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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.

Reviewed-by: Harini T <harini.t@amd.com>
Tested-by: Harini T <harini.t@amd.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://patch.msgid.link/20260122-zynqmp-rtc-updates-v4-5-d4edb966b499@vaisala.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Tomas Melin 2026-01-22 13:53:49 +00:00 • committed by Alexandre Belloni
parent 9f5af70268
commit 2254383176
1 changed files with 3 additions and 4 deletions
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7
drivers/rtc/rtc-zynqmp.c
View file

@ -44,8 +44,6 @@
#define RTC_FR_MASK 0xF0000
#define RTC_FR_MAX_TICKS 16
#define RTC_PPB 1000000000
#define RTC_MIN_OFFSET -32768000
#define RTC_MAX_OFFSET 32767000
struct xlnx_rtc_dev {
struct rtc_device *rtc;
@ -215,12 +213,13 @@ static int xlnx_rtc_set_offset(struct device *dev, long offset)
/* Tick to offset multiplier */
tick_mult = DIV_ROUND_CLOSEST(RTC_PPB, 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);