Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752689AbcDSHdj (ORCPT ); Tue, 19 Apr 2016 03:33:39 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:18324 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751747AbcDSHdg (ORCPT ); Tue, 19 Apr 2016 03:33:36 -0400 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Tue, 19 Apr 2016 00:31:37 -0700 From: Laxman Dewangan To: , , , , , , CC: , , , , Laxman Dewangan Subject: [PATCH V4 1/2] thermal: generic-adc: Add DT binding for ADC based thermal sensor Date: Tue, 19 Apr 2016 12:52:00 +0530 Message-ID: <1461050521-6080-1-git-send-email-ldewangan@nvidia.com> X-Mailer: git-send-email 2.1.4 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3769 Lines: 127 Sometimes, thermal sensors like NCT thermistors are connected to the ADC channel. The temperature is read by reading the voltage across the sensor resistance via ADC and referring the lookup table for ADC value to temperature. Add DT binding doc for the ADC based thermal sensor driver to detail the DT property and provide the example for how to use it. Signed-off-by: Laxman Dewangan Acked-by: Rob Herring --- Changes from V1: - Make the lookup table to two dimensional instead of single array of linear step of temperature. - Remove detailing of IIO frameowrk and drivers. - Added proper braces, indenting and labels. Changes from V2: - Handle comment from Rob for detailing the first and second value of the array and remove @ in the node name. Changes from V3: - Collected acks from Rob. - No change from V2 in content. --- .../bindings/thermal/thermal-generic-adc.txt | 89 ++++++++++++++++++++++ 1 file changed, 89 insertions(+) create mode 100644 Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt 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 0000000..d7235550 --- /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 + +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>; + }; + + }; + }; +}; -- 2.1.4