MIPS: c-r4k: Add CPU PM callback for coherency

Implement a CPU power management callback for the r4k cache, to set up
coherency again after leaving a powered down state.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>

arch/mips/mm/c-r4k.c

@@ -7,6 +7,7 @@
  * Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002 Ralf Baechle (ralf@gnu.org)
  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
  */
+#include <linux/cpu_pm.h>
 #include <linux/hardirq.h>
 #include <linux/init.h>
 #include <linux/highmem.h>
@@ -1644,3 +1645,26 @@ void r4k_cache_init(void)
 	coherency_setup();
 	board_cache_error_setup = r4k_cache_error_setup;
 }
+
+static int r4k_cache_pm_notifier(struct notifier_block *self, unsigned long cmd,
+			       void *v)
+{
+	switch (cmd) {
+	case CPU_PM_ENTER_FAILED:
+	case CPU_PM_EXIT:
+		coherency_setup();
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block r4k_cache_pm_notifier_block = {
+	.notifier_call = r4k_cache_pm_notifier,
+};
+
+int __init r4k_cache_init_pm(void)
+{
+	return cpu_pm_register_notifier(&r4k_cache_pm_notifier_block);
+}
+arch_initcall(r4k_cache_init_pm);