rtc: pm8xxx: implement qcom,no-alarm flag for non-HLOS owned alarm

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.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Link: https://lore.kernel.org/r/20241015004945.3676-2-jonathan@marek.ca
[ johan: drop no_alarm flag and restructure probe() ]
Tested-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
Tested-by: Steev Klimaszewski <steev@kali.org>
Tested-by: Joel Stanley <joel@jms.id.au>
Tested-by: Sebastian Reichel <sre@kernel.org> # Lenovo T14s Gen6
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20250219134118.31017-5-johan+linaro@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: flto

drivers/rtc/rtc-pm8xxx.c

@@ -606,9 +606,11 @@ 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;
+	if (!of_property_read_bool(pdev->dev.of_node, "qcom,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");
@@ -624,25 +626,29 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, rtc_dd);
 
-	devm_device_init_wakeup(&pdev->dev);
-
 	rtc_dd->rtc = devm_rtc_allocate_device(&pdev->dev);
 	if (IS_ERR(rtc_dd->rtc))
 		return PTR_ERR(rtc_dd->rtc);
 
 	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->alarm_irq) {
+		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_pm_set_wake_irq(&pdev->dev, rtc_dd->alarm_irq);
-	if (rc)
-		return rc;
+		rc = devm_pm_set_wake_irq(&pdev->dev, rtc_dd->alarm_irq);
+		if (rc)
+			return rc;
+
+		devm_device_init_wakeup(&pdev->dev);
+	} else {
+		clear_bit(RTC_FEATURE_ALARM, rtc_dd->rtc->features);
+	}
 
 	return devm_rtc_register_device(rtc_dd->rtc);
 }