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.
Signed-off-by: Stefan Wahren <[email protected]>
---
.../devicetree/bindings/hwmon/raspberrypi-hwmon.txt | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
create mode 100644
Documentation/devicetree/bindings/hwmon/raspberrypi-hwmon.txt
diff --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";
+ };
+};
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