[PATCH v4 2/3] hwmon: (adt7475) temperature smoothing

[Chris Packham <chris.packham@alliedtelesis.co.nz>]

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>
---
Changes in v2:
- use a single tempN_smoothing attribute
Changes in v3:
- change enh_acou to enh_acoustics
- simplify show_temp_st()
Changes in v4:
- removed dead code.
- Make the order of the smoothing attributes match the other temperature
  attributes.

Guenter,

We'd previously discussed making the smoothing values set CONFIG6[SLOW] to
expose the other set of potential values. I wasn't sure where you wanted to go
on that one.

Personally I was on the fence since the difference would only be noticeable for
the higher values. If we do want to add support for the other values it could
be done as a subsequent patch (or a v5 if you want it).

 Documentation/hwmon/adt7475 |  4 ++
 drivers/hwmon/adt7475.c     | 91 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)

diff --git a/Documentation/hwmon/adt7475 b/Documentation/hwmon/adt7475
index dc0b55794c47..09d73a10644c 100644
--- a/Documentation/hwmon/adt7475
+++ b/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
 -----
 
diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 3eb8c5c2f8af..3056076fae27 100644
--- a/drivers/hwmon/adt7475.c
+++ b/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
@@ -1008,6 +1090,8 @@ 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,
@@ -1024,6 +1108,8 @@ 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);
@@ -1041,6 +1127,8 @@ 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);
@@ -1125,6 +1213,7 @@ 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,
@@ -1134,6 +1223,7 @@ 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,
@@ -1144,6 +1234,7 @@ 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,
-- 
2.11.0.24.ge6920cf