Hi Loc, Grant,
On Thu, 14 Nov 2013 16:01:13 -0800, Loc Ho lho@xxxxxxx wrote:
Hi Mike,
I will be looking into covering the clock driver to support UEFI. Before I do this, can someone explain to me how x86 system handle each IP clock as I don't see such thing?
UEFI is completely unrelated to the clock drivers, it is only a firmware interface for the OS loader. UEFI mostly disappears after Linux is loaded. Are you perhaps asking about ACPI?
There isn't such a thing on x86. This is entirely new territory. On x86 as far as I know any clock manipulation that does need to be done would be performed by an ACPI method, but there is no concept of an IP clock in the ACPI namespace, and so no standard way of describing them.
Yes, there is no standard way (ACPI device object or ACPI table) to describe clocks for x86 in ACPI spec, but there is a table called GTDT (Generic Timer Description Table) for ARM which contains information for arch timer initialization.
you can refer to ACPI spec 5.0 chapter 5.2.24: http://www.acpi.info/spec50.htm
You'd be much better of talking to Al Stone and Grame Gregory about what their plans are for clock support in ACPI and to post your question to the ACPI mailing list.
We already finished the implementation of convert fixed clock and arch timer to ACPI, and I had already post the RFC patch set for review now:
http://marc.info/?l=linaro-acpi&m=138450991609818&w=2 http://marc.info/?l=linaro-acpi&m=138198249622451&w=2
Thanks Hanjun