drivers/hwmon/max6639.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * max6639.c - Support for Maxim MAX6639
  *
  * 2-Channel Temperature Monitor with Dual PWM Fan-Speed Controller
  *
  * Copyright (C) 2010, 2011 Roland Stigge <stigge@antcom.de>
  *
  * based on the initial MAX6639 support from semptian.net
  * by He Changqing <hechangqing@semptian.com>
  */

 #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/platform_data/max6639.h>
 #include <linux/regmap.h>
 #include <linux/util_macros.h>

 /* Addresses to scan */
 static const 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_GCONFIG_PWM_FREQ_HI		0x08

 #define MAX6639_FAN_CONFIG1_PWM			0x80
 #define MAX6639_FAN_CONFIG3_FREQ_MASK		0x03
 #define MAX6639_FAN_CONFIG3_THERM_FULL_SPEED	0x40

 #define MAX6639_NUM_CHANNELS			2

 static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };

 /* Supported PWM frequency */
 static const unsigned int freq_table[] = { 20, 33, 50, 100, 5000, 8333, 12500,
 					   25000 };

 #define FAN_FROM_REG(val, rpm_range)	((val) == 0 || (val) == 255 ? \
 				0 : (rpm_ranges[rpm_range] * 30) / (val))
 #define TEMP_LIMIT_TO_REG(val)	clamp_val((val) / 1000, 0, 255)

 /*
  * Client data (each client gets its own)
  */
 struct max6639_data {
 	struct regmap *regmap;
 	struct mutex update_lock;

 	/* Register values initialized only once */
 	u8 ppr[MAX6639_NUM_CHANNELS];	/* Pulses per rotation 0..3 for 1..4 ppr */
 	u8 rpm_range[MAX6639_NUM_CHANNELS]; /* Index in above rpm_ranges table */

 	/* Optional regulator for FAN supply */
 	struct regulator *reg;
 };

 static int max6639_temp_read_input(struct device *dev, int channel, long *temp)
 {
 	u32 regs[2] = { MAX6639_REG_TEMP_EXT(channel), MAX6639_REG_TEMP(channel) };
 	struct max6639_data *data = dev_get_drvdata(dev);
 	u8 regvals[2];
 	int res;

 	res = regmap_multi_reg_read(data->regmap, regs, regvals, 2);
 	if (res < 0)
 		return res;

 	*temp = ((regvals[0] >> 5) | (regvals[1] << 3)) * 125;

 	return 0;
 }

 static int max6639_temp_read_fault(struct device *dev, int channel, long *fault)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	unsigned int val;
 	int res;

 	res = regmap_read(data->regmap, MAX6639_REG_TEMP_EXT(channel), &val);
 	if (res < 0)
 		return res;

 	*fault = val & 1;

 	return 0;
 }

 static int max6639_temp_read_max(struct device *dev, int channel, long *max)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	unsigned int val;
 	int res;

 	res = regmap_read(data->regmap, MAX6639_REG_THERM_LIMIT(channel), &val);
 	if (res < 0)
 		return res;

 	*max = (long)val * 1000;

 	return 0;
 }

 static int max6639_temp_read_crit(struct device *dev, int channel, long *crit)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	unsigned int val;
 	int res;

 	res = regmap_read(data->regmap, MAX6639_REG_ALERT_LIMIT(channel), &val);
 	if (res < 0)
 		return res;

 	*crit = (long)val * 1000;

 	return 0;
 }

 static int max6639_temp_read_emergency(struct device *dev, int channel, long *emerg)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	unsigned int val;
 	int res;

 	res = regmap_read(data->regmap, MAX6639_REG_OT_LIMIT(channel), &val);
 	if (res < 0)
 		return res;

 	*emerg = (long)val * 1000;

 	return 0;
 }

 static int max6639_get_status(struct device *dev, unsigned int *status)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	unsigned int val;
 	int res;

 	res = regmap_read(data->regmap, MAX6639_REG_STATUS, &val);
 	if (res < 0)
 		return res;

 	*status = val;

 	return 0;
 }

 static int max6639_temp_set_max(struct max6639_data *data, int channel, long val)
 {
 	int res;

 	res = regmap_write(data->regmap, MAX6639_REG_THERM_LIMIT(channel),
 			   TEMP_LIMIT_TO_REG(val));
 	return res;
 }

 static int max6639_temp_set_crit(struct max6639_data *data, int channel, long val)
 {
 	int res;

 	res = regmap_write(data->regmap, MAX6639_REG_ALERT_LIMIT(channel), TEMP_LIMIT_TO_REG(val));

 	return res;
 }

 static int max6639_temp_set_emergency(struct max6639_data *data, int channel, long val)
 {
 	int res;

 	res = regmap_write(data->regmap, MAX6639_REG_OT_LIMIT(channel), TEMP_LIMIT_TO_REG(val));

 	return res;
 }

 static int max6639_read_fan(struct device *dev, u32 attr, int channel,
 			    long *fan_val)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	unsigned int val;
 	int res;

 	switch (attr) {
 	case hwmon_fan_input:
 		res = regmap_read(data->regmap, MAX6639_REG_FAN_CNT(channel), &val);
 		if (res < 0)
 			return res;
 		*fan_val = FAN_FROM_REG(val, data->rpm_range[channel]);
 		return 0;
 	case hwmon_fan_fault:
 		res = max6639_get_status(dev, &val);
 		if (res < 0)
 			return res;
 		*fan_val = !!(val & BIT(1 - channel));
 		return 0;
 	case hwmon_fan_pulses:
 		*fan_val = data->ppr[channel];
 		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static int max6639_set_ppr(struct max6639_data *data, int channel, u8 ppr)
 {
 	/* Decrement the PPR value and shift left by 6 to match the register format */
 	return regmap_write(data->regmap, MAX6639_REG_FAN_PPR(channel), ppr-- << 6);
 }

 static int max6639_write_fan(struct device *dev, u32 attr, int channel,
 			     long val)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	int err;

 	switch (attr) {
 	case hwmon_fan_pulses:
 		if (val <= 0 || val > 4)
 			return -EINVAL;

 		mutex_lock(&data->update_lock);
 		/* Set Fan pulse per revolution */
 		err = max6639_set_ppr(data, channel, val);
 		if (err < 0) {
 			mutex_unlock(&data->update_lock);
 			return err;
 		}
 		data->ppr[channel] = val;

 		mutex_unlock(&data->update_lock);
 		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static umode_t max6639_fan_is_visible(const void *_data, u32 attr, int channel)
 {
 	switch (attr) {
 	case hwmon_fan_input:
 	case hwmon_fan_fault:
 		return 0444;
 	case hwmon_fan_pulses:
 		return 0644;
 	default:
 		return 0;
 	}
 }

 static int max6639_read_pwm(struct device *dev, u32 attr, int channel,
 			    long *pwm_val)
 {
 	u32 regs[2] = { MAX6639_REG_FAN_CONFIG3(channel), MAX6639_REG_GCONFIG };
 	struct max6639_data *data = dev_get_drvdata(dev);
 	unsigned int val;
 	u8 regvals[2];
 	int res;
 	u8 i;

 	switch (attr) {
 	case hwmon_pwm_input:
 		res = regmap_read(data->regmap, MAX6639_REG_TARGTDUTY(channel), &val);
 		if (res < 0)
 			return res;
 		*pwm_val = val * 255 / 120;
 		return 0;
 	case hwmon_pwm_freq:
 		res = regmap_multi_reg_read(data->regmap, regs, regvals, 2);
 		if (res < 0)
 			return res;
 		i = regvals[0] & MAX6639_FAN_CONFIG3_FREQ_MASK;
 		if (regvals[1] & MAX6639_GCONFIG_PWM_FREQ_HI)
 			i |= 0x4;
 		*pwm_val = freq_table[i];
 		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static int max6639_write_pwm(struct device *dev, u32 attr, int channel,
 			     long val)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	int err;
 	u8 i;

 	switch (attr) {
 	case hwmon_pwm_input:
 		if (val < 0 || val > 255)
 			return -EINVAL;
 		err = regmap_write(data->regmap, MAX6639_REG_TARGTDUTY(channel),
 				   val * 120 / 255);
 		return err;
 	case hwmon_pwm_freq:
 		val = clamp_val(val, 0, 25000);

 		i = find_closest(val, freq_table, ARRAY_SIZE(freq_table));

 		mutex_lock(&data->update_lock);
 		err = regmap_update_bits(data->regmap, MAX6639_REG_FAN_CONFIG3(channel),
 					 MAX6639_FAN_CONFIG3_FREQ_MASK, i);
 		if (err < 0) {
 			mutex_unlock(&data->update_lock);
 			return err;
 		}

 		if (i >> 2)
 			err = regmap_set_bits(data->regmap, MAX6639_REG_GCONFIG,
 					      MAX6639_GCONFIG_PWM_FREQ_HI);
 		else
 			err = regmap_clear_bits(data->regmap, MAX6639_REG_GCONFIG,
 						MAX6639_GCONFIG_PWM_FREQ_HI);

 		mutex_unlock(&data->update_lock);
 		return err;
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static umode_t max6639_pwm_is_visible(const void *_data, u32 attr, int channel)
 {
 	switch (attr) {
 	case hwmon_pwm_input:
 	case hwmon_pwm_freq:
 		return 0644;
 	default:
 		return 0;
 	}
 }

 static int max6639_read_temp(struct device *dev, u32 attr, int channel,
 			     long *val)
 {
 	unsigned int status;
 	int res;

 	switch (attr) {
 	case hwmon_temp_input:
 		res = max6639_temp_read_input(dev, channel, val);
 		return res;
 	case hwmon_temp_fault:
 		res = max6639_temp_read_fault(dev, channel, val);
 		return res;
 	case hwmon_temp_max:
 		res = max6639_temp_read_max(dev, channel, val);
 		return res;
 	case hwmon_temp_crit:
 		res = max6639_temp_read_crit(dev, channel, val);
 		return res;
 	case hwmon_temp_emergency:
 		res = max6639_temp_read_emergency(dev, channel, val);
 		return res;
 	case hwmon_temp_max_alarm:
 		res = max6639_get_status(dev, &status);
 		if (res < 0)
 			return res;
 		*val = !!(status & BIT(3 - channel));
 		return 0;
 	case hwmon_temp_crit_alarm:
 		res = max6639_get_status(dev, &status);
 		if (res < 0)
 			return res;
 		*val = !!(status & BIT(7 - channel));
 		return 0;
 	case hwmon_temp_emergency_alarm:
 		res = max6639_get_status(dev, &status);
 		if (res < 0)
 			return res;
 		*val = !!(status & BIT(5 - channel));
 		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static int max6639_write_temp(struct device *dev, u32 attr, int channel,
 			      long val)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);

 	switch (attr) {
 	case hwmon_temp_max:
 		return max6639_temp_set_max(data, channel, val);
 	case hwmon_temp_crit:
 		return max6639_temp_set_crit(data, channel, val);
 	case hwmon_temp_emergency:
 		return max6639_temp_set_emergency(data, channel, val);
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static umode_t max6639_temp_is_visible(const void *_data, u32 attr, int channel)
 {
 	switch (attr) {
 	case hwmon_temp_input:
 	case hwmon_temp_fault:
 	case hwmon_temp_max_alarm:
 	case hwmon_temp_crit_alarm:
 	case hwmon_temp_emergency_alarm:
 		return 0444;
 	case hwmon_temp_max:
 	case hwmon_temp_crit:
 	case hwmon_temp_emergency:
 		return 0644;
 	default:
 		return 0;
 	}
 }

 static int max6639_read(struct device *dev, enum hwmon_sensor_types type,
 			u32 attr, int channel, long *val)
 {
 	switch (type) {
 	case hwmon_fan:
 		return max6639_read_fan(dev, attr, channel, val);
 	case hwmon_pwm:
 		return max6639_read_pwm(dev, attr, channel, val);
 	case hwmon_temp:
 		return max6639_read_temp(dev, attr, channel, val);
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static int max6639_write(struct device *dev, enum hwmon_sensor_types type,
 			 u32 attr, int channel, long val)
 {
 	switch (type) {
 	case hwmon_fan:
 		return max6639_write_fan(dev, attr, channel, val);
 	case hwmon_pwm:
 		return max6639_write_pwm(dev, attr, channel, val);
 	case hwmon_temp:
 		return max6639_write_temp(dev, attr, channel, val);
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static umode_t max6639_is_visible(const void *data,
 				  enum hwmon_sensor_types type,
 				  u32 attr, int channel)
 {
 	switch (type) {
 	case hwmon_fan:
 		return max6639_fan_is_visible(data, attr, channel);
 	case hwmon_pwm:
 		return max6639_pwm_is_visible(data, attr, channel);
 	case hwmon_temp:
 		return max6639_temp_is_visible(data, attr, channel);
 	default:
 		return 0;
 	}
 }

 static const struct hwmon_channel_info * const max6639_info[] = {
 	HWMON_CHANNEL_INFO(fan,
 			   HWMON_F_INPUT | HWMON_F_FAULT | HWMON_F_PULSES,
 			   HWMON_F_INPUT | HWMON_F_FAULT | HWMON_F_PULSES),
 	HWMON_CHANNEL_INFO(pwm,
 			   HWMON_PWM_INPUT | HWMON_PWM_FREQ,
 			   HWMON_PWM_INPUT | HWMON_PWM_FREQ),
 	HWMON_CHANNEL_INFO(temp,
 			   HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_MAX | HWMON_T_MAX_ALARM |
 			   HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_EMERGENCY |
 			   HWMON_T_EMERGENCY_ALARM,
 			   HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_MAX | HWMON_T_MAX_ALARM |
 			   HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_EMERGENCY |
 			   HWMON_T_EMERGENCY_ALARM),
 	NULL
 };

 static const struct hwmon_ops max6639_hwmon_ops = {
 	.is_visible = max6639_is_visible,
 	.read = max6639_read,
 	.write = max6639_write,
 };

 static const struct hwmon_chip_info max6639_chip_info = {
 	.ops = &max6639_hwmon_ops,
 	.info = max6639_info,
 };

 /*
  *  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)
 {
 	struct max6639_platform_data *max6639_info =
 		dev_get_platdata(&client->dev);
 	int i;
 	int rpm_range = 1; /* default: 4000 RPM */
 	int err, ppr;

 	/* Reset chip to default values, see below for GCONFIG setup */
 	err = regmap_write(data->regmap, MAX6639_REG_GCONFIG, MAX6639_GCONFIG_POR);
 	if (err)
 		return err;

 	/* Fans pulse per revolution is 2 by default */
 	if (max6639_info && max6639_info->ppr > 0 &&
 			max6639_info->ppr < 5)
 		ppr = max6639_info->ppr;
 	else
 		ppr = 2;

 	data->ppr[0] = ppr;
 	data->ppr[1] = ppr;

 	if (max6639_info)
 		rpm_range = rpm_range_to_reg(max6639_info->rpm_range);
 	data->rpm_range[0] = rpm_range;
 	data->rpm_range[1] = rpm_range;

 	for (i = 0; i < MAX6639_NUM_CHANNELS; i++) {
 		/* Set Fan pulse per revolution */
 		err = max6639_set_ppr(data, i, data->ppr[i]);
 		if (err)
 			return err;

 		/* Fans config PWM, RPM */
 		err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG1(i),
 				   MAX6639_FAN_CONFIG1_PWM | data->rpm_range[i]);
 		if (err)
 			return err;

 		/* Fans PWM polarity high by default */
 		if (max6639_info) {
 			if (max6639_info->pwm_polarity == 0)
 				err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG2a(i), 0x00);
 			else
 				err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG2a(i), 0x02);
 		}
 		if (err)
 			return err;

 		/*
 		 * /THERM full speed enable,
 		 * PWM frequency 25kHz, see also GCONFIG below
 		 */
 		err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG3(i),
 				   MAX6639_FAN_CONFIG3_THERM_FULL_SPEED | 0x03);
 		if (err)
 			return err;

 		/* Max. temp. 80C/90C/100C */
 		err = regmap_write(data->regmap, MAX6639_REG_THERM_LIMIT(i), 80);
 		if (err)
 			return err;
 		err = regmap_write(data->regmap, MAX6639_REG_ALERT_LIMIT(i), 90);
 		if (err)
 			return err;
 		err = regmap_write(data->regmap, MAX6639_REG_OT_LIMIT(i), 100);
 		if (err)
 			return err;

 		/* PWM 120/120 (i.e. 100%) */
 		err = regmap_write(data->regmap, MAX6639_REG_TARGTDUTY(i), 120);
 		if (err)
 			return err;
 	}
 	/* Start monitoring */
 	return regmap_write(data->regmap, MAX6639_REG_GCONFIG,
 			    MAX6639_GCONFIG_DISABLE_TIMEOUT | MAX6639_GCONFIG_CH2_LOCAL |
 			    MAX6639_GCONFIG_PWM_FREQ_HI);

 }

 /* 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;

 	strscpy(info->type, "max6639", I2C_NAME_SIZE);

 	return 0;
 }

 static void max6639_regulator_disable(void *data)
 {
 	regulator_disable(data);
 }

 static bool max6639_regmap_is_volatile(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MAX6639_REG_TEMP(0):
 	case MAX6639_REG_TEMP_EXT(0):
 	case MAX6639_REG_TEMP(1):
 	case MAX6639_REG_TEMP_EXT(1):
 	case MAX6639_REG_STATUS:
 	case MAX6639_REG_FAN_CNT(0):
 	case MAX6639_REG_FAN_CNT(1):
 	case MAX6639_REG_TARGTDUTY(0):
 	case MAX6639_REG_TARGTDUTY(1):
 		return true;
 	default:
 		return false;
 	}
 }

 static const struct regmap_config max6639_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.max_register = MAX6639_REG_DEVREV,
 	.cache_type = REGCACHE_MAPLE,
 	.volatile_reg = max6639_regmap_is_volatile,
 };

 static int max6639_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct max6639_data *data;
 	struct device *hwmon_dev;
 	int err;

 	data = devm_kzalloc(dev, sizeof(struct max6639_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->regmap = devm_regmap_init_i2c(client, &max6639_regmap_config);
 	if (IS_ERR(data->regmap))
 		return dev_err_probe(dev,
 				     PTR_ERR(data->regmap),
 				     "regmap initialization failed\n");

 	data->reg = devm_regulator_get_optional(dev, "fan");
 	if (IS_ERR(data->reg)) {
 		if (PTR_ERR(data->reg) != -ENODEV)
 			return PTR_ERR(data->reg);

 		data->reg = NULL;
 	} else {
 		/* Spin up fans */
 		err = regulator_enable(data->reg);
 		if (err) {
 			dev_err(dev, "Failed to enable fan supply: %d\n", err);
 			return err;
 		}
 		err = devm_add_action_or_reset(dev, max6639_regulator_disable,
 					       data->reg);
 		if (err) {
 			dev_err(dev, "Failed to register action: %d\n", err);
 			return err;
 		}
 	}

 	mutex_init(&data->update_lock);

 	/* Initialize the max6639 chip */
 	err = max6639_init_client(client, data);
 	if (err < 0)
 		return err;

 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
 							 data, &max6639_chip_info,
 							 NULL);

 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static int max6639_suspend(struct device *dev)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);

 	if (data->reg)
 		regulator_disable(data->reg);

 	return regmap_write_bits(data->regmap, MAX6639_REG_GCONFIG, MAX6639_GCONFIG_STANDBY,
 				 MAX6639_GCONFIG_STANDBY);
 }

 static int max6639_resume(struct device *dev)
 {
 	struct max6639_data *data = dev_get_drvdata(dev);
 	int ret;

 	if (data->reg) {
 		ret = regulator_enable(data->reg);
 		if (ret) {
 			dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 			return ret;
 		}
 	}

 	return regmap_write_bits(data->regmap, MAX6639_REG_GCONFIG, MAX6639_GCONFIG_STANDBY,
 				 ~MAX6639_GCONFIG_STANDBY);
 }

 static const struct i2c_device_id max6639_id[] = {
 	{"max6639"},
 	{ }
 };

 MODULE_DEVICE_TABLE(i2c, max6639_id);

 static DEFINE_SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);

 static const struct of_device_id max6639_of_match[] = {
 	{ .compatible = "maxim,max6639", },
 	{ },
 };

 static struct i2c_driver max6639_driver = {
 	.class = I2C_CLASS_HWMON,
 	.driver = {
 		   .name = "max6639",
 		   .pm = pm_sleep_ptr(&max6639_pm_ops),
 		   .of_match_table = max6639_of_match,
 		   },
 	.probe = max6639_probe,
 	.id_table = max6639_id,
 	.detect = max6639_detect,
 	.address_list = normal_i2c,
 };

 module_i2c_driver(max6639_driver);

 MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
 MODULE_DESCRIPTION("max6639 driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* max6639.c - Support for Maxim MAX6639
	*
	* 2-Channel Temperature Monitor with Dual PWM Fan-Speed Controller
	*
	* Copyright (C) 2010, 2011 Roland Stigge <stigge@antcom.de>
	*
	* based on the initial MAX6639 support from semptian.net
	* by He Changqing <hechangqing@semptian.com>
	*/

	#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/platform_data/max6639.h>
	#include <linux/regmap.h>
	#include <linux/util_macros.h>

	/* Addresses to scan */
	static const 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_GCONFIG_PWM_FREQ_HI 0x08

	#define MAX6639_FAN_CONFIG1_PWM 0x80
	#define MAX6639_FAN_CONFIG3_FREQ_MASK 0x03
	#define MAX6639_FAN_CONFIG3_THERM_FULL_SPEED 0x40

	#define MAX6639_NUM_CHANNELS 2

	static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };

	/* Supported PWM frequency */
	static const unsigned int freq_table[] = { 20, 33, 50, 100, 5000, 8333, 12500,
	25000 };

	#define FAN_FROM_REG(val, rpm_range) ((val) == 0 \|\| (val) == 255 ? \
	0 : (rpm_ranges[rpm_range] * 30) / (val))
	#define TEMP_LIMIT_TO_REG(val) clamp_val((val) / 1000, 0, 255)

	/*
	* Client data (each client gets its own)
	*/
	struct max6639_data {
	struct regmap *regmap;
	struct mutex update_lock;

	/* Register values initialized only once */
	u8 ppr[MAX6639_NUM_CHANNELS]; /* Pulses per rotation 0..3 for 1..4 ppr */
	u8 rpm_range[MAX6639_NUM_CHANNELS]; /* Index in above rpm_ranges table */

	/* Optional regulator for FAN supply */
	struct regulator *reg;
	};

	static int max6639_temp_read_input(struct device dev, int channel, long temp)
	{
	u32 regs[2] = { MAX6639_REG_TEMP_EXT(channel), MAX6639_REG_TEMP(channel) };
	struct max6639_data *data = dev_get_drvdata(dev);
	u8 regvals[2];
	int res;

	res = regmap_multi_reg_read(data->regmap, regs, regvals, 2);
	if (res < 0)
	return res;

	temp = ((regvals[0] >> 5) \| (regvals[1] << 3)) 125;

	return 0;
	}

	static int max6639_temp_read_fault(struct device dev, int channel, long fault)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	unsigned int val;
	int res;

	res = regmap_read(data->regmap, MAX6639_REG_TEMP_EXT(channel), &val);
	if (res < 0)
	return res;

	*fault = val & 1;

	return 0;
	}

	static int max6639_temp_read_max(struct device dev, int channel, long max)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	unsigned int val;
	int res;

	res = regmap_read(data->regmap, MAX6639_REG_THERM_LIMIT(channel), &val);
	if (res < 0)
	return res;

	max = (long)val 1000;

	return 0;
	}

	static int max6639_temp_read_crit(struct device dev, int channel, long crit)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	unsigned int val;
	int res;

	res = regmap_read(data->regmap, MAX6639_REG_ALERT_LIMIT(channel), &val);
	if (res < 0)
	return res;

	crit = (long)val 1000;

	return 0;
	}

	static int max6639_temp_read_emergency(struct device dev, int channel, long emerg)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	unsigned int val;
	int res;

	res = regmap_read(data->regmap, MAX6639_REG_OT_LIMIT(channel), &val);
	if (res < 0)
	return res;

	emerg = (long)val 1000;

	return 0;
	}

	static int max6639_get_status(struct device dev, unsigned int status)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	unsigned int val;
	int res;

	res = regmap_read(data->regmap, MAX6639_REG_STATUS, &val);
	if (res < 0)
	return res;

	*status = val;

	return 0;
	}

	static int max6639_temp_set_max(struct max6639_data *data, int channel, long val)
	{
	int res;

	res = regmap_write(data->regmap, MAX6639_REG_THERM_LIMIT(channel),
	TEMP_LIMIT_TO_REG(val));
	return res;
	}

	static int max6639_temp_set_crit(struct max6639_data *data, int channel, long val)
	{
	int res;

	res = regmap_write(data->regmap, MAX6639_REG_ALERT_LIMIT(channel), TEMP_LIMIT_TO_REG(val));

	return res;
	}

	static int max6639_temp_set_emergency(struct max6639_data *data, int channel, long val)
	{
	int res;

	res = regmap_write(data->regmap, MAX6639_REG_OT_LIMIT(channel), TEMP_LIMIT_TO_REG(val));

	return res;
	}

	static int max6639_read_fan(struct device *dev, u32 attr, int channel,
	long *fan_val)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	unsigned int val;
	int res;

	switch (attr) {
	case hwmon_fan_input:
	res = regmap_read(data->regmap, MAX6639_REG_FAN_CNT(channel), &val);
	if (res < 0)
	return res;
	*fan_val = FAN_FROM_REG(val, data->rpm_range[channel]);
	return 0;
	case hwmon_fan_fault:
	res = max6639_get_status(dev, &val);
	if (res < 0)
	return res;
	*fan_val = !!(val & BIT(1 - channel));
	return 0;
	case hwmon_fan_pulses:
	*fan_val = data->ppr[channel];
	return 0;
	default:
	return -EOPNOTSUPP;
	}
	}

	static int max6639_set_ppr(struct max6639_data *data, int channel, u8 ppr)
	{
	/* Decrement the PPR value and shift left by 6 to match the register format */
	return regmap_write(data->regmap, MAX6639_REG_FAN_PPR(channel), ppr-- << 6);
	}

	static int max6639_write_fan(struct device *dev, u32 attr, int channel,
	long val)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	int err;

	switch (attr) {
	case hwmon_fan_pulses:
	if (val <= 0 \|\| val > 4)
	return -EINVAL;

	mutex_lock(&data->update_lock);
	/* Set Fan pulse per revolution */
	err = max6639_set_ppr(data, channel, val);
	if (err < 0) {
	mutex_unlock(&data->update_lock);
	return err;
	}
	data->ppr[channel] = val;

	mutex_unlock(&data->update_lock);
	return 0;
	default:
	return -EOPNOTSUPP;
	}
	}

	static umode_t max6639_fan_is_visible(const void *_data, u32 attr, int channel)
	{
	switch (attr) {
	case hwmon_fan_input:
	case hwmon_fan_fault:
	return 0444;
	case hwmon_fan_pulses:
	return 0644;
	default:
	return 0;
	}
	}

	static int max6639_read_pwm(struct device *dev, u32 attr, int channel,
	long *pwm_val)
	{
	u32 regs[2] = { MAX6639_REG_FAN_CONFIG3(channel), MAX6639_REG_GCONFIG };
	struct max6639_data *data = dev_get_drvdata(dev);
	unsigned int val;
	u8 regvals[2];
	int res;
	u8 i;

	switch (attr) {
	case hwmon_pwm_input:
	res = regmap_read(data->regmap, MAX6639_REG_TARGTDUTY(channel), &val);
	if (res < 0)
	return res;
	pwm_val = val 255 / 120;
	return 0;
	case hwmon_pwm_freq:
	res = regmap_multi_reg_read(data->regmap, regs, regvals, 2);
	if (res < 0)
	return res;
	i = regvals[0] & MAX6639_FAN_CONFIG3_FREQ_MASK;
	if (regvals[1] & MAX6639_GCONFIG_PWM_FREQ_HI)
	i \|= 0x4;
	*pwm_val = freq_table[i];
	return 0;
	default:
	return -EOPNOTSUPP;
	}
	}

	static int max6639_write_pwm(struct device *dev, u32 attr, int channel,
	long val)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	int err;
	u8 i;

	switch (attr) {
	case hwmon_pwm_input:
	if (val < 0 \|\| val > 255)
	return -EINVAL;
	err = regmap_write(data->regmap, MAX6639_REG_TARGTDUTY(channel),
	val * 120 / 255);
	return err;
	case hwmon_pwm_freq:
	val = clamp_val(val, 0, 25000);

	i = find_closest(val, freq_table, ARRAY_SIZE(freq_table));

	mutex_lock(&data->update_lock);
	err = regmap_update_bits(data->regmap, MAX6639_REG_FAN_CONFIG3(channel),
	MAX6639_FAN_CONFIG3_FREQ_MASK, i);
	if (err < 0) {
	mutex_unlock(&data->update_lock);
	return err;
	}

	if (i >> 2)
	err = regmap_set_bits(data->regmap, MAX6639_REG_GCONFIG,
	MAX6639_GCONFIG_PWM_FREQ_HI);
	else
	err = regmap_clear_bits(data->regmap, MAX6639_REG_GCONFIG,
	MAX6639_GCONFIG_PWM_FREQ_HI);

	mutex_unlock(&data->update_lock);
	return err;
	default:
	return -EOPNOTSUPP;
	}
	}

	static umode_t max6639_pwm_is_visible(const void *_data, u32 attr, int channel)
	{
	switch (attr) {
	case hwmon_pwm_input:
	case hwmon_pwm_freq:
	return 0644;
	default:
	return 0;
	}
	}

	static int max6639_read_temp(struct device *dev, u32 attr, int channel,
	long *val)
	{
	unsigned int status;
	int res;

	switch (attr) {
	case hwmon_temp_input:
	res = max6639_temp_read_input(dev, channel, val);
	return res;
	case hwmon_temp_fault:
	res = max6639_temp_read_fault(dev, channel, val);
	return res;
	case hwmon_temp_max:
	res = max6639_temp_read_max(dev, channel, val);
	return res;
	case hwmon_temp_crit:
	res = max6639_temp_read_crit(dev, channel, val);
	return res;
	case hwmon_temp_emergency:
	res = max6639_temp_read_emergency(dev, channel, val);
	return res;
	case hwmon_temp_max_alarm:
	res = max6639_get_status(dev, &status);
	if (res < 0)
	return res;
	*val = !!(status & BIT(3 - channel));
	return 0;
	case hwmon_temp_crit_alarm:
	res = max6639_get_status(dev, &status);
	if (res < 0)
	return res;
	*val = !!(status & BIT(7 - channel));
	return 0;
	case hwmon_temp_emergency_alarm:
	res = max6639_get_status(dev, &status);
	if (res < 0)
	return res;
	*val = !!(status & BIT(5 - channel));
	return 0;
	default:
	return -EOPNOTSUPP;
	}
	}

	static int max6639_write_temp(struct device *dev, u32 attr, int channel,
	long val)
	{
	struct max6639_data *data = dev_get_drvdata(dev);

	switch (attr) {
	case hwmon_temp_max:
	return max6639_temp_set_max(data, channel, val);
	case hwmon_temp_crit:
	return max6639_temp_set_crit(data, channel, val);
	case hwmon_temp_emergency:
	return max6639_temp_set_emergency(data, channel, val);
	default:
	return -EOPNOTSUPP;
	}
	}

	static umode_t max6639_temp_is_visible(const void *_data, u32 attr, int channel)
	{
	switch (attr) {
	case hwmon_temp_input:
	case hwmon_temp_fault:
	case hwmon_temp_max_alarm:
	case hwmon_temp_crit_alarm:
	case hwmon_temp_emergency_alarm:
	return 0444;
	case hwmon_temp_max:
	case hwmon_temp_crit:
	case hwmon_temp_emergency:
	return 0644;
	default:
	return 0;
	}
	}

	static int max6639_read(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long *val)
	{
	switch (type) {
	case hwmon_fan:
	return max6639_read_fan(dev, attr, channel, val);
	case hwmon_pwm:
	return max6639_read_pwm(dev, attr, channel, val);
	case hwmon_temp:
	return max6639_read_temp(dev, attr, channel, val);
	default:
	return -EOPNOTSUPP;
	}
	}

	static int max6639_write(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long val)
	{
	switch (type) {
	case hwmon_fan:
	return max6639_write_fan(dev, attr, channel, val);
	case hwmon_pwm:
	return max6639_write_pwm(dev, attr, channel, val);
	case hwmon_temp:
	return max6639_write_temp(dev, attr, channel, val);
	default:
	return -EOPNOTSUPP;
	}
	}

	static umode_t max6639_is_visible(const void *data,
	enum hwmon_sensor_types type,
	u32 attr, int channel)
	{
	switch (type) {
	case hwmon_fan:
	return max6639_fan_is_visible(data, attr, channel);
	case hwmon_pwm:
	return max6639_pwm_is_visible(data, attr, channel);
	case hwmon_temp:
	return max6639_temp_is_visible(data, attr, channel);
	default:
	return 0;
	}
	}

	static const struct hwmon_channel_info * const max6639_info[] = {
	HWMON_CHANNEL_INFO(fan,
	HWMON_F_INPUT \| HWMON_F_FAULT \| HWMON_F_PULSES,
	HWMON_F_INPUT \| HWMON_F_FAULT \| HWMON_F_PULSES),
	HWMON_CHANNEL_INFO(pwm,
	HWMON_PWM_INPUT \| HWMON_PWM_FREQ,
	HWMON_PWM_INPUT \| HWMON_PWM_FREQ),
	HWMON_CHANNEL_INFO(temp,
	HWMON_T_INPUT \| HWMON_T_FAULT \| HWMON_T_MAX \| HWMON_T_MAX_ALARM \|
	HWMON_T_CRIT \| HWMON_T_CRIT_ALARM \| HWMON_T_EMERGENCY \|
	HWMON_T_EMERGENCY_ALARM,
	HWMON_T_INPUT \| HWMON_T_FAULT \| HWMON_T_MAX \| HWMON_T_MAX_ALARM \|
	HWMON_T_CRIT \| HWMON_T_CRIT_ALARM \| HWMON_T_EMERGENCY \|
	HWMON_T_EMERGENCY_ALARM),
	NULL
	};

	static const struct hwmon_ops max6639_hwmon_ops = {
	.is_visible = max6639_is_visible,
	.read = max6639_read,
	.write = max6639_write,
	};

	static const struct hwmon_chip_info max6639_chip_info = {
	.ops = &max6639_hwmon_ops,
	.info = max6639_info,
	};

	/*
	* 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)
	{
	struct max6639_platform_data *max6639_info =
	dev_get_platdata(&client->dev);
	int i;
	int rpm_range = 1; /* default: 4000 RPM */
	int err, ppr;

	/* Reset chip to default values, see below for GCONFIG setup */
	err = regmap_write(data->regmap, MAX6639_REG_GCONFIG, MAX6639_GCONFIG_POR);
	if (err)
	return err;

	/* Fans pulse per revolution is 2 by default */
	if (max6639_info && max6639_info->ppr > 0 &&
	max6639_info->ppr < 5)
	ppr = max6639_info->ppr;
	else
	ppr = 2;

	data->ppr[0] = ppr;
	data->ppr[1] = ppr;

	if (max6639_info)
	rpm_range = rpm_range_to_reg(max6639_info->rpm_range);
	data->rpm_range[0] = rpm_range;
	data->rpm_range[1] = rpm_range;

	for (i = 0; i < MAX6639_NUM_CHANNELS; i++) {
	/* Set Fan pulse per revolution */
	err = max6639_set_ppr(data, i, data->ppr[i]);
	if (err)
	return err;

	/* Fans config PWM, RPM */
	err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG1(i),
	MAX6639_FAN_CONFIG1_PWM \| data->rpm_range[i]);
	if (err)
	return err;

	/* Fans PWM polarity high by default */
	if (max6639_info) {
	if (max6639_info->pwm_polarity == 0)
	err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG2a(i), 0x00);
	else
	err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG2a(i), 0x02);
	}
	if (err)
	return err;

	/*
	* /THERM full speed enable,
	* PWM frequency 25kHz, see also GCONFIG below
	*/
	err = regmap_write(data->regmap, MAX6639_REG_FAN_CONFIG3(i),
	MAX6639_FAN_CONFIG3_THERM_FULL_SPEED \| 0x03);
	if (err)
	return err;

	/* Max. temp. 80C/90C/100C */
	err = regmap_write(data->regmap, MAX6639_REG_THERM_LIMIT(i), 80);
	if (err)
	return err;
	err = regmap_write(data->regmap, MAX6639_REG_ALERT_LIMIT(i), 90);
	if (err)
	return err;
	err = regmap_write(data->regmap, MAX6639_REG_OT_LIMIT(i), 100);
	if (err)
	return err;

	/* PWM 120/120 (i.e. 100%) */
	err = regmap_write(data->regmap, MAX6639_REG_TARGTDUTY(i), 120);
	if (err)
	return err;
	}
	/* Start monitoring */
	return regmap_write(data->regmap, MAX6639_REG_GCONFIG,
	MAX6639_GCONFIG_DISABLE_TIMEOUT \| MAX6639_GCONFIG_CH2_LOCAL \|
	MAX6639_GCONFIG_PWM_FREQ_HI);

	}

	/* 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;

	strscpy(info->type, "max6639", I2C_NAME_SIZE);

	return 0;
	}

	static void max6639_regulator_disable(void *data)
	{
	regulator_disable(data);
	}

	static bool max6639_regmap_is_volatile(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MAX6639_REG_TEMP(0):
	case MAX6639_REG_TEMP_EXT(0):
	case MAX6639_REG_TEMP(1):
	case MAX6639_REG_TEMP_EXT(1):
	case MAX6639_REG_STATUS:
	case MAX6639_REG_FAN_CNT(0):
	case MAX6639_REG_FAN_CNT(1):
	case MAX6639_REG_TARGTDUTY(0):
	case MAX6639_REG_TARGTDUTY(1):
	return true;
	default:
	return false;
	}
	}

	static const struct regmap_config max6639_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = MAX6639_REG_DEVREV,
	.cache_type = REGCACHE_MAPLE,
	.volatile_reg = max6639_regmap_is_volatile,
	};

	static int max6639_probe(struct i2c_client *client)
	{
	struct device *dev = &client->dev;
	struct max6639_data *data;
	struct device *hwmon_dev;
	int err;

	data = devm_kzalloc(dev, sizeof(struct max6639_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->regmap = devm_regmap_init_i2c(client, &max6639_regmap_config);
	if (IS_ERR(data->regmap))
	return dev_err_probe(dev,
	PTR_ERR(data->regmap),
	"regmap initialization failed\n");

	data->reg = devm_regulator_get_optional(dev, "fan");
	if (IS_ERR(data->reg)) {
	if (PTR_ERR(data->reg) != -ENODEV)
	return PTR_ERR(data->reg);

	data->reg = NULL;
	} else {
	/* Spin up fans */
	err = regulator_enable(data->reg);
	if (err) {
	dev_err(dev, "Failed to enable fan supply: %d\n", err);
	return err;
	}
	err = devm_add_action_or_reset(dev, max6639_regulator_disable,
	data->reg);
	if (err) {
	dev_err(dev, "Failed to register action: %d\n", err);
	return err;
	}
	}

	mutex_init(&data->update_lock);

	/* Initialize the max6639 chip */
	err = max6639_init_client(client, data);
	if (err < 0)
	return err;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
	data, &max6639_chip_info,
	NULL);

	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static int max6639_suspend(struct device *dev)
	{
	struct max6639_data *data = dev_get_drvdata(dev);

	if (data->reg)
	regulator_disable(data->reg);

	return regmap_write_bits(data->regmap, MAX6639_REG_GCONFIG, MAX6639_GCONFIG_STANDBY,
	MAX6639_GCONFIG_STANDBY);
	}

	static int max6639_resume(struct device *dev)
	{
	struct max6639_data *data = dev_get_drvdata(dev);
	int ret;

	if (data->reg) {
	ret = regulator_enable(data->reg);
	if (ret) {
	dev_err(dev, "Failed to enable fan supply: %d\n", ret);
	return ret;
	}
	}

	return regmap_write_bits(data->regmap, MAX6639_REG_GCONFIG, MAX6639_GCONFIG_STANDBY,
	~MAX6639_GCONFIG_STANDBY);
	}

	static const struct i2c_device_id max6639_id[] = {
	{"max6639"},
	{ }
	};

	MODULE_DEVICE_TABLE(i2c, max6639_id);

	static DEFINE_SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);

	static const struct of_device_id max6639_of_match[] = {
	{ .compatible = "maxim,max6639", },
	{ },
	};

	static struct i2c_driver max6639_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
	.name = "max6639",
	.pm = pm_sleep_ptr(&max6639_pm_ops),
	.of_match_table = max6639_of_match,
	},
	.probe = max6639_probe,
	.id_table = max6639_id,
	.detect = max6639_detect,
	.address_list = normal_i2c,
	};

	module_i2c_driver(max6639_driver);

	MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
	MODULE_DESCRIPTION("max6639 driver");
	MODULE_LICENSE("GPL");