powerpc/xics: Consolidate ipi message encode and decode

xics supports only one ipi per cpu, and expects software to use some
queue to know why the interrupt was sent.  In Linux, we use a an array
of bitmaps indexed by cpu to identify the message.  Currently the bits
are set in smp.c and decoded in xics.c, with the data structure in a
header file.   Consolidate the code in xics.c similar to mpic and other
interrupt controllers.

Also, while making the the array static, the message word doesn't need
to be volatile as set_bit and test_clear_bit take care of it for us, and
put it under ifdef smp.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/platforms/pseries/xics.h b/arch/powerpc/platforms/pseries/xics.h
index 1c5321a..d1d5a83 100644
--- a/arch/powerpc/platforms/pseries/xics.h
+++ b/arch/powerpc/platforms/pseries/xics.h
@@ -12,20 +12,12 @@
 #ifndef _POWERPC_KERNEL_XICS_H
 #define _POWERPC_KERNEL_XICS_H
 
-#include <linux/cache.h>
-
 extern void xics_init_IRQ(void);
 extern void xics_setup_cpu(void);
 extern void xics_teardown_cpu(void);
 extern void xics_kexec_teardown_cpu(int secondary);
-extern void xics_cause_IPI(int cpu);
-extern  void xics_request_IPIs(void);
 extern void xics_migrate_irqs_away(void);
-
-struct xics_ipi_struct {
-	volatile unsigned long value;
-} ____cacheline_aligned;
-
-extern struct xics_ipi_struct xics_ipi_message[NR_CPUS] __cacheline_aligned;
+extern int smp_xics_probe(void);
+extern void smp_xics_message_pass(int target, int msg);
 
 #endif /* _POWERPC_KERNEL_XICS_H */