hwmon: (powerpc/powernv) hwmon driver for power, fan rpm, voltage and temperature

This patch adds basic kernel support for reading power values, fan
speed rpm, voltage and temperature data on powernv platforms which
will be exported to user space through sysfs interface.

Test results:
-------------
[root@tul163p1 ~]# sensors
ibmpowernv-isa-0000
Adapter: ISA adapter
fan1:        5465 RPM  (min =    0 RPM)
fan2:        5152 RPM  (min =    0 RPM)
fan3:        5521 RPM  (min =    0 RPM)
fan4:        4891 RPM  (min =    0 RPM)
fan5:           0 RPM  (min =    0 RPM)
fan6:           0 RPM  (min =    0 RPM)
fan7:        7480 RPM  (min =    0 RPM)
fan8:        7944 RPM  (min =    0 RPM)
temp1:        +39.0°C  (high =  +0.0°C)
power1:      190.00 W

[root@tul163p1 ~]# ls /sys/devices/platform/
alarmtimer  ibmpowernv.0  power  rtc-generic  serial8250  uevent
[root@tul163p1 ~]# ls /sys/devices/platform/ibmpowernv.0/hwmon/hwmon0/
device	    fan2_min	fan4_min    fan6_min	fan8_min   power
fan1_fault  fan3_fault	fan5_fault  fan7_fault	in1_fault  power1_input
fan1_input  fan3_input	fan5_input  fan7_input	in2_fault  subsystem
fan1_min    fan3_min	fan5_min    fan7_min	in3_fault  temp1_input
fan2_fault  fan4_fault	fan6_fault  fan8_fault	in4_fault  temp1_max
fan2_input  fan4_input	fan6_input  fan8_input	name	   uevent
[root@tul163p1 ~]# ls /sys/class/hwmon/hwmon0/
device	    fan2_min	fan4_min    fan6_min	fan8_min   power
fan1_fault  fan3_fault	fan5_fault  fan7_fault	in1_fault  power1_input
fan1_input  fan3_input	fan5_input  fan7_input	in2_fault  subsystem
fan1_min    fan3_min	fan5_min    fan7_min	in3_fault  temp1_input
fan2_fault  fan4_fault	fan6_fault  fan8_fault	in4_fault  temp1_max
fan2_input  fan4_input	fan6_input  fan8_input	name	   uevent
[root@tul163p1 ~]#

Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

2 files changed, 64 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/hwmon/ibmpowernv.txt b/Documentation/devicetree/bindings/hwmon/ibmpowernv.txt
new file mode 100644
index 000000000000..f93242be60a1
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/ibmpowernv.txt
@@ -0,0 +1,23 @@
+IBM POWERNV platform sensors
+----------------------------
+
+Required node properties:
+- compatible: must be one of
+		"ibm,opal-sensor-cooling-fan"
+		"ibm,opal-sensor-amb-temp"
+		"ibm,opal-sensor-power-supply"
+		"ibm,opal-sensor-power"
+- sensor-id: an opaque id provided by the firmware to the kernel, identifies a
+	     given sensor and its attribute data
+
+Example sensors node:
+
+cooling-fan#8-data {
+	sensor-id = <0x7052107>;
+	compatible = "ibm,opal-sensor-cooling-fan";
+};
+
+amb-temp#1-thrs {
+	sensor-id = <0x5096000>;
+	compatible = "ibm,opal-sensor-amb-temp";
+};
diff --git a/Documentation/hwmon/ibmpowernv b/Documentation/hwmon/ibmpowernv
new file mode 100644
index 000000000000..8826ba29db36
--- /dev/null
+++ b/Documentation/hwmon/ibmpowernv
@@ -0,0 +1,41 @@
+Kernel Driver IBMPOWERNV
+========================
+
+Supported systems:
+  * Any recent IBM P servers based on POWERNV platform
+
+Author: Neelesh Gupta
+
+Description
+-----------
+
+This driver implements reading the platform sensors data like temperature/fan/
+voltage/power for 'POWERNV' platform.
+
+The driver uses the platform device infrastructure. It probes the device tree
+for sensor devices during the __init phase and registers them with the 'hwmon'.
+'hwmon' populates the 'sysfs' tree having attribute files, each for a given
+sensor type and its attribute data.
+
+All the nodes in the DT appear under "/ibm,opal/sensors" and each valid node in
+the DT maps to an attribute file in 'sysfs'. The node exports unique 'sensor-id'
+which the driver uses to make an OPAL call to the firmware.
+
+Usage notes
+-----------
+The driver is built statically with the kernel by enabling the config
+CONFIG_SENSORS_IBMPOWERNV. It can also be built as module 'ibmpowernv'.
+
+Sysfs attributes
+----------------
+
+fanX_input		Measured RPM value.
+fanX_min		Threshold RPM for alert generation.
+fanX_fault		0: No fail condition
+			1: Failing fan
+tempX_input		Measured ambient temperature.
+tempX_max		Threshold ambient temperature for alert generation.
+inX_input		Measured power supply voltage
+inX_fault		0: No fail condition.
+			1: Failing power supply.
+power1_input		System power consumption (microWatt)