rtc: extended session with set-signal

A client may register a signal handler to be notified whenever the
RTC value was changed, i.e., a mis-configured clock was synchronized,
by calling 'set_sigh()'.

Issue #3450

repos/os/include/rtc_session/client.h

@@ -35,6 +35,9 @@ struct Rtc::Session_client : Genode::Rpc_client<Session>
 	 ** Session interface **
 	 ***********************/
 
+	void set_sigh(Genode::Signal_context_capability sigh) override {
+		call<Rpc_set_sigh>(sigh); }
+
 	Timestamp current_time() override { return call<Rpc_current_time>(); }
 };
 

repos/os/include/rtc_session/rtc_session.h

@@ -19,6 +19,7 @@
 #include <session/session.h>
 #include <base/rpc.h>
 #include <base/stdint.h>
+#include <base/signal.h>
 
 namespace Rtc {
 	struct Timestamp;
@@ -60,6 +61,14 @@ struct Rtc::Session : Genode::Session
 	 ** Session interface **
 	 ***********************/
 
+	/**
+	 * Register set signal handler
+	 *
+	 * \param sigh  signal handler that is called when the RTC has
+	 *              been set
+	 */
+	virtual void set_sigh(Genode::Signal_context_capability sigh) = 0;
+
 	/**
 	 * Query current time
 	 *
@@ -71,8 +80,10 @@ struct Rtc::Session : Genode::Session
 	 ** RPC interface **
 	 *******************/
 
+	GENODE_RPC(Rpc_set_sigh, void, set_sigh,
+	           Genode::Signal_context_capability);
 	GENODE_RPC(Rpc_current_time, Timestamp, current_time);
-	GENODE_RPC_INTERFACE(Rpc_current_time);
+	GENODE_RPC_INTERFACE(Rpc_set_sigh, Rpc_current_time);
 };
 
 #endif /* _INCLUDE__RTC_SESSION__RTC_SESSION_H_ */

repos/os/src/drivers/rtc/main.cc

@@ -33,6 +33,13 @@ struct Rtc::Session_component : public Genode::Rpc_object<Session>
 {
 	Env &_env;
 
+	Signal_context_capability _set_sig_cap { };
+
+	void set_sigh(Signal_context_capability sigh) override
+	{
+		_set_sig_cap = sigh;
+	}
+
 	Timestamp current_time() override
 	{
 		Timestamp ret = Rtc::get_time(_env);