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>
diff --git a/include/asm-generic/spinlock.h b/include/asm-generic/spinlock.h
new file mode 100644
index 0000000..1547a03
--- /dev/null
+++ b/include/asm-generic/spinlock.h
@@ -0,0 +1,11 @@
+#ifndef __ASM_GENERIC_SPINLOCK_H
+#define __ASM_GENERIC_SPINLOCK_H
+/*
+ * You need to implement asm/spinlock.h for SMP support. The generic
+ * version does not handle SMP.
+ */
+#ifdef CONFIG_SMP
+#error need an architecture specific asm/spinlock.h
+#endif
+
+#endif /* __ASM_GENERIC_SPINLOCK_H */