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