firmware: arm_scmi: Add notification protocol-registration

Add the core SCMI notifications protocol-registration support: allow
protocols to register their own set of supported events, during their
initialization phase. Notification core can track multiple platform
instances by their handles.

Link: https://lore.kernel.org/r/20200701155348.52864-2-cristian.marussi@arm.comReviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 obj-y	= scmi-bus.o scmi-driver.o scmi-protocols.o scmi-transport.o
 scmi-bus-y = bus.o
-scmi-driver-y = driver.o
+scmi-driver-y = driver.o notify.o
 scmi-transport-y = shmem.o
 scmi-transport-$(CONFIG_MAILBOX) += mailbox.o
 scmi-transport-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smc.o

drivers/firmware/arm_scmi/common.h

@@ -6,6 +6,8 @@
  *
  * Copyright (C) 2018 ARM Ltd.
  */
+#ifndef _SCMI_COMMON_H
+#define _SCMI_COMMON_H
 
 #include <linux/bitfield.h>
 #include <linux/completion.h>
@@ -235,3 +237,5 @@ void shmem_fetch_notification(struct scmi_shared_mem __iomem *shmem,
 void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem);
 bool shmem_poll_done(struct scmi_shared_mem __iomem *shmem,
 		     struct scmi_xfer *xfer);
+
+#endif /* _SCMI_COMMON_H */

drivers/firmware/arm_scmi/notify.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * System Control and Management Interface (SCMI) Message Protocol
+ * notification header file containing some definitions, structures
+ * and function prototypes related to SCMI Notification handling.
+ *
+ * Copyright (C) 2020 ARM Ltd.
+ */
+#ifndef _SCMI_NOTIFY_H
+#define _SCMI_NOTIFY_H
+
+#include <linux/device.h>
+#include <linux/types.h>
+
+#define SCMI_PROTO_QUEUE_SZ	4096
+
+/**
+ * struct scmi_event  - Describes an event to be supported
+ * @id: Event ID
+ * @max_payld_sz: Max possible size for the payload of a notification message
+ * @max_report_sz: Max possible size for the report of a notification message
+ *
+ * Each SCMI protocol, during its initialization phase, can describe the events
+ * it wishes to support in a few struct scmi_event and pass them to the core
+ * using scmi_register_protocol_events().
+ */
+struct scmi_event {
+	u8	id;
+	size_t	max_payld_sz;
+	size_t	max_report_sz;
+};
+
+/**
+ * struct scmi_event_ops  - Protocol helpers called by the notification core.
+ * @set_notify_enabled: Enable/disable the required evt_id/src_id notifications
+ *			using the proper custom protocol commands.
+ *			Return 0 on Success
+ *
+ * Context: Helpers described in &struct scmi_event_ops are called only in
+ *	    process context.
+ */
+struct scmi_event_ops {
+	int (*set_notify_enabled)(const struct scmi_handle *handle,
+				  u8 evt_id, u32 src_id, bool enabled);
+};
+
+int scmi_notification_init(struct scmi_handle *handle);
+void scmi_notification_exit(struct scmi_handle *handle);
+
+int scmi_register_protocol_events(const struct scmi_handle *handle,
+				  u8 proto_id, size_t queue_sz,
+				  const struct scmi_event_ops *ops,
+				  const struct scmi_event *evt, int num_events,
+				  int num_sources);
+
+#endif /* _SCMI_NOTIFY_H */

include/linux/scmi_protocol.h

@@ -233,6 +233,8 @@ struct scmi_reset_ops {
  *	protocol(for internal use only)
  * @reset_priv: pointer to private data structure specific to reset
  *	protocol(for internal use only)
+ * @notify_priv: pointer to private data structure specific to notifications
+ *	(for internal use only)
  */
 struct scmi_handle {
 	struct device *dev;
@@ -248,6 +250,7 @@ struct scmi_handle {
 	void *power_priv;
 	void *sensor_priv;
 	void *reset_priv;
+	void *notify_priv;
 };
 
 enum scmi_std_protocol {