hwmon: Driver for Maxim MAX6639

2-Channel Temperature Monitor with Dual PWM Fan-Speed Controller

Signed-off-by: Roland Stigge <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>

Documentation/hwmon/max6639

···
+Kernel driver max6639
+=====================
+
+Supported chips:
+  * Maxim MAX6639
+    Prefix: 'max6639'
+    Addresses scanned: I2C 0x2c, 0x2e, 0x2f
+    Datasheet: http://pdfserv.maxim-ic.com/en/ds/MAX6639.pdf
+
+Authors:
+    He Changqing <[e-mail]>
+    Roland Stigge <[e-mail]>
+
+Description
+-----------
+
+This driver implements support for the Maxim MAX6639. This chip is a 2-channel
+temperature monitor with dual PWM fan speed controller. It can monitor its own
+temperature and one external diode-connected transistor or two external
+diode-connected transistors.
+
+The following device attributes are implemented via sysfs:
+
+Attribute              R/W  Contents
+----------------------------------------------------------------------------
+temp1_input            R    Temperature channel 1 input (0..150 C)
+temp2_input            R    Temperature channel 2 input (0..150 C)
+temp1_fault            R    Temperature channel 1 diode fault
+temp2_fault            R    Temperature channel 2 diode fault
+temp1_max              RW   Set THERM temperature for input 1
+                            (in C, see datasheet)
+temp2_max              RW   Set THERM temperature for input 2
+temp1_crit             RW   Set ALERT temperature for input 1
+temp2_crit             RW   Set ALERT temperature for input 2
+temp1_emergency        RW   Set OT temperature for input 1
+                            (in C, see datasheet)
+temp2_emergency        RW   Set OT temperature for input 2
+pwm1                   RW   Fan 1 target duty cycle (0..255)
+pwm2                   RW   Fan 2 target duty cycle (0..255)
+fan1_input             R    TACH1 fan tachometer input (in RPM)
+fan2_input             R    TACH2 fan tachometer input (in RPM)
+fan1_fault             R    Fan 1 fault
+fan2_fault             R    Fan 2 fault
+temp1_max_alarm        R    Alarm on THERM temperature on channel 1
+temp2_max_alarm        R    Alarm on THERM temperature on channel 2
+temp1_crit_alarm       R    Alarm on ALERT temperature on channel 1
+temp2_crit_alarm       R    Alarm on ALERT temperature on channel 2
+temp1_emergency_alarm  R    Alarm on OT temperature on channel 1
+temp2_emergency_alarm  R    Alarm on OT temperature on channel 2

drivers/hwmon/Kconfig

···
 	  This driver can also be built as a module.  If so, the module
 	  will be called max1619.
 
+config SENSORS_MAX6639
+	tristate "Maxim MAX6639 sensor chip"
+	depends on I2C && EXPERIMENTAL
+	help
+	  If you say yes here you get support for the MAX6639
+	  sensor chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called max6639.
+
 config SENSORS_MAX6650
 	tristate "Maxim MAX6650 sensor chip"
 	depends on I2C && EXPERIMENTAL

drivers/hwmon/Makefile

···
 obj-$(CONFIG_SENSORS_LTC4261)	+= ltc4261.o
 obj-$(CONFIG_SENSORS_MAX1111)	+= max1111.o
 obj-$(CONFIG_SENSORS_MAX1619)	+= max1619.o
+obj-$(CONFIG_SENSORS_MAX6639)	+= max6639.o
 obj-$(CONFIG_SENSORS_MAX6650)	+= max6650.o
 obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
 obj-$(CONFIG_SENSORS_PC87360)	+= pc87360.o

drivers/hwmon/max6639.c

···
+/*
+ * max6639.c - Support for Maxim MAX6639
+ *
+ * 2-Channel Temperature Monitor with Dual PWM Fan-Speed Controller
+ *
+ * Copyright (C) 2010, 2011 Roland Stigge <[e-mail]>
+ *
+ * based on the initial MAX6639 support from semptian.net
+ * by He Changqing <[e-mail]>
+ *
+ * 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>
+#include <linux/mutex.h>
+#include <linux/i2c/max6639.h>
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
+
+/* The MAX6639 registers, valid channel numbers: 0, 1 */
+#define MAX6639_REG_TEMP(ch)			(0x00 + (ch))
+#define MAX6639_REG_STATUS			0x02
+#define MAX6639_REG_OUTPUT_MASK			0x03
+#define MAX6639_REG_GCONFIG			0x04
+#define MAX6639_REG_TEMP_EXT(ch)		(0x05 + (ch))
+#define MAX6639_REG_ALERT_LIMIT(ch)		(0x08 + (ch))
+#define MAX6639_REG_OT_LIMIT(ch)		(0x0A + (ch))
+#define MAX6639_REG_THERM_LIMIT(ch)		(0x0C + (ch))
+#define MAX6639_REG_FAN_CONFIG1(ch)		(0x10 + (ch) * 4)
+#define MAX6639_REG_FAN_CONFIG2a(ch)		(0x11 + (ch) * 4)
+#define MAX6639_REG_FAN_CONFIG2b(ch)		(0x12 + (ch) * 4)
+#define MAX6639_REG_FAN_CONFIG3(ch)		(0x13 + (ch) * 4)
+#define MAX6639_REG_FAN_CNT(ch)			(0x20 + (ch))
+#define MAX6639_REG_TARGET_CNT(ch)		(0x22 + (ch))
+#define MAX6639_REG_FAN_PPR(ch)			(0x24 + (ch))
+#define MAX6639_REG_TARGTDUTY(ch)		(0x26 + (ch))
+#define MAX6639_REG_FAN_START_TEMP(ch)		(0x28 + (ch))
+#define MAX6639_REG_DEVID			0x3D
+#define MAX6639_REG_MANUID			0x3E
+#define MAX6639_REG_DEVREV			0x3F
+
+/* Register bits */
+#define MAX6639_GCONFIG_STANDBY			0x80
+#define MAX6639_GCONFIG_POR			0x40
+#define MAX6639_GCONFIG_DISABLE_TIMEOUT		0x20
+#define MAX6639_GCONFIG_CH2_LOCAL		0x10
+
+#define MAX6639_FAN_CONFIG1_PWM			0x80
+
+static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };
+
+#define FAN_FROM_REG(val, div, rpm_range)	((val) == 0 ? -1 : \
+	(val) == 255 ? 0 : (rpm_ranges[rpm_range] * 30) / ((div + 1) * (val)))
+#define TEMP_LIMIT_TO_REG(val)	SENSORS_LIMIT((val) / 1000, 0, 255)
+
+/*
+ * Client data (each client gets its own)
+ */
+struct max6639_data {
+	struct device *hwmon_dev;
+	struct mutex update_lock;
+	char valid;		/* !=0 if following fields are valid */
+	unsigned long last_updated;	/* In jiffies */
+
+	/* Register values sampled regularly */
+	u16 temp[2];		/* Temperature, in 1/8 C, 0..255 C */
+	bool temp_fault[2];	/* Detected temperature diode failure */
+	u8 fan[2];		/* Register value: TACH count for fans >=30 */
+	u8 status;		/* Detected channel alarms and fan failures */
+
+	/* Register values only written to */
+	u8 pwm[2];		/* Register value: Duty cycle 0..120 */
+	u8 temp_therm[2];	/* THERM Temperature, 0..255 C (->_max) */
+	u8 temp_alert[2];	/* ALERT Temperature, 0..255 C (->_crit) */
+	u8 temp_ot[2];		/* OT Temperature, 0..255 C (->_emergency) */
+
+	/* Register values initialized only once */
+	u8 ppr;			/* Pulses per rotation 0..3 for 1..4 ppr */
+	u8 rpm_range;		/* Index in above rpm_ranges table */
+};
+
+static struct max6639_data *max6639_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct max6639_data *ret = data;
+	int i;
+	int status_reg;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated + 2 * HZ) || !data->valid) {
+		int res;
+
+		dev_dbg(&client->dev, "Starting max6639 update\n");
+
+		status_reg = i2c_smbus_read_byte_data(client,
+						      MAX6639_REG_STATUS);
+		if (status_reg < 0) {
+			ret = ERR_PTR(status_reg);
+			goto abort;
+		}
+
+		data->status = status_reg;
+
+		for (i = 0; i < 2; i++) {
+			res = i2c_smbus_read_byte_data(client,
+					MAX6639_REG_FAN_CNT(i));
+			if (res < 0) {
+				ret = ERR_PTR(res);
+				goto abort;
+			}
+			data->fan[i] = res;
+
+			res = i2c_smbus_read_byte_data(client,
+					MAX6639_REG_TEMP_EXT(i));
+			if (res < 0) {
+				ret = ERR_PTR(res);
+				goto abort;
+			}
+			data->temp[i] = res >> 5;
+			data->temp_fault[i] = res & 0x01;
+
+			res = i2c_smbus_read_byte_data(client,
+					MAX6639_REG_TEMP(i));
+			if (res < 0) {
+				ret = ERR_PTR(res);
+				goto abort;
+			}
+			data->temp[i] |= res << 3;
+		}
+
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+abort:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+static ssize_t show_temp_input(struct device *dev,
+			       struct device_attribute *dev_attr, char *buf)
+{
+	long temp;
+	struct max6639_data *data = max6639_update_device(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	temp = data->temp[attr->index] * 125;
+	return sprintf(buf, "%ld\n", temp);
+}
+
+static ssize_t show_temp_fault(struct device *dev,
+			       struct device_attribute *dev_attr, char *buf)
+{
+	struct max6639_data *data = max6639_update_device(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n", data->temp_fault[attr->index]);
+}
+
+static ssize_t show_temp_max(struct device *dev,
+			     struct device_attribute *dev_attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	return sprintf(buf, "%d\n", (data->temp_therm[attr->index] * 1000));
+}
+
+static ssize_t set_temp_max(struct device *dev,
+			    struct device_attribute *dev_attr,
+			    const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+	unsigned long val;
+	int res;
+
+	res = strict_strtoul(buf, 10, &val);
+	if (res)
+		return res;
+
+	mutex_lock(&data->update_lock);
+	data->temp_therm[attr->index] = TEMP_LIMIT_TO_REG(val);
+	i2c_smbus_write_byte_data(client,
+				  MAX6639_REG_THERM_LIMIT(attr->index),
+				  data->temp_therm[attr->index]);
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t show_temp_crit(struct device *dev,
+			      struct device_attribute *dev_attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	return sprintf(buf, "%d\n", (data->temp_alert[attr->index] * 1000));
+}
+
+static ssize_t set_temp_crit(struct device *dev,
+			     struct device_attribute *dev_attr,
+			     const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+	unsigned long val;
+	int res;
+
+	res = strict_strtoul(buf, 10, &val);
+	if (res)
+		return res;
+
+	mutex_lock(&data->update_lock);
+	data->temp_alert[attr->index] = TEMP_LIMIT_TO_REG(val);
+	i2c_smbus_write_byte_data(client,
+				  MAX6639_REG_ALERT_LIMIT(attr->index),
+				  data->temp_alert[attr->index]);
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t show_temp_emergency(struct device *dev,
+				   struct device_attribute *dev_attr,
+				   char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	return sprintf(buf, "%d\n", (data->temp_ot[attr->index] * 1000));
+}
+
+static ssize_t set_temp_emergency(struct device *dev,
+				  struct device_attribute *dev_attr,
+				  const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+	unsigned long val;
+	int res;
+
+	res = strict_strtoul(buf, 10, &val);
+	if (res)
+		return res;
+
+	mutex_lock(&data->update_lock);
+	data->temp_ot[attr->index] = TEMP_LIMIT_TO_REG(val);
+	i2c_smbus_write_byte_data(client,
+				  MAX6639_REG_OT_LIMIT(attr->index),
+				  data->temp_ot[attr->index]);
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t show_pwm(struct device *dev,
+			struct device_attribute *dev_attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	return sprintf(buf, "%d\n", data->pwm[attr->index] * 255 / 120);
+}
+
+static ssize_t set_pwm(struct device *dev,
+		       struct device_attribute *dev_attr,
+		       const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+	unsigned long val;
+	int res;
+
+	res = strict_strtoul(buf, 10, &val);
+	if (res)
+		return res;
+
+	val = SENSORS_LIMIT(val, 0, 255);
+
+	mutex_lock(&data->update_lock);
+	data->pwm[attr->index] = (u8)(val * 120 / 255);
+	i2c_smbus_write_byte_data(client,
+				  MAX6639_REG_TARGTDUTY(attr->index),
+				  data->pwm[attr->index]);
+	mutex_unlock(&data->update_lock);
+	return count;
+}
+
+static ssize_t show_fan_input(struct device *dev,
+			      struct device_attribute *dev_attr, char *buf)
+{
+	struct max6639_data *data = max6639_update_device(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[attr->index],
+		       data->ppr, data->rpm_range));
+}
+
+static ssize_t show_alarm(struct device *dev,
+			  struct device_attribute *dev_attr, char *buf)
+{
+	struct max6639_data *data = max6639_update_device(dev);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n", !!(data->status & (1 << attr->index)));
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_input, NULL, 1);
+static SENSOR_DEVICE_ATTR(temp1_fault, S_IRUGO, show_temp_fault, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_temp_fault, NULL, 1);
+static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_max,
+		set_temp_max, 0);
+static SENSOR_DEVICE_ATTR(temp2_max, S_IWUSR | S_IRUGO, show_temp_max,
+		set_temp_max, 1);
+static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp_crit,
+		set_temp_crit, 0);
+static SENSOR_DEVICE_ATTR(temp2_crit, S_IWUSR | S_IRUGO, show_temp_crit,
+		set_temp_crit, 1);
+static SENSOR_DEVICE_ATTR(temp1_emergency, S_IWUSR | S_IRUGO,
+		show_temp_emergency, set_temp_emergency, 0);
+static SENSOR_DEVICE_ATTR(temp2_emergency, S_IWUSR | S_IRUGO,
+		show_temp_emergency, set_temp_emergency, 1);
+static SENSOR_DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, show_pwm, set_pwm, 0);
+static SENSOR_DEVICE_ATTR(pwm2, S_IWUSR | S_IRUGO, show_pwm, set_pwm, 1);
+static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, show_fan_input, NULL, 0);
+static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, show_fan_input, NULL, 1);
+static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, show_alarm, NULL, 1);
+static SENSOR_DEVICE_ATTR(fan2_fault, S_IRUGO, show_alarm, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 3);
+static SENSOR_DEVICE_ATTR(temp2_max_alarm, S_IRUGO, show_alarm, NULL, 2);
+static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 7);
+static SENSOR_DEVICE_ATTR(temp2_crit_alarm, S_IRUGO, show_alarm, NULL, 6);
+static SENSOR_DEVICE_ATTR(temp1_emergency_alarm, S_IRUGO, show_alarm, NULL, 5);
+static SENSOR_DEVICE_ATTR(temp2_emergency_alarm, S_IRUGO, show_alarm, NULL, 4);
+
+
+static struct attribute *max6639_attributes[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_temp2_input.dev_attr.attr,
+	&sensor_dev_attr_temp1_fault.dev_attr.attr,
+	&sensor_dev_attr_temp2_fault.dev_attr.attr,
+	&sensor_dev_attr_temp1_max.dev_attr.attr,
+	&sensor_dev_attr_temp2_max.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit.dev_attr.attr,
+	&sensor_dev_attr_temp2_crit.dev_attr.attr,
+	&sensor_dev_attr_temp1_emergency.dev_attr.attr,
+	&sensor_dev_attr_temp2_emergency.dev_attr.attr,
+	&sensor_dev_attr_pwm1.dev_attr.attr,
+	&sensor_dev_attr_pwm2.dev_attr.attr,
+	&sensor_dev_attr_fan1_input.dev_attr.attr,
+	&sensor_dev_attr_fan2_input.dev_attr.attr,
+	&sensor_dev_attr_fan1_fault.dev_attr.attr,
+	&sensor_dev_attr_fan2_fault.dev_attr.attr,
+	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp2_crit_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_emergency_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp2_emergency_alarm.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group max6639_group = {
+	.attrs = max6639_attributes,
+};
+
+/*
+ *  returns respective index in rpm_ranges table
+ *  1 by default on invalid range
+ */
+static int rpm_range_to_reg(int range)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(rpm_ranges); i++) {
+		if (rpm_ranges[i] == range)
+			return i;
+	}
+
+	return 1; /* default: 4000 RPM */
+}
+
+static int max6639_init_client(struct i2c_client *client)
+{
+	struct max6639_data *data = i2c_get_clientdata(client);
+	struct max6639_platform_data *max6639_info =
+		client->dev.platform_data;
+	int i = 0;
+	int rpm_range = 1; /* default: 4000 RPM */
+	int err = 0;
+
+	/* Reset chip to default values */
+	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
+				  MAX6639_GCONFIG_POR);
+	if (err)
+		goto exit;
+
+	/* Fans pulse per revolution is 2 by default */
+	if (max6639_info && max6639_info->ppr > 0 &&
+			max6639_info->ppr < 5)
+		data->ppr = max6639_info->ppr;
+	else
+		data->ppr = 2;
+	data->ppr -= 1;
+	err = i2c_smbus_write_byte_data(client,
+			MAX6639_REG_FAN_PPR(i),
+			data->ppr << 5);
+	if (err)
+		goto exit;
+
+	if (max6639_info)
+		rpm_range = rpm_range_to_reg(max6639_info->rpm_range);
+	data->rpm_range = rpm_range;
+
+	for (i = 0; i < 2; i++) {
+
+		/* Fans config PWM, RPM */
+		err = i2c_smbus_write_byte_data(client,
+			MAX6639_REG_FAN_CONFIG1(i),
+			MAX6639_FAN_CONFIG1_PWM | rpm_range);
+		if (err)
+			goto exit;
+
+		/* Fans PWM polarity high by default */
+		if (max6639_info && max6639_info->pwm_polarity == 0)
+			err = i2c_smbus_write_byte_data(client,
+				MAX6639_REG_FAN_CONFIG2a(i), 0x00);
+		else
+			err = i2c_smbus_write_byte_data(client,
+				MAX6639_REG_FAN_CONFIG2a(i), 0x02);
+		if (err)
+			goto exit;
+
+		/* Max. temp. 80C/90C/100C */
+		data->temp_therm[i] = 80;
+		data->temp_alert[i] = 90;
+		data->temp_ot[i] = 100;
+		err = i2c_smbus_write_byte_data(client,
+				MAX6639_REG_THERM_LIMIT(i),
+				data->temp_therm[i]);
+		if (err)
+			goto exit;
+		err = i2c_smbus_write_byte_data(client,
+				MAX6639_REG_ALERT_LIMIT(i),
+				data->temp_alert[i]);
+		if (err)
+			goto exit;
+		err = i2c_smbus_write_byte_data(client,
+				MAX6639_REG_OT_LIMIT(i), data->temp_ot[i]);
+		if (err)
+			goto exit;
+
+		/* PWM 120/120 (i.e. 100%) */
+		data->pwm[i] = 120;
+		err = i2c_smbus_write_byte_data(client,
+				MAX6639_REG_TARGTDUTY(i), data->pwm[i]);
+		if (err)
+			goto exit;
+	}
+	/* Start monitoring */
+	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
+		MAX6639_GCONFIG_DISABLE_TIMEOUT | MAX6639_GCONFIG_CH2_LOCAL);
+exit:
+	return err;
+}
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int max6639_detect(struct i2c_client *client,
+			  struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	int dev_id, manu_id;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	/* Actual detection via device and manufacturer ID */
+	dev_id = i2c_smbus_read_byte_data(client, MAX6639_REG_DEVID);
+	manu_id = i2c_smbus_read_byte_data(client, MAX6639_REG_MANUID);
+	if (dev_id != 0x58 || manu_id != 0x4D)
+		return -ENODEV;
+
+	strlcpy(info->type, "max6639", I2C_NAME_SIZE);
+
+	return 0;
+}
+
+static int max6639_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct max6639_data *data;
+	int err;
+
+	data = kzalloc(sizeof(struct max6639_data), GFP_KERNEL);
+	if (!data) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	i2c_set_clientdata(client, data);
+	mutex_init(&data->update_lock);
+
+	/* Initialize the max6639 chip */
+	err = max6639_init_client(client);
+	if (err < 0)
+		goto error_free;
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&client->dev.kobj, &max6639_group);
+	if (err)
+		goto error_free;
+
+	data->hwmon_dev = hwmon_device_register(&client->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		err = PTR_ERR(data->hwmon_dev);
+		goto error_remove;
+	}
+
+	dev_info(&client->dev, "temperature sensor and fan control found\n");
+
+	return 0;
+
+error_remove:
+	sysfs_remove_group(&client->dev.kobj, &max6639_group);
+error_free:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int max6639_remove(struct i2c_client *client)
+{
+	struct max6639_data *data = i2c_get_clientdata(client);
+
+	hwmon_device_unregister(data->hwmon_dev);
+	sysfs_remove_group(&client->dev.kobj, &max6639_group);
+
+	kfree(data);
+	return 0;
+}
+
+static int max6639_suspend(struct i2c_client *client, pm_message_t mesg)
+{
+	int data = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
+	if (data < 0)
+		return data;
+
+	return i2c_smbus_write_byte_data(client,
+			MAX6639_REG_GCONFIG, data | MAX6639_GCONFIG_STANDBY);
+}
+
+static int max6639_resume(struct i2c_client *client)
+{
+	int data = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
+	if (data < 0)
+		return data;
+
+	return i2c_smbus_write_byte_data(client,
+			MAX6639_REG_GCONFIG, data & ~MAX6639_GCONFIG_STANDBY);
+}
+
+static const struct i2c_device_id max6639_id[] = {
+	{"max6639", 0},
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, max6639_id);
+
+static struct i2c_driver max6639_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		   .name = "max6639",
+		   },
+	.probe = max6639_probe,
+	.remove = max6639_remove,
+	.suspend = max6639_suspend,
+	.resume = max6639_resume,
+	.id_table = max6639_id,
+	.detect = max6639_detect,
+	.address_list = normal_i2c,
+};
+
+static int __init max6639_init(void)
+{
+	return i2c_add_driver(&max6639_driver);
+}
+
+static void __exit max6639_exit(void)
+{
+	i2c_del_driver(&max6639_driver);
+}
+
+MODULE_AUTHOR("Roland Stigge <[e-mail]>");
+MODULE_DESCRIPTION("max6639 driver");
+MODULE_LICENSE("GPL");
+
+module_init(max6639_init);
+module_exit(max6639_exit);

include/linux/i2c/max6639.h

···
+#ifndef _LINUX_MAX6639_H
+#define _LINUX_MAX6639_H
+
+#include <linux/types.h>
+
+/* platform data for the MAX6639 temperature sensor and fan control */
+
+struct max6639_platform_data {
+	bool pwm_polarity;	/* Polarity low (0) or high (1, default) */
+	int ppr;		/* Pulses per rotation 1..4 (default == 2) */
+	int rpm_range;		/* 2000, 4000 (default), 8000 or 16000 */
+};
+
+#endif /* _LINUX_MAX6639_H */