dsp: add audio event notifier support

Add support for audio event notifier framework to
send/receive events across audio drivers.

CRs-Fixed: 2244131
Change-Id: I1e36703a91625cd52333596d66dc21a0e8876738
Signed-off-by: Vidyakumar Athota <vathota@codeaurora.org>
Signed-off-by: Vignesh Kulothungan <vigneshk@codeaurora.org>

include/dsp/msm-audio-event-notify.h

@@ -0,0 +1,44 @@
+/* Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ *
+ * 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 __MSM_AUDIO_EVENT_NOTIFY_H_
+#define __MSM_AUDIO_EVENT_NOTIFY_H_
+
+#include <linux/notifier.h>
+
+#if IS_ENABLED(CONFIG_SND_SOC_MSM_QDSP6V2_INTF)
+int msm_aud_evt_register_client(struct notifier_block *nb);
+int msm_aud_evt_unregister_client(struct notifier_block *nb);
+int msm_aud_evt_notifier_call_chain(unsigned long val, void *v);
+#else
+static inline int msm_aud_evt_register_client(struct notifier_block *nb)
+{
+	return -ENOSYS;
+}
+
+static inline int msm_aud_evt_unregister_client(struct notifier_block *nb)
+{
+	return -ENOSYS;
+}
+
+static inline int msm_aud_evt_notifier_call_chain(unsigned long val, void *v)
+{
+	return -ENOSYS;
+}
+#endif
+
+enum {
+	MSM_AUD_DC_EVENT = 1,
+};
+
+#endif