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From:   Mian Yousaf Kaukab <ykaukab@suse.de>
To:     a.zummo@towertech.it, alexandre.belloni@bootlin.com
Cc:     linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org,
        Mian Yousaf Kaukab <ykaukab@suse.de>
Subject: [PATCH] rtc: pcf2127: handle timestamp interrupts
Date:   Thu, 29 Apr 2021 16:47:58 +0200
Message-Id: <20210429144758.4552-1-ykaukab@suse.de>
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Precedence: bulk

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(). Display a message
in kernel log when a timestamp interrupt occurs. Don’t check for
TSF1 and TSF2 flags in timestamp0_show() as they are cleared in the
IRQ handler now.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 drivers/rtc/rtc-pcf2127.c | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index d13c20a2adf7..0dbc0473cc68 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -94,6 +94,13 @@
 #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;
@@ -437,20 +444,33 @@ 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)
+		dev_info(dev, "timestamp interrupt generated");
+
+	if (ctrl2 & PCF2127_BIT_CTRL2_AF)
+		rtc_update_irq(pcf2127->rtc, 1, RTC_IRQF | RTC_AF);
 
 	pcf2127_wdt_active_ping(&pcf2127->wdd);
 
@@ -524,10 +544,6 @@ 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))
-		return 0;
-
 	tm.tm_sec = bcd2bin(data[PCF2127_REG_TS_SC] & 0x7F);
 	tm.tm_min = bcd2bin(data[PCF2127_REG_TS_MN] & 0x7F);
 	tm.tm_hour = bcd2bin(data[PCF2127_REG_TS_HR] & 0x3F);
-- 
2.26.2