rtc: rzn1: Fix alarm range check truncation on 32-bit systems

alarm and farest were declared as unsigned long, but
rtc_tm_to_time64() returns time64_t (s64). On 32-bit systems where
unsigned long is 32 bits, the assignment silently truncates the upper
32 bits of the timestamp.

Fix by declaring alarm and farest as time64_t and replacing
time_after() with a direct signed comparison, which is correct for
time64_t values that will never realistically overflow.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://patch.msgid.link/20260821211032.13554-6-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-rzn1.c b/drivers/rtc/rtc-rzn1.c
index d4cba0d..f326865 100644 (file)
--- a/drivers/rtc/rtc-rzn1.c
+++ b/drivers/rtc/rtc-rzn1.c
@@ -268,7 +268,7 @@ static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
        struct rzn1_rtc *rtc = dev_get_drvdata(dev);
        struct rtc_time *tm = &alrm->time, tm_now;
-       unsigned long alarm, farest;
+       time64_t alarm, farest;
        int ret;
 
        ret = rzn1_rtc_read_time(dev, &tm_now);
@@ -278,7 +278,7 @@ static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
        /* We cannot set alarms more than one week ahead */
        farest = rtc_tm_to_time64(&tm_now) + rtc->rtcdev->alarm_offset_max;
        alarm = rtc_tm_to_time64(tm);
-       if (time_after(alarm, farest))
+       if (alarm > farest)
                return -ERANGE;
 
        writel(bin2bcd(tm->tm_min), rtc->base + RZN1_RTC_ALM);