summaryrefslogtreecommitdiff
path: root/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt')
-rw-r--r--Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt89
1 files changed, 89 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt b/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt
new file mode 100644
index 000000000..d72355502
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt
@@ -0,0 +1,89 @@
+General Purpose Analog To Digital Converter (ADC) based thermal sensor.
+
+On some of platforms, thermal sensor like thermistors are connected to
+one of ADC channel and sensor resistance is read via voltage across the
+sensor resistor. The voltage read across the sensor is mapped to
+temperature using voltage-temperature lookup table.
+
+Required properties:
+===================
+- compatible: Must be "generic-adc-thermal".
+- temperature-lookup-table: Two dimensional array of Integer; lookup table
+ to map the relation between ADC value and
+ temperature. When ADC is read, the value is
+ looked up on the table to get the equivalent
+ temperature.
+ The first value of the each row of array is the
+ temperature in milliCelsius and second value of
+ the each row of array is the ADC read value.
+- #thermal-sensor-cells: Should be 1. See ./thermal.txt for a description
+ of this property.
+
+Example :
+#include <dt-bindings/thermal/thermal.h>
+
+i2c@7000c400 {
+ ads1015: ads1015@4a {
+ reg = <0x4a>;
+ compatible = "ads1015";
+ sampling-frequency = <3300>;
+ #io-channel-cells = <1>;
+ };
+};
+
+tboard_thermistor: thermal-sensor {
+ compatible = "generic-adc-thermal";
+ #thermal-sensor-cells = <0>;
+ io-channels = <&ads1015 1>;
+ io-channel-names = "sensor-channel";
+ temperature-lookup-table = < (-40000) 2578
+ (-39000) 2577
+ (-38000) 2576
+ (-37000) 2575
+ (-36000) 2574
+ (-35000) 2573
+ (-34000) 2572
+ (-33000) 2571
+ (-32000) 2569
+ (-31000) 2568
+ (-30000) 2567
+ ::::::::::
+ 118000 254
+ 119000 247
+ 120000 240
+ 121000 233
+ 122000 226
+ 123000 220
+ 124000 214
+ 125000 208>;
+};
+
+dummy_cool_dev: dummy-cool-dev {
+ compatible = "dummy-cooling-dev";
+ #cooling-cells = <2>; /* min followed by max */
+};
+
+thermal-zones {
+ Tboard {
+ polling-delay = <15000>; /* milliseconds */
+ polling-delay-passive = <0>; /* milliseconds */
+ thermal-sensors = <&tboard_thermistor>;
+
+ trips {
+ therm_est_trip: therm_est_trip {
+ temperature = <40000>;
+ type = "active";
+ hysteresis = <1000>;
+ };
+ };
+
+ cooling-maps {
+ map0 {
+ trip = <&therm_est_trip>;
+ cooling-device = <&dummy_cool_dev THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+ contribution = <100>;
+ };
+
+ };
+ };
+};