[1/7] asm-generic/io.h: add io{read,write}64 accessors

Commit Message

Horia Geanta May 4, 2016, 5:16 p.m. UTC

This will allow device drivers to consistently use io{read,write}XX
also for 64-bit accesses.

Signed-off-by: Horia Geant? <[e-mail]>
---
 include/asm-generic/io.h    | 63 +++++++++++++++++++++++++++++++++++++++++++++
 include/asm-generic/iomap.h |  8 ++++++
 2 files changed, 71 insertions(+)

Comments

Arnd Bergmann May 4, 2016, 10:35 p.m. UTC | #1

On Wednesday 04 May 2016 20:16:19 Horia Geant? wrote:
> @@ -625,6 +645,16 @@ static inline u32 ioread32be(const volatile void __iomem *addr)
>  }
>  #endif
>  
> +#ifdef CONFIG_64BIT
> +#ifndef ioread64be
> +#define ioread64be ioread64be
> +static inline u64 ioread64be(const volatile void __iomem *addr)
> +{
> +       return __be64_to_cpu(__raw_readq(addr));
> +}
> +#endif
> +#endif /* CONFIG_64BIT */
> +
>  #ifndef iowrite16be
>  #define iowrite16be iowrite16be
>  static inline void iowrite16be(u16 value, void volatile __iomem *addr)
> @@ -641,6 +671,16 @@ static inline void iowrite32be(u32 value, volatile void __iomem *addr)
>  }
>  #endif
>  
> +#ifdef CONFIG_64BIT
> +#ifndef iowrite64be
> +#define iowrite64be iowrite64be
> +static inline void iowrite64be(u64 value, volatile void __iomem *addr)
> +{
> +       __raw_writeq(__cpu_to_be64(value), addr);
> +}
> +#endif
> +#endif /* CONFIG_64BIT */
> +
> 

I just noticed that these two are both a bit wrong, but they copy the
mistake that already exists in the 16 and 32 bit versions: If an
architecture overrides readq/writeq to have barriers but does not override
ioread64be/iowrite64be, this will lack the barriers and behave differently
from the little-endian version. I think the only affected architecture
is ARC, since ARM and ARM64 both override the big-endian accessors to
have the correct barriers, and all others don't use barriers at all.

Maybe you can add a patch before this one to replace the 16/32-bit accessors
with ones that do a

static inline void iowrite32be(u32 value, volatile void __iomem *addr)
{
	writel(swab32(value), addr);
}

This will lead to a double-swap on architectures that don't override it,
but it will work correctly on all architectures without them having
to override the big-endian accessors.

Aside from that, the patch looks fine.

	Arnd
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Patch

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index eed3bbe88c8a..0e2c73bb6d56 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -585,6 +585,16 @@  static inline u32 ioread32(const volatile void __iomem *addr)
 }
 #endif
 
+#ifdef CONFIG_64BIT
+#ifndef ioread64
+#define ioread64 ioread64
+static inline u64 ioread64(const volatile void __iomem *addr)
+{
+	return readq(addr);
+}
+#endif
+#endif /* CONFIG_64BIT */
+
 #ifndef iowrite8
 #define iowrite8 iowrite8
 static inline void iowrite8(u8 value, volatile void __iomem *addr)
@@ -609,6 +619,16 @@  static inline void iowrite32(u32 value, volatile void __iomem *addr)
 }
 #endif
 
+#ifdef CONFIG_64BIT
+#ifndef iowrite64
+#define iowrite64 iowrite64
+static inline void iowrite64(u64 value, volatile void __iomem *addr)
+{
+	writeq(value, addr);
+}
+#endif
+#endif /* CONFIG_64BIT */
+
 #ifndef ioread16be
 #define ioread16be ioread16be
 static inline u16 ioread16be(const volatile void __iomem *addr)
@@ -625,6 +645,16 @@  static inline u32 ioread32be(const volatile void __iomem *addr)
 }
 #endif
 
+#ifdef CONFIG_64BIT
+#ifndef ioread64be
+#define ioread64be ioread64be
+static inline u64 ioread64be(const volatile void __iomem *addr)
+{
+	return __be64_to_cpu(__raw_readq(addr));
+}
+#endif
+#endif /* CONFIG_64BIT */
+
 #ifndef iowrite16be
 #define iowrite16be iowrite16be
 static inline void iowrite16be(u16 value, void volatile __iomem *addr)
@@ -641,6 +671,16 @@  static inline void iowrite32be(u32 value, volatile void __iomem *addr)
 }
 #endif
 
+#ifdef CONFIG_64BIT
+#ifndef iowrite64be
+#define iowrite64be iowrite64be
+static inline void iowrite64be(u64 value, volatile void __iomem *addr)
+{
+	__raw_writeq(__cpu_to_be64(value), addr);
+}
+#endif
+#endif /* CONFIG_64BIT */
+
 #ifndef ioread8_rep
 #define ioread8_rep ioread8_rep
 static inline void ioread8_rep(const volatile void __iomem *addr, void *buffer,
@@ -668,6 +708,17 @@  static inline void ioread32_rep(const volatile void __iomem *addr,
 }
 #endif
 
+#ifdef CONFIG_64BIT
+#ifndef ioread64_rep
+#define ioread64_rep ioread64_rep
+static inline void ioread64_rep(const volatile void __iomem *addr,
+				void *buffer, unsigned int count)
+{
+	readsq(addr, buffer, count);
+}
+#endif
+#endif /* CONFIG_64BIT */
+
 #ifndef iowrite8_rep
 #define iowrite8_rep iowrite8_rep
 static inline void iowrite8_rep(volatile void __iomem *addr,
@@ -697,6 +748,18 @@  static inline void iowrite32_rep(volatile void __iomem *addr,
 	writesl(addr, buffer, count);
 }
 #endif
+
+#ifdef CONFIG_64BIT
+#ifndef iowrite64_rep
+#define iowrite64_rep iowrite64_rep
+static inline void iowrite64_rep(volatile void __iomem *addr,
+				 const void *buffer,
+				 unsigned int count)
+{
+	writesq(addr, buffer, count);
+}
+#endif
+#endif /* CONFIG_64BIT */
 #endif /* CONFIG_GENERIC_IOMAP */
 
 #ifdef __KERNEL__
diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
index d8f8622fa044..650fede33c25 100644
--- a/include/asm-generic/iomap.h
+++ b/include/asm-generic/iomap.h
@@ -30,12 +30,20 @@  extern unsigned int ioread16(void __iomem *);
 extern unsigned int ioread16be(void __iomem *);
 extern unsigned int ioread32(void __iomem *);
 extern unsigned int ioread32be(void __iomem *);
+#ifdef CONFIG_64BIT
+extern u64 ioread64(void __iomem *);
+extern u64 ioread64be(void __iomem *);
+#endif
 
 extern void iowrite8(u8, void __iomem *);
 extern void iowrite16(u16, void __iomem *);
 extern void iowrite16be(u16, void __iomem *);
 extern void iowrite32(u32, void __iomem *);
 extern void iowrite32be(u32, void __iomem *);
+#ifdef CONFIG_64BIT
+extern void iowrite64(u64, void __iomem *);
+extern void iowrite64be(u64, void __iomem *);
+#endif
 
 /*
  * "string" versions of the above. Note that they