rtc: zynqmp: Add clock framework support with calibration fallback

Add support for reading RTC clock from device tree using clock
framework also update the default calibration value to 0x7FFF
as per RTC specifications.

Falls back to 'calibration' property if clock unavailable, and uses
default calibration if neither is present. Only writes calibration when
hardware register reads zero.

The calibration write previously in zynqmp_rtc_set() has been moved to
the probe function. The earlier implementation wrote calibration on
every time update to clear the tick counter, but since calibration is
now dynamically configured from clock framework or device tree during probe,
it only requires one-time initialization. This avoids repeated tick
counter resets and unnecessary overhead.

Signed-off-by: Pranav Tilak <[email protected]>
Reviewed-by: Tomas Melin <[email protected]>
Signed-off-by: Michal Simek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

0 files changed, 0 insertions, 0 deletions