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  * 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 /*
  66  * MAX 6650/6651 registers
  67  */
  68
  69 #define MAX6650_REG_SPEED       0x00
  70 #define MAX6650_REG_CONFIG      0x02
  71 #define MAX6650_REG_GPIO_DEF    0x04
  72 #define MAX6650_REG_DAC         0x06
  73 #define MAX6650_REG_ALARM_EN    0x08
  74 #define MAX6650_REG_ALARM       0x0A
  75 #define MAX6650_REG_TACH0       0x0C
  76 #define MAX6650_REG_TACH1       0x0E
  77 #define MAX6650_REG_TACH2       0x10
  78 #define MAX6650_REG_TACH3       0x12
  79 #define MAX6650_REG_GPIO_STAT   0x14
  80 #define MAX6650_REG_COUNT       0x16
  81
  82 /*
  83  * Config register bits
  84  */
  85
  86 #define MAX6650_CFG_V12                 0x08
  87 #define MAX6650_CFG_PRESCALER_MASK      0x07
  88 #define MAX6650_CFG_PRESCALER_2         0x01
  89 #define MAX6650_CFG_PRESCALER_4         0x02
  90 #define MAX6650_CFG_PRESCALER_8         0x03
  91 #define MAX6650_CFG_PRESCALER_16        0x04
  92 #define MAX6650_CFG_MODE_MASK           0x30
  93 #define MAX6650_CFG_MODE_ON             0x00
  94 #define MAX6650_CFG_MODE_OFF            0x10
  95 #define MAX6650_CFG_MODE_CLOSED_LOOP    0x20
  96 #define MAX6650_CFG_MODE_OPEN_LOOP      0x30
  97 #define MAX6650_COUNT_MASK              0x03
  98
  99 /*
 100  * Alarm status register bits
 101  */
 102
 103 #define MAX6650_ALRM_MAX        0x01
 104 #define MAX6650_ALRM_MIN        0x02
 105 #define MAX6650_ALRM_TACH       0x04
 106 #define MAX6650_ALRM_GPIO1      0x08
 107 #define MAX6650_ALRM_GPIO2      0x10
 108
 109 /* Minimum and maximum values of the FAN-RPM */
 110 #define FAN_RPM_MIN 240
 111 #define FAN_RPM_MAX 30000
 112
 113 #define DIV_FROM_REG(reg) (1 << (reg & 7))
 114
 115 static int max6650_probe(struct i2c_client *client,
 116                          const struct i2c_device_id *id);
 117 static int max6650_detect(struct i2c_client *client,
 118                           struct i2c_board_info *info);
 119 static int max6650_init_client(struct i2c_client *client);
 120 static int max6650_remove(struct i2c_client *client);
 121 static struct max6650_data *max6650_update_device(struct device *dev);
 122
 123 /*
 124  * Driver data (common to all clients)
 125  */
 126
 127 static const struct i2c_device_id max6650_id[] = {
 128         { "max6650", 0 },
 129         { }
 130 };
 131 MODULE_DEVICE_TABLE(i2c, max6650_id);
 132
 133 static struct i2c_driver max6650_driver = {
 134         .class          = I2C_CLASS_HWMON,
 135         .driver = {
 136                 .name   = "max6650",
 137         },
 138         .probe          = max6650_probe,
 139         .remove         = max6650_remove,
 140         .id_table       = max6650_id,
 141         .detect         = max6650_detect,
 142         .address_list   = normal_i2c,
 143 };
 144
 145 /*
 146  * Client data (each client gets its own)
 147  */
 148
 149 struct max6650_data
 150 {
 151         struct device *hwmon_dev;
 152         struct mutex update_lock;
 153         char valid; /* zero until following fields are valid */
 154         unsigned long last_updated; /* in jiffies */
 155
 156         /* register values */
 157         u8 speed;
 158         u8 config;
 159         u8 tach[4];
 160         u8 count;
 161         u8 dac;
 162         u8 alarm;
 163 };
 164
 165 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
 166                        char *buf)
 167 {
 168         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 169         struct max6650_data *data = max6650_update_device(dev);
 170         int rpm;
 171
 172         /*
 173         * Calculation details:
 174         *
 175         * Each tachometer counts over an interval given by the "count"
 176         * register (0.25, 0.5, 1 or 2 seconds). This module assumes
 177         * that the fans produce two pulses per revolution (this seems
 178         * to be the most common).
 179         */
 180
 181         rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
 182         return sprintf(buf, "%d\n", rpm);
 183 }
 184
 185 /*
 186  * Set the fan speed to the specified RPM (or read back the RPM setting).
 187  * This works in closed loop mode only. Use pwm1 for open loop speed setting.
 188  *
 189  * The MAX6650/1 will automatically control fan speed when in closed loop
 190  * mode.
 191  *
 192  * Assumptions:
 193  *
 194  * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
 195  *    the clock module parameter if you need to fine tune this.
 196  *
 197  * 2) The prescaler (low three bits of the config register) has already
 198  *    been set to an appropriate value. Use the prescaler module parameter
 199  *    if your BIOS doesn't initialize the chip properly.
 200  *
 201  * The relevant equations are given on pages 21 and 22 of the datasheet.
 202  *
 203  * From the datasheet, the relevant equation when in regulation is:
 204  *
 205  *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
 206  *
 207  * where:
 208  *
 209  *    fCLK is the oscillator frequency (either the 254kHz internal
 210  *         oscillator or the externally applied clock)
 211  *
 212  *    KTACH is the value in the speed register
 213  *
 214  *    FanSpeed is the speed of the fan in rps
 215  *
 216  *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)
 217  *
 218  * When reading, we need to solve for FanSpeed. When writing, we need to
 219  * solve for KTACH.
 220  *
 221  * Note: this tachometer is completely separate from the tachometers
 222  * used to measure the fan speeds. Only one fan's speed (fan1) is
 223  * controlled.
 224  */
 225
 226 static ssize_t get_target(struct device *dev, struct device_attribute *devattr,
 227                          char *buf)
 228 {
 229         struct max6650_data *data = max6650_update_device(dev);
 230         int kscale, ktach, rpm;
 231
 232         /*
 233         * Use the datasheet equation:
 234         *
 235         *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
 236         *
 237         * then multiply by 60 to give rpm.
 238         */
 239
 240         kscale = DIV_FROM_REG(data->config);
 241         ktach = data->speed;
 242         rpm = 60 * kscale * clock / (256 * (ktach + 1));
 243         return sprintf(buf, "%d\n", rpm);
 244 }
 245
 246 static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
 247                          const char *buf, size_t count)
 248 {
 249         struct i2c_client *client = to_i2c_client(dev);
 250         struct max6650_data *data = i2c_get_clientdata(client);
 251         int rpm = simple_strtoul(buf, NULL, 10);
 252         int kscale, ktach;
 253
 254         rpm = SENSORS_LIMIT(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
 255
 256         /*
 257         * Divide the required speed by 60 to get from rpm to rps, then
 258         * use the datasheet equation:
 259         *
 260         *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
 261         */
 262
 263         mutex_lock(&data->update_lock);
 264
 265         kscale = DIV_FROM_REG(data->config);
 266         ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
 267         if (ktach < 0)
 268                 ktach = 0;
 269         if (ktach > 255)
 270                 ktach = 255;
 271         data->speed = ktach;
 272
 273         i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);
 274
 275         mutex_unlock(&data->update_lock);
 276
 277         return count;
 278 }
 279
 280 /*
 281  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 282  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 283  * speed. Note that this is done by writing directly to the chip's DAC,
 284  * it won't change the closed loop speed set by fan1_target.
 285  * Also note that due to rounding errors it is possible that you don't read
 286  * back exactly the value you have set.
 287  */
 288
 289 static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,
 290                        char *buf)
 291 {
 292         int pwm;
 293         struct max6650_data *data = max6650_update_device(dev);
 294
 295         /* Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 296            Lower DAC values mean higher speeds. */
 297         if (data->config & MAX6650_CFG_V12)
 298                 pwm = 255 - (255 * (int)data->dac)/180;
 299         else
 300                 pwm = 255 - (255 * (int)data->dac)/76;
 301
 302         if (pwm < 0)
 303                 pwm = 0;
 304
 305         return sprintf(buf, "%d\n", pwm);
 306 }
 307
 308 static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
 309                         const char *buf, size_t count)
 310 {
 311         struct i2c_client *client = to_i2c_client(dev);
 312         struct max6650_data *data = i2c_get_clientdata(client);
 313         int pwm = simple_strtoul(buf, NULL, 10);
 314
 315         pwm = SENSORS_LIMIT(pwm, 0, 255);
 316
 317         mutex_lock(&data->update_lock);
 318
 319         if (data->config & MAX6650_CFG_V12)
 320                 data->dac = 180 - (180 * pwm)/255;
 321         else
 322                 data->dac = 76 - (76 * pwm)/255;
 323
 324         i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 325
 326         mutex_unlock(&data->update_lock);
 327
 328         return count;
 329 }
 330
 331 /*
 332  * Get/Set controller mode:
 333  * Possible values:
 334  * 0 = Fan always on
 335  * 1 = Open loop, Voltage is set according to speed, not regulated.
 336  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 337  */
 338
 339 static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,
 340                           char *buf)
 341 {
 342         struct max6650_data *data = max6650_update_device(dev);
 343         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 344         int sysfs_modes[4] = {0, 1, 2, 1};
 345
 346         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 347 }
 348
 349 static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
 350                           const char *buf, size_t count)
 351 {
 352         struct i2c_client *client = to_i2c_client(dev);
 353         struct max6650_data *data = i2c_get_clientdata(client);
 354         int mode = simple_strtoul(buf, NULL, 10);
 355         int max6650_modes[3] = {0, 3, 2};
 356
 357         if ((mode < 0)||(mode > 2)) {
 358                 dev_err(&client->dev,
 359                         "illegal value for pwm1_enable (%d)\n", mode);
 360                 return -EINVAL;
 361         }
 362
 363         mutex_lock(&data->update_lock);
 364
 365         data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 366         data->config = (data->config & ~MAX6650_CFG_MODE_MASK)
 367                        | (max6650_modes[mode] << 4);
 368
 369         i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);
 370
 371         mutex_unlock(&data->update_lock);
 372
 373         return count;
 374 }
 375
 376 /*
 377  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 378  * divider. We handle this by converting between divider and counttime:
 379  *
 380  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 381  *
 382  * Lower values of k allow to connect a faster fan without the risk of
 383  * counter overflow. The price is lower resolution. You can also set counttime
 384  * using the module parameter. Note that the module parameter "prescaler" also
 385  * influences the behaviour. Unfortunately, there's no sysfs attribute
 386  * defined for that. See the data sheet for details.
 387  */
 388
 389 static ssize_t get_div(struct device *dev, struct device_attribute *devattr,
 390                        char *buf)
 391 {
 392         struct max6650_data *data = max6650_update_device(dev);
 393
 394         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 395 }
 396
 397 static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 398                        const char *buf, size_t count)
 399 {
 400         struct i2c_client *client = to_i2c_client(dev);
 401         struct max6650_data *data = i2c_get_clientdata(client);
 402         int div = simple_strtoul(buf, NULL, 10);
 403
 404         mutex_lock(&data->update_lock);
 405         switch (div) {
 406         case 1:
 407                 data->count = 0;
 408                 break;
 409         case 2:
 410                 data->count = 1;
 411                 break;
 412         case 4:
 413                 data->count = 2;
 414                 break;
 415         case 8:
 416                 data->count = 3;
 417                 break;
 418         default:
 419                 mutex_unlock(&data->update_lock);
 420                 dev_err(&client->dev,
 421                         "illegal value for fan divider (%d)\n", div);
 422                 return -EINVAL;
 423         }
 424
 425         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 426         mutex_unlock(&data->update_lock);
 427
 428         return count;
 429 }
 430
 431 /*
 432  * Get alarm stati:
 433  * Possible values:
 434  * 0 = no alarm
 435  * 1 = alarm
 436  */
 437
 438 static ssize_t get_alarm(struct device *dev, struct device_attribute *devattr,
 439                          char *buf)
 440 {
 441         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 442         struct max6650_data *data = max6650_update_device(dev);
 443         struct i2c_client *client = to_i2c_client(dev);
 444         int alarm = 0;
 445
 446         if (data->alarm & attr->index) {
 447                 mutex_lock(&data->update_lock);
 448                 alarm = 1;
 449                 data->alarm &= ~attr->index;
 450                 data->alarm |= i2c_smbus_read_byte_data(client,
 451                                                         MAX6650_REG_ALARM);
 452                 mutex_unlock(&data->update_lock);
 453         }
 454
 455         return sprintf(buf, "%d\n", alarm);
 456 }
 457
 458 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 459 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 460 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 461 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 462 static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 463 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 464 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 465 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 466 static SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
 467                           MAX6650_ALRM_MAX);
 468 static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
 469                           MAX6650_ALRM_MIN);
 470 static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
 471                           MAX6650_ALRM_TACH);
 472 static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
 473                           MAX6650_ALRM_GPIO1);
 474 static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
 475                           MAX6650_ALRM_GPIO2);
 476
 477 static mode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
 478                                     int n)
 479 {
 480         struct device *dev = container_of(kobj, struct device, kobj);
 481         struct i2c_client *client = to_i2c_client(dev);
 482         u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
 483         struct device_attribute *devattr;
 484
 485         /*
 486          * Hide the alarms that have not been enabled by the firmware
 487          */
 488
 489         devattr = container_of(a, struct device_attribute, attr);
 490         if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
 491          || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
 492          || devattr == &sensor_dev_attr_fan1_fault.dev_attr
 493          || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
 494          || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
 495                 if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
 496                         return 0;
 497         }
 498
 499         return a->mode;
 500 }
 501
 502 static struct attribute *max6650_attrs[] = {
 503         &sensor_dev_attr_fan1_input.dev_attr.attr,
 504         &sensor_dev_attr_fan2_input.dev_attr.attr,
 505         &sensor_dev_attr_fan3_input.dev_attr.attr,
 506         &sensor_dev_attr_fan4_input.dev_attr.attr,
 507         &dev_attr_fan1_target.attr,
 508         &dev_attr_fan1_div.attr,
 509         &dev_attr_pwm1_enable.attr,
 510         &dev_attr_pwm1.attr,
 511         &sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
 512         &sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
 513         &sensor_dev_attr_fan1_fault.dev_attr.attr,
 514         &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
 515         &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
 516         NULL
 517 };
 518
 519 static struct attribute_group max6650_attr_grp = {
 520         .attrs = max6650_attrs,
 521         .is_visible = max6650_attrs_visible,
 522 };
 523
 524 /*
 525  * Real code
 526  */
 527
 528 /* Return 0 if detection is successful, -ENODEV otherwise */
 529 static int max6650_detect(struct i2c_client *client,
 530                           struct i2c_board_info *info)
 531 {
 532         struct i2c_adapter *adapter = client->adapter;
 533         int address = client->addr;
 534
 535         dev_dbg(&adapter->dev, "max6650_detect called\n");
 536
 537         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
 538                 dev_dbg(&adapter->dev, "max6650: I2C bus doesn't support "
 539                                         "byte read mode, skipping.\n");
 540                 return -ENODEV;
 541         }
 542
 543         if (((i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG) & 0xC0)
 544             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_GPIO_STAT) & 0xE0)
 545             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN) & 0xE0)
 546             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM) & 0xE0)
 547             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT) & 0xFC))) {
 548                 dev_dbg(&adapter->dev,
 549                         "max6650: detection failed at 0x%02x.\n", address);
 550                 return -ENODEV;
 551         }
 552
 553         dev_info(&adapter->dev, "max6650: chip found at 0x%02x.\n", address);
 554
 555         strlcpy(info->type, "max6650", I2C_NAME_SIZE);
 556
 557         return 0;
 558 }
 559
 560 static int max6650_probe(struct i2c_client *client,
 561                          const struct i2c_device_id *id)
 562 {
 563         struct max6650_data *data;
 564         int err;
 565
 566         if (!(data = kzalloc(sizeof(struct max6650_data), GFP_KERNEL))) {
 567                 dev_err(&client->dev, "out of memory.\n");
 568                 return -ENOMEM;
 569         }
 570
 571         i2c_set_clientdata(client, data);
 572         mutex_init(&data->update_lock);
 573
 574         /*
 575          * Initialize the max6650 chip
 576          */
 577         err = max6650_init_client(client);
 578         if (err)
 579                 goto err_free;
 580
 581         err = sysfs_create_group(&client->dev.kobj, &max6650_attr_grp);
 582         if (err)
 583                 goto err_free;
 584
 585         data->hwmon_dev = hwmon_device_register(&client->dev);
 586         if (!IS_ERR(data->hwmon_dev))
 587                 return 0;
 588
 589         err = PTR_ERR(data->hwmon_dev);
 590         dev_err(&client->dev, "error registering hwmon device.\n");
 591         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 592 err_free:
 593         kfree(data);
 594         return err;
 595 }
 596
 597 static int max6650_remove(struct i2c_client *client)
 598 {
 599         struct max6650_data *data = i2c_get_clientdata(client);
 600
 601         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 602         hwmon_device_unregister(data->hwmon_dev);
 603         kfree(data);
 604         return 0;
 605 }
 606
 607 static int max6650_init_client(struct i2c_client *client)
 608 {
 609         struct max6650_data *data = i2c_get_clientdata(client);
 610         int config;
 611         int err = -EIO;
 612
 613         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 614
 615         if (config < 0) {
 616                 dev_err(&client->dev, "Error reading config, aborting.\n");
 617                 return err;
 618         }
 619
 620         switch (fan_voltage) {
 621                 case 0:
 622                         break;
 623                 case 5:
 624                         config &= ~MAX6650_CFG_V12;
 625                         break;
 626                 case 12:
 627                         config |= MAX6650_CFG_V12;
 628                         break;
 629                 default:
 630                         dev_err(&client->dev,
 631                                 "illegal value for fan_voltage (%d)\n",
 632                                 fan_voltage);
 633         }
 634
 635         dev_info(&client->dev, "Fan voltage is set to %dV.\n",
 636                  (config & MAX6650_CFG_V12) ? 12 : 5);
 637
 638         switch (prescaler) {
 639                 case 0:
 640                         break;
 641                 case 1:
 642                         config &= ~MAX6650_CFG_PRESCALER_MASK;
 643                         break;
 644                 case 2:
 645                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 646                                  | MAX6650_CFG_PRESCALER_2;
 647                         break;
 648                 case  4:
 649                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 650                                  | MAX6650_CFG_PRESCALER_4;
 651                         break;
 652                 case  8:
 653                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 654                                  | MAX6650_CFG_PRESCALER_8;
 655                         break;
 656                 case 16:
 657                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 658                                  | MAX6650_CFG_PRESCALER_16;
 659                         break;
 660                 default:
 661                         dev_err(&client->dev,
 662                                 "illegal value for prescaler (%d)\n",
 663                                 prescaler);
 664         }
 665
 666         dev_info(&client->dev, "Prescaler is set to %d.\n",
 667                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 668
 669         /* If mode is set to "full off", we change it to "open loop" and
 670          * set DAC to 255, which has the same effect. We do this because
 671          * there's no "full off" mode defined in hwmon specifcations.
 672          */
 673
 674         if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {
 675                 dev_dbg(&client->dev, "Change mode to open loop, full off.\n");
 676                 config = (config & ~MAX6650_CFG_MODE_MASK)
 677                          | MAX6650_CFG_MODE_OPEN_LOOP;
 678                 if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {
 679                         dev_err(&client->dev, "DAC write error, aborting.\n");
 680                         return err;
 681                 }
 682         }
 683
 684         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 685                 dev_err(&client->dev, "Config write error, aborting.\n");
 686                 return err;
 687         }
 688
 689         data->config = config;
 690         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 691
 692         return 0;
 693 }
 694
 695 static const u8 tach_reg[] = {
 696         MAX6650_REG_TACH0,
 697         MAX6650_REG_TACH1,
 698         MAX6650_REG_TACH2,
 699         MAX6650_REG_TACH3,
 700 };
 701
 702 static struct max6650_data *max6650_update_device(struct device *dev)
 703 {
 704         int i;
 705         struct i2c_client *client = to_i2c_client(dev);
 706         struct max6650_data *data = i2c_get_clientdata(client);
 707
 708         mutex_lock(&data->update_lock);
 709
 710         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 711                 data->speed = i2c_smbus_read_byte_data(client,
 712                                                        MAX6650_REG_SPEED);
 713                 data->config = i2c_smbus_read_byte_data(client,
 714                                                         MAX6650_REG_CONFIG);
 715                 for (i = 0; i < 4; i++) {
 716                         data->tach[i] = i2c_smbus_read_byte_data(client,
 717                                                                  tach_reg[i]);
 718                 }
 719                 data->count = i2c_smbus_read_byte_data(client,
 720                                                         MAX6650_REG_COUNT);
 721                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 722
 723                 /* Alarms are cleared on read in case the condition that
 724                  * caused the alarm is removed. Keep the value latched here
 725                  * for providing the register through different alarm files. */
 726                 data->alarm |= i2c_smbus_read_byte_data(client,
 727                                                         MAX6650_REG_ALARM);
 728
 729                 data->last_updated = jiffies;
 730                 data->valid = 1;
 731         }
 732
 733         mutex_unlock(&data->update_lock);
 734
 735         return data;
 736 }
 737
 738 static int __init sensors_max6650_init(void)
 739 {
 740         return i2c_add_driver(&max6650_driver);
 741 }
 742
 743 static void __exit sensors_max6650_exit(void)
 744 {
 745         i2c_del_driver(&max6650_driver);
 746 }
 747
 748 MODULE_AUTHOR("Hans J. Koch");
 749 MODULE_DESCRIPTION("MAX6650 sensor driver");
 750 MODULE_LICENSE("GPL");
 751
 752 module_init(sensors_max6650_init);
 753 module_exit(sensors_max6650_exit);