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rtc: rzn1: Handle unset alarm weekday in rzn1_rtc_read_alarm

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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
Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/rtc/rtc-rzn1.c
View File

@@ -235,13 +235,24 @@ static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
if (ret)
return ret;
ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
alrm->enabled = !!(ctl1 & (RZN1_RTC_CTL1_ALME | RZN1_RTC_CTL1_1SE));
min = readl(rtc->base + RZN1_RTC_ALM);
hour = readl(rtc->base + RZN1_RTC_ALH);
wday = readl(rtc->base + RZN1_RTC_ALW);
tm->tm_sec = 0;
tm->tm_min = bcd2bin(min);
tm->tm_hour = bcd2bin(hour);
/*
* If wday is zero, no bit is set in RZN1_RTC_ALW. This is the
* register's power-on reset value.
*/
wday = readl(rtc->base + RZN1_RTC_ALW);
if (!wday)
return 0;
delta_days = ((fls(wday) - 1) - tm->tm_wday + 7) % 7;
tm->tm_wday = fls(wday) - 1;
@@ -250,9 +261,6 @@ static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
rtc_time64_to_tm(alarm, tm);
}
ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
alrm->enabled = !!(ctl1 & (RZN1_RTC_CTL1_ALME | RZN1_RTC_CTL1_1SE));
return 0;
}