drivers/hwmon/max6650.c - kernel/msm-4.9 - Gitiles

 /*
  * max6650.c - Part of lm_sensors, Linux kernel modules for hardware
  *             monitoring.
  *
  * (C) 2007 by Hans J. Koch <hjk@hansjkoch.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.
  *
  * The 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>

 /*
  * 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);

 /*
  * 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

 /*
  * Alarm status register bits
  */

 #define MAX6650_ALRM_MAX	0x01
 #define MAX6650_ALRM_MIN	0x02
 #define MAX6650_ALRM_TACH	0x04
 #define MAX6650_ALRM_GPIO1	0x08
 #define MAX6650_ALRM_GPIO2	0x10

 /* 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))

 /*
  * Client data (each client gets its own)
  */

 struct max6650_data {
 	struct i2c_client *client;
 	const struct attribute_group *groups[3];
 	struct mutex update_lock;
 	int nr_fans;
 	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;
 	u8 alarm;
 };

 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)
 {
 	struct max6650_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	int i;

 	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 < data->nr_fans; 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);

 		/*
 		 * Alarms are cleared on read in case the condition that
 		 * caused the alarm is removed. Keep the value latched here
 		 * for providing the register through different alarm files.
 		 */
 		data->alarm |= i2c_smbus_read_byte_data(client,
 							MAX6650_REG_ALARM);

 		data->last_updated = jiffies;
 		data->valid = 1;
 	}

 	mutex_unlock(&data->update_lock);

 	return data;
 }

 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 max6650_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	int kscale, ktach;
 	unsigned long rpm;
 	int err;

 	err = kstrtoul(buf, 10, &rpm);
 	if (err)
 		return err;

 	rpm = clamp_val(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 max6650_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	unsigned long pwm;
 	int err;

 	err = kstrtoul(buf, 10, &pwm);
 	if (err)
 		return err;

 	pwm = clamp_val(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 max6650_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	int max6650_modes[3] = {0, 3, 2};
 	unsigned long mode;
 	int err;

 	err = kstrtoul(buf, 10, &mode);
 	if (err)
 		return err;

 	if (mode > 2)
 		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 max6650_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	unsigned long div;
 	int err;

 	err = kstrtoul(buf, 10, &div);
 	if (err)
 		return err;

 	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:
 		mutex_unlock(&data->update_lock);
 		return -EINVAL;
 	}

 	i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
 	mutex_unlock(&data->update_lock);

 	return count;
 }

 /*
  * Get alarm stati:
  * Possible values:
  * 0 = no alarm
  * 1 = alarm
  */

 static ssize_t get_alarm(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);
 	struct i2c_client *client = data->client;
 	int alarm = 0;

 	if (data->alarm & attr->index) {
 		mutex_lock(&data->update_lock);
 		alarm = 1;
 		data->alarm &= ~attr->index;
 		data->alarm |= i2c_smbus_read_byte_data(client,
 							MAX6650_REG_ALARM);
 		mutex_unlock(&data->update_lock);
 	}

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

 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 SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
 			  MAX6650_ALRM_MAX);
 static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
 			  MAX6650_ALRM_MIN);
 static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
 			  MAX6650_ALRM_TACH);
 static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
 			  MAX6650_ALRM_GPIO1);
 static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
 			  MAX6650_ALRM_GPIO2);

 static umode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
 				    int n)
 {
 	struct device *dev = container_of(kobj, struct device, kobj);
 	struct max6650_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
 	struct device_attribute *devattr;

 	/*
 	 * Hide the alarms that have not been enabled by the firmware
 	 */

 	devattr = container_of(a, struct device_attribute, attr);
 	if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
 	 || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
 	 || devattr == &sensor_dev_attr_fan1_fault.dev_attr
 	 || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
 	 || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
 		if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
 			return 0;
 	}

 	return a->mode;
 }

 static struct attribute *max6650_attrs[] = {
 	&sensor_dev_attr_fan1_input.dev_attr.attr,
 	&dev_attr_fan1_target.attr,
 	&dev_attr_fan1_div.attr,
 	&dev_attr_pwm1_enable.attr,
 	&dev_attr_pwm1.attr,
 	&sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
 	&sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_fan1_fault.dev_attr.attr,
 	&sensor_dev_attr_gpio1_alarm.dev_attr.attr,
 	&sensor_dev_attr_gpio2_alarm.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group max6650_group = {
 	.attrs = max6650_attrs,
 	.is_visible = max6650_attrs_visible,
 };

 static struct attribute *max6651_attrs[] = {
 	&sensor_dev_attr_fan2_input.dev_attr.attr,
 	&sensor_dev_attr_fan3_input.dev_attr.attr,
 	&sensor_dev_attr_fan4_input.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group max6651_group = {
 	.attrs = max6651_attrs,
 };

 /*
  * Real code
  */

 static int max6650_init_client(struct max6650_data *data,
 			       struct i2c_client *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 specifications.
 	 */

 	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 int max6650_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct max6650_data *data;
 	struct device *hwmon_dev;
 	int err;

 	data = devm_kzalloc(&client->dev, sizeof(struct max6650_data),
 			    GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->client = client;
 	mutex_init(&data->update_lock);
 	data->nr_fans = id->driver_data;

 	/*
 	 * Initialize the max6650 chip
 	 */
 	err = max6650_init_client(data, client);
 	if (err)
 		return err;

 	data->groups[0] = &max6650_group;
 	/* 3 additional fan inputs for the MAX6651 */
 	if (data->nr_fans == 4)
 		data->groups[1] = &max6651_group;

 	hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
 							   client->name, data,
 							   data->groups);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static const struct i2c_device_id max6650_id[] = {
 	{ "max6650", 1 },
 	{ "max6651", 4 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, max6650_id);

 static struct i2c_driver max6650_driver = {
 	.driver = {
 		.name	= "max6650",
 	},
 	.probe		= max6650_probe,
 	.id_table	= max6650_id,
 };

 module_i2c_driver(max6650_driver);

 MODULE_AUTHOR("Hans J. Koch");
 MODULE_DESCRIPTION("MAX6650 sensor driver");
 MODULE_LICENSE("GPL");
	/*
	* max6650.c - Part of lm_sensors, Linux kernel modules for hardware
	* monitoring.
	*
	* (C) 2007 by Hans J. Koch <hjk@hansjkoch.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.
	*
	* The 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>

	/*
	* 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);

	/*
	* 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

	/*
	* Alarm status register bits
	*/

	#define MAX6650_ALRM_MAX 0x01
	#define MAX6650_ALRM_MIN 0x02
	#define MAX6650_ALRM_TACH 0x04
	#define MAX6650_ALRM_GPIO1 0x08
	#define MAX6650_ALRM_GPIO2 0x10

	/* 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))

	/*
	* Client data (each client gets its own)
	*/

	struct max6650_data {
	struct i2c_client *client;
	const struct attribute_group *groups[3];
	struct mutex update_lock;
	int nr_fans;
	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;
	u8 alarm;
	};

	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)
	{
	struct max6650_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int i;

	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 < data->nr_fans; 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);

	/*
	* Alarms are cleared on read in case the condition that
	* caused the alarm is removed. Keep the value latched here
	* for providing the register through different alarm files.
	*/
	data->alarm \|= i2c_smbus_read_byte_data(client,
	MAX6650_REG_ALARM);

	data->last_updated = jiffies;
	data->valid = 1;
	}

	mutex_unlock(&data->update_lock);

	return data;
	}

	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 max6650_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int kscale, ktach;
	unsigned long rpm;
	int err;

	err = kstrtoul(buf, 10, &rpm);
	if (err)
	return err;

	rpm = clamp_val(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 max6650_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	unsigned long pwm;
	int err;

	err = kstrtoul(buf, 10, &pwm);
	if (err)
	return err;

	pwm = clamp_val(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 max6650_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int max6650_modes[3] = {0, 3, 2};
	unsigned long mode;
	int err;

	err = kstrtoul(buf, 10, &mode);
	if (err)
	return err;

	if (mode > 2)
	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 max6650_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	unsigned long div;
	int err;

	err = kstrtoul(buf, 10, &div);
	if (err)
	return err;

	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:
	mutex_unlock(&data->update_lock);
	return -EINVAL;
	}

	i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
	mutex_unlock(&data->update_lock);

	return count;
	}

	/*
	* Get alarm stati:
	* Possible values:
	* 0 = no alarm
	* 1 = alarm
	*/

	static ssize_t get_alarm(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);
	struct i2c_client *client = data->client;
	int alarm = 0;

	if (data->alarm & attr->index) {
	mutex_lock(&data->update_lock);
	alarm = 1;
	data->alarm &= ~attr->index;
	data->alarm \|= i2c_smbus_read_byte_data(client,
	MAX6650_REG_ALARM);
	mutex_unlock(&data->update_lock);
	}

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

	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 SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
	MAX6650_ALRM_MAX);
	static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
	MAX6650_ALRM_MIN);
	static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
	MAX6650_ALRM_TACH);
	static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
	MAX6650_ALRM_GPIO1);
	static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
	MAX6650_ALRM_GPIO2);

	static umode_t max6650_attrs_visible(struct kobject kobj, struct attribute a,
	int n)
	{
	struct device *dev = container_of(kobj, struct device, kobj);
	struct max6650_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
	struct device_attribute *devattr;

	/*
	* Hide the alarms that have not been enabled by the firmware
	*/

	devattr = container_of(a, struct device_attribute, attr);
	if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
	\|\| devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
	\|\| devattr == &sensor_dev_attr_fan1_fault.dev_attr
	\|\| devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
	\|\| devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
	if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
	return 0;
	}

	return a->mode;
	}

	static struct attribute *max6650_attrs[] = {
	&sensor_dev_attr_fan1_input.dev_attr.attr,
	&dev_attr_fan1_target.attr,
	&dev_attr_fan1_div.attr,
	&dev_attr_pwm1_enable.attr,
	&dev_attr_pwm1.attr,
	&sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
	&sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
	&sensor_dev_attr_fan1_fault.dev_attr.attr,
	&sensor_dev_attr_gpio1_alarm.dev_attr.attr,
	&sensor_dev_attr_gpio2_alarm.dev_attr.attr,
	NULL
	};

	static const struct attribute_group max6650_group = {
	.attrs = max6650_attrs,
	.is_visible = max6650_attrs_visible,
	};

	static struct attribute *max6651_attrs[] = {
	&sensor_dev_attr_fan2_input.dev_attr.attr,
	&sensor_dev_attr_fan3_input.dev_attr.attr,
	&sensor_dev_attr_fan4_input.dev_attr.attr,
	NULL
	};

	static const struct attribute_group max6651_group = {
	.attrs = max6651_attrs,
	};

	/*
	* Real code
	*/

	static int max6650_init_client(struct max6650_data *data,
	struct i2c_client *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 specifications.
	*/

	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 int max6650_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct max6650_data *data;
	struct device *hwmon_dev;
	int err;

	data = devm_kzalloc(&client->dev, sizeof(struct max6650_data),
	GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->client = client;
	mutex_init(&data->update_lock);
	data->nr_fans = id->driver_data;

	/*
	* Initialize the max6650 chip
	*/
	err = max6650_init_client(data, client);
	if (err)
	return err;

	data->groups[0] = &max6650_group;
	/* 3 additional fan inputs for the MAX6651 */
	if (data->nr_fans == 4)
	data->groups[1] = &max6651_group;

	hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
	client->name, data,
	data->groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static const struct i2c_device_id max6650_id[] = {
	{ "max6650", 1 },
	{ "max6651", 4 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, max6650_id);

	static struct i2c_driver max6650_driver = {
	.driver = {
	.name = "max6650",
	},
	.probe = max6650_probe,
	.id_table = max6650_id,
	};

	module_i2c_driver(max6650_driver);

	MODULE_AUTHOR("Hans J. Koch");
	MODULE_DESCRIPTION("MAX6650 sensor driver");
	MODULE_LICENSE("GPL");