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ARC: Add missing io barriers to io{read,write}{16,32}be() 

While reviewing a different change to asm-generic/io.h Arnd spotted that
ARC ioread32 and ioread32be both of which come from asm-generic versions
are not symmetrical in terms of calling the io barriers.

generic ioread32   -> ARC readl()                  [ has barriers]
generic ioread32be -> __be32_to_cpu(__raw_readl()) [ lacks barriers]

While generic ioread32be is being remediated to call readl(), that involves
a swab32(), causing double swaps on ioread32be() on Big Endian systems.

So provide our versions of big endian IO accessors to ensure io barrier
calls while also keeping them optimal

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org  [4.2+]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2016-05-05 13:32:34 +05:30
parent 1b10cb21d8
commit e5bc0478ab
1 changed files with 18 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
arch/arc/include/asm/io.h
View File

@ -13,6 +13,15 @@
#include <asm/byteorder.h>
#include <asm/page.h>
#ifdef CONFIG_ISA_ARCV2
#include <asm/barrier.h>
#define __iormb() rmb()
#define __iowmb() wmb()
#else
#define __iormb() do { } while (0)
#define __iowmb() do { } while (0)
#endif
extern void __iomem *ioremap(phys_addr_t paddr, unsigned long size);
extern void __iomem *ioremap_prot(phys_addr_t paddr, unsigned long size,
unsigned long flags);
@ -31,6 +40,15 @@ extern void iounmap(const void __iomem *addr);
#define ioremap_wc(phy, sz) ioremap(phy, sz)
#define ioremap_wt(phy, sz) ioremap(phy, sz)
/*
* io{read,write}{16,32}be() macros
*/
#define ioread16be(p) ({ u16 __v = be16_to_cpu((__force __be16)__raw_readw(p)); __iormb(); __v; })
#define ioread32be(p) ({ u32 __v = be32_to_cpu((__force __be32)__raw_readl(p)); __iormb(); __v; })
#define iowrite16be(v,p) ({ __iowmb(); __raw_writew((__force u16)cpu_to_be16(v), p); })
#define iowrite32be(v,p) ({ __iowmb(); __raw_writel((__force u32)cpu_to_be32(v), p); })
/* Change struct page to physical address */
#define page_to_phys(page) (page_to_pfn(page) << PAGE_SHIFT)
@ -108,15 +126,6 @@ static inline void __raw_writel(u32 w, volatile void __iomem *addr)
}
#ifdef CONFIG_ISA_ARCV2
#include <asm/barrier.h>
#define __iormb() rmb()
#define __iowmb() wmb()
#else
#define __iormb() do { } while (0)
#define __iowmb() do { } while (0)
#endif
/*
* MMIO can also get buffered/optimized in micro-arch, so barriers needed
* Based on ARM model for the typical use case