rtc: zynqmp: Write Calibration value before setting time
It is suggested to program CALIB_WRITE register with the calibration
value before updating the SET_TIME_WRITE register, doing so will
clear the Tick Counter and force the next second to be signaled
exactly in 1 second.
Signed-off-by: Anurag Kumar Vulisha <anuragku@xilinx.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
index 6adb603..f87f971 100644
--- a/drivers/rtc/rtc-zynqmp.c
+++ b/drivers/rtc/rtc-zynqmp.c
@@ -56,6 +56,7 @@
void __iomem *reg_base;
int alarm_irq;
int sec_irq;
+ int calibval;
};
static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
@@ -68,6 +69,13 @@
if (new_time > RTC_SEC_MAX_VAL)
return -EINVAL;
+ /*
+ * Writing into calibration register will clear the Tick Counter and
+ * force the next second to be signaled exactly in 1 second period
+ */
+ xrtcdev->calibval &= RTC_CALIB_MASK;
+ writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+
writel(new_time, xrtcdev->reg_base + RTC_SET_TM_WR);
return 0;
@@ -121,7 +129,7 @@
return 0;
}
-static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev, u32 calibval)
+static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
{
u32 rtc_ctrl;
@@ -136,8 +144,8 @@
* to default value suggested as per design spec
* to correct RTC delay in frequency over period of time.
*/
- calibval &= RTC_CALIB_MASK;
- writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+ xrtcdev->calibval &= RTC_CALIB_MASK;
+ writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
}
static const struct rtc_class_ops xlnx_rtc_ops = {
@@ -174,7 +182,6 @@
struct xlnx_rtc_dev *xrtcdev;
struct resource *res;
int ret;
- unsigned int calibvalue;
xrtcdev = devm_kzalloc(&pdev->dev, sizeof(*xrtcdev), GFP_KERNEL);
if (!xrtcdev)
@@ -215,11 +222,11 @@
}
ret = of_property_read_u32(pdev->dev.of_node, "calibration",
- &calibvalue);
+ &xrtcdev->calibval);
if (ret)
- calibvalue = RTC_CALIB_DEF;
+ xrtcdev->calibval = RTC_CALIB_DEF;
- xlnx_init_rtc(xrtcdev, calibvalue);
+ xlnx_init_rtc(xrtcdev);
device_init_wakeup(&pdev->dev, 1);