ARM64: Implement pci_remap_cfgspace() interface
authorLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Wed, 19 Apr 2017 16:48:52 +0000 (17:48 +0100)
committerBjorn Helgaas <bhelgaas@google.com>
Mon, 24 Apr 2017 18:53:13 +0000 (13:53 -0500)
commitf1e209b7f80288a711268af9054a04d3f6900a6b
treedecff099f45f8b358bae1d0cb010570afe8a2c97
parentcf9ea8ca4a0bea7eda12f8fb04dc34146839a215
ARM64: Implement pci_remap_cfgspace() interface

The PCI bus specification (rev 3.0, 3.2.5 "Transaction Ordering and
Posting") defines rules for PCI configuration space transactions ordering
and posting, that state that configuration writes are non-posted
transactions.

This rule is reinforced by the ARM v8 architecture reference manual (issue
A.k, Early Write Acknowledgment) that explicitly recommends that No Early
Write Acknowledgment attribute should be used to map PCI configuration
(write) transactions.

Current ioremap interface on ARM64 implements mapping functions where the
Early Write Acknowledgment hint is enabled, so they cannot be used to map
PCI configuration space in a PCI specs compliant way.

Implement an ARM64 specific pci_remap_cfgspace() interface that allows to
map PCI config region with nGnRnE attributes, providing a remap function
that complies with PCI specifications and the ARMv8 architecture reference
manual recommendations.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
arch/arm64/include/asm/io.h