[POWERPC] powermac: Suspend to disk on G5

Powermac G5 suspend to disk implementation.  The code is platform
agnostic but only tested on powermac, no other 64-bit powerpc
machines.

Because nvidiafb still breaks suspend I have marked it EXPERIMENTAL on
powermac and because I can't test it and some lowlevel code will need
changes it is BROKEN on all other 64-bit platforms.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/swsusp.c

@@ -24,6 +24,11 @@ void save_processor_state(void)
 	flush_fp_to_thread(current);
 	flush_altivec_to_thread(current);
 	flush_spe_to_thread(current);
+
+#ifdef CONFIG_PPC64
+	hard_irq_disable();
+#endif
+
 }
 
 void restore_processor_state(void)
@@ -31,4 +36,8 @@ void restore_processor_state(void)
 #ifdef CONFIG_PPC32
 	set_context(current->active_mm->context.id, current->active_mm->pgd);
 #endif
+
+#ifdef CONFIG_PPC64
+	hard_irq_enable();
+#endif
 }