On 23/07/2020 11:49:05-0600, Rob Herring wrote:
> On Mon, Jul 20, 2020 at 12:23:59PM +0100, miguelborgesdefreitas@xxxxxxxxx wrote:
> > From: Miguel Borges de Freitas <miguelborgesdefreitas@xxxxxxxxx>
> >
> > This adds direct-switching mode as a configurable DT flag for
> > RTC modules supporting it (e.g. nxp pcf8523).
> > DSM switches the power source to the battery supply whenever the
> > VDD drops below VBAT. The option is recommended for hw designs
> > where VDD is always expected to be higher than VBAT.
> >
> > Signed-off-by: Miguel Borges de Freitas <miguelborgesdefreitas@xxxxxxxxx>
> > ---
> > Changes in v2:
> > - Added extended commit message for git history
> > - Separate dt bindings documentation into a single patch
> >
> > Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt | 7 ++++++-
> > Documentation/devicetree/bindings/rtc/rtc.yaml | 7 +++++++
> > 2 files changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
> > index 0b1080c..f715a8f 100644
> > --- a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
> > +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
> > @@ -4,10 +4,14 @@ Required properties:
> > - compatible: Should contain "nxp,pcf8523".
> > - reg: I2C address for chip.
> >
> > -Optional property:
> > +Optional properties:
> > - quartz-load-femtofarads: The capacitive load of the quartz(x-tal),
> > expressed in femto Farad (fF). Valid values are 7000 and 12500.
> > Default value (if no value is specified) is 12500fF.
> > +- pm-enable-dsm: battery switch-over function is enabled in direct
> > + switching mode. The power failure condition happens when VDD < VBAT,
> > + without requiring VDD to drop below Vth(sw)bat.
> > + Default value (if not provided) is the standard mode.
> >
> > Example:
> >
> > @@ -15,4 +19,5 @@ pcf8523: rtc@68 {
> > compatible = "nxp,pcf8523";
> > reg = <0x68>;
> > quartz-load-femtofarads = <7000>;
> > + pm-enable-dsm;
> > };
> > diff --git a/Documentation/devicetree/bindings/rtc/rtc.yaml b/Documentation/devicetree/bindings/rtc/rtc.yaml
> > index ee237b2..a0048f4 100644
> > --- a/Documentation/devicetree/bindings/rtc/rtc.yaml
> > +++ b/Documentation/devicetree/bindings/rtc/rtc.yaml
> > @@ -47,4 +47,11 @@ properties:
> > description:
> > Enables wake up of host system on alarm.
> >
> > + pm-enable-dsm:
> > + $ref: /schemas/types.yaml#/definitions/flag
> > + description:
> > + Enables the battery switch-over function in direct switching
> > + mode. Should be set in systems where VDD is higher than VBAT
> > + at all times.
>
> I'm all for common properties, but is this common across vendors?
>
This is but this shouldn't be a DT property as it has to be changed
dynamically. I'm working on an ioctl interface to change this
configuration.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
