Re: [PATCH] drivers/rtc/rtc-palmas.c: support for backup battery charging

From: Tomasz Figa
Date: Fri Jul 26 2013 - 16:46:06 EST


On Friday 26 of July 2013 09:40:15 Stephen Warren wrote:
> (CC'ing the new DT binding maintainers and mailing list on this reply,
> hence quoting the whole of the DT binding)
>
> On 07/25/2013 06:29 AM, Laxman Dewangan wrote:
> > Palmas series device like TPS65913, TPS80036 supports the backup
> > battery for powering the RTC when no other energy source is
> > available.
> >
> > The backup battery is optional, connected to the VBACKUP pin, and can
> > be nonrechargeable or rechargeable. The rechargeable battery can be
> > charged from the system supply using the backup battery charger.
> >
> > Add support for enabling charging of this backup battery. Also add
> > the DT binding document and the new properties to have this support.
> >
> > Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
> > ---
> >
> > .../devicetree/bindings/rtc/rtc-palmas.txt | 28
> > ++++++++++++++ drivers/rtc/rtc-palmas.c |
> > 39 ++++++++++++++++++++ 2 files changed, 67 insertions(+), 0
> > deletions(-)
> > create mode 100644
> > Documentation/devicetree/bindings/rtc/rtc-palmas.txt
> >
> > diff --git a/Documentation/devicetree/bindings/rtc/rtc-palmas.txt
> > b/Documentation/devicetree/bindings/rtc/rtc-palmas.txt new file mode
> > 100644
> > index 0000000..e4b6910
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/rtc/rtc-palmas.txt
> > @@ -0,0 +1,28 @@
> > +Palmas RTC controller bindings
> > +
> > +Required properties:
> > +- compatible:
> > + - "ti,palams-rtc" for palma series of the RTC controller
> > +- interrupt-parent: Parent interrupt device, must be handle of palams
> > node. +- interrupts: Interrupt number of RTC submodule on device.
> > +
> > +Optional properties:
> > +- ti,back-bat-chg-enable: The palmas series device like TPS65913 or
> > TPS80036 + supports the battery backup for powering the RTC when main
> > battery is + removed or in very low power state. This flag will
> > enable the backup + battery charging.
> > +- ti,back-bat-chg-current: Configure charging current. Device
> > supports the + charging current as < 100mA or >100mA.
>
> Does the HW support just two options; less-than or greater-than 100mA?
> If so, a Boolean property here might be better. The code below certainly
> implies this.
>
> Given there's only 1 battery, I think "back-" is redundant in the
> property names. Since that shortens the names a bit, I'd suggest
> spelling everything out in full, perhaps:
>
> battery-charge-enable
> battery-charge-low-current

First of all, are those even properties for the RTC binding? Doesn't this
PMIC contain a charger part which handles battery charging and so requires
such kind of information?

Best regards,
Tomasz

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