Split the switch_to() wrapper out of asm-generic/system.h

Split the switch_to() wrapper out of asm-generic/system.h into its own
asm-generic/system.h as part of the asm/system.h disintegration.

Signed-off-by: David Howells <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>

include/asm-generic/switch_to.h

···
+/* Generic task switch macro wrapper, based on MN10300 definitions.
+ *
+ * It should be possible to use these on really simple architectures,
+ * but it serves more as a starting point for new ports.
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells ([e-mail])
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#ifndef __ASM_GENERIC_SWITCH_TO_H
+#define __ASM_GENERIC_SWITCH_TO_H
+
+#include <linux/thread_info.h>
+
+/*
+ * Context switching is now performed out-of-line in switch_to.S
+ */
+extern struct task_struct *__switch_to(struct task_struct *,
+				       struct task_struct *);
+
+#define switch_to(prev, next, last)					\
+	do {								\
+		((last) = __switch_to((prev), (next)));			\
+	} while (0)
+
+#endif /* __ASM_GENERIC_SWITCH_TO_H */

include/asm-generic/system.h

···
 #ifndef __ASM_GENERIC_SYSTEM_H
 #define __ASM_GENERIC_SYSTEM_H
 
-#ifndef __ASSEMBLY__
-
-#include <linux/types.h>
-
 #include <asm/barrier.h>
 #include <asm/cmpxchg.h>
-
-struct task_struct;
-
-/* context switching is now performed out-of-line in switch_to.S */
-extern struct task_struct *__switch_to(struct task_struct *,
-		struct task_struct *);
-#define switch_to(prev, next, last)					\
-	do {								\
-		((last) = __switch_to((prev), (next)));			\
-	} while (0)
+#include <asm/switch_to.h>
 
 #define arch_align_stack(x) (x)
-
-#endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_GENERIC_SYSTEM_H */