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  * Tha 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 unsigned short normal_i2c[] = {0x1b, 0x1f, 0x48, 0x4b, I2C_CLIENT_END};
  48
  49 /*
  50  * Insmod parameters
  51  */
  52
  53 /* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */
  54 static int fan_voltage;
  55 /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
  56 static int prescaler;
  57 /* clock: The clock frequency of the chip the driver should assume */
  58 static int clock = 254000;
  59
  60 module_param(fan_voltage, int, S_IRUGO);
  61 module_param(prescaler, int, S_IRUGO);
  62 module_param(clock, int, S_IRUGO);
  63
  64 I2C_CLIENT_INSMOD_1(max6650);
  65
  66 /*
  67  * MAX 6650/6651 registers
  68  */
  69
  70 #define MAX6650_REG_SPEED       0x00
  71 #define MAX6650_REG_CONFIG      0x02
  72 #define MAX6650_REG_GPIO_DEF    0x04
  73 #define MAX6650_REG_DAC         0x06
  74 #define MAX6650_REG_ALARM_EN    0x08
  75 #define MAX6650_REG_ALARM       0x0A
  76 #define MAX6650_REG_TACH0       0x0C
  77 #define MAX6650_REG_TACH1       0x0E
  78 #define MAX6650_REG_TACH2       0x10
  79 #define MAX6650_REG_TACH3       0x12
  80 #define MAX6650_REG_GPIO_STAT   0x14
  81 #define MAX6650_REG_COUNT       0x16
  82
  83 /*
  84  * Config register bits
  85  */
  86
  87 #define MAX6650_CFG_V12                 0x08
  88 #define MAX6650_CFG_PRESCALER_MASK      0x07
  89 #define MAX6650_CFG_PRESCALER_2         0x01
  90 #define MAX6650_CFG_PRESCALER_4         0x02
  91 #define MAX6650_CFG_PRESCALER_8         0x03
  92 #define MAX6650_CFG_PRESCALER_16        0x04
  93 #define MAX6650_CFG_MODE_MASK           0x30
  94 #define MAX6650_CFG_MODE_ON             0x00
  95 #define MAX6650_CFG_MODE_OFF            0x10
  96 #define MAX6650_CFG_MODE_CLOSED_LOOP    0x20
  97 #define MAX6650_CFG_MODE_OPEN_LOOP      0x30
  98 #define MAX6650_COUNT_MASK              0x03
  99
 100 /* Minimum and maximum values of the FAN-RPM */
 101 #define FAN_RPM_MIN 240
 102 #define FAN_RPM_MAX 30000
 103
 104 #define DIV_FROM_REG(reg) (1 << (reg & 7))
 105
 106 static int max6650_attach_adapter(struct i2c_adapter *adapter);
 107 static int max6650_detect(struct i2c_adapter *adapter, int address, int kind);
 108 static int max6650_init_client(struct i2c_client *client);
 109 static int max6650_detach_client(struct i2c_client *client);
 110 static struct max6650_data *max6650_update_device(struct device *dev);
 111
 112 /*
 113  * Driver data (common to all clients)
 114  */
 115
 116 static struct i2c_driver max6650_driver = {
 117         .driver = {
 118                 .name   = "max6650",
 119         },
 120         .attach_adapter = max6650_attach_adapter,
 121         .detach_client  = max6650_detach_client,
 122 };
 123
 124 /*
 125  * Client data (each client gets its own)
 126  */
 127
 128 struct max6650_data
 129 {
 130         struct i2c_client client;
 131         struct device *hwmon_dev;
 132         struct mutex update_lock;
 133         char valid; /* zero until following fields are valid */
 134         unsigned long last_updated; /* in jiffies */
 135
 136         /* register values */
 137         u8 speed;
 138         u8 config;
 139         u8 tach[4];
 140         u8 count;
 141         u8 dac;
 142 };
 143
 144 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
 145                        char *buf)
 146 {
 147         struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 148         struct max6650_data *data = max6650_update_device(dev);
 149         int rpm;
 150
 151         /*
 152         * Calculation details:
 153         *
 154         * Each tachometer counts over an interval given by the "count"
 155         * register (0.25, 0.5, 1 or 2 seconds). This module assumes
 156         * that the fans produce two pulses per revolution (this seems
 157         * to be the most common).
 158         */
 159
 160         rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
 161         return sprintf(buf, "%d\n", rpm);
 162 }
 163
 164 /*
 165  * Set the fan speed to the specified RPM (or read back the RPM setting).
 166  * This works in closed loop mode only. Use pwm1 for open loop speed setting.
 167  *
 168  * The MAX6650/1 will automatically control fan speed when in closed loop
 169  * mode.
 170  *
 171  * Assumptions:
 172  *
 173  * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
 174  *    the clock module parameter if you need to fine tune this.
 175  *
 176  * 2) The prescaler (low three bits of the config register) has already
 177  *    been set to an appropriate value. Use the prescaler module parameter
 178  *    if your BIOS doesn't initialize the chip properly.
 179  *
 180  * The relevant equations are given on pages 21 and 22 of the datasheet.
 181  *
 182  * From the datasheet, the relevant equation when in regulation is:
 183  *
 184  *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
 185  *
 186  * where:
 187  *
 188  *    fCLK is the oscillator frequency (either the 254kHz internal
 189  *         oscillator or the externally applied clock)
 190  *
 191  *    KTACH is the value in the speed register
 192  *
 193  *    FanSpeed is the speed of the fan in rps
 194  *
 195  *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)
 196  *
 197  * When reading, we need to solve for FanSpeed. When writing, we need to
 198  * solve for KTACH.
 199  *
 200  * Note: this tachometer is completely separate from the tachometers
 201  * used to measure the fan speeds. Only one fan's speed (fan1) is
 202  * controlled.
 203  */
 204
 205 static ssize_t get_target(struct device *dev, struct device_attribute *devattr,
 206                          char *buf)
 207 {
 208         struct max6650_data *data = max6650_update_device(dev);
 209         int kscale, ktach, rpm;
 210
 211         /*
 212         * Use the datasheet equation:
 213         *
 214         *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
 215         *
 216         * then multiply by 60 to give rpm.
 217         */
 218
 219         kscale = DIV_FROM_REG(data->config);
 220         ktach = data->speed;
 221         rpm = 60 * kscale * clock / (256 * (ktach + 1));
 222         return sprintf(buf, "%d\n", rpm);
 223 }
 224
 225 static ssize_t set_target(struct device *dev, struct device_attribute *devattr,
 226                          const char *buf, size_t count)
 227 {
 228         struct i2c_client *client = to_i2c_client(dev);
 229         struct max6650_data *data = i2c_get_clientdata(client);
 230         int rpm = simple_strtoul(buf, NULL, 10);
 231         int kscale, ktach;
 232
 233         rpm = SENSORS_LIMIT(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
 234
 235         /*
 236         * Divide the required speed by 60 to get from rpm to rps, then
 237         * use the datasheet equation:
 238         *
 239         *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
 240         */
 241
 242         mutex_lock(&data->update_lock);
 243
 244         kscale = DIV_FROM_REG(data->config);
 245         ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
 246         if (ktach < 0)
 247                 ktach = 0;
 248         if (ktach > 255)
 249                 ktach = 255;
 250         data->speed = ktach;
 251
 252         i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);
 253
 254         mutex_unlock(&data->update_lock);
 255
 256         return count;
 257 }
 258
 259 /*
 260  * Get/set the fan speed in open loop mode using pwm1 sysfs file.
 261  * Speed is given as a relative value from 0 to 255, where 255 is maximum
 262  * speed. Note that this is done by writing directly to the chip's DAC,
 263  * it won't change the closed loop speed set by fan1_target.
 264  * Also note that due to rounding errors it is possible that you don't read
 265  * back exactly the value you have set.
 266  */
 267
 268 static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,
 269                        char *buf)
 270 {
 271         int pwm;
 272         struct max6650_data *data = max6650_update_device(dev);
 273
 274         /* Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
 275            Lower DAC values mean higher speeds. */
 276         if (data->config & MAX6650_CFG_V12)
 277                 pwm = 255 - (255 * (int)data->dac)/180;
 278         else
 279                 pwm = 255 - (255 * (int)data->dac)/76;
 280
 281         if (pwm < 0)
 282                 pwm = 0;
 283
 284         return sprintf(buf, "%d\n", pwm);
 285 }
 286
 287 static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
 288                         const char *buf, size_t count)
 289 {
 290         struct i2c_client *client = to_i2c_client(dev);
 291         struct max6650_data *data = i2c_get_clientdata(client);
 292         int pwm = simple_strtoul(buf, NULL, 10);
 293
 294         pwm = SENSORS_LIMIT(pwm, 0, 255);
 295
 296         mutex_lock(&data->update_lock);
 297
 298         if (data->config & MAX6650_CFG_V12)
 299                 data->dac = 180 - (180 * pwm)/255;
 300         else
 301                 data->dac = 76 - (76 * pwm)/255;
 302
 303         i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
 304
 305         mutex_unlock(&data->update_lock);
 306
 307         return count;
 308 }
 309
 310 /*
 311  * Get/Set controller mode:
 312  * Possible values:
 313  * 0 = Fan always on
 314  * 1 = Open loop, Voltage is set according to speed, not regulated.
 315  * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
 316  */
 317
 318 static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,
 319                           char *buf)
 320 {
 321         struct max6650_data *data = max6650_update_device(dev);
 322         int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
 323         int sysfs_modes[4] = {0, 1, 2, 1};
 324
 325         return sprintf(buf, "%d\n", sysfs_modes[mode]);
 326 }
 327
 328 static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,
 329                           const char *buf, size_t count)
 330 {
 331         struct i2c_client *client = to_i2c_client(dev);
 332         struct max6650_data *data = i2c_get_clientdata(client);
 333         int mode = simple_strtoul(buf, NULL, 10);
 334         int max6650_modes[3] = {0, 3, 2};
 335
 336         if ((mode < 0)||(mode > 2)) {
 337                 dev_err(&client->dev,
 338                         "illegal value for pwm1_enable (%d)\n", mode);
 339                 return -EINVAL;
 340         }
 341
 342         mutex_lock(&data->update_lock);
 343
 344         data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 345         data->config = (data->config & ~MAX6650_CFG_MODE_MASK)
 346                        | (max6650_modes[mode] << 4);
 347
 348         i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);
 349
 350         mutex_unlock(&data->update_lock);
 351
 352         return count;
 353 }
 354
 355 /*
 356  * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
 357  * divider. We handle this by converting between divider and counttime:
 358  *
 359  * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
 360  *
 361  * Lower values of k allow to connect a faster fan without the risk of
 362  * counter overflow. The price is lower resolution. You can also set counttime
 363  * using the module parameter. Note that the module parameter "prescaler" also
 364  * influences the behaviour. Unfortunately, there's no sysfs attribute
 365  * defined for that. See the data sheet for details.
 366  */
 367
 368 static ssize_t get_div(struct device *dev, struct device_attribute *devattr,
 369                        char *buf)
 370 {
 371         struct max6650_data *data = max6650_update_device(dev);
 372
 373         return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
 374 }
 375
 376 static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 377                        const char *buf, size_t count)
 378 {
 379         struct i2c_client *client = to_i2c_client(dev);
 380         struct max6650_data *data = i2c_get_clientdata(client);
 381         int div = simple_strtoul(buf, NULL, 10);
 382
 383         mutex_lock(&data->update_lock);
 384         switch (div) {
 385         case 1:
 386                 data->count = 0;
 387                 break;
 388         case 2:
 389                 data->count = 1;
 390                 break;
 391         case 4:
 392                 data->count = 2;
 393                 break;
 394         case 8:
 395                 data->count = 3;
 396                 break;
 397         default:
 398                 dev_err(&client->dev,
 399                         "illegal value for fan divider (%d)\n", div);
 400                 return -EINVAL;
 401         }
 402
 403         i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 404         mutex_unlock(&data->update_lock);
 405
 406         return count;
 407 }
 408
 409 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 410 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 411 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
 412 static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);
 413 static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 414 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 415 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 416 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 417
 418
 419 static struct attribute *max6650_attrs[] = {
 420         &sensor_dev_attr_fan1_input.dev_attr.attr,
 421         &sensor_dev_attr_fan2_input.dev_attr.attr,
 422         &sensor_dev_attr_fan3_input.dev_attr.attr,
 423         &sensor_dev_attr_fan4_input.dev_attr.attr,
 424         &dev_attr_fan1_target.attr,
 425         &dev_attr_fan1_div.attr,
 426         &dev_attr_pwm1_enable.attr,
 427         &dev_attr_pwm1.attr,
 428         NULL
 429 };
 430
 431 static struct attribute_group max6650_attr_grp = {
 432         .attrs = max6650_attrs,
 433 };
 434
 435 /*
 436  * Real code
 437  */
 438
 439 static int max6650_attach_adapter(struct i2c_adapter *adapter)
 440 {
 441         if (!(adapter->class & I2C_CLASS_HWMON)) {
 442                 dev_dbg(&adapter->dev,
 443                         "FATAL: max6650_attach_adapter class HWMON not set\n");
 444                 return 0;
 445         }
 446
 447         return i2c_probe(adapter, &addr_data, max6650_detect);
 448 }
 449
 450 /*
 451  * The following function does more than just detection. If detection
 452  * succeeds, it also registers the new chip.
 453  */
 454
 455 static int max6650_detect(struct i2c_adapter *adapter, int address, int kind)
 456 {
 457         struct i2c_client *client;
 458         struct max6650_data *data;
 459         int err = -ENODEV;
 460
 461         dev_dbg(&adapter->dev, "max6650_detect called, kind = %d\n", kind);
 462
 463         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
 464                 dev_dbg(&adapter->dev, "max6650: I2C bus doesn't support "
 465                                         "byte read mode, skipping.\n");
 466                 return 0;
 467         }
 468
 469         if (!(data = kzalloc(sizeof(struct max6650_data), GFP_KERNEL))) {
 470                 dev_err(&adapter->dev, "max6650: out of memory.\n");
 471                 return -ENOMEM;
 472         }
 473
 474         client = &data->client;
 475         i2c_set_clientdata(client, data);
 476         client->addr = address;
 477         client->adapter = adapter;
 478         client->driver = &max6650_driver;
 479
 480         /*
 481          * Now we do the remaining detection. A negative kind means that
 482          * the driver was loaded with no force parameter (default), so we
 483          * must both detect and identify the chip (actually there is only
 484          * one possible kind of chip for now, max6650). A zero kind means that
 485          * the driver was loaded with the force parameter, the detection
 486          * step shall be skipped. A positive kind means that the driver
 487          * was loaded with the force parameter and a given kind of chip is
 488          * requested, so both the detection and the identification steps
 489          * are skipped.
 490          *
 491          * Currently I can find no way to distinguish between a MAX6650 and
 492          * a MAX6651. This driver has only been tried on the former.
 493          */
 494
 495         if ((kind < 0) &&
 496            (  (i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG) & 0xC0)
 497             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_GPIO_STAT) & 0xE0)
 498             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN) & 0xE0)
 499             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM) & 0xE0)
 500             ||(i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT) & 0xFC))) {
 501                 dev_dbg(&adapter->dev,
 502                         "max6650: detection failed at 0x%02x.\n", address);
 503                 goto err_free;
 504         }
 505
 506         dev_info(&adapter->dev, "max6650: chip found at 0x%02x.\n", address);
 507
 508         strlcpy(client->name, "max6650", I2C_NAME_SIZE);
 509         mutex_init(&data->update_lock);
 510
 511         if ((err = i2c_attach_client(client))) {
 512                 dev_err(&adapter->dev, "max6650: failed to attach client.\n");
 513                 goto err_free;
 514         }
 515
 516         /*
 517          * Initialize the max6650 chip
 518          */
 519         if (max6650_init_client(client))
 520                 goto err_detach;
 521
 522         err = sysfs_create_group(&client->dev.kobj, &max6650_attr_grp);
 523         if (err)
 524                 goto err_detach;
 525
 526         data->hwmon_dev = hwmon_device_register(&client->dev);
 527         if (!IS_ERR(data->hwmon_dev))
 528                 return 0;
 529
 530         err = PTR_ERR(data->hwmon_dev);
 531         dev_err(&client->dev, "error registering hwmon device.\n");
 532         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 533 err_detach:
 534         i2c_detach_client(client);
 535 err_free:
 536         kfree(data);
 537         return err;
 538 }
 539
 540 static int max6650_detach_client(struct i2c_client *client)
 541 {
 542         struct max6650_data *data = i2c_get_clientdata(client);
 543         int err;
 544
 545         sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);
 546         hwmon_device_unregister(data->hwmon_dev);
 547         err = i2c_detach_client(client);
 548         if (!err)
 549                 kfree(data);
 550         return err;
 551 }
 552
 553 static int max6650_init_client(struct i2c_client *client)
 554 {
 555         struct max6650_data *data = i2c_get_clientdata(client);
 556         int config;
 557         int err = -EIO;
 558
 559         config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 560
 561         if (config < 0) {
 562                 dev_err(&client->dev, "Error reading config, aborting.\n");
 563                 return err;
 564         }
 565
 566         switch (fan_voltage) {
 567                 case 0:
 568                         break;
 569                 case 5:
 570                         config &= ~MAX6650_CFG_V12;
 571                         break;
 572                 case 12:
 573                         config |= MAX6650_CFG_V12;
 574                         break;
 575                 default:
 576                         dev_err(&client->dev,
 577                                 "illegal value for fan_voltage (%d)\n",
 578                                 fan_voltage);
 579         }
 580
 581         dev_info(&client->dev, "Fan voltage is set to %dV.\n",
 582                  (config & MAX6650_CFG_V12) ? 12 : 5);
 583
 584         switch (prescaler) {
 585                 case 0:
 586                         break;
 587                 case 1:
 588                         config &= ~MAX6650_CFG_PRESCALER_MASK;
 589                         break;
 590                 case 2:
 591                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 592                                  | MAX6650_CFG_PRESCALER_2;
 593                         break;
 594                 case  4:
 595                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 596                                  | MAX6650_CFG_PRESCALER_4;
 597                         break;
 598                 case  8:
 599                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 600                                  | MAX6650_CFG_PRESCALER_8;
 601                         break;
 602                 case 16:
 603                         config = (config & ~MAX6650_CFG_PRESCALER_MASK)
 604                                  | MAX6650_CFG_PRESCALER_16;
 605                         break;
 606                 default:
 607                         dev_err(&client->dev,
 608                                 "illegal value for prescaler (%d)\n",
 609                                 prescaler);
 610         }
 611
 612         dev_info(&client->dev, "Prescaler is set to %d.\n",
 613                  1 << (config & MAX6650_CFG_PRESCALER_MASK));
 614
 615         /* If mode is set to "full off", we change it to "open loop" and
 616          * set DAC to 255, which has the same effect. We do this because
 617          * there's no "full off" mode defined in hwmon specifcations.
 618          */
 619
 620         if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {
 621                 dev_dbg(&client->dev, "Change mode to open loop, full off.\n");
 622                 config = (config & ~MAX6650_CFG_MODE_MASK)
 623                          | MAX6650_CFG_MODE_OPEN_LOOP;
 624                 if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {
 625                         dev_err(&client->dev, "DAC write error, aborting.\n");
 626                         return err;
 627                 }
 628         }
 629
 630         if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
 631                 dev_err(&client->dev, "Config write error, aborting.\n");
 632                 return err;
 633         }
 634
 635         data->config = config;
 636         data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
 637
 638         return 0;
 639 }
 640
 641 static const u8 tach_reg[] = {
 642         MAX6650_REG_TACH0,
 643         MAX6650_REG_TACH1,
 644         MAX6650_REG_TACH2,
 645         MAX6650_REG_TACH3,
 646 };
 647
 648 static struct max6650_data *max6650_update_device(struct device *dev)
 649 {
 650         int i;
 651         struct i2c_client *client = to_i2c_client(dev);
 652         struct max6650_data *data = i2c_get_clientdata(client);
 653
 654         mutex_lock(&data->update_lock);
 655
 656         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 657                 data->speed = i2c_smbus_read_byte_data(client,
 658                                                        MAX6650_REG_SPEED);
 659                 data->config = i2c_smbus_read_byte_data(client,
 660                                                         MAX6650_REG_CONFIG);
 661                 for (i = 0; i < 4; i++) {
 662                         data->tach[i] = i2c_smbus_read_byte_data(client,
 663                                                                  tach_reg[i]);
 664                 }
 665                 data->count = i2c_smbus_read_byte_data(client,
 666                                                         MAX6650_REG_COUNT);
 667                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 668
 669                 data->last_updated = jiffies;
 670                 data->valid = 1;
 671         }
 672
 673         mutex_unlock(&data->update_lock);
 674
 675         return data;
 676 }
 677
 678 static int __init sensors_max6650_init(void)
 679 {
 680         return i2c_add_driver(&max6650_driver);
 681 }
 682
 683 static void __exit sensors_max6650_exit(void)
 684 {
 685         i2c_del_driver(&max6650_driver);
 686 }
 687
 688 MODULE_AUTHOR("Hans J. Koch");
 689 MODULE_DESCRIPTION("MAX6650 sensor driver");
 690 MODULE_LICENSE("GPL");
 691
 692 module_init(sensors_max6650_init);
 693 module_exit(sensors_max6650_exit);