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

From: [email-masked] (Lokesh Vutla)
Date: Tue, 28 Oct 2014 15:19:32 +0530

On Friday 24 October 2014 06:56 PM, Nishanth Menon wrote:
> 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.
Ok. will do it.
> 
>> 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?
Yes I agree that enable/disable would just do the default voltage of SMPS/LDO.
If default voltage needs to be changed, driver should explicitly call regulator_set_voltage.
Currently this is missing. Ill update and repost it. Thanks for pointing it out.
> 
>>
>> 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?
Okay. will update it in next version.
> 
>>  
>>  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.
Will update it in next version.

Thanks and regards,
Lokesh