hwmon: (nct7802) Add pwmX_enable attribute

index a0d9010..a53e6e1 100644
@@ -53,6 +53,7 @@ static const u8 REG_VOLTAGE_LIMIT_MSB_SHIFT[2][5] = {
 #define REG_PECI_ENABLE		0x23
 #define REG_FAN_ENABLE		0x24
 #define REG_VMON_ENABLE		0x25
+#define REG_SMARTFAN_EN_BASE	0x64
 #define REG_VENDOR_ID		0xfd
 #define REG_CHIP_ID		0xfe
 #define REG_VERSION_ID		0xff

@@ -151,6 +152,43 @@ static ssize_t store_pwm(struct device *dev, struct device_attribute *devattr,
 	return err ? : count;
 }
 
+static ssize_t show_pwm_enable(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct nct7802_data *data = dev_get_drvdata(dev);
+	struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
+	unsigned int reg, enabled, pwm;
+	int ret;
+
+	ret = regmap_read(data->regmap, REG_SMARTFAN_EN_BASE + sattr->index / 2,
+			  &reg);
+	if (ret < 0)
+		return ret;
+	enabled = reg >> (sattr->index % 2 * 4) & 1;
+	return sprintf(buf, "%u\n", enabled + 1);
+}
+
+static ssize_t store_pwm_enable(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct nct7802_data *data = dev_get_drvdata(dev);
+	struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
+	u8 val;
+	int ret;
+
+	ret = kstrtou8(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+	if (val < 1 || val > 3)
+		return -EINVAL;
+	ret = regmap_update_bits(data->regmap,
+				 REG_SMARTFAN_EN_BASE + sattr->index / 2,
+				 1 << sattr->index % 2 * 4,
+				 (val - 1) << sattr->index % 2 * 4);
+	return ret ? : count;
+}
+
 static int nct7802_read_temp(struct nct7802_data *data,
 			     u8 reg_temp, u8 reg_temp_low, int *temp)
 {

@@ -793,6 +831,11 @@ static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, store_pwm, 0x60);
 static SENSOR_DEVICE_ATTR(pwm2, S_IRUGO | S_IWUSR, show_pwm, store_pwm, 0x61);
 static SENSOR_DEVICE_ATTR(pwm3, S_IRUGO | S_IWUSR, show_pwm, store_pwm, 0x62);
 
+/* 7.2.95... Temperature to Fan mapping Relationships Register */
+static SENSOR_DEVICE_ATTR(pwm1_enable, S_IRUGO | S_IWUSR, show_pwm_enable, store_pwm_enable, 0);
+static SENSOR_DEVICE_ATTR(pwm2_enable, S_IRUGO | S_IWUSR, show_pwm_enable, store_pwm_enable, 1);
+static SENSOR_DEVICE_ATTR(pwm3_enable, S_IRUGO | S_IWUSR, show_pwm_enable, store_pwm_enable, 2);
+
 static struct attribute *nct7802_fan_attrs[] = {
 	&sensor_dev_attr_fan1_input.dev_attr.attr,
 	&sensor_dev_attr_fan1_min.dev_attr.attr,

@@ -832,10 +875,13 @@ static struct attribute_group nct7802_fan_group = {
 };
 
 static struct attribute *nct7802_pwm_attrs[] = {
+	&sensor_dev_attr_pwm1_enable.dev_attr.attr,
 	&sensor_dev_attr_pwm1_mode.dev_attr.attr,
 	&sensor_dev_attr_pwm1.dev_attr.attr,
+	&sensor_dev_attr_pwm2_enable.dev_attr.attr,
 	&sensor_dev_attr_pwm2_mode.dev_attr.attr,
 	&sensor_dev_attr_pwm2.dev_attr.attr,
+	&sensor_dev_attr_pwm3_enable.dev_attr.attr,
 	&sensor_dev_attr_pwm3_mode.dev_attr.attr,
 	&sensor_dev_attr_pwm3.dev_attr.attr,
 	NULL