rtc: rzn1: Handle unset alarm weekday in rzn1_rtc_read_alarm

Browse source

RZN1_RTC_ALW is a weekday bitmask where bit N represents weekday N.
When no alarm has been configured, the register has its power-on-reset
value of zero.

rzn1_rtc_read_alarm() uses fls() to convert the weekday bitmask into a
weekday number. When RZN1_RTC_ALW is zero, fls(0) returns zero and
fls(wday) - 1 evaluates to -1. This invalid weekday is then used to
calculate the alarm date and can either leave tm_wday set to -1 or
produce a fabricated alarm date.

Treat a zero RZN1_RTC_ALW value as an unset alarm weekday and return
without calculating the alarm date. Move reading RZN1_RTC_CTL1 before
this check so that alrm->enabled is updated for both configured and
unconfigured alarms.

Fixes: b5ad1bf00d ("rtc: rzn1: Add alarm support")
Cc: stable@vger.kernel.org
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://patch.msgid.link/20260821211032.13554-5-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

...

This commit is contained in:

Lad Prabhakar 2026-08-21 22:10:19 +01:00 • committed by Alexandre Belloni

parent 022a2839a5

commit 457b5dbce3

1 changed files with 12 additions and 4 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

16

drivers/rtc/rtc-rzn1.c

View file