soc: qcom: Service notification driver for remote services

Introduction

=============

The service notifier driver facilitates a mechanism for a client

to register for state notifications regarding a particular remote service.

A remote service here refers to a process providing certain services like audio,

the identifier for which is provided by the service locator. The process

domain will typically run on a remote processor within the same SoC.

Software Description

=====================

The driver provides the following two APIs:

* service_notif_register_notifier() - Register a notifier for a service

  On success, it returns back a handle. It takes the following arguments:

  service_path: Individual service identifier path for which a client

		registers for notifications.

  instance_id: Instance id specific to a subsystem.

  current_state: Current state of service returned by the registration

		 process.

  notifier block: notifier callback for service events.

* service_notif_unregister_notifier() - Unregister a notifier for a service.

  This takes the handle returned during registration and the notifier block

  previously registered as the arguments.

Types of notifications:

=======================

A client can get either a SERVICE_DOWN notification or a SERVICE_UP

notification. A SERVICE_UP notification will be sent out when the SERVICE comes

up and is functional while a SERVICE_DOWN notification is sent after a

service ceases to exist. At the point a SERVICE_DOWN notification is sent out,

all the clients should assume that the service is already dead.

Interaction with SSR

=====================

In general, it is recommended that clients register for either service

notifications using the service notifier or SSR notifications, but not both.

In case it is necessary to register for both, the client can expect to get

the SERVICE_DOWN notification before the SUBSYS_AFTER_SHUTDOWN notification.

However, the client may receive the SUBSYS_BEFORE_SHUTDOWN notification

either before or after the SERVICE_DOWN notification.

	  to what process domain exports the service, and which subsystem

	  that process domain will execute in.

config MSM_SERVICE_NOTIFIER

	bool "Service Notifier"

	depends on MSM_SERVICE_LOCATOR && MSM_SUBSYSTEM_RESTART

	help

	  The Service Notifier provides a library for a kernel client to

	  register for state change notifications regarding a remote service.

	  A remote service here refers to a process providing certain services

	  like audio, the identifier for which is provided by the service

	  locator.

source "drivers/soc/qcom/memshare/Kconfig"

endif # ARCH_MSM

	obj-y += subsystem_restart.o

	obj-y += ramdump.o

endif

obj-$(CONFIG_MSM_SUBSYSTEM_NOTIFIER) += service-notifier.o

obj-$(CONFIG_MSM_SYSMON_COMM) += sysmon.o sysmon-qmi.o

obj-$(CONFIG_MSM_SECURE_BUFFER) += secure_buffer.o

obj-$(CONFIG_TRACER_PKT) += tracer_pkt.o