rtc: zynqmp: Restore alarm functionality after kexec transition

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[ Upstream commit e22f4d1321 ]

During kexec reboots, RTC alarms that are fired during the kernel
transition experience delayed execution. The new kernel would eventually
honor these alarms, but the interrupt handlers would only execute after
the driver probe is completed rather than at the intended alarm time.

This is because pending alarm interrupt status from the previous kernel
is not properly cleared during driver initialization, causing timing
discrepancies in alarm delivery.

To ensure precise alarm timing across kexec transitions, enhance the
probe function to:
1. Clear any pending alarm interrupt status from previous boot.
2. Detect existing valid alarms and preserve their state.
3. Re-enable alarm interrupts for future alarms.

Signed-off-by: Harini T <harini.t@amd.com>
Link: https://lore.kernel.org/r/20250730142110.2354507-1-harini.t@amd.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Harini T 2025-07-30 19:51:10 +05:30 • committed by Greg Kroah-Hartman

parent dfe6c9a3b6

commit e825c583a2

1 changed files with 19 additions and 0 deletions

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drivers/rtc/rtc-zynqmp.c

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