rtc: cmos: Report supported alarm limit to rtc infrastructure

The alarm window supported by the cmos RTC depends on the chip
and its configuration. Report the limit to the RTC core.

Cc: Brian Norris <briannorris@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230817225537.4053865-5-linux@roeck-us.net
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index c9416fe..228fb2d 100644 (file)
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -913,6 +913,10 @@ static inline void cmos_check_acpi_rtc_status(struct device *dev,
 #define        INITSECTION     __init
 #endif
 
+#define SECS_PER_DAY   (24 * 60 * 60)
+#define SECS_PER_MONTH (28 * SECS_PER_DAY)
+#define SECS_PER_YEAR  (365 * SECS_PER_DAY)
+
 static int INITSECTION
 cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 {
@@ -1019,6 +1023,13 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
                goto cleanup0;
        }
 
+       if (cmos_rtc.mon_alrm)
+               cmos_rtc.rtc->alarm_offset_max = SECS_PER_YEAR - 1;
+       else if (cmos_rtc.day_alrm)
+               cmos_rtc.rtc->alarm_offset_max = SECS_PER_MONTH - 1;
+       else
+               cmos_rtc.rtc->alarm_offset_max = SECS_PER_DAY - 1;
+
        rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
 
        if (!mc146818_does_rtc_work()) {