(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
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.
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