ZynqMp RTC controller has a calibration feature to compensate
time deviation due to input clock inaccuracy.
Set and get calibration API's are used for setting and getting
calibration value from the controller calibration register.
Signed-off-by: Srinivas Goud <srinivas.goud@xxxxxxxxxx>
Signed-off-by: Srinivas Neeli <srinivas.neeli@xxxxxxxxxx>
---
drivers/rtc/rtc-zynqmp.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 78 insertions(+)
diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
index 4b1077e2f826..b4118e9e4fcc 100644
--- a/drivers/rtc/rtc-zynqmp.c
+++ b/drivers/rtc/rtc-zynqmp.c
@@ -40,6 +40,12 @@
#define RTC_CALIB_MASK 0x1FFFFF
#define RTC_ALRM_MASK BIT(1)
#define RTC_MSEC 1000
+#define RTC_FR_MASK 0xF0000
+#define RTC_SEC_MAX_VAL 0xFFFFFFFF
+#define RTC_FR_MAX_TICKS 16
+#define RTC_OFFSET_MAX 150000
+#define RTC_OFFSET_MIN -150000
+#define RTC_PPB 1000000000LL
struct xlnx_rtc_dev {
struct rtc_device *rtc;
@@ -184,12 +190,84 @@ static void xlnx_init_rtc(struct xlnx_rtc_dev *xrtcdev)
writel(xrtcdev->calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
}
+static int xlnx_rtc_read_offset(struct device *dev, long *offset)
+{
+ struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+ long offset_val;
+ unsigned int reg;
+ unsigned int tick_mult = RTC_PPB / xrtcdev->calibval;
+
+ reg = readl(xrtcdev->reg_base + RTC_CALIB_RD);
+
+ /* Offset with seconds ticks */
+ offset_val = reg & RTC_TICK_MASK;
+ offset_val = offset_val - xrtcdev->calibval;
+ offset_val = offset_val * tick_mult;
+
+ /* Offset with fractional ticks */
+ if (reg & RTC_FR_EN)
+ offset_val += ((reg & RTC_FR_MASK) >> RTC_FR_DATSHIFT)
+ * (tick_mult / RTC_FR_MAX_TICKS);
+ *offset = offset_val;
+
+ return 0;
+}
+
+static int xlnx_rtc_set_offset(struct device *dev, long offset)
+{
+ struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
+ short int max_tick;
+ unsigned char fract_tick = 0;
+ unsigned int calibval;
+ int fract_offset;
+ unsigned int tick_mult = RTC_PPB / xrtcdev->calibval;
+
+ /* Make sure offset value is within supported range */
+ if (offset < RTC_OFFSET_MIN || offset > RTC_OFFSET_MAX)
+ return -ERANGE;
+
+ /* Number ticks for given offset */
+ max_tick = div_s64_rem(offset, tick_mult, &fract_offset);
+
+ /* Number fractional ticks for given offset */
+ if (fract_offset) {
+ if (fract_offset < 0) {
+ fract_offset = fract_offset + tick_mult;
+ max_tick--;
+ }
+ if (fract_offset > (tick_mult / RTC_FR_MAX_TICKS)) {
+ for (fract_tick = 1; fract_tick < 16; fract_tick++) {
+ if (fract_offset <=
+ (fract_tick *
+ (tick_mult / RTC_FR_MAX_TICKS)))
+ break;
+ }
+ }
+ }
+
+ /* Zynqmp RTC uses second and fractional tick
+ * counters for compensation
+ */
+ calibval = max_tick + xrtcdev->calibval;
+
+ if (fract_tick)
+ calibval |= RTC_FR_EN;
+
+ calibval |= (fract_tick << RTC_FR_DATSHIFT);
+
+ writel(calibval, (xrtcdev->reg_base + RTC_CALIB_WR));
+
+ return 0;
+}
+
static const struct rtc_class_ops xlnx_rtc_ops = {
.set_time = xlnx_rtc_set_time,
.read_time = xlnx_rtc_read_time,
.read_alarm = xlnx_rtc_read_alarm,
.set_alarm = xlnx_rtc_set_alarm,
.alarm_irq_enable = xlnx_rtc_alarm_irq_enable,
+ .read_offset = xlnx_rtc_read_offset,
+ .set_offset = xlnx_rtc_set_offset,
};
static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
--
2.7.4
