Re: [PATCH v3 00/17] Cross-architecture definitions of relaxed MMIO accessors

From: Arnd Bergmann
Date: Thu Sep 25 2014 - 11:18:03 EST


On Thursday 25 September 2014 17:07:47 Arnd Bergmann wrote:

> The current version doesn't let you do that, so I'll keel the #ifdef
> sections separate. This also means that I won't apply your patch 17:
> we will keep needing the #ifdef to support all three relevant combinations:
>
> a) architectures that provide neither and want to get the defaults
> from asm-generic
> b) architectures that provide the non-relaxed versions and want tog
> to get just the relaxed version from asm-generic
> c) architectures that provide both
>

And here is the new version I applied:

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 508a57257de5..3e976be3bdd4 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -174,6 +174,43 @@ static inline void writeq(u64 value, void __iomem *addr)
#endif /* CONFIG_64BIT */

/*
+ * {read,write}{b,w,l,q}_relaxed() are like the regular version, but
+ * are not guaranteed to provide ordering against spinlocks or memory
+ * accesses.
+ */
+#ifndef readb_relaxed
+#define readb_relaxed readb
+#endif
+
+#ifndef readw_relaxed
+#define readw_relaxed readw
+#endif
+
+#ifndef readl_relaxed
+#define readl_relaxed readl
+#endif
+
+#ifndef readq_relaxed
+#define readq_relaxed readq
+#endif
+
+#ifndef writeb_relaxed
+#define writeb_relaxed writeb
+#endif
+
+#ifndef writew_relaxed
+#define writew_relaxed writew
+#endif
+
+#ifndef writel_relaxed
+#define writel_relaxed writel
+#endif
+
+#ifndef writeq_relaxed
+#define writeq_relaxed writeq
+#endif
+
+/*
* {read,write}s{b,w,l,q}() repeatedly access the same memory address in
* native endianness in 8-, 16-, 32- or 64-bit chunks (@count times).
*/


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