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authorAnurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>2016-04-20 17:47:35 +0200
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-05-20 12:33:51 +0200
commitb62c3a1158c0abc98e03c68934fa7ee6ca10dd49 (patch)
tree2142a220dfe34610e95b13ff8385aef341a356d3 /drivers/rtc/rtc-zynqmp.c
parentrtc: sa1100: DT spelling s/interrupt-name/interrupt-names/ (diff)
downloadlinux-b62c3a1158c0abc98e03c68934fa7ee6ca10dd49.tar.xz
linux-b62c3a1158c0abc98e03c68934fa7ee6ca10dd49.zip
rtc: zynqmp: Update seconds time programming logic
We program 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 a 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. Signed-off-by: Anurag Kumar Vulisha <anuragku@xilinx.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Diffstat (limited to 'drivers/rtc/rtc-zynqmp.c')
-rw-r--r--drivers/rtc/rtc-zynqmp.c45
1 files changed, 39 insertions, 6 deletions
diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
index f87f971a72c2..da18a8ae3c1d 100644
--- a/drivers/rtc/rtc-zynqmp.c
+++ b/drivers/rtc/rtc-zynqmp.c
@@ -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);