linux-kernel - [PATCH 3/7] rtc: expose correction feature

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Message-Id: <20211015192121.817642-4-alexandre.belloni@bootlin.com>
Date:   Fri, 15 Oct 2021 21:21:16 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/7] rtc: expose correction feature

Add a new feature for RTCs able to correct the oscillator imprecision. This
is also called offset or trimming. Such drivers have a .set_offset callback,
use that to set the feature bit from the core.

Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
 drivers/rtc/class.c      | 3 +++
 include/uapi/linux/rtc.h | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index dbccd71589b9..2e0cbc190a8a 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -389,6 +389,9 @@ int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc)
 	if (!rtc->ops->set_alarm)
 		clear_bit(RTC_FEATURE_ALARM, rtc->features);
 
+	if (rtc->ops->set_offset)
+		set_bit(RTC_FEATURE_CORRECTION, rtc->features);
+
 	rtc->owner = owner;
 	rtc_device_get_offset(rtc);
 
diff --git a/include/uapi/linux/rtc.h b/include/uapi/linux/rtc.h
index e4128be7963b..ded2aaab7ec7 100644
--- a/include/uapi/linux/rtc.h
+++ b/include/uapi/linux/rtc.h
@@ -131,7 +131,8 @@ struct rtc_param {
 #define RTC_FEATURE_ALARM_RES_2S	2
 #define RTC_FEATURE_UPDATE_INTERRUPT	3
 #define RTC_FEATURE_NEED_WEEK_DAY	4
-#define RTC_FEATURE_CNT			5
+#define RTC_FEATURE_CORRECTION		5
+#define RTC_FEATURE_CNT			6
 
 /* parameter list */
 #define RTC_PARAM_FEATURES		0
-- 
2.31.1