[PATCH 6.19 443/844] rtc: zynqmp: correct frequency value

[Sasha Levin]

From: Tomas Melin <tomas.melin@xxxxxxxxxxx>

[ Upstream commit 2724fb4d429cbb724dcb6fa17953040918ebe3a2 ]

Fix calibration value in case a clock reference is provided.
The actual calibration value written into register is
frequency - 1.

Reviewed-by: Harini T <harini.t@xxxxxxx>
Tested-by: Harini T <harini.t@xxxxxxx>
Signed-off-by: Tomas Melin <tomas.melin@xxxxxxxxxxx>
Acked-by: Michal Simek <michal.simek@xxxxxxx>
Link: https://patch.msgid.link/20260122-zynqmp-rtc-updates-v4-1-d4edb966b499@xxxxxxxxxxx
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/rtc/rtc-zynqmp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
index 3baa2b481d9f2..856bc1678e7d3 100644
--- a/drivers/rtc/rtc-zynqmp.c
+++ b/drivers/rtc/rtc-zynqmp.c
@@ -345,7 +345,10 @@ static int xlnx_rtc_probe(struct platform_device *pdev)
 					   &xrtcdev->freq);
 		if (ret)
 			xrtcdev->freq = RTC_CALIB_DEF;
+	} else {
+		xrtcdev->freq--;
 	}
+
 	ret = readl(xrtcdev->reg_base + RTC_CALIB_RD);
 	if (!ret)
 		writel(xrtcdev->freq, (xrtcdev->reg_base + RTC_CALIB_WR));
-- 
2.51.0