-----Original Message-----
From: Tomas Melin <redacted>
Sent: Thursday, January 8, 2026 6:21 PM
To: Alexandre Belloni <alexandre.belloni@bootlin.com>; Simek, Michal
[off-list ref]
Cc: linux-rtc@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
kernel@vger.kernel.org; Tomas Melin [off-list ref]
Subject: [PATCH v2 5/5] rtc: zynqmp: use dynamic max and min offset ranges

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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 <redacted>
---
 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