Raspberry Pi are all over the board, and the reality is that there's no harm
in including all of the definitions by default but plenty of harm in the
current situation. This change is safe because we match a definition by root
/compatible in the FDT, so there will be no false-positives because of it.
The main array of definitions grows, but it's only walked exactly once to
determine which we need to use.
I've opted for just duplicating the two entries needed for this, rather than
writing any other mechanism for maintaining two root compat entries to map
to one config, for simplicity. We'll eventually declare these legacy DTB
unsupported, but let's not do that yet while there's no real burden.
r354875 pushed VCBUS <-> ARMC translations to runtime determination, but
incorrectly mapped addresses for the BCM2836 -- SOC_BCM2835 and SOC_BCM2836
are actually mutually exclusive, so the BCM2836 config (GENERIC) would have
taken the latter path in the header and used 0x3f000000 as peripheral start.
Easily fixed -- split out the BCM2836 into its own memmap config and use
that instead if SOC_BCM2836 is included. With this, we get back to userland
again.
Reported by: Marek Zarychta <zarychtam@plan-b.pwste.edu.pl>
We could maintain the static conversions for the !AArch64 Raspberry Pis, but
I'm not sure it's worth it -- we'll traverse the platform list exactly once
(of which there are only two for armv7), then every conversion there-after
traverses the memory map listing of which there are at-most two entries for
these boards: sdram and peripheral space.
Detecting this at runtime is necessary for the AArch64 SOC, though, because
of the distinct IO windows being otherwise not discernible just from support
compiled into the kernel. We currently select the correct window based on
/compatible in the FDT.
We also use a similar mechanism to describe the DMA restrictions- the RPi 4
can have up to 4GB of RAM while the DMA controller and mailbox mechanism can
technically, kind of, only access the lowest 1GB. See the comment in
bcm2835_vcbus.h for a fun description/clarification of this.
Differential Revision: https://reviews.freebsd.org/D22301
