rtc: sc27xx: Add check to see if need to enable the alarm interrupt

The RTC interrupt enable register is not put in always-power-on region
supplied by VDDRTC, so we should check if we need enable the alarm
interrupt when system booting.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-sc27xx.c b/drivers/rtc/rtc-sc27xx.c
index 4ecabe6c9429..72bb002c88ec 100644
--- a/drivers/rtc/rtc-sc27xx.c
+++ b/drivers/rtc/rtc-sc27xx.c
@@ -563,6 +563,32 @@ static int sprd_rtc_check_power_down(struct sprd_rtc *rtc)
         return 0;
 }
 
+static int sprd_rtc_check_alarm_int(struct sprd_rtc *rtc)
+{
+        u32 val;
+        int ret;
+
+        ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_SPG_VALUE, &val);
+        if (ret)
+                return ret;
+
+        /*
+         * The SPRD_RTC_INT_EN register is not put in always-power-on region
+         * supplied by VDDRTC, so we should check if we need enable the alarm
+         * interrupt when system booting.
+         *
+         * If we have set SPRD_RTC_POWEROFF_ALM_FLAG which is saved in
+         * always-power-on region, that means we have set one alarm last time,
+         * so we should enable the alarm interrupt to help RTC core to see if
+         * there is an alarm already set in RTC hardware.
+         */
+        if (!(val & SPRD_RTC_POWEROFF_ALM_FLAG))
+                return 0;
+
+        return regmap_update_bits(rtc->regmap, rtc->base + SPRD_RTC_INT_EN,
+                                  SPRD_RTC_ALARM_EN, SPRD_RTC_ALARM_EN);
+}
+
 static int sprd_rtc_probe(struct platform_device *pdev)
 {
         struct device_node *node = pdev->dev.of_node;
@@ -596,6 +622,13 @@ static int sprd_rtc_probe(struct platform_device *pdev)
         rtc->dev = &pdev->dev;
         platform_set_drvdata(pdev, rtc);
 
+        /* check if we need set the alarm interrupt */
+        ret = sprd_rtc_check_alarm_int(rtc);
+        if (ret) {
+                dev_err(&pdev->dev, "failed to check RTC alarm interrupt\n");
+                return ret;
+        }
+
         /* check if RTC time values are valid */
         ret = sprd_rtc_check_power_down(rtc);
         if (ret) {