Re: [PATCH 1/3] Device tree binding documentation for chromeos-firmware

[Martyn Welch]

On 02/12/15 15:15, Rob Herring wrote:
> On Tue, Dec 01, 2015 at 07:12:49PM +0000, Martyn Welch wrote:
> > This patch adds documentation for the chromeos-firmware binding.
> >
> > Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> > Cc: Pawel Moll <pawel.moll@xxxxxxx>
> > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > Cc: Ian Campbell <ijc+devicetree@xxxxxxxxxxxxxx>
> > Cc: Kumar Gala <galak@xxxxxxxxxxxxxx>
> > Cc: devicetree@xxxxxxxxxxxxxxx
> > Signed-off-by: Martyn Welch <martyn.welch@xxxxxxxxxxxxxxx>
> > ---
> >   .../devicetree/bindings/misc/chromeos-firmware.txt | 27 ++++++++++++++++++++++
>
> bindings/firmware/ please.

OK.

> >   1 file changed, 27 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/misc/chromeos-firmware.txt
> >
> > diff --git a/Documentation/devicetree/bindings/misc/chromeos-firmware.txt b/Documentation/devicetree/bindings/misc/chromeos-firmware.txt
> > new file mode 100644
> > index 0000000..8240611
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/misc/chromeos-firmware.txt
> > @@ -0,0 +1,27 @@
> > +Device-Tree bindings for chromeos-firmware.c.
>
> Perhaps a bit more description what this is.
>
> What aspect of this is firmware? How does this relate to the EC?

With respect to write-protect, this line is the write protection for the 
flash which holds the bootloader.

For the developer-switch and recovery-switch, I understand that pulling 
these lines low result in the stock firmware forcing the device to boot 
into developer mode and recovery mode respectively. The device I have no 
longer runs the stock firmware, so I'm not able to confirm this, though 
I am able to drive these lines.

As far as I'm aware, none of these are related to the operation of the EC.

Will update the binding documentation.

> > +
> > +Required properties:
> > +	- compatible = "google,gpio-firmware";
>
> No versions?

I'm not aware of any and would rather not start inventing ones that 
aren't already there.

> > +
> > +Each signal is represented as a sub-node of "chromeos_firmware":
> > +Subnode properties:
> > +
> > +	- gpios: OF device-tree gpio specification.
> > +
> > +Example nodes:
> > +
> > +	chromeos_firmware {
>
> This should go under /firmware

Ok, will do.

> > +		compatible = "google,gpio-firmware";
> > +
> > +		write-protect {
>
> You need to define what are valid sub nodes. The example is not
> documentation.

Ok

> > +			gpios = <&gpx3 0 GPIO_ACTIVE_LOW>;
> > +		};
> > +
> > +		developer-switch {
> > +			gpios = <&gpx1 3 GPIO_ACTIVE_HIGH>;
> > +		};
> > +
> > +		recovery-switch {
> > +			gpios = <&gpx0 7 GPIO_ACTIVE_LOW>;
> > +		};
> > +	};
> > --
> > 2.1.4
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