[rtc-linux] Re: [PATCH 2/2] rtc: omap: Add external clock enabling support

[Vaibhav Hiremath <vaibhav.hiremath@linaro.org>]

On Friday 14 August 2015 02:03 PM, Alexandre Belloni wrote:
> On 13/08/2015 at 12:37:48 +0530, Keerthy wrote :
>> Configure the clock source to either internal clock
>> or external clock based on the availability of the clocks.
>> External clock is preferred as it can be ticking during suspend.
>>
>> Signed-off-by: Keerthy <j-keerthy@ti.com>
>> ---
>>   drivers/rtc/rtc-omap.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
>> index 8b6355f..479f730 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/clk.h>
>>
>>   /*
>>    * The OMAP RTC is a year/month/day/hours/minutes/seconds BCD clock
>> @@ -107,6 +108,7 @@
>>
>>   /* OMAP_RTC_OSC_REG bit fields: */
>>   #define OMAP_RTC_OSC_32KCLK_EN		BIT(6)
>> +#define OMAP_RTC_OSC_SEL_32KCLK_SRC	BIT(3)
>>
>>   /* OMAP_RTC_IRQWAKEEN bit fields: */
>>   #define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN	BIT(1)
>> @@ -136,6 +138,7 @@ struct omap_rtc {
>>   	int irq_timer;
>>   	u8 interrupts_reg;
>>   	bool is_pmic_controller;
>> +	bool has_ext_clk;
>>   	const struct omap_rtc_device_type *type;
>>   };
>>
>> @@ -525,6 +528,7 @@ static int omap_rtc_probe(struct platform_device *pdev)
>>   {
>>   	struct omap_rtc	*rtc;
>>   	struct resource	*res;
>> +	struct clk *ext_clk, *int_clk;
>>   	u8 reg, mask, new_ctrl;
>>   	const struct platform_device_id *id_entry;
>>   	const struct of_device_id *of_id;
>> @@ -553,6 +557,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
>>   	if (rtc->irq_alarm <= 0)
>>   		return -ENOENT;
>>
>> +	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
>> +	if (!IS_ERR(ext_clk)) {
>> +		rtc->has_ext_clk = true;
>> +		clk_prepare(ext_clk);
>
> I'd say this has to be prepare_enable because you are not enabling those
> clocks anywhere
>
>> +	} else {
>> +		int_clk = devm_clk_get(&pdev->dev, "int-clk");
>> +
>> +		if (!IS_ERR(int_clk))
>> +			clk_prepare(int_clk);
>> +	}
>> +
>>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>   	rtc->base = devm_ioremap_resource(&pdev->dev, res);
>>   	if (IS_ERR(rtc->base))
>> @@ -627,6 +642,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
>>   	if (reg != new_ctrl)
>>   		rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);
>>
>> +	/*
>> +	 * If we have the external clock then
>> +	 * Switch to external clock so we can keep ticking
>> +	 * acorss suspend
>> +	 */
>> +	if (rtc->has_ext_clk) {
>> +		reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
>> +		rtc_write(rtc, OMAP_RTC_OSC_REG, reg |
>> +			  OMAP_RTC_OSC_SEL_32KCLK_SRC);
>> +	}
>> +
>>   	rtc->type->lock(rtc);
>>
>>   	device_init_wakeup(&pdev->dev, true);
>> @@ -672,6 +698,8 @@ err:
>>   static int __exit omap_rtc_remove(struct platform_device *pdev)
>>   {
>>   	struct omap_rtc *rtc = platform_get_drvdata(pdev);
>> +	struct clk *ext_clk, *int_clk;
>> +	u8 reg;
>>
>>   	if (pm_power_off == omap_rtc_power_off &&
>>   			omap_rtc_power_off_rtc == rtc) {
>> @@ -681,10 +709,26 @@ static int __exit omap_rtc_remove(struct platform_device *pdev)
>>
>>   	device_init_wakeup(&pdev->dev, 0);
>>
>> +	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
>> +	if (!IS_ERR(ext_clk)) {
>> +		clk_unprepare(ext_clk);
>> +	} else {
>> +		int_clk = devm_clk_get(&pdev->dev, "int-clk");
>> +
>> +		if (!IS_ERR(int_clk))
>> +			clk_unprepare(int_clk);
>> +	}
>> +
>
> You can probably add ext_clk and int_clk to struct omap_rtc and avoid
> those devm_clk_get.
>


Since both int_clk and ext_clk are mutual exclusive, you can have only 
one variable.


Thanks,
Vaibhav

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