ARC: [BE] readl()/writel() to work in Big Endian CPU configuration

[firefly-linux-kernel-4.4.55.git] / arch / arc / include / asm / io.h

diff --git a/arch/arc/include/asm/io.h b/arch/arc/include/asm/io.h
index 694ece8a024372bef7fd24b3ccb1e9dc323b4afe..27b17adea50df65d293799718da0163ad926ef1b 100644 (file)
--- a/arch/arc/include/asm/io.h
+++ b/arch/arc/include/asm/io.h
@@ -129,15 +129,23 @@ static inline void __raw_writel(u32 w, volatile void __iomem *addr)
 #define writel(v,c)            ({ __iowmb(); writel_relaxed(v,c); })
 
 /*
- * Relaxed API for drivers which can handle any ordering themselves
+ * 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)       __raw_readw(c)
-#define readl_relaxed(c)       __raw_readl(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(v,c)
-#define writel_relaxed(v,c)    __raw_writel(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>