[M] Change in coreboot[master]: allocator_v4: Use memranges only for toplevel

[Nico Huber (Code Review)]

Attention is currently required from: Arthur Heymans, Arthur Heymans, Bill XIE, Eric Lai, Jonathan Zhang, Kyösti Mälkki, Werner Zeh.

Hello Arthur Heymans, Arthur Heymans, Bill XIE, Eric Lai, Kyösti Mälkki, Lean Sheng Tan, Tim Wawrzynczak, Werner Zeh, build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/65420?usp=email

to look at the new patch set (#18).

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Verified+1 by build bot (Jenkins)

Change subject: allocator_v4: Use memranges only for toplevel
......................................................................

allocator_v4: Use memranges only for toplevel

During phase 1 of the resource allocation we gather all the size
requirements. Starting from the leafs of our devicetree, we cal-
culate the requirements per bus, until we reach the resource do-
main.

However, because alignment plays a role, we can't just accumulate
the sizes of all resources on a bus. Instead, we already sort all
the resources per bus to predict their relative placement, inclu-
ding alignment gaps. Then, phase 2 has to perform the final allo-
cations with the exact same relative placement.

This patch introduces a very simple mechanism to avoid repeating
all the calculations: In phase 1, we note the relative `base` of
each resource on a bus. And after we allocated all the resources
directly below the domain in phase 2, we add the absolute `base`
of bridge resources to the relative `base` of child resources.

This saves most of the computational complexity in phase 2. How-
ever, with a shallow devicetree with most devices directly below
the domain, this won't have a measurable impact.

Example after phase 1:

domain
    |
    `-- bridge #0
          |   res #0, base 0x000000 (relative),
          |   size 12M, align 8M
          |
          |-- device #0
          |         res #1, base 0x800000 (relative),
          |         size 4M, align 4M
          |
          `-- bridge #1
                |   res #2, base 0x000000 (relative),
                |   size 8M, align 8M
                |
                `-- device #1
                          res #3, base 0x000000 (relative),
                          size 8M, align 8M

After phase 2 allocation at the domain level (assuming res #0 got
0xa000000 assigned):

domain
    |
    `-- bridge #0
          |   res #0, base 0xa000000 (absolute),
          |   size 12M, align 8M
          |
          |-- device #0
          |         res #1, base 0x800000 (relative),
          |         size 4M, align 4M
          |
          `-- bridge #1
                |   res #2, base 0x000000 (relative),
                |   size 8M, align 8M
                |
                `-- device #1
                          res #3, base 0x000000 (relative),
                          size 8M, align 8M

Now, all we need to do is to add the `base` of bridge resources
recursively. Starting with resources on the bus below bridge #0:

domain
    |
    `-- bridge #0
          |   res #0, base 0xa000000 (absolute),
          |   size 12M, align 8M
          |
          |-- device #0
          |         res #1, base 0xa800000 (absolute),
          |         size 4M, align 4M
          |
          `-- bridge #1
                |   res #2, base 0xa000000 (absolute),
                |   size 8M, align 8M
                |
                `-- device #1
                          res #3, base 0x000000 (relative),
                          size 8M, align 8M

And finally for resources on the bus below bridge #1:

domain
    |
    `-- bridge #0
          |   res #0, base 0xa000000 (absolute),
          |   size 12M, align 8M
          |
          |-- device #0
          |         res #1, base 0xa800000 (absolute),
          |         size 4M, align 4M
          |
          `-- bridge #1
                |   res #2, base 0xa000000 (absolute),
                |   size 8M, align 8M
                |
                `-- device #1
                          res #3, base 0xa000000 (absolute),
                          size 8M, align 8M

Change-Id: I70c700318a85f6760f27597730bc9c9a86dbe6b3
Signed-off-by: Nico Huber 
---
M src/device/resource_allocator_v4.c
1 file changed, 123 insertions(+), 125 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/20/65420/18