[PATCH v3 3/4] rtc: pcf85063: preserve the alarm flag in clkout register updates

["A. Sverdlin" <alexander.sverdlin@siemens.com>]

From: Alexander Sverdlin <alexander.sverdlin@siemens.com>

The clkout rate and enable/disable helpers update CTRL2 with
regmap_update_bits() but leave the alarm flag (AF) out of the mask. AF is
write-0-to-clear, so an AF that gets asserted between the read and the
write of the read-modify-write is written back as 0 and the pending alarm
interrupt is lost.

Add AF to the mask and write it back as 1 (write-1-to-preserve) so a
concurrently asserted alarm flag survives a clkout reconfiguration.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
---
Changelog:
v3:
- new patch

 drivers/rtc/rtc-pcf85063.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index af900fe8ae15e..a3af86456ccfc 100644
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -431,7 +431,8 @@ static int pcf85063_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
 		if (clkout_rates[i] == rate)
 			return regmap_update_bits(pcf85063->regmap,
 				PCF85063_REG_CTRL2,
-				PCF85063_REG_CLKO_F_MASK, i);
+				PCF85063_REG_CLKO_F_MASK | PCF85063_CTRL2_AF,
+				i | PCF85063_CTRL2_AF);
 
 	return -EINVAL;
 }
@@ -460,7 +461,8 @@ static int pcf85063_clkout_control(struct clk_hw *hw, bool enable)
 	}
 
 	return regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2,
-					PCF85063_REG_CLKO_F_MASK, buf);
+				  PCF85063_REG_CLKO_F_MASK | PCF85063_CTRL2_AF,
+				  buf | PCF85063_CTRL2_AF);
 }
 
 static int pcf85063_clkout_prepare(struct clk_hw *hw)
-- 
2.55.0