[PATCH 3/4] rtc: add battery low voltage detection feature

From: Hugo Villeneuve

Date: Wed Mar 11 2026 - 16:03:26 EST


From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>

Some RTCs have a battery low voltage detection function. Add new feature
so that it can be enabled, disabled or queried at runtime.

Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
---
include/uapi/linux/rtc.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/rtc.h b/include/uapi/linux/rtc.h
index 97aca4503a6a3..596eec119bb3a 100644
--- a/include/uapi/linux/rtc.h
+++ b/include/uapi/linux/rtc.h
@@ -134,18 +134,23 @@ struct rtc_param {
#define RTC_FEATURE_CORRECTION 5
#define RTC_FEATURE_BACKUP_SWITCH_MODE 6
#define RTC_FEATURE_ALARM_WAKEUP_ONLY 7
-#define RTC_FEATURE_CNT 8
+#define RTC_FEATURE_BATTERY_LOW_DETECT 8
+#define RTC_FEATURE_CNT 9

/* parameter list */
#define RTC_PARAM_FEATURES 0
#define RTC_PARAM_CORRECTION 1
#define RTC_PARAM_BACKUP_SWITCH_MODE 2
+#define RTC_PARAM_BATTERY_LOW_DETECT 3

#define RTC_BSM_DISABLED 0
#define RTC_BSM_DIRECT 1
#define RTC_BSM_LEVEL 2
#define RTC_BSM_STANDBY 3

+#define RTC_BATTERY_LOW_DETECT_DISABLED 0
+#define RTC_BATTERY_LOW_DETECT_ENABLED 1
+
#define RTC_MAX_FREQ 8192


--
2.47.3