@@ -64,7 +64,12 @@ static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
unsigned long new_time;
- new_time = rtc_tm_to_time64(tm);
+ /*
+ * The value written will be updated after 1 sec into the
+ * seconds read register, so we need to program time +1 sec
+ * to get the correct time on read.
+ */
+ new_time = rtc_tm_to_time64(tm) + 1;
if (new_time > RTC_SEC_MAX_VAL)
return -EINVAL;
@@ -78,14 +83,44 @@ static int xlnx_rtc_set_time(struct device *dev, struct rtc_time *tm)
writel(new_time, xrtcdev->reg_base + RTC_SET_TM_WR);
+ /*
+ * Clear the rtc interrupt status register after setting the
+ * time. During a read_time function, the code should read the
+ * RTC_INT_STATUS register and if bit 0 is still 0, it means
+ * that one second has not elapsed yet since RTC was set and
+ * the current time should be read from SET_TIME_READ register;
+ * otherwise, CURRENT_TIME register is read to report the time
+ */
+ writel(RTC_INT_SEC, xrtcdev->reg_base + RTC_INT_STS);
+
return 0;
}
static int xlnx_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
+ u32 status;
+ unsigned long read_time;
struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
- rtc_time64_to_tm(readl(xrtcdev->reg_base + RTC_CUR_TM), tm);
+ status = readl(xrtcdev->reg_base + RTC_INT_STS);
+
+ if (status & RTC_INT_SEC) {
+ /*
+ * RTC has updated the CURRENT_TIME with the time written into
+ * SET_TIME_WRITE register.
+ */
+ rtc_time64_to_tm(readl(xrtcdev->reg_base + RTC_CUR_TM), tm);
+ } else {
+ /*
+ * Time written in SET_TIME_WRITE has not yet updated into
+ * the seconds read register, so read the time from the
+ * SET_TIME_WRITE instead of CURRENT_TIME register.
+ * Since we add +1 sec while writing, we need to -1 sec while
+ * reading.
+ */
+ read_time = readl(xrtcdev->reg_base + RTC_SET_TM_RD) - 1;
+ rtc_time64_to_tm(read_time, tm);
+ }
return rtc_valid_tm(tm);
}
@@ -166,11 +201,9 @@ static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
if (!(status & (RTC_INT_SEC | RTC_INT_ALRM)))
return IRQ_NONE;
- /* Clear interrupt */
- writel(status, xrtcdev->reg_base + RTC_INT_STS);
+ /* Clear RTC_INT_ALRM interrupt only */
+ writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_STS);
- if (status & RTC_INT_SEC)
- rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_UF);
if (status & RTC_INT_ALRM)
rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_AF);
We programe RTC time using SET_TIME_WRITE register and read the RTC current time using CURRENT_TIME register. When we set the time by writing into SET_TIME_WRITE Register and immediately try to read the rtc time from CURRENT_TIME register, the previous old value is returned instead of the new loaded time. This is because RTC takes nearly 1 sec to update the new loaded value into the CURRENT_TIME register. This behaviour is expected in our RTC IP. This patch updates the driver to read the current time from SET_TIME_WRITE register instead of CURRENT_TIME when rtc time is requested within an 1sec period after setting the RTC time. Doing so will ensure the correct time is given to the user. Since there is an delay of 1sec in updating the CURRENT_TIME we are loading set time +1sec while programming the SET_TIME_WRITE register, doing this will give correct time without any delay when read from CURRENT_TIME. This patch updates the above said. Signed-off-by: Anurag Kumar Vulisha <anuragku@xilinx.com> --- Changes in v4: 1. Corrected the read time logic Changes in v2: 1. Updated the Time programming logic as suggested by Alexandre Belloni 2. Changed the commit message --- drivers/rtc/rtc-zynqmp.c | 45 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-)