Disintegrate asm/system.h for Blackfin [ver #2]

Disintegrate asm/system.h for Blackfin.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: uclinux-dist-devel@blackfin.uclinux.org
Signed-off-by: Bob Liu <lliubbo@gmail.com>

arch/blackfin/include/asm/switch_to.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2004-2009 Analog Devices Inc.
+ *               Tony Kou (tonyko@lineo.ca)
+ *
+ * Licensed under the GPL-2 or later
+ */
+
+#ifndef _BLACKFIN_SWITCH_TO_H
+#define _BLACKFIN_SWITCH_TO_H
+
+#define prepare_to_switch()     do { } while(0)
+
+/*
+ * switch_to(n) should switch tasks to task ptr, first checking that
+ * ptr isn't the current task, in which case it does nothing.
+ */
+
+#include <asm/l1layout.h>
+#include <asm/mem_map.h>
+
+asmlinkage struct task_struct *resume(struct task_struct *prev, struct task_struct *next);
+
+#ifndef CONFIG_SMP
+#define switch_to(prev,next,last) \
+do {    \
+	memcpy (&task_thread_info(prev)->l1_task_info, L1_SCRATCH_TASK_INFO, \
+		sizeof *L1_SCRATCH_TASK_INFO); \
+	memcpy (L1_SCRATCH_TASK_INFO, &task_thread_info(next)->l1_task_info, \
+		sizeof *L1_SCRATCH_TASK_INFO); \
+	(last) = resume (prev, next);   \
+} while (0)
+#else
+#define switch_to(prev, next, last) \
+do {    \
+	(last) = resume(prev, next);   \
+} while (0)
+#endif
+
+#endif /* _BLACKFIN_SWITCH_TO_H */