linux-kernel - Re: [PATCH v3 1/5] rtc: pm8xxx: implement qcom,no-alarm flag for non-HLOS owned alarm

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Message-ID: <Zw9gZkLPMB9ZBQlh@hovoldconsulting.com>
Date: Wed, 16 Oct 2024 08:42:46 +0200
From: Johan Hovold <johan@...nel.org>
To: Jonathan Marek <jonathan@...ek.ca>
Cc: linux-arm-msm@...r.kernel.org,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	"open list:REAL TIME CLOCK (RTC) SUBSYSTEM" <linux-rtc@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/5] rtc: pm8xxx: implement qcom,no-alarm flag for
 non-HLOS owned alarm

On Mon, Oct 14, 2024 at 08:47:26PM -0400, Jonathan Marek wrote:
> Qualcomm x1e80100 firmware sets the ownership of the RTC alarm to ADSP.
> Thus writing to RTC alarm registers and receiving alarm interrupts is not
> possible.
> 
> Add a qcom,no-alarm flag to support RTC on this platform.

An alternative may be to drop the alarm interrupt from DT and use that
as an indicator.

> Signed-off-by: Jonathan Marek <jonathan@...ek.ca>
> ---
>  drivers/rtc/rtc-pm8xxx.c | 44 +++++++++++++++++++++++++++-------------
>  1 file changed, 30 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
> index c32fba550c8e0..1e78939625622 100644
> --- a/drivers/rtc/rtc-pm8xxx.c
> +++ b/drivers/rtc/rtc-pm8xxx.c
> @@ -61,6 +61,7 @@ struct pm8xxx_rtc {
>  	struct rtc_device *rtc;
>  	struct regmap *regmap;
>  	bool allow_set_time;
> +	bool no_alarm;

How about inverting this one and naming it has_alarm or similar to avoid
the double negation in your conditionals (!no_alarm)?

>  	int alarm_irq;
>  	const struct pm8xxx_rtc_regs *regs;
>  	struct device *dev;
> @@ -473,9 +474,14 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
>  	if (!rtc_dd->regmap)
>  		return -ENXIO;
>  
> -	rtc_dd->alarm_irq = platform_get_irq(pdev, 0);
> -	if (rtc_dd->alarm_irq < 0)
> -		return -ENXIO;
> +	rtc_dd->no_alarm = of_property_read_bool(pdev->dev.of_node,
> +						 "qcom,no-alarm");
> +

Stray newline.

> +	if (!rtc_dd->no_alarm) {
> +		rtc_dd->alarm_irq = platform_get_irq(pdev, 0);
> +		if (rtc_dd->alarm_irq < 0)
> +			return -ENXIO;
> +	}
>  
>  	rtc_dd->allow_set_time = of_property_read_bool(pdev->dev.of_node,
>  						      "allow-set-time");
> @@ -503,7 +509,8 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, rtc_dd);
>  
> -	device_init_wakeup(&pdev->dev, 1);
> +	if (!rtc_dd->no_alarm)
> +		device_init_wakeup(&pdev->dev, 1);
>  
>  	rtc_dd->rtc = devm_rtc_allocate_device(&pdev->dev);
>  	if (IS_ERR(rtc_dd->rtc))
> @@ -512,27 +519,36 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
>  	rtc_dd->rtc->ops = &pm8xxx_rtc_ops;
>  	rtc_dd->rtc->range_max = U32_MAX;
>  
> -	rc = devm_request_any_context_irq(&pdev->dev, rtc_dd->alarm_irq,
> -					  pm8xxx_alarm_trigger,
> -					  IRQF_TRIGGER_RISING,
> -					  "pm8xxx_rtc_alarm", rtc_dd);
> -	if (rc < 0)
> -		return rc;
> +	if (!rtc_dd->no_alarm) {
> +		rc = devm_request_any_context_irq(&pdev->dev, rtc_dd->alarm_irq,
> +						  pm8xxx_alarm_trigger,
> +						  IRQF_TRIGGER_RISING,
> +						  "pm8xxx_rtc_alarm", rtc_dd);
> +		if (rc < 0)
> +			return rc;
> +	}
>  
>  	rc = devm_rtc_register_device(rtc_dd->rtc);
>  	if (rc)
>  		return rc;
>  
> -	rc = dev_pm_set_wake_irq(&pdev->dev, rtc_dd->alarm_irq);
> -	if (rc)
> -		return rc;
> +	if (!rtc_dd->no_alarm) {
> +		rc = dev_pm_set_wake_irq(&pdev->dev, rtc_dd->alarm_irq);
> +		if (rc)
> +			return rc;
> +	} else {
> +		clear_bit(RTC_FEATURE_ALARM, rtc_dd->rtc->features);

I assume that you should be clearing the feature bit before registering
the RTC.

> +	}
>  
>  	return 0;
>  }

Johan