From f1e209b7f80288a711268af9054a04d3f6900a6b Mon Sep 17 00:00:00 2001 From: Lorenzo Pieralisi Date: Wed, 19 Apr 2017 17:48:52 +0100 Subject: [PATCH] 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 Signed-off-by: Bjorn Helgaas Acked-by: Catalin Marinas Cc: Will Deacon --- arch/arm64/include/asm/io.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index 0c00c87bb9dd..35b2e50f17fb 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -172,6 +172,16 @@ extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size); #define ioremap_wt(addr, size) __ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRE)) #define iounmap __iounmap +/* + * PCI configuration space mapping function. + * + * The PCI specification disallows posted write configuration transactions. + * Add an arch specific pci_remap_cfgspace() definition that is implemented + * through nGnRnE device memory attribute as recommended by the ARM v8 + * Architecture reference manual Issue A.k B2.8.2 "Device memory". + */ +#define pci_remap_cfgspace(addr, size) __ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRnE)) + /* * io{read,write}{16,32,64}be() macros */ -- 2.30.2