linux-kernel - [PATCH] rtc: Disable alarm irq if alarm time is less than rtc time and irq is enabled

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Date:   Thu, 23 Sep 2021 15:17:34 +0800
From:   jianbinz <quic_jianbinz@...cinc.com>
To:     <alexandre.belloni@...tlin.com>, <a.zummo@...ertech.it>
CC:     jianbinz <quic_jianbinz@...cinc.com>,
        <linux-kernel@...r.kernel.org>, <linux-rtc@...r.kernel.org>
Subject: [PATCH] rtc: Disable alarm irq if alarm time is less than rtc time and irq is enabled

If device is boot up by rtc alarm, the alarm irq will still be enabled and the alarm time is smaller than current rtc time before any alarm is set or canceled.
If the device is shutdown this time, the device will reboot automatically.

So disable irq if alarm time is less than rtc time and irq is enabled.

Signed-off-by: jianbin zhang <quic_jianbinz@...cinc.com>
---
 drivers/rtc/rtc-pm8xxx.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
index 29a1c65661e9..c8a75d3e9c43 100644
--- a/drivers/rtc/rtc-pm8xxx.c
+++ b/drivers/rtc/rtc-pm8xxx.c
@@ -267,16 +267,19 @@ static int pm8xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	int rc;
 	unsigned int ctrl_reg;
+	unsigned long irq_flags;
 	u8 value[NUM_8_BIT_RTC_REGS];
 	unsigned long secs;
 	struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
 	const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
 
+	spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);
+
 	rc = regmap_bulk_read(rtc_dd->regmap, regs->alarm_rw, value,
 			      sizeof(value));
 	if (rc) {
 		dev_err(dev, "RTC alarm time read failed\n");
-		return rc;
+		goto rtc_rw_fail;
 	}
 
 	secs = value[0] | (value[1] << 8) | (value[2] << 16) |
@@ -287,14 +290,30 @@ static int pm8xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 	rc = regmap_read(rtc_dd->regmap, regs->alarm_ctrl, &ctrl_reg);
 	if (rc) {
 		dev_err(dev, "Read from RTC alarm control register failed\n");
-		return rc;
+		goto rtc_rw_fail;
+	}
+
+	if (ctrl_reg && (rtc_tm_to_ktime(alarm->time) >=
+				rtc_dd->rtc->aie_timer.node.expires)) {
+		ctrl_reg &= ~regs->alarm_en;
+		rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
+		if (rc) {
+			dev_err(dev, "Update RTC control register failed \n");
+			goto rtc_rw_fail;
+		}
 	}
 	alarm->enabled = !!(ctrl_reg & PM8xxx_RTC_ALARM_ENABLE);
 
+	spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+
 	dev_dbg(dev, "Alarm set for - h:m:s=%ptRt, y-m-d=%ptRdr\n",
 		&alarm->time, &alarm->time);
 
 	return 0;
+
+rtc_rw_fail:
+	spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
+	return rc;
 }
 
 static int pm8xxx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
-- 
2.17.1