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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>
This commit is contained in:
Anurag Kumar Vulisha 2016-04-20 21:17:35 +05:30 committed by Alexandre Belloni
parent 01dc6992b3
commit b62c3a1158
1 changed files with 39 additions and 6 deletions
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45
drivers/rtc/rtc-zynqmp.c
View File

@ -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);