[PATCH RFC 2/6] dt-bindings: hwmon: Add Raspberry Pi voltage sensor
From: robin.murphy@arm.com (Robin Murphy)
Date: 2018-05-16 14:23:27
Also in:
linux-devicetree, linux-hwmon
On 16/05/18 14:37, Stefan Wahren wrote:
Recent VC4 firmware provides a hardware-independent way to retrieve the under-voltage sensor on the following Raspberry Pi boards: - Raspberry Pi B+ (via GPIO on SoC) - Raspberry Pi A+ (via GPIO on SoC) - Raspberry Pi 2 B (via GPIO on SoC) - Raspberry Pi 3 B (via GPIO on port expander) - Raspberry Pi 3 B+ (via PMIC) TODO: - try to make bcm2835 firmware a bus driver
Do you actually need a DT binding? From the probe routine in patch 2 it looks like this capability can be discovered dynamically by asking the firmware, therefore it might be more straightforward for the firmware driver itself to probe that and create a child device iff the feature is present, which the hwmon driver can then bind to as a pure platform driver. Robin.
quoted hunk ↗ jump to hunk
Signed-off-by: Stefan Wahren <redacted> --- .../devicetree/bindings/hwmon/raspberrypi-hwmon.txt | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 Documentation/devicetree/bindings/hwmon/raspberrypi-hwmon.txtdiff --git a/Documentation/devicetree/bindings/hwmon/raspberrypi-hwmon.txt b/Documentation/devicetree/bindings/hwmon/raspberrypi-hwmon.txt new file mode 100644 index 0000000..ec2523f --- /dev/null +++ b/Documentation/devicetree/bindings/hwmon/raspberrypi-hwmon.txt@@ -0,0 +1,19 @@ +Raspberry Pi voltage sensor +--------------------------- + +The VC4 firmware exposes a mailbox interface that allows the ARM core +to access the board's voltage sensor. + +Required properties : +- compatible : Should be "raspberrypi,bcm2835-hwmon" + +Example: + +firmware: firmware-rpi { + compatible = "raspberrypi,bcm2835-firmware"; + mboxes = <&mailbox>; + + voltage-sensor { + compatible = "raspberrypi,bcm2835-hwmon"; + }; +};