rpmsg: add helper macro module_rpmsg_driver

This patch introduces the module_rpmsg_driver macro which is a
convenience macro for rpmsg driver modules similar to
module_platform_driver. It is intended to be used by drivers which
init/exit section does nothing but register/unregister the rpmsg driver.
By using this macro it is possible to eliminate a few lines of
boilerplate code per rpmsg driver.
Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

include/linux/rpmsg.h

@@ -181,6 +181,18 @@ rpmsg_send_offchannel_raw(struct rpmsg_channel *, u32, u32, void *, int, bool);
 #define register_rpmsg_driver(drv) \
 	__register_rpmsg_driver(drv, THIS_MODULE)
 
+/**
+ * module_rpmsg_driver() - Helper macro for registering an rpmsg driver
+ * @__rpmsg_driver: rpmsg_driver struct
+ *
+ * Helper macro for rpmsg drivers which do not do anything special in module
+ * init/exit. This eliminates a lot of boilerplate.  Each module may only
+ * use this macro once, and calling it replaces module_init() and module_exit()
+ */
+#define module_rpmsg_driver(__rpmsg_driver) \
+	module_driver(__rpmsg_driver, register_rpmsg_driver, \
+			unregister_rpmsg_driver)
+
 /**
  * rpmsg_send() - send a message across to the remote processor
  * @rpdev: the rpmsg channel