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: <20241016122613e1ba2e2a@mail.local>
Date: Wed, 16 Oct 2024 14:26:13 +0200
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: Johan Hovold <johan@...nel.org>
Cc: Jonathan Marek <jonathan@...ek.ca>, linux-arm-msm@...r.kernel.org,
	"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 16/10/2024 08:42:46+0200, Johan Hovold wrote:
> 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;

Also, probe must not fail after devm_rtc_allocate_device has been
called.so you could fix this with this patch.

> > +	} 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

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com