[PATCH v3] rtc: pcf2127: handle timestamp interrupts

[Mian Yousaf Kaukab <ykaukab@xxxxxxx>]

commit 03623b4b041c ("rtc: pcf2127: add tamper detection support")
added support for timestamp interrupts. However they are not being
handled in the irq handler. If a timestamp interrupt occurs it
results in kernel disabling the interrupt and displaying the call
trace:

[  121.145580] irq 78: nobody cared (try booting with the "irqpoll" option)
...
[  121.238087] [<00000000c4d69393>] irq_default_primary_handler threaded [<000000000a90d25b>] pcf2127_rtc_irq [rtc_pcf2127]
[  121.248971] Disabling IRQ #78

Handle timestamp interrupts in pcf2127_rtc_irq(). Set a flag to mark
the timestamp as valid and only report to sysfs if the flag is set.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@xxxxxxx>
---
history:
v3: -Restore call to pcf2127_wdt_active_ping() in timestamp0_store().
     It was removed by mistake.
v2: -Add a flag to mark the occurrence of timestamp interrupt
    -Add Biwen Li in Cc

 drivers/rtc/rtc-pcf2127.c | 48 +++++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index d13c20a2adf7..d8dec4cbe39f 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -94,10 +94,18 @@
 #define PCF2127_WD_VAL_MAX		255
 #define PCF2127_WD_VAL_DEFAULT		60
 
+/* Mask for currently enabled interrupts */
+#define PCF2127_CTRL1_IRQ_MASK (PCF2127_BIT_CTRL1_TSF1)
+#define PCF2127_CTRL2_IRQ_MASK ( \
+		PCF2127_BIT_CTRL2_AF | \
+		PCF2127_BIT_CTRL2_WDTF | \
+		PCF2127_BIT_CTRL2_TSF2)
+
 struct pcf2127 {
 	struct rtc_device *rtc;
 	struct watchdog_device wdd;
 	struct regmap *regmap;
+	bool timestamp_valid;
 };
 
 /*
@@ -437,20 +445,33 @@ static int pcf2127_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 static irqreturn_t pcf2127_rtc_irq(int irq, void *dev)
 {
 	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
-	unsigned int ctrl2 = 0;
+	unsigned int ctrl1, ctrl2;
 	int ret = 0;
 
+	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL1, &ctrl1);
+	if (ret)
+		return IRQ_NONE;
+
 	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL2, &ctrl2);
 	if (ret)
 		return IRQ_NONE;
 
-	if (!(ctrl2 & PCF2127_BIT_CTRL2_AF))
+	if (!(ctrl1 & PCF2127_CTRL1_IRQ_MASK || ctrl2 & PCF2127_CTRL2_IRQ_MASK))
 		return IRQ_NONE;
 
-	regmap_write(pcf2127->regmap, PCF2127_REG_CTRL2,
-		     ctrl2 & ~(PCF2127_BIT_CTRL2_AF | PCF2127_BIT_CTRL2_WDTF));
+	if (ctrl1 & PCF2127_CTRL1_IRQ_MASK)
+		regmap_write(pcf2127->regmap, PCF2127_REG_CTRL1,
+			ctrl1 & ~PCF2127_CTRL1_IRQ_MASK);
 
-	rtc_update_irq(pcf2127->rtc, 1, RTC_IRQF | RTC_AF);
+	if (ctrl2 & PCF2127_CTRL2_IRQ_MASK)
+		regmap_write(pcf2127->regmap, PCF2127_REG_CTRL2,
+			ctrl2 & ~PCF2127_CTRL2_IRQ_MASK);
+
+	if (ctrl1 & PCF2127_BIT_CTRL1_TSF1 || ctrl2 & PCF2127_BIT_CTRL2_TSF2)
+		pcf2127->timestamp_valid = true;
+
+	if (ctrl2 & PCF2127_BIT_CTRL2_AF)
+		rtc_update_irq(pcf2127->rtc, 1, RTC_IRQF | RTC_AF);
 
 	pcf2127_wdt_active_ping(&pcf2127->wdd);
 
@@ -475,19 +496,7 @@ static ssize_t timestamp0_store(struct device *dev,
 	struct pcf2127 *pcf2127 = dev_get_drvdata(dev->parent);
 	int ret;
 
-	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
-				 PCF2127_BIT_CTRL1_TSF1, 0);
-	if (ret) {
-		dev_err(dev, "%s: update ctrl1 ret=%d\n", __func__, ret);
-		return ret;
-	}
-
-	ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_CTRL2,
-				 PCF2127_BIT_CTRL2_TSF2, 0);
-	if (ret) {
-		dev_err(dev, "%s: update ctrl2 ret=%d\n", __func__, ret);
-		return ret;
-	}
+	pcf2127->timestamp_valid = false;
 
 	ret = pcf2127_wdt_active_ping(&pcf2127->wdd);
 	if (ret)
@@ -524,8 +533,7 @@ static ssize_t timestamp0_show(struct device *dev,
 	if (ret)
 		return ret;
 
-	if (!(data[PCF2127_REG_CTRL1] & PCF2127_BIT_CTRL1_TSF1) &&
-	    !(data[PCF2127_REG_CTRL2] & PCF2127_BIT_CTRL2_TSF2))
+	if (!pcf2127->timestamp_valid)
 		return 0;
 
 	tm.tm_sec = bcd2bin(data[PCF2127_REG_TS_SC] & 0x7F);
-- 
2.26.2