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/*

 * max6650.c - Part of lm_sensors, Linux kernel modules for hardware

 *             monitoring.

 *

 * (C) 2007 by Hans J. Koch <hjk@linutronix.de>

 *

 * based on code written by John Morris <john.morris@spirentcom.com>

 * Copyright (c) 2003 Spirent Communications

 * and Claus Gindhart <claus.gindhart@kontron.com>

 *

 * This module has only been tested with the MAX6650 chip. It should

 * also work with the MAX6651. It does not distinguish max6650 and max6651

 * chips.

 *

 * Tha datasheet was last seen at:

 *

 *        http://pdfserv.maxim-ic.com/en/ds/MAX6650-MAX6651.pdf

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

#include <linux/module.h>

#include <linux/init.h>

#include <linux/slab.h>

#include <linux/jiffies.h>

#include <linux/i2c.h>

#include <linux/hwmon.h>

#include <linux/hwmon-sysfs.h>

#include <linux/err.h>

/*

 * Addresses to scan. There are four disjoint possibilities, by pin config.

 */

static unsigned short normal_i2c[] = {0x1b, 0x1f, 0x48, 0x4b, I2C_CLIENT_END};

/*

 * Insmod parameters

 */

/* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */

static int fan_voltage;

/* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */

static int prescaler;

/* clock: The clock frequency of the chip the driver should assume */

static int clock = 254000;

module_param(fan_voltage, int, S_IRUGO);

module_param(prescaler, int, S_IRUGO);

module_param(clock, int, S_IRUGO);

I2C_CLIENT_INSMOD_1(max6650);

/*

 * MAX 6650/6651 registers

 */

#define MAX6650_REG_SPEED       0x00

#define MAX6650_REG_CONFIG      0x02

#define MAX6650_REG_GPIO_DEF    0x04

#define MAX6650_REG_DAC         0x06

#define MAX6650_REG_ALARM_EN    0x08

#define MAX6650_REG_ALARM       0x0A

#define MAX6650_REG_TACH0       0x0C

#define MAX6650_REG_TACH1       0x0E

#define MAX6650_REG_TACH2       0x10

#define MAX6650_REG_TACH3       0x12

#define MAX6650_REG_GPIO_STAT   0x14

#define MAX6650_REG_COUNT       0x16

/*

 * Config register bits

 */

#define MAX6650_CFG_V12                 0x08

#define MAX6650_CFG_PRESCALER_MASK      0x07

#define MAX6650_CFG_PRESCALER_2         0x01

#define MAX6650_CFG_PRESCALER_4         0x02

#define MAX6650_CFG_PRESCALER_8         0x03

#define MAX6650_CFG_PRESCALER_16        0x04

#define MAX6650_CFG_MODE_MASK           0x30

#define MAX6650_CFG_MODE_ON             0x00

#define MAX6650_CFG_MODE_OFF            0x10

#define MAX6650_CFG_MODE_CLOSED_LOOP    0x20

#define MAX6650_CFG_MODE_OPEN_LOOP      0x30

#define MAX6650_COUNT_MASK              0x03

/* Minimum and maximum values of the FAN-RPM */

#define FAN_RPM_MIN 240

#define FAN_RPM_MAX 30000

#define DIV_FROM_REG(reg) (1 << (reg & 7))

static int max6650_attach_adapter(struct i2c_adapter *adapter);

static int max6650_detect(struct i2c_adapter *adapter, int address, int kind);

static int max6650_init_client(struct i2c_client *client);

static int max6650_detach_client(struct i2c_client *client);

static struct max6650_data *max6650_update_device(struct device *dev);

/*

 * Driver data (common to all clients)

 */

static struct i2c_driver max6650_driver = {

        .driver = {

                .name   = "max6650",

        },

        .attach_adapter = max6650_attach_adapter,

        .detach_client  = max6650_detach_client,

};

/*

 * Client data (each client gets its own)

 */

struct max6650_data

{

        struct i2c_client client;

        struct device *hwmon_dev;

        struct mutex update_lock;

        char valid; /* zero until following fields are valid */

        unsigned long last_updated; /* in jiffies */

        /* register values */

        u8 speed;

        u8 config;

        u8 tach[4];

        u8 count;

        u8 dac;

};

static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,

                       char *buf)

{

        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

        struct max6650_data *data = max6650_update_device(dev);

        int rpm;

        /*

        * Calculation details:

        *

        * Each tachometer counts over an interval given by the "count"

        * register (0.25, 0.5, 1 or 2 seconds). This module assumes

        * that the fans produce two pulses per revolution (this seems

        * to be the most common).

        */

        rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));

        return sprintf(buf, "%d\n", rpm);

}

/*

 * Set the fan speed to the specified RPM (or read back the RPM setting).

 * This works in closed loop mode only. Use pwm1 for open loop speed setting.

 *

 * The MAX6650/1 will automatically control fan speed when in closed loop

 * mode.

 *

 * Assumptions:

 *

 * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use

 *    the clock module parameter if you need to fine tune this.

 *

 * 2) The prescaler (low three bits of the config register) has already

 *    been set to an appropriate value. Use the prescaler module parameter

 *    if your BIOS doesn't initialize the chip properly.

 *

 * The relevant equations are given on pages 21 and 22 of the datasheet.

 *

 * From the datasheet, the relevant equation when in regulation is:

 *

 *    [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE

 *

 * where:

 *

 *    fCLK is the oscillator frequency (either the 254kHz internal

 *         oscillator or the externally applied clock)

 *

 *    KTACH is the value in the speed register

 *

 *    FanSpeed is the speed of the fan in rps

 *

 *    KSCALE is the prescaler value (1, 2, 4, 8, or 16)

 *

 * When reading, we need to solve for FanSpeed. When writing, we need to

 * solve for KTACH.

 *

 * Note: this tachometer is completely separate from the tachometers

 * used to measure the fan speeds. Only one fan's speed (fan1) is

 * controlled.

 */

static ssize_t get_target(struct device *dev, struct device_attribute *devattr,

                         char *buf)

{

        struct max6650_data *data = max6650_update_device(dev);

        int kscale, ktach, rpm;

        /*

        * Use the datasheet equation:

        *

        *    FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]

        *

        * then multiply by 60 to give rpm.

        */

        kscale = DIV_FROM_REG(data->config);

        ktach = data->speed;

        rpm = 60 * kscale * clock / (256 * (ktach + 1));

        return sprintf(buf, "%d\n", rpm);

}

static ssize_t set_target(struct device *dev, struct device_attribute *devattr,

                         const char *buf, size_t count)

{

        struct i2c_client *client = to_i2c_client(dev);

        struct max6650_data *data = i2c_get_clientdata(client);

        int rpm = simple_strtoul(buf, NULL, 10);

        int kscale, ktach;

        rpm = SENSORS_LIMIT(rpm, FAN_RPM_MIN, FAN_RPM_MAX);

        /*

        * Divide the required speed by 60 to get from rpm to rps, then

        * use the datasheet equation:

        *

        *     KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1

        */

        mutex_lock(&data->update_lock);

        kscale = DIV_FROM_REG(data->config);

        ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;

        if (ktach < 0)

                ktach = 0;

        if (ktach > 255)

                ktach = 255;

        data->speed = ktach;

        i2c_smbus_write_byte_data(client, MAX6650_REG_SPEED, data->speed);

        mutex_unlock(&data->update_lock);

        return count;

}

/*

 * Get/set the fan speed in open loop mode using pwm1 sysfs file.

 * Speed is given as a relative value from 0 to 255, where 255 is maximum

 * speed. Note that this is done by writing directly to the chip's DAC,

 * it won't change the closed loop speed set by fan1_target.

 * Also note that due to rounding errors it is possible that you don't read

 * back exactly the value you have set.

 */

static ssize_t get_pwm(struct device *dev, struct device_attribute *devattr,

                       char *buf)

{

        int pwm;

        struct max6650_data *data = max6650_update_device(dev);

        /* Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.

           Lower DAC values mean higher speeds. */

        if (data->config & MAX6650_CFG_V12)

                pwm = 255 - (255 * (int)data->dac)/180;

        else

                pwm = 255 - (255 * (int)data->dac)/76;

        if (pwm < 0)

                pwm = 0;

        return sprintf(buf, "%d\n", pwm);

}

static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,

                        const char *buf, size_t count)

{

        struct i2c_client *client = to_i2c_client(dev);

        struct max6650_data *data = i2c_get_clientdata(client);

        int pwm = simple_strtoul(buf, NULL, 10);

        pwm = SENSORS_LIMIT(pwm, 0, 255);

        mutex_lock(&data->update_lock);

        if (data->config & MAX6650_CFG_V12)

                data->dac = 180 - (180 * pwm)/255;

        else

                data->dac = 76 - (76 * pwm)/255;

        i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);

        mutex_unlock(&data->update_lock);

        return count;

}

/*

 * Get/Set controller mode:

 * Possible values:

 * 0 = Fan always on

 * 1 = Open loop, Voltage is set according to speed, not regulated.

 * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer

 */

static ssize_t get_enable(struct device *dev, struct device_attribute *devattr,

                          char *buf)

{

        struct max6650_data *data = max6650_update_device(dev);

        int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;

        int sysfs_modes[4] = {0, 1, 2, 1};

        return sprintf(buf, "%d\n", sysfs_modes[mode]);

}

static ssize_t set_enable(struct device *dev, struct device_attribute *devattr,

                          const char *buf, size_t count)

{

        struct i2c_client *client = to_i2c_client(dev);

        struct max6650_data *data = i2c_get_clientdata(client);

        int mode = simple_strtoul(buf, NULL, 10);

        int max6650_modes[3] = {0, 3, 2};

        if ((mode < 0)||(mode > 2)) {

                dev_err(&client->dev,

                        "illegal value for pwm1_enable (%d)\n", mode);

                return -EINVAL;

        }

        mutex_lock(&data->update_lock);

        data->config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);

        data->config = (data->config & ~MAX6650_CFG_MODE_MASK)

                       | (max6650_modes[mode] << 4);

        i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, data->config);

        mutex_unlock(&data->update_lock);

        return count;

}

/*

 * Read/write functions for fan1_div sysfs file. The MAX6650 has no such

 * divider. We handle this by converting between divider and counttime:

 *

 * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3

 *

 * Lower values of k allow to connect a faster fan without the risk of

 * counter overflow. The price is lower resolution. You can also set counttime

 * using the module parameter. Note that the module parameter "prescaler" also

 * influences the behaviour. Unfortunately, there's no sysfs attribute

 * defined for that. See the data sheet for details.

 */

static ssize_t get_div(struct device *dev, struct device_attribute *devattr,

                       char *buf)

{

        struct max6650_data *data = max6650_update_device(dev);

        return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));

}

static ssize_t set_div(struct device *dev, struct device_attribute *devattr,

                       const char *buf, size_t count)

{

        struct i2c_client *client = to_i2c_client(dev);

        struct max6650_data *data = i2c_get_clientdata(client);

        int div = simple_strtoul(buf, NULL, 10);

        mutex_lock(&data->update_lock);

        switch (div) {

        case 1:

                data->count = 0;

                break;

        case 2:

                data->count = 1;

                break;

        case 4:

                data->count = 2;

                break;

        case 8:

                data->count = 3;

                break;

        default:

                dev_err(&client->dev,

                        "illegal value for fan divider (%d)\n", div);

                return -EINVAL;

        }

        i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);

        mutex_unlock(&data->update_lock);

        return count;

}

static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);

static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);

static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);

static SENSOR_DEVICE_ATTR(fan4_input, S_IRUGO, get_fan, NULL, 3);

static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);

static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);

static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);

static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);

static struct attribute *max6650_attrs[] = {

        &sensor_dev_attr_fan1_input.dev_attr.attr,

        &sensor_dev_attr_fan2_input.dev_attr.attr,

        &sensor_dev_attr_fan3_input.dev_attr.attr,

        &sensor_dev_attr_fan4_input.dev_attr.attr,

        &dev_attr_fan1_target.attr,

        &dev_attr_fan1_div.attr,

        &dev_attr_pwm1_enable.attr,

        &dev_attr_pwm1.attr,

        NULL

};

static struct attribute_group max6650_attr_grp = {

        .attrs = max6650_attrs,

};

/*

 * Real code

 */

static int max6650_attach_adapter(struct i2c_adapter *adapter)

{

        if (!(adapter->class & I2C_CLASS_HWMON)) {

                dev_dbg(&adapter->dev,

                        "FATAL: max6650_attach_adapter class HWMON not set\n");

                return 0;

        }

        return i2c_probe(adapter, &addr_data, max6650_detect);

}

/*

 * The following function does more than just detection. If detection

 * succeeds, it also registers the new chip.

 */

static int max6650_detect(struct i2c_adapter *adapter, int address, int kind)

{

        struct i2c_client *client;

        struct max6650_data *data;

        int err = -ENODEV;

        dev_dbg(&adapter->dev, "max6650_detect called, kind = %d\n", kind);

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {

                dev_dbg(&adapter->dev, "max6650: I2C bus doesn't support "

                                        "byte read mode, skipping.\n");

                return 0;

        }

        if (!(data = kzalloc(sizeof(struct max6650_data), GFP_KERNEL))) {

                dev_err(&adapter->dev, "max6650: out of memory.\n");

                return -ENOMEM;

        }

        client = &data->client;

        i2c_set_clientdata(client, data);

        client->addr = address;

        client->adapter = adapter;

        client->driver = &max6650_driver;

        /*

         * Now we do the remaining detection. A negative kind means that

         * the driver was loaded with no force parameter (default), so we

         * must both detect and identify the chip (actually there is only

         * one possible kind of chip for now, max6650). A zero kind means that

         * the driver was loaded with the force parameter, the detection

         * step shall be skipped. A positive kind means that the driver

         * was loaded with the force parameter and a given kind of chip is

         * requested, so both the detection and the identification steps

         * are skipped.

         *

         * Currently I can find no way to distinguish between a MAX6650 and

         * a MAX6651. This driver has only been tried on the former.

         */

        if ((kind < 0) &&

           (  (i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG) & 0xC0)

            ||(i2c_smbus_read_byte_data(client, MAX6650_REG_GPIO_STAT) & 0xE0)

            ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN) & 0xE0)

            ||(i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM) & 0xE0)

            ||(i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT) & 0xFC))) {

                dev_dbg(&adapter->dev,

                        "max6650: detection failed at 0x%02x.\n", address);

                goto err_free;

        }

        dev_info(&adapter->dev, "max6650: chip found at 0x%02x.\n", address);

        strlcpy(client->name, "max6650", I2C_NAME_SIZE);

        mutex_init(&data->update_lock);

        if ((err = i2c_attach_client(client))) {

                dev_err(&adapter->dev, "max6650: failed to attach client.\n");

                goto err_free;

        }

        /*

         * Initialize the max6650 chip

         */

        if (max6650_init_client(client))

                goto err_detach;

        err = sysfs_create_group(&client->dev.kobj, &max6650_attr_grp);

        if (err)

                goto err_detach;

        data->hwmon_dev = hwmon_device_register(&client->dev);

        if (!IS_ERR(data->hwmon_dev))

                return 0;

        err = PTR_ERR(data->hwmon_dev);

        dev_err(&client->dev, "error registering hwmon device.\n");

        sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);

err_detach:

        i2c_detach_client(client);

err_free:

        kfree(data);

        return err;

}

static int max6650_detach_client(struct i2c_client *client)

{

        struct max6650_data *data = i2c_get_clientdata(client);

        int err;

        sysfs_remove_group(&client->dev.kobj, &max6650_attr_grp);

        hwmon_device_unregister(data->hwmon_dev);

        err = i2c_detach_client(client);

        if (!err)

                kfree(data);

        return err;

}

static int max6650_init_client(struct i2c_client *client)

{

        struct max6650_data *data = i2c_get_clientdata(client);

        int config;

        int err = -EIO;

        config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);

        if (config < 0) {

                dev_err(&client->dev, "Error reading config, aborting.\n");

                return err;

        }

        switch (fan_voltage) {

                case 0:

                        break;

                case 5:

                        config &= ~MAX6650_CFG_V12;

                        break;

                case 12:

                        config |= MAX6650_CFG_V12;

                        break;

                default:

                        dev_err(&client->dev,

                                "illegal value for fan_voltage (%d)\n",

                                fan_voltage);

        }

        dev_info(&client->dev, "Fan voltage is set to %dV.\n",

                 (config & MAX6650_CFG_V12) ? 12 : 5);

        switch (prescaler) {

                case 0:

                        break;

                case 1:

                        config &= ~MAX6650_CFG_PRESCALER_MASK;

                        break;

                case 2:

                        config = (config & ~MAX6650_CFG_PRESCALER_MASK)

                                 | MAX6650_CFG_PRESCALER_2;

                        break;

                case  4:

                        config = (config & ~MAX6650_CFG_PRESCALER_MASK)

                                 | MAX6650_CFG_PRESCALER_4;

                        break;

                case  8:

                        config = (config & ~MAX6650_CFG_PRESCALER_MASK)

                                 | MAX6650_CFG_PRESCALER_8;

                        break;

                case 16:

                        config = (config & ~MAX6650_CFG_PRESCALER_MASK)

                                 | MAX6650_CFG_PRESCALER_16;

                        break;

                default:

                        dev_err(&client->dev,

                                "illegal value for prescaler (%d)\n",

                                prescaler);

        }

        dev_info(&client->dev, "Prescaler is set to %d.\n",

                 1 << (config & MAX6650_CFG_PRESCALER_MASK));

        /* If mode is set to "full off", we change it to "open loop" and

         * set DAC to 255, which has the same effect. We do this because

         * there's no "full off" mode defined in hwmon specifcations.

         */

        if ((config & MAX6650_CFG_MODE_MASK) == MAX6650_CFG_MODE_OFF) {

                dev_dbg(&client->dev, "Change mode to open loop, full off.\n");

                config = (config & ~MAX6650_CFG_MODE_MASK)

                         | MAX6650_CFG_MODE_OPEN_LOOP;

                if (i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, 255)) {

                        dev_err(&client->dev, "DAC write error, aborting.\n");

                        return err;

                }

        }

        if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {

                dev_err(&client->dev, "Config write error, aborting.\n");

                return err;

        }

        data->config = config;

        data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);

        return 0;

}

static const u8 tach_reg[] = {

        MAX6650_REG_TACH0,

        MAX6650_REG_TACH1,

        MAX6650_REG_TACH2,

        MAX6650_REG_TACH3,

};

static struct max6650_data *max6650_update_device(struct device *dev)

{

        int i;

        struct i2c_client *client = to_i2c_client(dev);

        struct max6650_data *data = i2c_get_clientdata(client);

        mutex_lock(&data->update_lock);

        if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {

                data->speed = i2c_smbus_read_byte_data(client,

                                                       MAX6650_REG_SPEED);

                data->config = i2c_smbus_read_byte_data(client,

                                                        MAX6650_REG_CONFIG);

                for (i = 0; i < 4; i++) {

                        data->tach[i] = i2c_smbus_read_byte_data(client,

                                                                 tach_reg[i]);

                }

                data->count = i2c_smbus_read_byte_data(client,

                                                        MAX6650_REG_COUNT);

                data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);

                data->last_updated = jiffies;

                data->valid = 1;

        }

        mutex_unlock(&data->update_lock);

        return data;

}

static int __init sensors_max6650_init(void)

{

        return i2c_add_driver(&max6650_driver);

}

static void __exit sensors_max6650_exit(void)

{

        i2c_del_driver(&max6650_driver);

}

MODULE_AUTHOR("Hans J. Koch");

MODULE_DESCRIPTION("MAX6650 sensor driver");

MODULE_LICENSE("GPL");