powerpc/powernv: Add opal_notifier_unregister() and export to modules

opal_notifier_register() is missing a pending "unregister" variant
and should be exposed to modules.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 16 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index fe2aa0b48d2b..6fb5f90e6464 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -892,6 +892,8 @@ extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
                                    int depth, void *data);
 
 extern int opal_notifier_register(struct notifier_block *nb);
+extern int opal_notifier_unregister(struct notifier_block *nb);
+
 extern int opal_message_notifier_register(enum OpalMessageType msg_type,
                                                 struct notifier_block *nb);
 extern void opal_notifier_enable(void);
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index e92f2f67640f..7835d5bb973f 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -180,6 +180,20 @@ int opal_notifier_register(struct notifier_block *nb)
         atomic_notifier_chain_register(&opal_notifier_head, nb);
         return 0;
 }
+EXPORT_SYMBOL_GPL(opal_notifier_register);
+
+int opal_notifier_unregister(struct notifier_block *nb)
+{
+        if (!nb) {
+                pr_warning("%s: Invalid argument (%p)\n",
+                           __func__, nb);
+                return -EINVAL;
+        }
+
+        atomic_notifier_chain_unregister(&opal_notifier_head, nb);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(opal_notifier_unregister);
 
 static void opal_do_notifier(uint64_t events)
 {