linux/arch/arc/include/asm/io.h
Vineet Gupta e5bc0478ab 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>
2016-05-05 16:35:28 +05:30

171 lines
4.4 KiB
C

/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _ASM_ARC_IO_H
#define _ASM_ARC_IO_H
#include <linux/types.h>
#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);
static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
{
return (void __iomem *)port;
}
static inline void ioport_unmap(void __iomem *addr)
{
}
extern void iounmap(const void __iomem *addr);
#define ioremap_nocache(phy, sz) ioremap(phy, sz)
#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)
#define __raw_readb __raw_readb
static inline u8 __raw_readb(const volatile void __iomem *addr)
{
u8 b;
__asm__ __volatile__(
" ldb%U1 %0, %1 \n"
: "=r" (b)
: "m" (*(volatile u8 __force *)addr)
: "memory");
return b;
}
#define __raw_readw __raw_readw
static inline u16 __raw_readw(const volatile void __iomem *addr)
{
u16 s;
__asm__ __volatile__(
" ldw%U1 %0, %1 \n"
: "=r" (s)
: "m" (*(volatile u16 __force *)addr)
: "memory");
return s;
}
#define __raw_readl __raw_readl
static inline u32 __raw_readl(const volatile void __iomem *addr)
{
u32 w;
__asm__ __volatile__(
" ld%U1 %0, %1 \n"
: "=r" (w)
: "m" (*(volatile u32 __force *)addr)
: "memory");
return w;
}
#define __raw_writeb __raw_writeb
static inline void __raw_writeb(u8 b, volatile void __iomem *addr)
{
__asm__ __volatile__(
" stb%U1 %0, %1 \n"
:
: "r" (b), "m" (*(volatile u8 __force *)addr)
: "memory");
}
#define __raw_writew __raw_writew
static inline void __raw_writew(u16 s, volatile void __iomem *addr)
{
__asm__ __volatile__(
" stw%U1 %0, %1 \n"
:
: "r" (s), "m" (*(volatile u16 __force *)addr)
: "memory");
}
#define __raw_writel __raw_writel
static inline void __raw_writel(u32 w, volatile void __iomem *addr)
{
__asm__ __volatile__(
" st%U1 %0, %1 \n"
:
: "r" (w), "m" (*(volatile u32 __force *)addr)
: "memory");
}
/*
* MMIO can also get buffered/optimized in micro-arch, so barriers needed
* Based on ARM model for the typical use case
*
* <ST [DMA buffer]>
* <writel MMIO "go" reg>
* or:
* <readl MMIO "status" reg>
* <LD [DMA buffer]>
*
* http://lkml.kernel.org/r/20150622133656.GG1583@arm.com
*/
#define readb(c) ({ u8 __v = readb_relaxed(c); __iormb(); __v; })
#define readw(c) ({ u16 __v = readw_relaxed(c); __iormb(); __v; })
#define readl(c) ({ u32 __v = readl_relaxed(c); __iormb(); __v; })
#define writeb(v,c) ({ __iowmb(); writeb_relaxed(v,c); })
#define writew(v,c) ({ __iowmb(); writew_relaxed(v,c); })
#define writel(v,c) ({ __iowmb(); writel_relaxed(v,c); })
/*
* Relaxed API for drivers which can handle barrier ordering themselves
*
* Also these are defined to perform little endian accesses.
* To provide the typical device register semantics of fixed endian,
* swap the byte order for Big Endian
*
* http://lkml.kernel.org/r/201603100845.30602.arnd@arndb.de
*/
#define readb_relaxed(c) __raw_readb(c)
#define readw_relaxed(c) ({ u16 __r = le16_to_cpu((__force __le16) \
__raw_readw(c)); __r; })
#define readl_relaxed(c) ({ u32 __r = le32_to_cpu((__force __le32) \
__raw_readl(c)); __r; })
#define writeb_relaxed(v,c) __raw_writeb(v,c)
#define writew_relaxed(v,c) __raw_writew((__force u16) cpu_to_le16(v),c)
#define writel_relaxed(v,c) __raw_writel((__force u32) cpu_to_le32(v),c)
#include <asm-generic/io.h>
#endif /* _ASM_ARC_IO_H */