Hi Pavel, On Fri, Dec 26, 2014 at 06:19:44PM +0100, Pavel Machek wrote: > On Fri 2014-12-26 13:34:52, Sebastian Reichel wrote: > > OMAP34xx and OMAP36xx processors contain a register in the syscon area, > > which can be used to determine the SoCs temperature. This provides a > > DT binding specification for the temperature monitor. > > > > Signed-off-by: Sebastian Reichel <s...@kernel.org> > > --- > > .../bindings/hwmon/omap3-temperature.txt | 25 > > ++++++++++++++++++++++ > > 1 file changed, 25 insertions(+) > > create mode 100644 > > Documentation/devicetree/bindings/hwmon/omap3-temperature.txt > > > > diff --git a/Documentation/devicetree/bindings/hwmon/omap3-temperature.txt > > b/Documentation/devicetree/bindings/hwmon/omap3-temperature.txt > > new file mode 100644 > > index 0000000..99631ad > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/hwmon/omap3-temperature.txt > > @@ -0,0 +1,25 @@ > > +* OMAP3 temperature sensor > > + > > +The OMAP34xx and OMAP36xx processors contain a register in the syscon area, > > +which can be used to determine the SoCs temperature. > > + > > +Requires node properties: > > +- compatible : should contain one of > > + - "ti,omap34xx-temperature-sensor" for OMAP34xx > > + - "ti,omap36xx-temperature-sensor" for OMAP36xx > > +- syscon : Should be a phandle to system configuration node which > > + encompases the temperature register > > +- clocks : Should contain 32KHz fclk clock specifier > > +- clock-names : Should contain clock names > > + - "fck" for the 32KHz fclk clock specifier > > I don't quite get it. The temperature sensor is internal on the CPU, > right? Why do we need device tree to describe it? As soon as we have > CPU that is compatible to ti,omap3430, we know everything we need to > know, no?
Lots of stuff is SoC internal and described in the DT (e.g. serial
controllers). Just have a look in omap3.dtsi or omap34xx.dtsi.
I put the temperature sensor into its own node for the following
reasons:
* syscon reference
* clock reference
I first thought about loading the driver from the syscon driver,
but omap uses a generic one, so that's not an option. Apart from
that one would still need the clock reference.
> > +Example for omap34xx:
> > +
> > +/ {
> > + temperature-sensor {
> > + compatible = "ti,omap34xx-temperature-sensor";
> > + syscon = <&omap3_scm_general>;
> > + clocks = <&ts_fck>;
> > + clock-names = "fck";
> > + };
> > +};
>
> Or is there something that depends on the board there? Or do we want
> to do it like this to be consistent with existing bindings?
This is SoC specific and should go into the omap34xx.dtsi and
omap36xx.dtsi files. See also PATCH 3/3.
-- Sebastian
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