On Tue, May 10, 2016 at 5:19 PM, Tomasz Nowicki [off-list ref] wrote:

This patch is going to implement generic PCI host controller for
ACPI world, similar to what pci-host-generic.c driver does for DT world.

All such drivers, which we have seen so far, were implemented within
arch/ directory since they had some arch assumptions (x86 and ia64).
However, they all are doing similar thing, so it makes sense to find
some common code and abstract it into the generic driver.

In order to handle PCI config space regions properly, we define new
MCFG interface which does sanity checks on MCFG table and keeps its
root pointer. User is able to lookup MCFG regions based on that root
pointer and specified domain:bus_start:bus_end touple. We are using
pci_mmcfg_late_init old prototype to avoid another function name.

The implementation of pci_acpi_scan_root() looks up the MCFG entries
and sets up a new mapping (regions are not mapped until host controller ask
for it). Generic PCI functions are used for accessing config space.
Driver selects PCI_ECAM and uses functions from drivers/pci/ecam.h
to create and access ECAM mappings.

As mentioned in Kconfig help section, ACPI_PCI_HOST_GENERIC choice
should be made on a per-architecture basis.

Signed-off-by: Tomasz Nowicki <redacted>
Signed-off-by: Jayachandran C <redacted>
---
 drivers/acpi/Kconfig            |   8 +++
 drivers/acpi/Makefile           |   1 +
 drivers/acpi/pci_mcfg.c         |  97 ++++++++++++++++++++++++++
 drivers/acpi/pci_root_generic.c | 149 ++++++++++++++++++++++++++++++++++++++++

Why do we need a new file?  Would there be any problem with adding
that code to pci_root.c?