libsensors: Add support for humidity sensors

This patch adds support for humidity sensors to libsensors.

--
Index: doc/libsensors-API.txt
=================================> --- doc/libsensors-API.txt (revision 5917)
+++ doc/libsensors-API.txt (working copy)

(quoted diff) +3 -0

@@ -33,6 +33,9 @@
   enum sensors_subfeature_type SENSORS_SUBFEATURE_CURR_CRIT
   enum sensors_subfeature_type SENSORS_SUBFEATURE_CURR_LCRIT_ALARM
   enum sensors_subfeature_type SENSORS_SUBFEATURE_CURR_CRIT_ALARM
+* Added support for humidity sensors
+  enum sensors_feature_type SENSORS_FEATURE_HUMIDITY
+  enum sensors_subfeature_type SENSORS_SUBFEATURE_HUMIDITY_INPUT
 
 0x430	lm-sensors 3.2.0
 * License changed from GPL to LGPL

Index: lib/sensors.h
=================================> --- lib/sensors.h (revision 5917)
+++ lib/sensors.h (working copy)

(quoted diff) +3 -0

@@ -140,6 +140,7 @@
 	SENSORS_FEATURE_POWER		= 0x03,
 	SENSORS_FEATURE_ENERGY		= 0x04,
 	SENSORS_FEATURE_CURR		= 0x05,
+	SENSORS_FEATURE_HUMIDITY	= 0x06,
 	SENSORS_FEATURE_MAX_MAIN,
 	SENSORS_FEATURE_VID		= 0x10,
 	SENSORS_FEATURE_INTRUSION	= 0x11,

@@ -220,6 +221,8 @@
 	SENSORS_SUBFEATURE_CURR_LCRIT_ALARM,
 	SENSORS_SUBFEATURE_CURR_CRIT_ALARM,
 
+	SENSORS_SUBFEATURE_HUMIDITY_INPUT = SENSORS_FEATURE_HUMIDITY << 8,
+
 	SENSORS_SUBFEATURE_VID = SENSORS_FEATURE_VID << 8,
 
 	SENSORS_SUBFEATURE_INTRUSION_ALARM = SENSORS_FEATURE_INTRUSION << 8,

Index: lib/sysfs.c
=================================> --- lib/sysfs.c (revision 5917)
+++ lib/sysfs.c (working copy)

(quoted diff) +8 -0

@@ -158,6 +158,7 @@
 	case SENSORS_SUBFEATURE_IN_INPUT:
 	case SENSORS_SUBFEATURE_TEMP_INPUT:
 	case SENSORS_SUBFEATURE_CURR_INPUT:
+	case SENSORS_SUBFEATURE_HUMIDITY_INPUT:
 		return 1000;
 	case SENSORS_SUBFEATURE_FAN_INPUT:
 		return 1;

@@ -190,6 +191,7 @@
 	case SENSORS_FEATURE_POWER:
 	case SENSORS_FEATURE_ENERGY:
 	case SENSORS_FEATURE_CURR:
+	case SENSORS_FEATURE_HUMIDITY:
 	case SENSORS_FEATURE_INTRUSION:
 		underscore = strchr(sfname, '_');
 		name = strndup(sfname, underscore - sfname);

@@ -306,6 +308,11 @@
 	{ NULL, 0 }
 };
 
+static const struct subfeature_type_match humidity_matches[] = {
+	{ "input", SENSORS_SUBFEATURE_HUMIDITY_INPUT },
+	{ NULL, 0 }
+};
+
 static const struct subfeature_type_match cpu_matches[] = {
 	{ "vid", SENSORS_SUBFEATURE_VID },
 	{ NULL, 0 }

@@ -325,6 +332,7 @@
 	{ "curr%d%c", curr_matches },
 	{ "energy%d%c", energy_matches },
 	{ "intrusion%d%c", intrusion_matches },
+	{ "humidity%d%c", humidity_matches },
 };
 
 /* Return the subfeature type and channel number based on the subfeature

Hi Guenter,

Quoted 1 line · Guenter Roeck

This patch adds support for humidity sensors to libsensors.

Maybe it's a little late to discuss this now that humidity[1-*]_input is already described in Documentation/hwmon/sysfs-interface, but... do humidity sensors really belong to the hardware monitoring framework? What are the use cases of these sensors in practice?

We let the accelerometer drivers slip in in the past (thankfully without documenting their attributes), and now we have a hard time getting them moved to the right place. I wouldn't want to do the same mistake with humidity sensors. My feeling is that they don't belong to hwmon.

Quoted 10 lines · Jean Delvare

Hi Guenter,

Quoted 1 line · Guenter Roeck

This patch adds support for humidity sensors to libsensors.

Maybe it's a little late to discuss this now that humidity[1-*]_input is already described in Documentation/hwmon/sysfs-interface, but... do humidity sensors really belong to the hardware monitoring framework? What are the use cases of these sensors in practice?

Quoted 6 lines

We let the accelerometer drivers slip in in the past (thankfully without documenting their attributes), and now we have a hard time getting them moved to the right place. I wouldn't want to do the same mistake with humidity sensors. My feeling is that they don't belong to hwmon.

The argument is that humidity is an environmental parameter which does affect system operation, and thus it does belong to the hwmon framework. I don't know what the existing/supported sensors are used for, but could well imagine one in an industrial computer used to ensure that the system isn't running in too much humidity.

Quoted 17 lines · Guenter Roeck

Quoted 10 lines · Jean Delvare

Hi Guenter,

Quoted 1 line · Guenter Roeck

This patch adds support for humidity sensors to libsensors.

Maybe it's a little late to discuss this now that humidity[1-*]_input is already described in Documentation/hwmon/sysfs-interface, but... do humidity sensors really belong to the hardware monitoring framework? What are the use cases of these sensors in practice?

Quoted 6 lines

We let the accelerometer drivers slip in in the past (thankfully without documenting their attributes), and now we have a hard time getting them moved to the right place. I wouldn't want to do the same mistake with humidity sensors. My feeling is that they don't belong to hwmon.

Quoted 5 lines

The argument is that humidity is an environmental parameter which does affect system operation, and thus it does belong to the hwmon framework. I don't know what the existing/supported sensors are used for, but could well imagine one in an industrial computer used to ensure that the system isn't running in too much humidity.

Copying Jonathan for additional comments.

I did some search on the web, and noticed that many environmental monitoring systems for server environments include humidity sensors, and it is often listed at the same level of importance as temperature sensors.