Thread (18 messages) 18 messages, 6 authors, 2025-10-30

Re: [PATCH 0/4] clocksource: Add standalone MMIO ARM arch timer driver

From: Sudeep Holla <hidden>
Date: 2025-08-13 10:55:54
Also in: linux-acpi, lkml

+Alexandru

On Thu, Aug 07, 2025 at 05:02:39PM +0100, Marc Zyngier wrote:
For the past 10 years, both Mark and I have been lamenting about the
sorry state of the badly named "arch_timer" driver, and about the way
the MMIO part is intricately weaved into the system-register part.

The time has finally come to have a stab at it.

This small series simply creates a new timer driver for the MMIO arch
timer, and only that. It is an actual driver, and not some kludge that
has to run super early (that's what the per-CPU timers are for). This
allows, in turn, a pretty large cleanup of the per-CPU driver, though
there is more to come -- one thing at a time.

As an added bonus, we get a clocksource, which the original code
didn't provide. Just in case it might be useful. The end-result is far
more readable, and about 100 lines smaller.
(Tested it on Juno R2 and FVP in both DT and ACPI boot)

Tested-by: Sudeep Holla <redacted>
Reviewed-by: Sudeep Holla <redacted>

Alexandru found it useful(avoids some unexpected hang IIUC) in his setup
based on bootwrapper which doesn't initialise MMIO timers.

-- 
Regards,
Sudeep
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