Subject: [PATCH V3 3/3] rtc: omap: Support regulator supply for RTC

From: [email-masked] (Nishanth Menon)
Date: Fri, 24 Oct 2014 08:26:43 -0500

On 10/23/2014 11:53 PM, Lokesh Vutla wrote:
> On some Soc's RTC is powered by an external power regulator.
SoC ? -> could you rephrase this to indicate "certain SoCs such as
DRA7, RTC is an independent voltage domain of it's own and on
platforms such as DRA7-evm, this may be supplied by individual
regulator on it's own.

> e.g. RTC on DRA7 SoC. Make the OMAP RTC driver support a
> power regulator.

Question ofcourse is what voltage would you like that regulator to be
at? As you are aware, certain LDOs and SMPS can drive varying voltage
and just enable/disable would do just the default voltage of the
SMPS/LDO, right? OR am i missing something here?

> 
> Signed-off-by: Lokesh Vutla <[email-masked]>
> ---
>  Documentation/devicetree/bindings/rtc/rtc-omap.txt |  3 +++
>  drivers/rtc/rtc-omap.c                             | 24 ++++++++++++++++++++++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/rtc/rtc-omap.txt b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> index 750efd4..e7ad12b 100644
> --- a/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> +++ b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
> @@ -15,6 +15,8 @@ Required properties:
>  Optional properties:
>  - ti,system-power-controller: whether the rtc is controlling the system power
>    through pmic_power_en
> +Optional Properties:
^^ already commented on..

> +- vrtc-supply: phandle to the regulator device tree node if needed

"phandle to supply regulator" ? since it is optional, "if needed" is
redundant?

>  
>  Example:
>  
> @@ -25,4 +27,5 @@ rtc at 1c23000 {
>  		      19>;
>  	interrupt-parent = <&intc>;
>  	ti,system-power-controller;
> +	vrtc-supply = <&ldo9_reg>;
>  };
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index d9bb5e7..61fe630 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -25,6 +25,7 @@
>  #include <linux/of_device.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/io.h>
> +#include <linux/regulator/consumer.h>
>  
>  /*
>   * The OMAP RTC is a year/month/day/hours/minutes/seconds BCD clock
> @@ -134,6 +135,7 @@ struct omap_rtc {
>  	u8 interrupts_reg;
>  	bool is_pmic_controller;
>  	const struct omap_rtc_device_type *type;
> +	struct regulator *supply;
>  };
>  
>  static inline u8 rtc_read(struct omap_rtc *rtc, unsigned int reg)
> @@ -516,6 +518,22 @@ static int omap_rtc_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, rtc);
>  
> +	rtc->supply = devm_regulator_get_optional(&pdev->dev, "vrtc");
> +	if (IS_ERR(rtc->supply)) {
> +		if (PTR_ERR(rtc->supply) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +
> +		rtc->supply = NULL;
> +	}
> +
> +	if (rtc->supply) {
> +		ret = regulator_enable(rtc->supply);
> +		if (ret) {
> +			dev_err(&pdev->dev, "regulator enable failed\n");

would be nice to print the result as well - since it helps debug from
log a little easier.

-- 
Regards,
Nishanth Menon