rtc: rzn1: Report maximum alarm limit to rtc core

RZN1 only supports alarms up to one week in the future.
Report the limit to the RTC core and use the reported limit
to validate the requested alarm time when setting it.

Cc: Brian Norris <briannorris@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230817225537.4053865-8-linux@roeck-us.net
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: groeck

drivers/rtc/rtc-rzn1.c

@@ -227,7 +227,7 @@ static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 		return ret;
 
 	/* We cannot set alarms more than one week ahead */
-	farest = rtc_tm_to_time64(&tm_now) + (7 * 86400);
+	farest = rtc_tm_to_time64(&tm_now) + rtc->rtcdev->alarm_offset_max;
 	alarm = rtc_tm_to_time64(tm);
 	if (time_after(alarm, farest))
 		return -ERANGE;
@@ -351,6 +351,7 @@ static int rzn1_rtc_probe(struct platform_device *pdev)
 
 	rtc->rtcdev->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	rtc->rtcdev->range_max = RTC_TIMESTAMP_END_2099;
+	rtc->rtcdev->alarm_offset_max = 7 * 86400;
 	rtc->rtcdev->ops = &rzn1_rtc_ops;
 	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->rtcdev->features);
 	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtcdev->features);