[PATCH v3 05/32] alpha: include default ioremap_nopost() implementation

Lorenzo Pieralisi lorenzo.pieralisi at arm.com
Tue Apr 11 05:28:45 PDT 2017


The PCI specifications (Rev 3.0, 3.2.5 "Transaction Ordering and Posting")
mandate non-posted configuration transactions. As further highlighted in
the PCIe specifications (4.0 - Rev0.3, "Ordering Considerations for the
Enhanced Configuration Access Mechanism"), through ECAM and
ECAM-derivative configuration mechanism, the memory mapped transactions
from the host CPU into Configuration Requests on the PCI express fabric
may create ordering problems for software because writes to memory
address are typically posted transactions (unless the architecture can
enforce through virtual address mapping non-posted write transactions
behaviour) but writes to Configuration Space are not posted on the PCI
express fabric.

Include the asm-generic ioremap_nopost() implementation (currently
falling back to ioremap_nocache()) to provide a non-posted writes
ioremap interface to kernel subsystems.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Bjorn Helgaas <bhelgaas at google.com>
Cc: Richard Henderson <rth at twiddle.net>
Cc: Ivan Kokshaysky <ink at jurassic.park.msu.ru>
Cc: Matt Turner <mattst88 at gmail.com>
---
 arch/alpha/include/asm/io.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/alpha/include/asm/io.h b/arch/alpha/include/asm/io.h
index ff40491..5d7cc11 100644
--- a/arch/alpha/include/asm/io.h
+++ b/arch/alpha/include/asm/io.h
@@ -300,6 +300,7 @@ static inline void __iomem * ioremap_nocache(unsigned long offset,
 }
 
 #define ioremap_uc ioremap_nocache
+#include <asm-generic/ioremap-nopost.h>
 
 static inline void iounmap(volatile void __iomem *addr)
 {
-- 
2.10.0




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