powerpc/cell: Add support for power button of future IBM cell blades

This patch adds support for the power button on future IBM cell blades.
It actually doesn't shut down the machine. Instead it exposes an
input device /dev/input/event0 to userspace which sends KEY_POWER
if power button has been pressed.
haldaemon actually recognizes the button, so a plattform independent acpid
replacement should handle it correctly.

Signed-off-by: Christian Krafft <krafft@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/include/asm-powerpc/pmi.h b/include/asm-powerpc/pmi.h
index e1dc090..b4e91fb 100644
--- a/include/asm-powerpc/pmi.h
+++ b/include/asm-powerpc/pmi.h
@@ -30,6 +30,7 @@
 #ifdef __KERNEL__
 
 #define PMI_TYPE_FREQ_CHANGE	0x01
+#define PMI_TYPE_POWER_BUTTON	0x02
 #define PMI_READ_TYPE		0
 #define PMI_READ_DATA0		1
 #define PMI_READ_DATA1		2