hwmon: (adt7475) temperature smoothing

When enabled temperature smoothing allows ramping the fan speed over a
configurable period of time instead of jumping to the new speed
instantaneously.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/adt7475

@@ -114,6 +114,10 @@ minimum (i.e. auto_point1_pwm). This behaviour can be configured using the
 pwm[1-*]_stall_disable sysfs attribute. A value of 0 means the fans will shut
 off. A value of 1 means the fans will run at auto_point1_pwm.
 
+The responsiveness of the ADT747x to temperature changes can be configured.
+This allows smoothing of the fan speed transition. To set the transition time
+set the value in ms in the temp[1-*]_smoothing sysfs attribute.
+
 Notes
 -----
 

drivers/hwmon/adt7475.c

@@ -526,6 +526,88 @@ static ssize_t set_temp(struct device *dev, struct device_attribute *attr,
 	return count;
 }
 
+/* Assuming CONFIG6[SLOW] is 0 */
+static const int ad7475_st_map[] = {
+	37500, 18800, 12500, 7500, 4700, 3100, 1600, 800,
+};
+
+static ssize_t show_temp_st(struct device *dev, struct device_attribute *attr,
+				  char *buf)
+{
+	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
+	struct i2c_client *client = to_i2c_client(dev);
+	struct adt7475_data *data = i2c_get_clientdata(client);
+	long val;
+
+	switch (sattr->index) {
+	case 0:
+		val = data->enh_acoustics[0] & 0xf;
+		break;
+	case 1:
+		val = (data->enh_acoustics[1] >> 4) & 0xf;
+		break;
+	case 2:
+	default:
+		val = data->enh_acoustics[1] & 0xf;
+		break;
+	}
+
+	if (val & 0x8)
+		return sprintf(buf, "%d\n", ad7475_st_map[val & 0x7]);
+	else
+		return sprintf(buf, "0\n");
+}
+
+static ssize_t set_temp_st(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 i2c_client *client = to_i2c_client(dev);
+	struct adt7475_data *data = i2c_get_clientdata(client);
+	unsigned char reg;
+	int shift, idx;
+	ulong val;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	switch (sattr->index) {
+	case 0:
+		reg = REG_ENHANCE_ACOUSTICS1;
+		shift = 0;
+		idx = 0;
+		break;
+	case 1:
+		reg = REG_ENHANCE_ACOUSTICS2;
+		shift = 0;
+		idx = 1;
+		break;
+	case 2:
+	default:
+		reg = REG_ENHANCE_ACOUSTICS2;
+		shift = 4;
+		idx = 1;
+		break;
+	}
+
+	if (val > 0) {
+		val = find_closest_descending(val, ad7475_st_map,
+					      ARRAY_SIZE(ad7475_st_map));
+		val |= 0x8;
+	}
+
+	mutex_lock(&data->lock);
+
+	data->enh_acoustics[idx] &= ~(0xf << shift);
+	data->enh_acoustics[idx] |= (val << shift);
+
+	i2c_smbus_write_byte_data(client, reg, data->enh_acoustics[idx]);
+
+	mutex_unlock(&data->lock);
+
+	return count;
+}
+
 /*
  * Table of autorange values - the user will write the value in millidegrees,
  * and we'll convert it
@@ -1009,6 +1091,8 @@ static SENSOR_DEVICE_ATTR_2(temp1_crit, S_IRUGO | S_IWUSR, show_temp, set_temp,
 			    THERM, 0);
 static SENSOR_DEVICE_ATTR_2(temp1_crit_hyst, S_IRUGO | S_IWUSR, show_temp,
 			    set_temp, HYSTERSIS, 0);
+static SENSOR_DEVICE_ATTR_2(temp1_smoothing, S_IRUGO | S_IWUSR, show_temp_st,
+			    set_temp_st, 0, 0);
 static SENSOR_DEVICE_ATTR_2(temp2_input, S_IRUGO, show_temp, NULL, INPUT, 1);
 static SENSOR_DEVICE_ATTR_2(temp2_alarm, S_IRUGO, show_temp, NULL, ALARM, 1);
 static SENSOR_DEVICE_ATTR_2(temp2_max, S_IRUGO | S_IWUSR, show_temp, set_temp,
@@ -1025,6 +1109,8 @@ static SENSOR_DEVICE_ATTR_2(temp2_crit, S_IRUGO | S_IWUSR, show_temp, set_temp,
 			    THERM, 1);
 static SENSOR_DEVICE_ATTR_2(temp2_crit_hyst, S_IRUGO | S_IWUSR, show_temp,
 			    set_temp, HYSTERSIS, 1);
+static SENSOR_DEVICE_ATTR_2(temp2_smoothing, S_IRUGO | S_IWUSR, show_temp_st,
+			    set_temp_st, 0, 1);
 static SENSOR_DEVICE_ATTR_2(temp3_input, S_IRUGO, show_temp, NULL, INPUT, 2);
 static SENSOR_DEVICE_ATTR_2(temp3_alarm, S_IRUGO, show_temp, NULL, ALARM, 2);
 static SENSOR_DEVICE_ATTR_2(temp3_fault, S_IRUGO, show_temp, NULL, FAULT, 2);
@@ -1042,6 +1128,8 @@ static SENSOR_DEVICE_ATTR_2(temp3_crit, S_IRUGO | S_IWUSR, show_temp, set_temp,
 			    THERM, 2);
 static SENSOR_DEVICE_ATTR_2(temp3_crit_hyst, S_IRUGO | S_IWUSR, show_temp,
 			    set_temp, HYSTERSIS, 2);
+static SENSOR_DEVICE_ATTR_2(temp3_smoothing, S_IRUGO | S_IWUSR, show_temp_st,
+			    set_temp_st, 0, 2);
 static SENSOR_DEVICE_ATTR_2(fan1_input, S_IRUGO, show_tach, NULL, INPUT, 0);
 static SENSOR_DEVICE_ATTR_2(fan1_min, S_IRUGO | S_IWUSR, show_tach, set_tach,
 			    MIN, 0);
@@ -1126,6 +1214,7 @@ static struct attribute *adt7475_attrs[] = {
 	&sensor_dev_attr_temp1_auto_point2_temp.dev_attr.attr,
 	&sensor_dev_attr_temp1_crit.dev_attr.attr,
 	&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
+	&sensor_dev_attr_temp1_smoothing.dev_attr.attr,
 	&sensor_dev_attr_temp2_input.dev_attr.attr,
 	&sensor_dev_attr_temp2_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp2_max.dev_attr.attr,
@@ -1135,6 +1224,7 @@ static struct attribute *adt7475_attrs[] = {
 	&sensor_dev_attr_temp2_auto_point2_temp.dev_attr.attr,
 	&sensor_dev_attr_temp2_crit.dev_attr.attr,
 	&sensor_dev_attr_temp2_crit_hyst.dev_attr.attr,
+	&sensor_dev_attr_temp2_smoothing.dev_attr.attr,
 	&sensor_dev_attr_temp3_input.dev_attr.attr,
 	&sensor_dev_attr_temp3_fault.dev_attr.attr,
 	&sensor_dev_attr_temp3_alarm.dev_attr.attr,
@@ -1145,6 +1235,7 @@ static struct attribute *adt7475_attrs[] = {
 	&sensor_dev_attr_temp3_auto_point2_temp.dev_attr.attr,
 	&sensor_dev_attr_temp3_crit.dev_attr.attr,
 	&sensor_dev_attr_temp3_crit_hyst.dev_attr.attr,
+	&sensor_dev_attr_temp3_smoothing.dev_attr.attr,
 	&sensor_dev_attr_fan1_input.dev_attr.attr,
 	&sensor_dev_attr_fan1_min.dev_attr.attr,
 	&sensor_dev_attr_fan1_alarm.dev_attr.attr,