[PATCH v2 5/5] rtc: zynqmp: use dynamic max and min offset ranges

[T, Harini]

[Public]

Reviewed-by: Harini T <harini.t at amd.com>

Thanks,
Harini T

> -----Original Message-----
> From: Tomas Melin <tomas.melin at vaisala.com>
> Sent: Thursday, January 8, 2026 6:21 PM
> To: Alexandre Belloni <alexandre.belloni at bootlin.com>; Simek, Michal
> <michal.simek at amd.com>
> Cc: linux-rtc at vger.kernel.org; linux-arm-kernel at lists.infradead.org; linux-
> kernel at vger.kernel.org; Tomas Melin <tomas.melin at vaisala.com>
> Subject: [PATCH v2 5/5] rtc: zynqmp: use dynamic max and min offset ranges
>
> Caution: This message originated from an External Source. Use proper
> caution when opening attachments, clicking links, or responding.
>
>
> Maximum and minimum offsets in ppb that can be handled are dependent
> on the rtc clock frequency and what can fit in the 16-bit register field.
>
> Signed-off-by: Tomas Melin <tomas.melin at vaisala.com>
> ---
>  drivers/rtc/rtc-zynqmp.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c index
> d15c256e7ae56058ddc38849af6424cd29b8965e..f508c61f4046e906d9569cc7
> 79a1360474a85fd2 100644
> --- a/drivers/rtc/rtc-zynqmp.c
> +++ b/drivers/rtc/rtc-zynqmp.c
> @@ -44,8 +44,6 @@
>  #define RTC_FR_MASK            0xF0000
>  #define RTC_FR_MAX_TICKS       16
>  #define RTC_PPB                        1000000000LL
> -#define RTC_MIN_OFFSET         -32768000
> -#define RTC_MAX_OFFSET         32767000
>
>  struct xlnx_rtc_dev {
>         struct rtc_device       *rtc;
> @@ -215,12 +213,12 @@ static int xlnx_rtc_set_offset(struct device *dev,
> long offset)
>
>         /* Tick to offset multiplier */
>         tick_mult = DIV_ROUND_CLOSEST(RTC_PPB, xrtcdev->freq);
> -       if (offset < RTC_MIN_OFFSET || offset > RTC_MAX_OFFSET)
> -               return -ERANGE;
> -
>         /* Number ticks for given offset */
>         max_tick = div_s64_rem(offset, tick_mult, &fract_offset);
>
> +       if (freq + max_tick > RTC_TICK_MASK || (freq + max_tick < 1))
> +               return -ERANGE;
> +
>         /* Number fractional ticks for given offset */
>         if (fract_offset) {
>                 fract_part = DIV_ROUND_UP(tick_mult, RTC_FR_MAX_TICKS);
>
> --
> 2.47.3
>