drm: Add drm notifier support

drivers/gpu/drm/Makefile

@@ -72,6 +72,7 @@ drm-y := \
 	drm_vblank.o \
 	drm_vblank_work.o \
 	drm_vma_manager.o \
+	drm_notifier.o \
 	drm_writeback.o
 drm-$(CONFIG_DRM_CLIENT) += \
 	drm_client.o \

drivers/gpu/drm/drm_notifier.c

+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2021 XiaoMi, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/notifier.h>
+#include <drm/drm_notifier.h>
+
+static BLOCKING_NOTIFIER_HEAD(mi_drm_notifier_list);
+
+/**
+ * mi_drm_register_client - register a client notifier
+ * @nb: notifier block to callback on events
+ *
+ * This function registers a notifier callback function
+ * to msm_drm_notifier_list, which would be called when
+ * received unblank/power down event.
+ */
+int mi_drm_register_client(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&mi_drm_notifier_list, nb);
+}
+EXPORT_SYMBOL(mi_drm_register_client);
+
+/**
+ * mi_drm_unregister_client - unregister a client notifier
+ * @nb: notifier block to callback on events
+ *
+ * This function unregisters the callback function from
+ * msm_drm_notifier_list.
+ */
+int mi_drm_unregister_client(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&mi_drm_notifier_list, nb);
+}
+EXPORT_SYMBOL(mi_drm_unregister_client);
+
+/**
+ * mi_drm_notifier_call_chain - notify clients of drm_events
+ * @val: event MSM_DRM_EARLY_EVENT_BLANK or MSM_DRM_EVENT_BLANK
+ * @v: notifier data, inculde display id and display blank
+ *     event(unblank or power down).
+ */
+int mi_drm_notifier_call_chain(unsigned long val, void *v)
+{
+	return blocking_notifier_call_chain(&mi_drm_notifier_list, val, v);
+}
+EXPORT_SYMBOL(mi_drm_notifier_call_chain);

include/drm/drm_notifier.h

+/*
+ * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2021 XiaoMi, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _DRM_NOTIFIER_H_
+#define _DRM_NOTIFIER_H_
+
+#include <linux/notifier.h>
+
+/* A hardware display blank change occurred */
+#define MI_DRM_EVENT_BLANK              0x01
+/* A hardware display blank early change occurred */
+#define MI_DRM_EARLY_EVENT_BLANK        0x02
+
+enum drm_notifier_data {
+	/* panel: power on */
+	MI_DRM_BLANK_UNBLANK,
+	/* panel: power down */
+	MI_DRM_BLANK_POWERDOWN,
+};
+
+int mi_drm_register_client(struct notifier_block *nb);
+int mi_drm_unregister_client(struct notifier_block *nb);
+int mi_drm_notifier_call_chain(unsigned long val, void *v);
+
+#endif /* _DRM_NOTIFIER_H */