Re: [PATCH v3 1/4] dt-bindings: mfd: Add Gateworks System Controller bindings
From: Guenter Roeck <linux@roeck-us.net>
Date: 2018-03-28 16:24:22
Also in:
linux-arm-kernel, linux-devicetree, linux-hwmon, linux-watchdog, lkml
On Wed, Mar 28, 2018 at 08:14:00AM -0700, Tim Harvey wrote:
quoted hunk ↗ jump to hunk
This patch adds documentation of device-tree bindings for the Gateworks System Controller (GSC). Signed-off-by: Tim Harvey <tharvey@gateworks.com> --- v3: - replaced _ with - - remove input bindings - added full description of hwmon - fix unit address of hwmon child nodes --- .../devicetree/bindings/mfd/gateworks-gsc.txt | 135 +++++++++++++++++++++ 1 file changed, 135 insertions(+) create mode 100644 Documentation/devicetree/bindings/mfd/gateworks-gsc.txtdiff --git a/Documentation/devicetree/bindings/mfd/gateworks-gsc.txt b/Documentation/devicetree/bindings/mfd/gateworks-gsc.txt new file mode 100644 index 0000000..8f530ed --- /dev/null +++ b/Documentation/devicetree/bindings/mfd/gateworks-gsc.txt@@ -0,0 +1,135 @@ +Gateworks System Controller multi-function device + +The GSC is a Multifunction I2C slave device with the following submodules: +- WDT +- GPIO +- Pushbutton controller +- HWMON + +Required properties: +- compatible : Must be "gw,gsc" +- reg: I2C address of the device +- interrupts: interrupt triggered by GSC_IRQ# signal +- interrupt-parent: Interrupt controller GSC is connected to +- #interrupt-cells: should be <1>, index of the interrupt within the + controller, in accordance with the "one cell" variant of + <devicetree/bindings/interrupt-controller/interrupt.txt> + +Optional nodes: +* watchdog: +The GSC provides a Watchdog monitor which can power cycle the board's +primary power supply on most board models when tripped. + +Required watchdog properties: +- compatible: must be "gw,gsc-watchdog" + +* hwmon: +The GSC provides a set of Analog to Digitcal Converter (ADC) pins used for +temperature and/or voltage monitoring. + +Required hwmon properties: +- compatible: must be "gw,gsc-hwmon" +
"hwmon" is a very Linux specific term. It might make sense to find a more generic term.
+Optional hwmon properties: +- gw,reference-voltage: ADC reference voltage (mV) used in scaling raw ADCs
AFAIK devicetree likes to specify voltages in uV.
+- gw,resolution: ADC resolution (ie 4096) used in scaling raw ADCs +
4096 what ?
+Each hwmon child node defines an ADC input on the chip which the GSC may +report cooked values (ie temperature sensor based on thermister), raw values, +(ie voltage rail with a pre-scaling resistor divider), or a fan controller +setpoint. + +Required hwmon child properties: +- type: one of the following ADC types: + "gw,hwmon-temperature" - reports temperature in C*10 + "gw,hwmon-voltage" - reports a pre-scaled voltage value + "gw,hwmon-voltage-raw" - reports a raw ADC that is scaled with + vreference, resolution, and optional resistor divider + "gw,hwmon-fan" - a fan temperature setpoint in C*10
What is a "fan temperature setpoint" ?
+- reg: offset of the ADC register
+- label: name of the ADC input or FAN setpoint
+
+Optional hwmon child properties:
+- gw,voltage-divider: An array of two integers containing the resistor
+ values R1 and R2 of the optinal resistor divider on a raw ADC
+- gw,voltage-offset: a mV voltage offset to apply to a raw ADC (ie to
+ compensate for a diode drop)
+
+Example:
+
+ gsc: gsc@20 {
+ compatible = "gw,gsc";
+ reg = <0x20>;
+ interrupt-parent = <&gpio1>;
+ interrupts = <4 GPIO_ACTIVE_LOW>;
+ interrupt-controller;
+ #interrupt-cells = <1>;
+
+ watchdog {
+ compatible = "gw,gsc-watchdog";
+ };
+
+ hwmon {
+ compatible = "gw,gsc-hwmon";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ gw,reference-voltage = <2500>;
+ gw,resolution = <4096>;
+
+ hwmon@0 { /* A0: Board Temperature */
+ type = "gw,hwmon-temperature";
+ reg = <0x00>;
+ label = "temp";
+ };
+
+ hwmon@2 { /* A1: Input Voltage (raw ADC) */
+ type = "gw,hwmon-voltage-raw";
+ reg = <0x02>;
+ label = "vdd_vin";
+ gw,voltage-divider = <22100 1000>;
+ gw,voltage-offset = <800>;
+ };
+
+ hwmon@b { /* A2: Battery voltage */
+ type = "gw,hwmon-voltage";
+ reg = <0x0b>;
+ label = "vdd_bat";
+ };
+
+ hwmon@2c { /* fan temperature setpoint for 50% duty */
+ type = "gw,hwmon-fan";
+ reg = <0x2c>;
+ label = "fan_50p";
+ };
+
+ hwmon@2e { /* fan1 */
+ type = "gw,hwmon-fan";
+ reg = <0x2e>;
+ label = "fan_60p";
+ };
+
+ hwmon@30 { /* fan2 */
+ type = "gw,hwmon-fan";
+ reg = <0x30>;
+ label = "fan_70p";
+ };
+
+ hwmon@32 { /* fan3 */
+ type = "gw,hwmon-fan";
+ reg = <0x32>;
+ label = "fan_80p";
+ };
+
+ hwmon@34 { /* fan4 */
+ type = "gw,hwmon-fan";
+ reg = <0x34>;
+ label = "fan_90p";
+ };
+
+ hwmon@36 { /* fan5 */
+ type = "gw,hwmon-fan";
+ reg = <0x36>;
+ label = "fan_100p";
+ };No idea what this is supposed to be doing, but whatever it is, it appears to be wrong. I'll comment more on it in the hwmon driver. Guenter
+ }; + }; -- 2.7.4