[PATCH v4 05/41] misc/mei/hdcp: Notifier chain for mei cldev state change

[Ramalingam C <ramalingam.c@intel.com>]

Notifier Chain is defined to inform all its clients about the mei
client device state change. Routine is defined for the clients to
register and unregister for the notification on state change.

v2:
  Rebased.
v3:
  Notifier chain is adopted for cldev state update [Tomas]
v4:
  Made static dummy functions as inline in mei_hdcp.h
  API for polling client device status
  IS_ENABLED used in header, for config status for mei_hdcp.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
---
 drivers/misc/mei/hdcp/mei_hdcp.c | 46 ++++++++++++++++++++++++++++++++--
 include/linux/mei_hdcp.h         | 53 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+), 2 deletions(-)
 create mode 100644 include/linux/mei_hdcp.h

diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
index 4cd6fdd01181..0b4e85511a25 100644
--- a/drivers/misc/mei/hdcp/mei_hdcp.c
+++ b/drivers/misc/mei/hdcp/mei_hdcp.c
@@ -31,6 +31,42 @@
 #include <linux/slab.h>
 #include <linux/uuid.h>
 #include <linux/mei_cl_bus.h>
+#include <linux/notifier.h>
+#include <linux/mei_hdcp.h>
+
+static struct mei_cl_device *mei_cldev;
+static BLOCKING_NOTIFIER_HEAD(mei_cldev_notifier_list);
+
+static void
+mei_cldev_state_notify_clients(struct mei_cl_device *cldev, bool enabled)
+{
+	if (enabled)
+		blocking_notifier_call_chain(&mei_cldev_notifier_list,
+					     MEI_CLDEV_ENABLED, cldev);
+	else
+		blocking_notifier_call_chain(&mei_cldev_notifier_list,
+					     MEI_CLDEV_DISABLED, NULL);
+}
+
+int mei_cldev_register_notify(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&mei_cldev_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(mei_cldev_register_notify);
+
+int mei_cldev_unregister_notify(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&mei_cldev_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(mei_cldev_unregister_notify);
+
+int mei_cldev_poll_notification(void)
+{
+	if (mei_cldev)
+		mei_cldev_state_notify_clients(mei_cldev, true);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mei_cldev_poll_notification);
 
 static int mei_hdcp_probe(struct mei_cl_device *cldev,
 			  const struct mei_cl_device_id *id)
@@ -38,14 +74,20 @@ static int mei_hdcp_probe(struct mei_cl_device *cldev,
 	int ret;
 
 	ret = mei_cldev_enable(cldev);
-	if (ret < 0)
+	if (ret < 0) {
 		dev_err(&cldev->dev, "mei_cldev_enable Failed. %d\n", ret);
+		return ret;
+	}
 
-	return ret;
+	mei_cldev = cldev;
+	mei_cldev_state_notify_clients(cldev, true);
+	return 0;
 }
 
 static int mei_hdcp_remove(struct mei_cl_device *cldev)
 {
+	mei_cldev = NULL;
+	mei_cldev_state_notify_clients(cldev, false);
 	mei_cldev_set_drvdata(cldev, NULL);
 	return mei_cldev_disable(cldev);
 }
diff --git a/include/linux/mei_hdcp.h b/include/linux/mei_hdcp.h
new file mode 100644
index 000000000000..9c8f140f5344
--- /dev/null
+++ b/include/linux/mei_hdcp.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
+/*
+ * Copyright © 2017-2018 Intel Corporation
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ *
+ * Authors:
+ *	Ramalingam C <ramalingam.c@intel.com>
+ */
+
+#ifndef _LINUX_MEI_HDCP_H
+#define _LINUX_MEI_HDCP_H
+
+enum mei_cldev_state {
+	MEI_CLDEV_DISABLED,
+	MEI_CLDEV_ENABLED
+};
+
+#if IS_ENABLED(CONFIG_INTEL_MEI_HDCP)
+int mei_cldev_register_notify(struct notifier_block *nb);
+int mei_cldev_unregister_notify(struct notifier_block *nb);
+int mei_cldev_poll_notification(void);
+#else
+static inline int mei_cldev_register_notify(struct notifier_block *nb)
+{
+	return -ENODEV;
+}
+static inline int mei_cldev_unregister_notify(struct notifier_block *nb)
+{
+	return -ENODEV;
+}
+static inline int mei_cldev_poll_notification(void)
+{
+	return -ENODEV;
+}
+#endif /* IS_ENABLED(CONFIG_INTEL_MEI_HDCP) */
+#endif /* defined (_LINUX_MEI_HDCP_H) */
-- 
2.7.4

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