * Use the datasheet equation:
 281          *
 282          *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
 283          *
 284          * then multiply by 60 to give rpm.
 285          */
 286
 287         kscale = DIV_FROM_REG(data->config);
 288         ktach = data->speed;
 289         rpm = 60 * kscale * clock / (256 * (ktach + 1));
 290         return sprintf(buf, "%d\n", rpm);
 291 }
 292
 293 static int max6650_set_target(struct max6650_data *data, unsigned long rpm)
 294 {
 295         int kscale, ktach;
 296
 297         if (rpm == 0)
 298                 return max6650_set_operating_mode(data, MAX6650_CFG_MODE_OFF);
 299
 300         rpm = clamp_val(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
 301
 302         /*
 303          * Divide the required speed by 60 to get from rpm to rps, then
 304          * use the datasheet equation:
 305          *
 306          *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
 307          */
 308
 309         kscale = DIV_FROM_REG(data->config);
 310         ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
 311         if (ktach < 0)
 312                 ktach = 0;
 313         if (ktach > 255)
 314                 ktach = 255;
 315         data->speed = ktach;
 316
 317         return i2c_smbus_write_byte_data(data->client, MAX6650_REG_SPEED,
 318                                          data->speed);
 319 }
 320
 321 static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
 322                          const char *buf, size_t count)
 323 {
 324         struct max6650_data *data = dev_get_drvdata(dev);
 325         unsigned long rpm;
 326         int err;
 327
 328         err = kstrtoul(buf, 10, &rpm);
 329         if (err)
 330                 return err;
 331
 332         mutex_lock(&data->update_lock);
 333
 334         err = max6650_set_target(data, rpm);
 335
 336         mutex_unlock(&data->update_lock);
 337
 338         if (err < 0)
 339                 return err;
 340
 341         return count;
 342 }
 343
 344 /*
 345  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 346  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 347  * speed. Note that this is done by writing directly to the chip's DAC,
 348  * it won't change the closed loop speed set by fan1_target.
 349  * Also note that due to rounding errors it is possible that you don't read
 350  * back exactly the value you have set.
 351  */
 352
 353 static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,
 354                        char *buf)
 355 {
 356         int pwm;
 357         struct max6650_data *data = max6650_update_device(dev);
 358
 359         /*
 360          * Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 361          * Lower DAC values mean higher speeds.
 362          */
 363         if (data->config & MAX6650_CFG_V12)
 364                 pwm = 255 - (255 * (int)data->dac)/180;
 365         else
 366                 pwm = 255 - (255 * (int)data->dac)/76;
 367
 368         if (pwm < 0)
 369                 pwm = 0;
 370
 371         return sprintf(buf, "%d\n", pwm);
 372 }
 373
 374 static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
 375                         const char *buf, size_t count)
 376 {
 377         struct max6650_data *data = dev_get_drvdata(dev);
 378         struct i2c_client *client = data->client;
 379         unsigned long pwm;
 380         int err;
 381
 382         err = kstrtoul(buf, 10, &pwm);
 383         if (err)
 384                 return err;
 385
 386         pwm = clamp_val(pwm, 0, 255);
 387
 388         mutex_lock(&data->update_lock);
 389
 390         if (data->config & MAX6650_CFG_V12)
 391                 data->dac = 180 - (180 * pwm)/255;
 392         else
 393                 data->dac = 76 - (76 * pwm)/255;
 394         err = i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 395
 396         mutex_unlock(&data->update_lock);
 397
 398         return err < 0 ? err : count;
 399 }
 400
 401 /*
 402  * Get/Set controller mode:
 403  * Possible values:
 404  * 0 = Fan always on
 405  * 1 = Open loop, Voltage is set according to speed, not regulated.
 406  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 407  * 3 = Fan off
 408  */
 409 static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,
 410                           char *buf)
 411 {
 412         struct max6650_data *data = max6650_update_device(dev);
 413         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 414         int sysfs_modes[4] = {0, 3, 2, 1};
 415
 416         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 417 }
 418
 419 static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
 420                           const char *buf, size_t count)
 421 {
 422         struct max6650_data *data = dev_get_drvdata(dev);
 423         unsigned long mode;
 424         int err;
 425         const u8 max6650_modes[] = {
 426                 MAX6650_CFG_MODE_ON,
 427                 MAX6650_CFG_MODE_OPEN_LOOP,
 428                 MAX6650_CFG_MODE_CLOSED_LOOP,
 429                 MAX6650_CFG_MODE_OFF,
 430                 };
 431
 432         err = kstrtoul(buf, 10, &mode);
 433         if (err)
 434                 return err;
 435
 436         if (mode >= ARRAY_SIZE(max6650_modes))
 437                 return -EINVAL;
 438
 439         mutex_lock(&data->update_lock);
 440
 441         max6650_set_operating_mode(data, max6650_modes[mode]);
 442
 443         mutex_unlock(&data->update_lock);
 444
 445         return count;
 446 }
 447
 448 /*
 449  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 450  * divider. We handle this by converting between divider and counttime:
 451  *
 452  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 453  *
 454  * Lower values of k allow to connect a faster fan without the risk of
 455  * counter overflow. The price is lower resolution. You can also set counttime
 456  * using the module parameter. Note that the module parameter "prescaler" also
 457  * influences the behaviour. Unfortunately, there's no sysfs attribute
 458  * defined for that. See the data sheet for details.
 459  */
 460
 461 static ssize_t get_div(struct device *dev, struct device_attribute *devattr,
 462                        char *buf)
 463 {
 464         struct max6650_data *data = max6650_update_device(dev);
 465
 466         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 467 }
 468
 469 static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 470                        const char *buf, size_t count)
 471 {
 472         struct max6650_data *data = dev_get_drvdata(dev);
 473         struct i2c_client *client = data->client;
 474         unsigned long div;
 475         int err;
 476
 477         err = kstrtoul(buf, 10, &div);
 478         if (err)
 479                 return err;
 480
 481         mutex_lock(&data->update_lock);
 482         switch (div) {
 483         case 1:
 484                 data->count = 0;
 485                 break;
 486         case 2:
 487                 data->count = 1;
 488                 break;
 489         case 4:
 490                 data->count = 2;
 491                 break;
 492         case 8:
 493                 data->count = 3;
 494                 break;
 495         default:
 496                 mutex_unlock(&data->update_lock);
 497                 return -EINVAL;
 498         }
 499
 500         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 501         mutex_unlock(&data->update_lock);
 502
 503         return count;
 504 }
 505
 506 /*
 507  * Get alarm stati:
 508  * Possible values:
 509  * 0 = no alarm
 510  * 1 = alarm
 511  */
 512
 513 static ssize_t get_alarm(struct device *dev, struct device_attribute *devattr,
 514                          char *buf)
 515 {
 516         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 517         struct max6650_data *data = max6650_update_device(dev);
 518         struct i2c_client *client = data->client;
 519         int alarm = 0;
 520
 521         if (data->alarm & attr->index) {
 522                 mutex_lock(&data->update_lock);
 523                 alarm = 1;
 524                 data->alarm &= ~attr->index;
 525                 data->alarm |= i2c_smbus_read_byte_data(client,
 526                                                         MAX6650_REG_ALARM);
 527                 mutex_unlock(&data->update_lock);
 528         }
 529
 530         return sprintf(buf, "%d\n", alarm);
 531 }
 532
 533 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 534 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 535 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 536 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 537 static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 538 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 539 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 540 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 541 static SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
 542                           MAX6650_ALRM_MAX);
 543 static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
 544                           MAX6650_ALRM_MIN);
 545 static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
 546                           MAX6650_ALRM_TACH);
 547 static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
 548                           MAX6650_ALRM_GPIO1);
 549 static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
 550                           MAX6650_ALRM_GPIO2);
 551
 552 static umode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
 553                                     int n)
 554 {
 555         struct device *dev = container_of(kobj, struct device, kobj);
 556         struct max6650_data *data = dev_get_drvdata(dev);
 557         struct i2c_client *client = data->client;
 558         u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
 559         struct device_attribute *devattr;
 560
 561         /*
 562          * Hide the alarms that have not been enabled by the firmware
 563          */
 564
 565         devattr = container_of(a, struct device_attribute, attr);
 566         if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
 567          || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
 568          || devattr == &sensor_dev_attr_fan1_fault.dev_attr
 569          || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
 570          || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
 571                 if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
 572                         return 0;
 573         }
 574
 575         return a->mode;
 576 }
 577
 578 static struct attribute *max6650_attrs[] = {
 579         &sensor_dev_attr_fan1_input.dev_attr.attr,
 580         &dev_attr_fan1_target.attr,
 581         &dev_attr_fan1_div.attr,
 582         &dev_attr_pwm1_enable.attr,
 583         &dev_attr_pwm1.attr,
 584         &sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
 585         &sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
 586         &sensor_dev_attr_fan1_fault.dev_attr.attr,
 587         &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
 588         &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
 589         NULL
 590 };
 591
 592 static const struct attribute_group max6650_group = {
 593         .attrs = max6650_attrs,
 594         .is_visible = max6650_attrs_visible,
 595 };
 596
 597 static struct attribute *max6651_attrs[] = {
 598         &sensor_dev_attr_fan2_input.dev_attr.attr,
 599         &sensor_dev_attr_fan3_input.dev_attr.attr,
 600         &sensor_dev_attr_fan4_input.dev_attr.attr,
 601         NULL
 602 };
 603
 604 static const struct attribute_group max6651_group = {
 605         .attrs = max6651_attrs,
 606 };
 607
 608 /*
 609  * Real code
 610  */
 611
 612 static int max6650_init_client(struct max6650_data *data,
 613                                struct i2c_client *client)
 614 {
 615         struct device *dev = &client->dev;
 616         int config;
 617         int err = -EIO;
 618         u32 voltage;
 619         u32 prescale;
 620         u32 target_rpm;
 621
 622         if (of_property_read_u32(dev->of_node, "maxim,fan-microvolt",
 623                                  &voltage))
 624                 voltage = fan_voltage;
 625         else
 626                 voltage /= 1000000; /* Microvolts to volts */
 627         if (of_property_read_u32(dev->of_node, "maxim,fan-prescale",
 628                                  &prescale))
 629                 prescale = prescaler;
 630
 631         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 632
 633         if (config < 0) {
 634                 dev_err(dev, "Error reading config, aborting.\n");
 635                 return err;
 636         }
 637
 638         switch (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(dev, "illegal value for fan_voltage (%d)\n", voltage);
 649         }
 650
 651         switch (prescale) {
 652         case 0:
 653                 break;
 654         case 1:
 655                 config &= ~MAX6650_CFG_PRESCALER_MASK;
 656                 break;
 657         case 2:
 658                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 659                          | MAX6650_CFG_PRESCALER_2;
 660                 break;
 661         case  4:
 662                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 663                          | MAX6650_CFG_PRESCALER_4;
 664                 break;
 665         case  8:
 666                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 667                          | MAX6650_CFG_PRESCALER_8;
 668                 break;
 669         case 16:
 670                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 671                          | MAX6650_CFG_PRESCALER_16;
 672                 break;
 673         default:
 674                 dev_err(dev, "illegal value for prescaler (%d)\n", prescale);
 675         }
 676
 677         dev_info(dev, "Fan voltage: %dV, prescaler: %d.\n",
 678                  (config & MAX6650_CFG_V12) ? 12 : 5,
 679                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 680
 681         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 682                 dev_err(dev, "Config write error, aborting.\n");
 683                 return err;
 684         }
 685
 686         data->config = config;
 687         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 688
 689         if (!of_property_read_u32(client->dev.of_node, "maxim,fan-target-rpm",
 690                                   &target_rpm)) {
 691                 max6650_set_target(data, target_rpm);
 692                 max6650_set_operating_mode(data, MAX6650_CFG_MODE_CLOSED_LOOP);
 693         }
 694
 695         return 0;
 696 }
 697
 698 static int max6650_probe(struct i2c_client *client,
 699                          const struct i2c_device_id *id)
 700 {
 701         struct device *dev = &client->dev;
 702         const struct of_device_id *of_id =
 703                 of_match_device(of_match_ptr(max6650_dt_match), dev);
 704         struct max6650_data *data;
 705         struct device *hwmon_dev;
 706         int err;
 707
 708         data = devm_kzalloc(dev, sizeof(struct max6650_data), GFP_KERNEL);
 709         if (!data)
 710                 return -ENOMEM;
 711
 712         data->client = client;
 713         mutex_init(&data->update_lock);
 714         data->nr_fans = of_id ? (int)(uintptr_t)of_id->data : id->driver_data;
 715
 716         /*
 717          * Initialize the max6650 chip
 718          */
 719         err = max6650_init_client(data, client);
 720         if (err)
 721                 return err;
 722
 723         data->groups[0] = &max6650_group;
 724         /* 3 additional fan inputs for the MAX6651 */
 725         if (data->nr_fans == 4)
 726                 data->groups[1] = &max6651_group;
 727
 728         hwmon_dev = devm_hwmon_device_register_with_groups(dev,
 729                                                            client->name, data,
 730                                                            data->groups);
 731         return PTR_ERR_OR_ZERO(hwmon_dev);
 732 }
 733
 734 static const struct i2c_device_id max6650_id[] = {
 735         { "max6650", 1 },
 736         { "max6651", 4 },
 737         { }
 738 };
 739 MODULE_DEVICE_TABLE(i2c, max6650_id);
 740
 741 static struct i2c_driver max6650_driver = {
 742         .driver = {
 743                 .name   = "max6650",
 744                 .of_match_table = of_match_ptr(max6650_dt_match),
 745         },
 746         .probe          = max6650_probe,
 747         .id_table       = max6650_id,
 748 };
 749
 750 module_i2c_driver(max6650_driver);
 751
 752 MODULE_AUTHOR("Hans J. Koch");
 753 MODULE_DESCRIPTION("MAX6650 sensor driver");
 754 MODULE_LICENSE("GPL");