diff mbox series

[kvmtool,v2,1/6] rtc: Initialize the Register D for MC146818 RTC

Message ID 1547130046-14729-2-git-send-email-julien.thierry@arm.com (mailing list archive)
State New, archived
Headers show
Series arm: Add support for firmware booting | expand

Commit Message

Julien Thierry Jan. 10, 2019, 2:20 p.m. UTC 
From: Sami Mujawar <sami.mujawar@arm.com>

Some software drivers check the VRT bit (BIT7) of Register D before
using the MC146818 RTC. Initialized the VRT bit in rtc__init() to
indicate that the RAM and time contents are valid.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
---
 hw/rtc.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/hw/rtc.c b/hw/rtc.c
index 0649b5d..c1fa72f 100644
--- a/hw/rtc.c
+++ b/hw/rtc.c
@@ -25,6 +25,11 @@ 
 #define RTC_REG_C			0x0C
 #define RTC_REG_D			0x0D
 
+/*
+ * Register D Bits
+ */
+#define RTC_REG_D_VRT			(1 << 7)
+
 struct rtc_device {
 	u8			cmos_idx;
 	u8			cmos_data[128];
@@ -140,6 +145,9 @@  int rtc__init(struct kvm *kvm)
 		return r;
 	}
 
+	/* Set the VRT bit in Register D to indicate valid RAM and time */
+	rtc.cmos_data[RTC_REG_D] = RTC_REG_D_VRT;
+
 	return r;
 }
 dev_init(rtc__init);