asm-generic: add generic versions of common headers

These are all kernel internal interfaces that get copied
around a lot. In most cases, architectures can provide
their own optimized versions, but these generic versions
can work as well.

I have tried to use the most common contents of each
header to allow existing architectures to migrate easily.

Thanks to Remis for suggesting a number of cleanups.

Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/asm-generic/unaligned.h

@@ -0,0 +1,30 @@
+#ifndef __ASM_GENERIC_UNALIGNED_H
+#define __ASM_GENERIC_UNALIGNED_H
+
+/*
+ * This is the most generic implementation of unaligned accesses
+ * and should work almost anywhere.
+ *
+ * If an architecture can handle unaligned accesses in hardware,
+ * it may want to use the linux/unaligned/access_ok.h implementation
+ * instead.
+ */
+#include <asm/byteorder.h>
+
+#if defined(__LITTLE_ENDIAN)
+# include <linux/unaligned/le_struct.h>
+# include <linux/unaligned/be_byteshift.h>
+# include <linux/unaligned/generic.h>
+# define get_unaligned	__get_unaligned_le
+# define put_unaligned	__put_unaligned_le
+#elif defined(__BIG_ENDIAN)
+# include <linux/unaligned/be_struct.h>
+# include <linux/unaligned/le_byteshift.h>
+# include <linux/unaligned/generic.h>
+# define get_unaligned	__get_unaligned_be
+# define put_unaligned	__put_unaligned_be
+#else
+# error need to define endianess
+#endif
+
+#endif /* __ASM_GENERIC_UNALIGNED_H */