[PATCH AUTOSEL 4.4 104/174] rtc: pcf8563: Clear event flags and disable interrupts before requesting irq

[Sasha Levin <sashal@kernel.org>]

From: Chen-Yu Tsai <wens@csie.org>

[ Upstream commit 3572e8aea3bf925dac1dbf86127657c39fe5c254 ]

Besides the alarm, the PCF8563 also has a timer triggered interrupt.
In cases where the previous system left the timer and interrupts on,
or somehow the bits got enabled, the interrupt would keep triggering
as the kernel doesn't know about it.

Clear both the alarm and timer event flags, and disable the interrupts,
before requesting the interrupt line.

Fixes: ede3e9d47cca ("drivers/rtc/rtc-pcf8563.c: add alarm support")
Fixes: a45d528aab8b ("rtc: pcf8563: clear expired alarm at boot time")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/rtc/rtc-pcf8563.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index 45b5a3d47ccf..1982eec0a3ea 100644
--- a/drivers/rtc/rtc-pcf8563.c
+++ b/drivers/rtc/rtc-pcf8563.c
@@ -568,7 +568,6 @@ static int pcf8563_probe(struct i2c_client *client,
 	struct pcf8563 *pcf8563;
 	int err;
 	unsigned char buf;
-	unsigned char alm_pending;
 
 	dev_dbg(&client->dev, "%s\n", __func__);
 
@@ -594,13 +593,13 @@ static int pcf8563_probe(struct i2c_client *client,
 		return err;
 	}
 
-	err = pcf8563_get_alarm_mode(client, NULL, &alm_pending);
-	if (err) {
-		dev_err(&client->dev, "%s: read error\n", __func__);
+	/* Clear flags and disable interrupts */
+	buf = 0;
+	err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
+	if (err < 0) {
+		dev_err(&client->dev, "%s: write error\n", __func__);
 		return err;
 	}
-	if (alm_pending)
-		pcf8563_set_alarm_mode(client, 0);
 
 	pcf8563->rtc = devm_rtc_device_register(&client->dev,
 				pcf8563_driver.driver.name,
-- 
2.20.1