[PATCH] rtc: pcf2127: handle timestamp interrupts

From: Mian Yousaf Kaukab
Date: Thu Apr 29 2021 - 10:48:00 EST


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@xxxxxxx>
---
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