/*
 * nct7802 - Driver for Nuvoton NCT7802Y
 *
 * Copyright (C) 2014  Guenter Roeck <linux@roeck-us.net>
 *
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#define DRVNAME "nct7802"

static const u8 REG_VOLTAGE[5] = { 0x09, 0x0a, 0x0c, 0x0d, 0x0e };

static const u8 REG_VOLTAGE_LIMIT_LSB[2][5] = {
	{ 0x40, 0x00, 0x42, 0x44, 0x46 },
	{ 0x3f, 0x00, 0x41, 0x43, 0x45 },
};

static const u8 REG_VOLTAGE_LIMIT_MSB[5] = { 0x48, 0x00, 0x47, 0x47, 0x48 };

static const u8 REG_VOLTAGE_LIMIT_MSB_SHIFT[2][5] = {
	{ 0, 0, 4, 0, 4 },
	{ 2, 0, 6, 2, 6 },
};

#define REG_BANK		0x00
#define REG_TEMP_LSB		0x05
#define REG_TEMP_PECI_LSB	0x08
#define REG_VOLTAGE_LOW		0x0f
#define REG_FANCOUNT_LOW	0x13
#define REG_START		0x21
#define REG_MODE		0x22
#define REG_PECI_ENABLE		0x23
#define REG_FAN_ENABLE		0x24
#define REG_VMON_ENABLE		0x25
#define REG_VENDOR_ID		0xfd
#define REG_CHIP_ID		0xfe
#define REG_VERSION_ID		0xff

/*
 * Data structures and manipulation thereof
 */

struct nct7802_data {
	struct regmap *regmap;
	struct mutex access_lock; /* for multi-byte read and write operations */
};

static int nct7802_read_temp(struct nct7802_data *data,
			     u8 reg_temp, u8 reg_temp_low, int *temp)
{
	unsigned int t1, t2 = 0;
	int err;

	*temp = 0;

	mutex_lock(&data->access_lock);
	err = regmap_read(data->regmap, reg_temp, &t1);
	if (err < 0)
		goto abort;
	t1 <<= 8;
	if (reg_temp_low) {	/* 11 bit data */
		err = regmap_read(data->regmap, reg_temp_low, &t2);
		if (err < 0)
			goto abort;
	}
	t1 |= t2 & 0xe0;
	*temp = (s16)t1 / 32 * 125;
abort:
	mutex_unlock(&data->access_lock);
	return err;
}

static int nct7802_read_fan(struct nct7802_data *data, u8 reg_fan)
{
	unsigned int f1, f2;
	int ret;

	mutex_lock(&data->access_lock);
	ret = regmap_read(data->regmap, reg_fan, &f1);
	if (ret < 0)
		goto abort;
	ret = regmap_read(data->regmap, REG_FANCOUNT_LOW, &f2);
	if (ret < 0)
		goto abort;
	ret = (f1 << 5) | (f2 >> 3);
	/* convert fan count to rpm */
	if (ret == 0x1fff)	/* maximum value, assume fan is stopped */
		ret = 0;
	else if (ret)
		ret = DIV_ROUND_CLOSEST(1350000U, ret);
abort:
	mutex_unlock(&data->access_lock);
	return ret;
}

static int nct7802_read_fan_min(struct nct7802_data *data, u8 reg_fan_low,
				u8 reg_fan_high)
{
	unsigned int f1, f2;
	int ret;

	mutex_lock(&data->access_lock);
	ret = regmap_read(data->regmap, reg_fan_low, &f1);
	if (ret < 0)
		goto abort;
	ret = regmap_read(data->regmap, reg_fan_high, &f2);
	if (ret < 0)
		goto abort;
	ret = f1 | ((f2 & 0xf8) << 5);
	/* convert fan count to rpm */
	if (ret == 0x1fff)	/* maximum value, assume no limit */
		ret = 0;
	else if (ret)
		ret = DIV_ROUND_CLOSEST(1350000U, ret);
abort:
	mutex_unlock(&data->access_lock);
	return ret;
}

static int nct7802_write_fan_min(struct nct7802_data *data, u8 reg_fan_low,
				 u8 reg_fan_high, unsigned int limit)
{
	int err;

	if (limit)
		limit = DIV_ROUND_CLOSEST(1350000U, limit);
	else
		limit = 0x1fff;
	limit = clamp_val(limit, 0, 0x1fff);

	mutex_lock(&data->access_lock);
	err = regmap_write(data->regmap, reg_fan_low, limit & 0xff);
	if (err < 0)
		goto abort;

	err = regmap_write(data->regmap, reg_fan_high, (limit & 0x1f00) >> 5);
abort:
	mutex_unlock(&data->access_lock);
	return err;
}

static u8 nct7802_vmul[] = { 4, 2, 2, 2, 2 };

static int nct7802_read_voltage(struct nct7802_data *data, int nr, int index)
{
	unsigned int v1, v2;
	int ret;

	mutex_lock(&data->access_lock);
	if (index == 0) {	/* voltage */
		ret = regmap_read(data->regmap, REG_VOLTAGE[nr], &v1);
		if (ret < 0)
			goto abort;
		ret = regmap_read(data->regmap, REG_VOLTAGE_LOW, &v2);
		if (ret < 0)
			goto abort;
		ret = ((v1 << 2) | (v2 >> 6)) * nct7802_vmul[nr];
	}  else {	/* limit */
		int shift = 8 - REG_VOLTAGE_LIMIT_MSB_SHIFT[index - 1][nr];

		ret = regmap_read(data->regmap,
				  REG_VOLTAGE_LIMIT_LSB[index - 1][nr], &v1);
		if (ret < 0)
			goto abort;
		ret = regmap_read(data->regmap, REG_VOLTAGE_LIMIT_MSB[nr],
				  &v2);
		if (ret < 0)
			goto abort;
		ret = (v1 | ((v2 << shift) & 0x300)) * nct7802_vmul[nr];
	}
abort:
	mutex_unlock(&data->access_lock);
	return ret;
}

static int nct7802_write_voltage(struct nct7802_data *data, int nr, int index,
				 unsigned int voltage)
{
	int shift = 8 - REG_VOLTAGE_LIMIT_MSB_SHIFT[index - 1][nr];
	int err;

	voltage = DIV_ROUND_CLOSEST(voltage, nct7802_vmul[nr]);
	voltage = clamp_val(voltage, 0, 0x3ff);

	mutex_lock(&data->access_lock);
	err = regmap_write(data->regmap,
			   REG_VOLTAGE_LIMIT_LSB[index - 1][nr],
			   voltage & 0xff);
	if (err < 0)
		goto abort;

	err = regmap_update_bits(data->regmap, REG_VOLTAGE_LIMIT_MSB[nr],
				 0x0300 >> shift, (voltage & 0x0300) >> shift);
abort:
	mutex_unlock(&data->access_lock);
	return err;
}

static ssize_t show_in(struct device *dev, struct device_attribute *attr,
		       char *buf)
{
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	int voltage;

	voltage = nct7802_read_voltage(data, sattr->nr, sattr->index);
	if (voltage < 0)
		return voltage;

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

static ssize_t store_in(struct device *dev, struct device_attribute *attr,
			const char *buf, size_t count)
{
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	int index = sattr->index;
	int nr = sattr->nr;
	unsigned long val;
	int err;

	err = kstrtoul(buf, 10, &val);
	if (err < 0)
		return err;

	err = nct7802_write_voltage(data, nr, index, val);
	return err ? : count;
}

static ssize_t show_temp(struct device *dev, struct device_attribute *attr,
			 char *buf)
{
	struct nct7802_data *data = dev_get_drvdata(dev);
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	int err, temp;

	err = nct7802_read_temp(data, sattr->nr, sattr->index, &temp);
	if (err < 0)
		return err;

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

static ssize_t store_temp(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t count)
{
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	int nr = sattr->nr;
	long val;
	int err;

	err = kstrtol(buf, 10, &val);
	if (err < 0)
		return err;

	val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), -128, 127);

	err = regmap_write(data->regmap, nr, val & 0xff);
	return err ? : count;
}

static ssize_t show_fan(struct device *dev, struct device_attribute *attr,
			char *buf)
{
	struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	int speed;

	speed = nct7802_read_fan(data, sattr->index);
	if (speed < 0)
		return speed;

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

static ssize_t show_fan_min(struct device *dev, struct device_attribute *attr,
			    char *buf)
{
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	int speed;

	speed = nct7802_read_fan_min(data, sattr->nr, sattr->index);
	if (speed < 0)
		return speed;

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

static ssize_t store_fan_min(struct device *dev, struct device_attribute *attr,
			     const char *buf, size_t count)
{
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	unsigned long val;
	int err;

	err = kstrtoul(buf, 10, &val);
	if (err < 0)
		return err;

	err = nct7802_write_fan_min(data, sattr->nr, sattr->index, val);
	return err ? : count;
}

static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	struct nct7802_data *data = dev_get_drvdata(dev);
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	int bit = sattr->index;
	unsigned int val;
	int ret;

	ret = regmap_read(data->regmap, sattr->nr, &val);
	if (ret < 0)
		return ret;

	return sprintf(buf, "%u\n", !!(val & (1 << bit)));
}

static ssize_t
show_beep(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;

	err = regmap_read(data->regmap, sattr->nr, &regval);
	if (err)
		return err;

	return sprintf(buf, "%u\n", !!(regval & (1 << sattr->index)));
}

static ssize_t
store_beep(struct device *dev, struct device_attribute *attr, const char *buf,
	   size_t count)
{
	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
	struct nct7802_data *data = dev_get_drvdata(dev);
	unsigned long val;
	int err;

	err = kstrtoul(buf, 10, &val);
	if (err < 0)
		return err;
	if (val > 1)
		return -EINVAL;

	err = regmap_update_bits(data->regmap, sattr->nr, 1 << sattr->index,
				 val ? 1 << sattr->index : 0);
	return err ? : count;
}

static SENSOR_DEVICE_ATTR_2(temp1_input, S_IRUGO, show_temp, NULL, 0x01,
			    REG_TEMP_LSB);
static SENSOR_DEVICE_ATTR_2(temp1_min, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x31, 0);
static SENSOR_DEVICE_ATTR_2(temp1_max, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x30, 0);
static SENSOR_DEVICE_ATTR_2(temp1_crit, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x3a, 0);

static SENSOR_DEVICE_ATTR_2(temp2_input, S_IRUGO, show_temp, NULL, 0x02,
			    REG_TEMP_LSB);
static SENSOR_DEVICE_ATTR_2(temp2_min, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x33, 0);
static SENSOR_DEVICE_ATTR_2(temp2_max, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x32, 0);
static SENSOR_DEVICE_ATTR_2(temp2_crit, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x3b, 0);

static SENSOR_DEVICE_ATTR_2(temp3_input, S_IRUGO, show_temp, NULL, 0x03,
			    REG_TEMP_LSB);
static SENSOR_DEVICE_ATTR_2(temp3_min, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x35, 0);
static SENSOR_DEVICE_ATTR_2(temp3_max, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x34, 0);
static SENSOR_DEVICE_ATTR_2(temp3_crit, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x3c, 0);

static SENSOR_DEVICE_ATTR_2(temp4_input, S_IRUGO, show_temp, NULL, 0x04, 0);
static SENSOR_DEVICE_ATTR_2(temp4_min, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x37, 0);
static SENSOR_DEVICE_ATTR_2(temp4_max, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x36, 0);
static SENSOR_DEVICE_ATTR_2(temp4_crit, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x3d, 0);

static SENSOR_DEVICE_ATTR_2(temp5_input, S_IRUGO, show_temp, NULL, 0x06,
			    REG_TEMP_PECI_LSB);
static SENSOR_DEVICE_ATTR_2(temp5_min, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x39, 0);
static SENSOR_DEVICE_ATTR_2(temp5_max, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x38, 0);
static SENSOR_DEVICE_ATTR_2(temp5_crit, S_IRUGO | S_IWUSR, show_temp,
			    store_temp, 0x3e, 0);

static SENSOR_DEVICE_ATTR_2(temp6_input, S_IRUGO, show_temp, NULL, 0x07,
			    REG_TEMP_PECI_LSB);

static SENSOR_DEVICE_ATTR_2(temp1_min_alarm, S_IRUGO, show_alarm, NULL,
			    0x18, 0);
static SENSOR_DEVICE_ATTR_2(temp2_min_alarm, S_IRUGO, show_alarm, NULL,
			    0x18, 1);
static SENSOR_DEVICE_ATTR_2(temp3_min_alarm, S_IRUGO, show_alarm, NULL,
			    0x18, 2);
static SENSOR_DEVICE_ATTR_2(temp4_min_alarm, S_IRUGO, show_alarm, NULL,
			    0x18, 3);
static SENSOR_DEVICE_ATTR_2(temp5_min_alarm, S_IRUGO, show_alarm, NULL,
			    0x18, 4);

static SENSOR_DEVICE_ATTR_2(temp1_max_alarm, S_IRUGO, show_alarm, NULL,
			    0x19, 0);
static SENSOR_DEVICE_ATTR_2(temp2_max_alarm, S_IRUGO, show_alarm, NULL,
			    0x19, 1);
static SENSOR_DEVICE_ATTR_2(temp3_max_alarm, S_IRUGO, show_alarm, NULL,
			    0x19, 2);
static SENSOR_DEVICE_ATTR_2(temp4_max_alarm, S_IRUGO, show_alarm, NULL,
			    0x19, 3);
static SENSOR_DEVICE_ATTR_2(temp5_max_alarm, S_IRUGO, show_alarm, NULL,
			    0x19, 4);

static SENSOR_DEVICE_ATTR_2(temp1_crit_alarm, S_IRUGO, show_alarm, NULL,
			    0x1b, 0);
static SENSOR_DEVICE_ATTR_2(temp2_crit_alarm, S_IRUGO, show_alarm, NULL,
			    0x1b, 1);
static SENSOR_DEVICE_ATTR_2(temp3_crit_alarm, S_IRUGO, show_alarm, NULL,
			    0x1b, 2);
static SENSOR_DEVICE_ATTR_2(temp4_crit_alarm, S_IRUGO, show_alarm, NULL,
			    0x1b, 3);
static SENSOR_DEVICE_ATTR_2(temp5_crit_alarm, S_IRUGO, show_alarm, NULL,
			    0x1b, 4);

static SENSOR_DEVICE_ATTR_2(temp1_fault, S_IRUGO, show_alarm, NULL, 0x17, 0);
static SENSOR_DEVICE_ATTR_2(temp2_fault, S_IRUGO, show_alarm, NULL, 0x17, 1);
static SENSOR_DEVICE_ATTR_2(temp3_fault, S_IRUGO, show_alarm, NULL, 0x17, 2);

static SENSOR_DEVICE_ATTR_2(temp1_beep, S_IRUGO | S_IWUSR, show_beep,
			    store_beep, 0x5c, 0);
static SENSOR_DEVICE_ATTR_2(temp2_beep, S_IRUGO | S_IWUSR, show_beep,
			    store_beep, 0x5c, 1);
static SENSOR_DEVICE_ATTR_2(temp3_beep, S_IRUGO | S_IWUSR, show_beep,
			    store_beep, 0x5c, 2);
static SENSOR_DEVICE_ATTR_2(temp4_beep, S_IRUGO | S_IWUSR, show_beep,
			    store_beep, 0x5c, 3);
static SENSOR_DEVICE_ATTR_2(temp5_beep, S_IRUGO | S_IWUSR, show_beep,
			    store_beep, 0x5c, 4);
static SENSOR_DEVICE_ATTR_2(temp6_beep, S_IRUGO | S_IWUSR, show_beep,
			    store_beep, 0x5c, 5);

static struct attribute *nct7802_temp_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_temp1_min.dev_attr.attr,
	&sensor_dev_attr_temp1_max.dev_attr.attr,
	&sensor_dev_attr_temp1_crit.dev_attr.attr,
	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
	&sensor_dev_attr_temp1_fault.dev_attr.attr,
	&sensor_dev_attr_temp1_beep.dev_attr.attr,

	&sensor_dev_attr_temp2_input.dev_attr.attr,		/* 9 */
	&sensor_dev_attr_temp2_min.dev_attr.attr,
	&sensor_dev_attr_temp2_max.dev_attr.attr,
	&sensor_dev_attr_temp2_crit.dev_attr.attr,
	&sensor_dev_attr_temp2_min_alarm.dev_attr.attr,
	&sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
	&sensor_dev_attr_temp2_crit_alarm.dev_attr.attr,
	&sensor_dev_attr_temp2_fault.dev_attr.attr,
	&sensor_dev_attr_temp2_beep.dev_attr.attr,

	&sensor_dev_attr_temp3_input.dev_attr.attr,		/* 18 */
	&sensor_dev_attr_temp3_min.dev_attr.attr,
	&sensor_dev_attr_temp3_max.dev_attr.attr,
	&sensor_dev_attr_temp3_crit.dev_attr.attr,
	&sensor_dev_attr_temp3_min_alarm.dev_attr.attr,
	&sensor_dev_attr_temp3_max_alarm.dev_attr.attr,
	&sensor_dev_attr_temp3_crit_alarm.dev_attr.attr,
	&sensor_dev_attr_temp3_fault.dev_attr.attr,
	&sensor_dev_attr_temp3_beep.dev_attr.attr,

	&sensor_dev_attr_temp4_input.dev_attr.attr,		/* 27 */
	&sensor_dev_attr_temp4_min.dev_attr.attr,
	&sensor_dev_attr_temp4_max.dev_attr.attr,
	&sensor_dev_attr_temp4_crit.dev_attr.attr,
	&sensor_dev_attr_temp4_min_alarm.dev_attr.attr,
	&sensor_dev_attr_temp4_max_alarm.dev_attr.attr,
	&sensor_dev_attr_temp4_crit_alarm.dev_attr.attr,
	&sensor_dev_attr_temp4_beep.dev_attr.attr,

	&sensor_dev_attr_temp5_input.dev_attr.attr,		/* 35 */
	&sensor_dev_attr_temp5_min.dev_attr.attr,
	&sensor_dev_attr_temp5_max.dev_attr.attr,
	&sensor_dev_attr_temp5_crit.dev_attr.attr,
	&sensor_dev_attr_temp5_min_alarm.dev_attr.attr,
	&sensor_dev_attr_temp5_max_alarm.dev_attr.attr,
	&sensor_dev_attr_temp5_crit_alarm.dev_attr.attr,
	&sensor_dev_attr_temp5_beep.dev_attr.attr,

	&sensor_dev_attr_temp6_input.dev_attr.attr,		/* 43 */
	&sensor_dev_attr_temp6_beep.dev_attr.attr,

	NULL
};

static umode_t nct7802_temp_is_visible(struct kobject *kobj,
				       struct attribute *attr, int index)
{
	struct device *dev = container_of(kobj, struct device, kobj);
	struct nct7802_data *data = dev_get_drvdata(dev);
	unsigned int reg;
	int err;

	err = regmap_read(data->regmap, REG_MODE, &reg);
	if (err < 0)
		return 0;

	if (index < 9 &&
	    (reg & 03) != 0x01 && (reg & 0x03) != 0x02)		/* RD1 */
		return 0;
	if (index >= 9 && index < 18 &&
	    (reg & 0x0c) != 0x04 && (reg & 0x0c) != 0x08)	/* RD2 */
		return 0;
	if (index >= 18 && index < 27 && (reg & 0x30) != 0x10)	/* RD3 */
		return 0;
	if (index >= 27 && index < 35)				/* local */
		return attr->mode;

	err = regmap_read(data->regmap, REG_PECI_ENABLE, &reg);
	if (err < 0)
		return 0;

	if (index >= 35 && index < 43 && !(reg & 0x01))		/* PECI 0 */
		return 0;

	if (index >= 0x43 && (!(reg & 0x02)))			/* PECI 1 */
		return 0;

	return attr->mode;
}

static struct attribute_group nct7802_temp_group = {
	.attrs = nct7802_temp_attrs,
	.is_visible = nct7802_temp_is_visible,
};

static SENSOR_DEVICE_ATTR_2(in0_input, S_IRUGO, show_in, NULL, 0, 0);
static SENSOR_DEVICE_ATTR_2(in0_min, S_IRUGO | S_IWUSR, show_in, store_in,
			    0, 1);
static SENSOR_DEVICE_ATTR_2(in0_max, S_IRUGO | S_IWUSR, show_in, store_in,
			    0, 2);
static SENSOR_DEVICE_ATTR_2(in0_alarm, S_IRUGO, show_alarm, NULL, 0x1e, 3);
static SENSOR_DEVICE_ATTR_2(in0_beep, S_IRUGO | S_IWUSR, show_beep, store_beep,
			    0x5a, 3);

static SENSOR_DEVICE_ATTR_2(in1_input, S_IRUGO, show_in, NULL, 1, 0);

static SENSOR_DEVICE_ATTR_2(in2_input, S_IRUGO, show_in, NULL, 2, 0);
static SENSOR_DEVICE_ATTR_2(in2_min, S_IRUGO | S_IWUSR, show_in, store_in,
			    2, 1);
static SENSOR_DEVICE_ATTR_2(in2_max, S_IRUGO | S_IWUSR, show_in, store_in,
			    2, 2);
static SENSOR_DEVICE_ATTR_2(in2_alarm, S_IRUGO, show_alarm, NULL, 0x1e, 0);
static SENSOR_DEVICE_ATTR_2(in2_beep, S_IRUGO | S_IWUSR, show_beep, store_beep,
			    0x5a, 0);

static SENSOR_DEVICE_ATTR_2(in3_input, S_IRUGO, show_in, NULL, 3, 0);
static SENSOR_DEVICE_ATTR_2(in3_min, S_IRUGO | S_IWUSR, show_in, store_in,
			    3, 1);
static SENSOR_DEVICE_ATTR_2(in3_max, S_IRUGO | S_IWUSR, show_in, store_in,
			    3, 2);
static SENSOR_DEVICE_ATTR_2(in3_alarm, S_IRUGO, show_alarm, NULL, 0x1e, 1);
static SENSOR_DEVICE_ATTR_2(in3_beep, S_IRUGO | S_IWUSR, show_beep, store_beep,
			    0x5a, 1);

static SENSOR_DEVICE_ATTR_2(in4_input, S_IRUGO, show_in, NULL, 4, 0);
static SENSOR_DEVICE_ATTR_2(in4_min, S_IRUGO | S_IWUSR, show_in, store_in,
			    4, 1);
static SENSOR_DEVICE_ATTR_2(in4_max, S_IRUGO | S_IWUSR, show_in, store_in,
			    4, 2);
static SENSOR_DEVICE_ATTR_2(in4_alarm, S_IRUGO, show_alarm, NULL, 0x1e, 2);
static SENSOR_DEVICE_ATTR_2(in4_beep, S_IRUGO | S_IWUSR, show_beep, store_beep,
			    0x5a, 2);

static struct attribute *nct7802_in_attrs[] = {
	&sensor_dev_attr_in0_input.dev_attr.attr,
	&sensor_dev_attr_in0_min.dev_attr.attr,
	&sensor_dev_attr_in0_max.dev_attr.attr,
	&sensor_dev_attr_in0_alarm.dev_attr.attr,
	&sensor_dev_attr_in0_beep.dev_attr.attr,

	&sensor_dev_attr_in1_input.dev_attr.attr,	/* 5 */

	&sensor_dev_attr_in2_input.dev_attr.attr,	/* 6 */
	&sensor_dev_attr_in2_min.dev_attr.attr,
	&sensor_dev_attr_in2_max.dev_attr.attr,
	&sensor_dev_attr_in2_alarm.dev_attr.attr,
	&sensor_dev_attr_in2_beep.dev_attr.attr,

	&sensor_dev_attr_in3_input.dev_attr.attr,	/* 11 */
	&sensor_dev_attr_in3_min.dev_attr.attr,
	&sensor_dev_attr_in3_max.dev_attr.attr,
	&sensor_dev_attr_in3_alarm.dev_attr.attr,
	&sensor_dev_attr_in3_beep.dev_attr.attr,

	&sensor_dev_attr_in4_input.dev_attr.attr,	/* 17 */
	&sensor_dev_attr_in4_min.dev_attr.attr,
	&sensor_dev_attr_in4_max.dev_attr.attr,
	&sensor_dev_attr_in4_alarm.dev_attr.attr,
	&sensor_dev_attr_in4_beep.dev_attr.attr,

	NULL,
};

static umode_t nct7802_in_is_visible(struct kobject *kobj,
				     struct attribute *attr, int index)
{
	struct device *dev = container_of(kobj, struct device, kobj);
	struct nct7802_data *data = dev_get_drvdata(dev);
	unsigned int reg;
	int err;

	if (index < 6)						/* VCC, VCORE */
		return attr->mode;

	err = regmap_read(data->regmap, REG_MODE, &reg);
	if (err < 0)
		return 0;

	if (index >= 6 && index < 11 && (reg & 0x03) != 0x03)	/* VSEN1 */
		return 0;
	if (index >= 11 && index < 17 && (reg & 0x0c) != 0x0c)	/* VSEN2 */
		return 0;
	if (index >= 17 && (reg & 0x30) != 0x30)		/* VSEN3 */
		return 0;

	return attr->mode;
}

static struct attribute_group nct7802_in_group = {
	.attrs = nct7802_in_attrs,
	.is_visible = nct7802_in_is_visible,
};

static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL, 0x10);
static SENSOR_DEVICE_ATTR_2(fan1_min, S_IRUGO | S_IWUSR, show_fan_min,
			    store_fan_min, 0x49, 0x4c);
static SENSOR_DEVICE_ATTR_2(fan1_alarm, S_IRUGO, show_alarm, NULL, 0x1a, 0);
static SENSOR_DEVICE_ATTR_2(fan1_beep, S_IRUGO | S_IWUSR, show_beep, store_beep,
			    0x5b, 0);
static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, show_fan, NULL, 0x11);
static SENSOR_DEVICE_ATTR_2(fan2_min, S_IRUGO | S_IWUSR, show_fan_min,
			    store_fan_min, 0x4a, 0x4d);
static SENSOR_DEVICE_ATTR_2(fan2_alarm, S_IRUGO, show_alarm, NULL, 0x1a, 1);
static SENSOR_DEVICE_ATTR_2(fan2_beep, S_IRUGO | S_IWUSR, show_beep, store_beep,
			    0x5b, 1);
static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, show_fan, NULL, 0x12);
static SENSOR_DEVICE_ATTR_2(fan3_min, S_IRUGO | S_IWUSR, show_fan_min,
			    store_fan_min, 0x4b, 0x4e);
static SENSOR_DEVICE_ATTR_2(fan3_alarm, S_IRUGO, show_alarm, NULL, 0x1a, 2);
static SENSOR_DEVICE_ATTR_2(fan3_beep, S_IRUGO | S_IWUSR, show_beep, store_beep,
			    0x5b, 2);

static struct attribute *nct7802_fan_attrs[] = {
	&sensor_dev_attr_fan1_input.dev_attr.attr,
	&sensor_dev_attr_fan1_min.dev_attr.attr,
	&sensor_dev_attr_fan1_alarm.dev_attr.attr,
	&sensor_dev_attr_fan1_beep.dev_attr.attr,
	&sensor_dev_attr_fan2_input.dev_attr.attr,
	&sensor_dev_attr_fan2_min.dev_attr.attr,
	&sensor_dev_attr_fan2_alarm.dev_attr.attr,
	&sensor_dev_attr_fan2_beep.dev_attr.attr,
	&sensor_dev_attr_fan3_input.dev_attr.attr,
	&sensor_dev_attr_fan3_min.dev_attr.attr,
	&sensor_dev_attr_fan3_alarm.dev_attr.attr,
	&sensor_dev_attr_fan3_beep.dev_attr.attr,

	NULL
};

static umode_t nct7802_fan_is_visible(struct kobject *kobj,
				      struct attribute *attr, int index)
{
	struct device *dev = container_of(kobj, struct device, kobj);
	struct nct7802_data *data = dev_get_drvdata(dev);
	int fan = index / 4;	/* 4 attributes per fan */
	unsigned int reg;
	int err;

	err = regmap_read(data->regmap, REG_FAN_ENABLE, &reg);
	if (err < 0 || !(reg & (1 << fan)))
		return 0;

	return attr->mode;
}

static struct attribute_group nct7802_fan_group = {
	.attrs = nct7802_fan_attrs,
	.is_visible = nct7802_fan_is_visible,
};

static const struct attribute_group *nct7802_groups[] = {
	&nct7802_temp_group,
	&nct7802_in_group,
	&nct7802_fan_group,
	NULL
};

static int nct7802_detect(struct i2c_client *client,
			  struct i2c_board_info *info)
{
	int reg;

	/*
	 * Chip identification registers are only available in bank 0,
	 * so only attempt chip detection if bank 0 is selected
	 */
	reg = i2c_smbus_read_byte_data(client, REG_BANK);
	if (reg != 0x00)
		return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, REG_VENDOR_ID);
	if (reg != 0x50)
		return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, REG_CHIP_ID);
	if (reg != 0xc3)
		return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, REG_VERSION_ID);
	if (reg < 0 || (reg & 0xf0) != 0x20)
		return -ENODEV;

	/* Also validate lower bits of voltage and temperature registers */
	reg = i2c_smbus_read_byte_data(client, REG_TEMP_LSB);
	if (reg < 0 || (reg & 0x1f))
		return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, REG_TEMP_PECI_LSB);
	if (reg < 0 || (reg & 0x3f))
		return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, REG_VOLTAGE_LOW);
	if (reg < 0 || (reg & 0x3f))
		return -ENODEV;

	strlcpy(info->type, "nct7802", I2C_NAME_SIZE);
	return 0;
}

static bool nct7802_regmap_is_volatile(struct device *dev, unsigned int reg)
{
	return reg != REG_BANK && reg <= 0x20;
}

static struct regmap_config nct7802_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.cache_type = REGCACHE_RBTREE,
	.volatile_reg = nct7802_regmap_is_volatile,
};

static int nct7802_init_chip(struct nct7802_data *data)
{
	int err;

	/* Enable ADC */
	err = regmap_update_bits(data->regmap, REG_START, 0x01, 0x01);
	if (err)
		return err;

	/* Enable local temperature sensor */
	err = regmap_update_bits(data->regmap, REG_MODE, 0x40, 0x40);
	if (err)
		return err;

	/* Enable Vcore and VCC voltage monitoring */
	return regmap_update_bits(data->regmap, REG_VMON_ENABLE, 0x03, 0x03);
}

static int nct7802_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct device *dev = &client->dev;
	struct nct7802_data *data;
	struct device *hwmon_dev;
	int ret;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (data == NULL)
		return -ENOMEM;

	data->regmap = devm_regmap_init_i2c(client, &nct7802_regmap_config);
	if (IS_ERR(data->regmap))
		return PTR_ERR(data->regmap);

	mutex_init(&data->access_lock);

	ret = nct7802_init_chip(data);
	if (ret < 0)
		return ret;

	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
							   data,
							   nct7802_groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const unsigned short nct7802_address_list[] = {
	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, I2C_CLIENT_END
};

static const struct i2c_device_id nct7802_idtable[] = {
	{ "nct7802", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, nct7802_idtable);

static struct i2c_driver nct7802_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
		.name = DRVNAME,
	},
	.detect = nct7802_detect,
	.probe = nct7802_probe,
	.id_table = nct7802_idtable,
	.address_list = nct7802_address_list,
};

module_i2c_driver(nct7802_driver);

MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("NCT7802Y Hardware Monitoring Driver");
MODULE_LICENSE("GPL v2");