On Fri, Jul 26, 2013 at 04:40:15PM +0100, Stephen Warren wrote:
> (CC'ing the new DT binding maintainers and mailing list on this reply,
> hence quoting the whole of the DT binding)
Thanks Stephen.
>
> 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 <ldewan...@nvidia.com>
> > ---
> > .../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.
Perhaps "ti,has-rechargeable-battery" would be better, as this describes
the hardware rather than an intent relating to it.
> > +- ti,back-bat-chg-current: Configure charging current. Device supports the
> > + charging current as < 100mA or >100mA.
Are either of these values unsafe or unsupported in some configurations?
>
> 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
>
> Both Boolean.
>
> > +Example:
> > + palmas: tps65913@58 {
> > + :::::::::::
>
> "..." is probably more common than lots of colons, or you could just
> delete this line.
>
> > + palmas_rtc: rtc {
> > + compatible = "ti,palmas-rtc";
> > + interrupt-parent = <&palmas>;
> > + interrupts = <8 0>;
> > + ti,back-bat-chg-enable;
> > + ti,back-bat-chg-current = <100>;
> > + };
> > + :::::::::::
> > + };
>
> > diff --git a/drivers/rtc/rtc-palmas.c b/drivers/rtc/rtc-palmas.c
>
> > @@ -238,6 +238,19 @@ static int palmas_rtc_probe(struct platform_device
> > *pdev)
>
> > + ret = of_property_read_u32(pdev->dev.of_node,
> > + "ti,back-bat-chg-current", &pval);
> > + if (!ret)
> > + bb_charging_current = pval;
>
> Do you need to validate that pval is one of the legal values?
>
> > @@ -254,6 +267,32 @@ static int palmas_rtc_probe(struct platform_device
> > *pdev)
> > palmas_rtc->dev = &pdev->dev;
> > platform_set_drvdata(pdev, palmas_rtc);
> >
> > + if (enable_bb_charging) {
> > + unsigned reg = 0;
> > +
> > + if (bb_charging_current < 100)
> > + reg |= PALMAS_BACKUP_BATTERY_CTRL_BBS_BBC_LOW_ICHRG;
>
> This implies that a Boolean property would be a better representation of HW.
>
Otherwise, +1 to Stephen's comments.
Thanks,
Mark.
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