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 fan1_target_show(struct device *dev,
 274                                 struct device_attribute *devattr, 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 fan1_target_store(struct device *dev,
 322                                  struct device_attribute *devattr,
 323                                  const char *buf, size_t count)
 324 {
 325         struct max6650_data *data = dev_get_drvdata(dev);
 326         unsigned long rpm;
 327         int err;
 328
 329         err = kstrtoul(buf, 10, &rpm);
 330         if (err)
 331                 return err;
 332
 333         mutex_lock(&data->update_lock);
 334
 335         err = max6650_set_target(data, rpm);
 336
 337         mutex_unlock(&data->update_lock);
 338
 339         if (err < 0)
 340                 return err;
 341
 342         return count;
 343 }
 344
 345 /*
 346  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 347  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 348  * speed. Note that this is done by writing directly to the chip's DAC,
 349  * it won't change the closed loop speed set by fan1_target.
 350  * Also note that due to rounding errors it is possible that you don't read
 351  * back exactly the value you have set.
 352  */
 353
 354 static ssize_t pwm1_show(struct device *dev, struct device_attribute *devattr,
 355                          char *buf)
 356 {
 357         int pwm;
 358         struct max6650_data *data = max6650_update_device(dev);
 359
 360         /*
 361          * Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 362          * Lower DAC values mean higher speeds.
 363          */
 364         if (data->config & MAX6650_CFG_V12)
 365                 pwm = 255 - (255 * (int)data->dac)/180;
 366         else
 367                 pwm = 255 - (255 * (int)data->dac)/76;
 368
 369         if (pwm < 0)
 370                 pwm = 0;
 371
 372         return sprintf(buf, "%d\n", pwm);
 373 }
 374
 375 static ssize_t pwm1_store(struct device *dev,
 376                           struct device_attribute *devattr, const char *buf,
 377                           size_t count)
 378 {
 379         struct max6650_data *data = dev_get_drvdata(dev);
 380         struct i2c_client *client = data->client;
 381         unsigned long pwm;
 382         int err;
 383
 384         err = kstrtoul(buf, 10, &pwm);
 385         if (err)
 386                 return err;
 387
 388         pwm = clamp_val(pwm, 0, 255);
 389
 390         mutex_lock(&data->update_lock);
 391
 392         if (data->config & MAX6650_CFG_V12)
 393                 data->dac = 180 - (180 * pwm)/255;
 394         else
 395                 data->dac = 76 - (76 * pwm)/255;
 396         err = i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 397
 398         mutex_unlock(&data->update_lock);
 399
 400         return err < 0 ? err : count;
 401 }
 402
 403 /*
 404  * Get/Set controller mode:
 405  * Possible values:
 406  * 0 = Fan always on
 407  * 1 = Open loop, Voltage is set according to speed, not regulated.
 408  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 409  * 3 = Fan off
 410  */
 411 static ssize_t pwm1_enable_show(struct device *dev,
 412                                 struct device_attribute *devattr, char *buf)
 413 {
 414         struct max6650_data *data = max6650_update_device(dev);
 415         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 416         int sysfs_modes[4] = {0, 3, 2, 1};
 417
 418         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 419 }
 420
 421 static ssize_t pwm1_enable_store(struct device *dev,
 422                                  struct device_attribute *devattr,
 423                                  const char *buf, size_t count)
 424 {
 425         struct max6650_data *data = dev_get_drvdata(dev);
 426         unsigned long mode;
 427         int err;
 428         const u8 max6650_modes[] = {
 429                 MAX6650_CFG_MODE_ON,
 430                 MAX6650_CFG_MODE_OPEN_LOOP,
 431                 MAX6650_CFG_MODE_CLOSED_LOOP,
 432                 MAX6650_CFG_MODE_OFF,
 433                 };
 434
 435         err = kstrtoul(buf, 10, &mode);
 436         if (err)
 437                 return err;
 438
 439         if (mode >= ARRAY_SIZE(max6650_modes))
 440                 return -EINVAL;
 441
 442         mutex_lock(&data->update_lock);
 443
 444         max6650_set_operating_mode(data, max6650_modes[mode]);
 445
 446         mutex_unlock(&data->update_lock);
 447
 448         return count;
 449 }
 450
 451 /*
 452  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 453  * divider. We handle this by converting between divider and counttime:
 454  *
 455  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 456  *
 457  * Lower values of k allow to connect a faster fan without the risk of
 458  * counter overflow. The price is lower resolution. You can also set counttime
 459  * using the module parameter. Note that the module parameter "prescaler" also
 460  * influences the behaviour. Unfortunately, there's no sysfs attribute
 461  * defined for that. See the data sheet for details.
 462  */
 463
 464 static ssize_t fan1_div_show(struct device *dev,
 465                              struct device_attribute *devattr, char *buf)
 466 {
 467         struct max6650_data *data = max6650_update_device(dev);
 468
 469         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 470 }
 471
 472 static ssize_t fan1_div_store(struct device *dev,
 473                               struct device_attribute *devattr,
 474                               const char *buf, size_t count)
 475 {
 476         struct max6650_data *data = dev_get_drvdata(dev);
 477         struct i2c_client *client = data->client;
 478         unsigned long div;
 479         int err;
 480
 481         err = kstrtoul(buf, 10, &div);
 482         if (err)
 483                 return err;
 484
 485         mutex_lock(&data->update_lock);
 486         switch (div) {
 487         case 1:
 488                 data->count = 0;
 489                 break;
 490         case 2:
 491                 data->count = 1;
 492                 break;
 493         case 4:
 494                 data->count = 2;
 495                 break;
 496         case 8:
 497                 data->count = 3;
 498                 break;
 499         default:
 500                 mutex_unlock(&data->update_lock);
 501                 return -EINVAL;
 502         }
 503
 504         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 505         mutex_unlock(&data->update_lock);
 506
 507         return count;
 508 }
 509
 510 /*
 511  * Get alarm stati:
 512  * Possible values:
 513  * 0 = no alarm
 514  * 1 = alarm
 515  */
 516
 517 static ssize_t get_alarm(struct device *dev, struct device_attribute *devattr,
 518                          char *buf)
 519 {
 520         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 521         struct max6650_data *data = max6650_update_device(dev);
 522         struct i2c_client *client = data->client;
 523         int alarm = 0;
 524
 525         if (data->alarm & attr->index) {
 526                 mutex_lock(&data->update_lock);
 527                 alarm = 1;
 528                 data->alarm &= ~attr->index;
 529                 data->alarm |= i2c_smbus_read_byte_data(client,
 530                                                         MAX6650_REG_ALARM);
 531                 mutex_unlock(&data->update_lock);
 532         }
 533
 534         return sprintf(buf, "%d\n", alarm);
 535 }
 536
 537 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 538 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 539 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 540 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 541 static DEVICE_ATTR_RW(fan1_target);
 542 static DEVICE_ATTR_RW(fan1_div);
 543 static DEVICE_ATTR_RW(pwm1_enable);
 544 static DEVICE_ATTR_RW(pwm1);
 545 static SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
 546                           MAX6650_ALRM_MAX);
 547 static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
 548                           MAX6650_ALRM_MIN);
 549 static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
 550                           MAX6650_ALRM_TACH);
 551 static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
 552                           MAX6650_ALRM_GPIO1);
 553 static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
 554                           MAX6650_ALRM_GPIO2);
 555
 556 static umode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
 557                                     int n)
 558 {
 559         struct device *dev = container_of(kobj, struct device, kobj);
 560         struct max6650_data *data = dev_get_drvdata(dev);
 561         struct i2c_client *client = data->client;
 562         u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
 563         struct device_attribute *devattr;
 564
 565         /*
 566          * Hide the alarms that have not been enabled by the firmware
 567          */
 568
 569         devattr = container_of(a, struct device_attribute, attr);
 570         if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
 571          || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
 572          || devattr == &sensor_dev_attr_fan1_fault.dev_attr
 573          || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
 574          || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
 575                 if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
 576                         return 0;
 577         }
 578
 579         return a->mode;
 580 }
 581
 582 static struct attribute *max6650_attrs[] = {
 583         &sensor_dev_attr_fan1_input.dev_attr.attr,
 584         &dev_attr_fan1_target.attr,
 585         &dev_attr_fan1_div.attr,
 586         &dev_attr_pwm1_enable.attr,
 587         &dev_attr_pwm1.attr,
 588         &sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
 589         &sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
 590         &sensor_dev_attr_fan1_fault.dev_attr.attr,
 591         &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
 592         &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
 593         NULL
 594 };
 595
 596 static const struct attribute_group max6650_group = {
 597         .attrs = max6650_attrs,
 598         .is_visible = max6650_attrs_visible,
 599 };
 600
 601 static struct attribute *max6651_attrs[] = {
 602         &sensor_dev_attr_fan2_input.dev_attr.attr,
 603         &sensor_dev_attr_fan3_input.dev_attr.attr,
 604         &sensor_dev_attr_fan4_input.dev_attr.attr,
 605         NULL
 606 };
 607
 608 static const struct attribute_group max6651_group = {
 609         .attrs = max6651_attrs,
 610 };
 611
 612 /*
 613  * Real code
 614  */
 615
 616 static int max6650_init_client(struct max6650_data *data,
 617                                struct i2c_client *client)
 618 {
 619         struct device *dev = &client->dev;
 620         int config;
 621         int err = -EIO;
 622         u32 voltage;
 623         u32 prescale;
 624         u32 target_rpm;
 625
 626         if (of_property_read_u32(dev->of_node, "maxim,fan-microvolt",
 627                                  &voltage))
 628                 voltage = fan_voltage;
 629         else
 630                 voltage /= 1000000; /* Microvolts to volts */
 631         if (of_property_read_u32(dev->of_node, "maxim,fan-prescale",
 632                                  &prescale))
 633                 prescale = prescaler;
 634
 635         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 636
 637         if (config < 0) {
 638                 dev_err(dev, "Error reading config, aborting.\n");
 639                 return err;
 640         }
 641
 642         switch (voltage) {
 643         case 0:
 644                 break;
 645         case 5:
 646                 config &= ~MAX6650_CFG_V12;
 647                 break;
 648         case 12:
 649                 config |= MAX6650_CFG_V12;
 650                 break;
 651         default:
 652                 dev_err(dev, "illegal value for fan_voltage (%d)\n", voltage);
 653         }
 654
 655         switch (prescale) {
 656         case 0:
 657                 break;
 658         case 1:
 659                 config &= ~MAX6650_CFG_PRESCALER_MASK;
 660                 break;
 661         case 2:
 662                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 663                          | MAX6650_CFG_PRESCALER_2;
 664                 break;
 665         case  4:
 666                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 667                          | MAX6650_CFG_PRESCALER_4;
 668                 break;
 669         case  8:
 670                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 671                          | MAX6650_CFG_PRESCALER_8;
 672                 break;
 673         case 16:
 674                 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 675                          | MAX6650_CFG_PRESCALER_16;
 676                 break;
 677         default:
 678                 dev_err(dev, "illegal value for prescaler (%d)\n", prescale);
 679         }
 680
 681         dev_info(dev, "Fan voltage: %dV, prescaler: %d.\n",
 682                  (config & MAX6650_CFG_V12) ? 12 : 5,
 683                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 684
 685         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 686                 dev_err(dev, "Config write error, aborting.\n");
 687                 return err;
 688         }
 689
 690         data->config = config;
 691         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 692
 693         if (!of_property_read_u32(client->dev.of_node, "maxim,fan-target-rpm",
 694                                   &target_rpm)) {
 695                 max6650_set_target(data, target_rpm);
 696                 max6650_set_operating_mode(data, MAX6650_CFG_MODE_CLOSED_LOOP);
 697         }
 698
 699         return 0;
 700 }
 701
 702 static int max6650_probe(struct i2c_client *client,
 703                          const struct i2c_device_id *id)
 704 {
 705         struct device *dev = &client->dev;
 706         const struct of_device_id *of_id =
 707                 of_match_device(of_match_ptr(max6650_dt_match), dev);
 708         struct max6650_data *data;
 709         struct device *hwmon_dev;
 710         int err;
 711
 712         data = devm_kzalloc(dev, sizeof(struct max6650_data), GFP_KERNEL);
 713         if (!data)
 714                 return -ENOMEM;
 715
 716         data->client = client;
 717         mutex_init(&data->update_lock);
 718         data->nr_fans = of_id ? (int)(uintptr_t)of_id->data : id->driver_data;
 719
 720         /*
 721          * Initialize the max6650 chip
 722          */
 723         err = max6650_init_client(data, client);
 724         if (err)
 725                 return err;
 726
 727         data->groups[0] = &max6650_group;
 728         /* 3 additional fan inputs for the MAX6651 */
 729         if (data->nr_fans == 4)
 730                 data->groups[1] = &max6651_group;
 731
 732         hwmon_dev = devm_hwmon_device_register_with_groups(dev,
 733                                                            client->name, data,
 734                                                            data->groups);
 735         return PTR_ERR_OR_ZERO(hwmon_dev);
 736 }
 737
 738 static const struct i2c_device_id max6650_id[] = {
 739         { "max6650", 1 },
 740         { "max6651", 4 },
 741         { }
 742 };
 743 MODULE_DEVICE_TABLE(i2c, max6650_id);
 744
 745 static struct i2c_driver max6650_driver = {
 746         .driver = {
 747                 .name   = "max6650",
 748                 .of_match_table = of_match_ptr(max6650_dt_match),
 749         },
 750         .probe          = max6650_probe,
 751         .id_table       = max6650_id,
 752 };
 753
 754 module_i2c_driver(max6650_driver);
 755
 756 MODULE_AUTHOR("Hans J. Koch");
 757 MODULE_DESCRIPTION("MAX6650 sensor driver");
 758 MODULE_LICENSE("GPL");