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Message-ID: <3802E9A6666DF54886E2B9CBF743BA9825E0B56D@XAP-PVEXMBX01.xlnx.xilinx.com>
Date: Wed, 20 Apr 2016 15:06:51 +0000
From: Anurag Kumar Vulisha <anurag.kumar.vulisha@...inx.com>
To: Anurag Kumar Vulisha <anuragku@...inx.com>,
Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
Soren Brinkmann <sorenb@...inx.com>
CC: Michal Simek <michals@...inx.com>,
"rtc-linux@...glegroups.com" <rtc-linux@...glegroups.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Punnaiah Choudary Kalluri <punnaia@...inx.com>,
Anirudha Sarangi <anirudh@...inx.com>,
Srikanth Vemula <svemula@...inx.com>,
Srinivas Goud <sgoud@...inx.com>
Subject: RE: [PATCH V3] rtc: zynqmp: Update seconds time programming logic
Hi all,
Made a small typo mistake , Please ignore this patch. Sorry for the inconvenience caused.
Thanks,
Anurag Kumar V
> -----Original Message-----
> From: Anurag Kumar Vulisha [mailto:anurag.kumar.vulisha@...inx.com]
> Sent: Wednesday, April 20, 2016 8:29 PM
> To: Alessandro Zummo <a.zummo@...ertech.it>; Alexandre Belloni
> <alexandre.belloni@...e-electrons.com>; Soren Brinkmann
> <sorenb@...inx.com>
> Cc: Michal Simek <michals@...inx.com>; rtc-linux@...glegroups.com; linux-
> arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; Punnaiah
> Choudary Kalluri <punnaia@...inx.com>; Anirudha Sarangi
> <anirudh@...inx.com>; Srikanth Vemula <svemula@...inx.com>; Srinivas
> Goud <sgoud@...inx.com>; Anurag Kumar Vulisha <anuragku@...inx.com>
> Subject: [PATCH V3] rtc: zynqmp: Update seconds time programming logic
>
> 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@...inx.com>
> ---
> Changes in v3:
> 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 | 44
> ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 38 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c index
> f87f971..c2f4495 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 +83,43 @@ 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, 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 +200,9 @@ 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);
>
> --
> 2.1.2
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