From c7c7c8db00ace48f538f4b51d606cd6e4f537df1 Mon Sep 17 00:00:00 2001
From: Dario Binacchi <dariobin@libero.it>
Date: Wed, 2 Jun 2021 22:38:02 +0200
Subject: [PATCH] rtc: davinci: use unlock/lock mechanism
The RTC module contains a kicker mechanism to prevent any spurious
writes from changing the register values. To set the time, you must
first unlock the TC registers, update them and then lock.
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210602203805.11494-6-dariobin@libero.it
---
drivers/rtc/davinci.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/rtc/davinci.c b/drivers/rtc/davinci.c
index 7b8c729f3b..82e5eb3b43 100644
--- a/drivers/rtc/davinci.c
+++ b/drivers/rtc/davinci.c
@@ -16,6 +16,18 @@
#define RTC_BASE DAVINCI_RTC_BASE
#endif
+static void davinci_rtc_lock(struct davinci_rtc *rtc)
+{
+ writel(0, &rtc->kick0r);
+ writel(0, &rtc->kick1r);
+}
+
+static void davinci_rtc_unlock(struct davinci_rtc *rtc)
+{
+ writel(RTC_KICK0R_WE, &rtc->kick0r);
+ writel(RTC_KICK1R_WE, &rtc->kick1r);
+}
+
static int davinci_rtc_wait_not_busy(struct davinci_rtc *rtc)
{
int count;
@@ -89,6 +101,7 @@ int rtc_set(struct rtc_time *tmp)
if (ret)
return ret;
+ davinci_rtc_unlock(rtc);
writeb(bin2bcd(tmp->tm_year % 100), &rtc->year);
writeb(bin2bcd(tmp->tm_mon), &rtc->month);
@@ -97,6 +110,7 @@ int rtc_set(struct rtc_time *tmp)
writeb(bin2bcd(tmp->tm_hour), &rtc->hours);
writeb(bin2bcd(tmp->tm_min), &rtc->minutes);
writeb(bin2bcd(tmp->tm_sec), &rtc->second);
+ davinci_rtc_lock(rtc);
debug("Set DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n",
tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
--
2.39.5