tree 245bad7b4f5e8b8ce35227d452b1e12fddf09517
parent 3c88dc85f6d50cf294ebc2cadebbadab648b5f02
author Werner Zeh <werner.zeh@siemens.com> 1651744530 +0200
committer Felix Held <felix-coreboot@felixheld.de> 1653150017 +0000

src/soc/intel/cmn/fast-spi: Add SSDT extension to fast SPI driver

If the SPI controller is hidden from the OS (which is default on Apollo
Lake) then OS has no chance to probe the device and therefore can not be
aware of the resources this PCI device occupies. If the OS needs to move
some resources for a reason it can happen that the new allocated window
will be shadowed by the hidden PCI device resource and hence causing a
conflict. As a result this MMIO window will be inaccessible from the OS
which will cause issues in applications. For instance on Apollo Lake
this causes flashrom to stop working.

This patch adds a SSDT extension for the PCI device if it is hidden from
the OS and reports the occupied resource via ACPI to the OS. For the
cases where the device is hidden later at coreboot runtime and therefore
is not marked as hidden in the PCI device itself a Kconfig switch called
'FAST_SPI_GENERATE_SSDT' is introduced. It defaults to 'no' and can be
set from SOC code to override it.

Since there is no defined ACPI ID for the fast SPI controller available
now, the generic one (PNP0C02) is used.

Test: Boot mc_apl4 and make sure flashrom works again.

Change-Id: Ia16dfe6e001188aad26418afe0f04c53ecfd56f1
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64076
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-by: Subrata Banik <subratabanik@google.com>