device: Enable resource allocator to use multiple ranges

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This change updates the resource allocator in coreboot to allow using
multiple ranges for resource allocation rather than restricting
available window to a single base/limit pair. This is done in
preparation to allow 64-bit resource allocation.

Following changes are made as part of this:
a) Resource allocator still makes 2 passes at the entire tree. The
first pass is to gather the resource requirements of each device
under each domain. It walks recursively in DFS fashion to gather the
requirements of the leaf devices and propagates this back up to the
downstream bridges of the domain. Domain is special in the sense that
it has fixed resource ranges. Hence, the resource requirements from
the downstream devices have no effect on the domain resource
windows. This results in domain resource limits being unmodified after
the first pass.

b) Once the requirements for all the devices under the domain are
gathered, resource allocator walks a second time to allocate resources
to downstream devices as per the requirements. Here, instead of
maintaining a single window for allocating resources, it creates a
list of memranges starting with the resource window at domain and then
applying constraints to create holes for any fixed resources. This
ensures that there is no overlap with fixed resources under the
domain.

c) Domain does not differentiate between mem and prefmem. Since they
are allocated space from the same resource window at the domain level,
it considers all resource requests from downstream devices of the
domain independent of the prefetch type.

d) Once resource allocation is done at the domain level, resource
allocator walks down the downstream bridges and continues the same
process until it reaches the leaves. Bridges have separate windows for
mem and prefmem. Hence, unlike domain, the resource allocator at
bridge level ensures that downstream requirements are satisfied by
taking prefetch type into consideration.

e) This whole 2-pass process is performed for every domain in the
system under the assumption that domains do not have overlapping
address spaces.

Noticeable differences from previous resource allocator:
a) Changes in print logs observed due to flows being slightly
different.
b) Base, limit and size of domain resources are no longer updated
based on downstream requirements.
c) Memranges are used instead of a single base/limit pair for
determining resource allocation.
d) Previously, if a resource request did not fit in the available
base/limit window, then the resource would be allocated over DRAM or
any other address space defeating the principle of "no overlap". With
this change, any time a resource cannot fit in the available ranges,
it complains and ensures that the resource is effectively disabled by
setting base same as the limit.
e) Resource allocator no longer looks at multiple links to determine
the right bus for a resource. None of the current boards have multiple
buses under any downstream device of the domain. The only device with
multiple links seems to be the cpu cluster device for some AMD
platforms.

BUG=b:149186922
TEST=Verified that resource allocation looks correct based on
addresses assigned on Volteer.

Signed-off-by: Furquan Shaikh <furquan@google.com>
Change-Id: Ia1f089877c62e119c6a994a10809c9cc0050ec9a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39486
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

...

This commit is contained in:

Furquan Shaikh 2020-04-27 12:03:49 -07:00 committed by Patrick Georgi

parent e6fb1344ed

commit 3b02006afe

1 changed files with 511 additions and 514 deletions

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