| Message ID | 1526477827-10859-3-git-send-email-stefan.wahren@i2se.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <stefan.wahren@i2se.com> > --- > .../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"; > + }; > +}; >
On Wed, May 16, 2018 at 03:37:03PM +0200, 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 > > Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> > --- > .../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" 'hwmon' is very Linux specific. DT bindings are supposed to be OS agnostic. Guenter > + > +Example: > + > +firmware: firmware-rpi { > + compatible = "raspberrypi,bcm2835-firmware"; > + mboxes = <&mailbox>; > + > + voltage-sensor { > + compatible = "raspberrypi,bcm2835-hwmon"; > + }; > +}; > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
Robin Murphy <robin.murphy@arm.com> writes: > 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. Agreed, let's skip doing this in DT. I just switched the bcm2835-camera driver over to not need DT, and I think you could do something similar (and use the pdev->dev.parent to get at the firmware device).
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"; + }; +};
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 Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> --- .../devicetree/bindings/hwmon/raspberrypi-hwmon.txt | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 Documentation/devicetree/bindings/hwmon/raspberrypi-hwmon.txt