alarmtimers: Fix error handling

commit 8bc0dafb (alarmtimers: Rework RTC device selection using class
interface) did not implement required error checks. Add them.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

kernel/time/alarmtimer.c

@@ -100,19 +100,25 @@ static struct class_interface alarmtimer_rtc_interface = {
 	.add_dev = &alarmtimer_rtc_add_device,
 };
 
-static void alarmtimer_rtc_interface_setup(void)
+static int alarmtimer_rtc_interface_setup(void)
 {
 	alarmtimer_rtc_interface.class = rtc_class;
-	class_interface_register(&alarmtimer_rtc_interface);
+	return class_interface_register(&alarmtimer_rtc_interface);
+}
+static void alarmtimer_rtc_interface_remove(void)
+{
+	class_interface_unregister(&alarmtimer_rtc_interface);
 }
 #else
-#define alarmtimer_get_rtcdev() (0)
-#define rtcdev (0)
-#define alarmtimer_rtc_interface_setup()
+static inline struct rtc_device *alarmtimer_get_rtcdev(void)
+{
+	return NULL;
+}
+#define rtcdev (NULL)
+static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
+static inline void alarmtimer_rtc_interface_remove(void) { }
 #endif
 
-
-
 /**
  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
  * @base: pointer to the base where the timer is being run
@@ -764,6 +770,7 @@ static struct platform_driver alarmtimer_driver = {
  */
 static int __init alarmtimer_init(void)
 {
+	struct platform_device *pdev;
 	int error = 0;
 	int i;
 	struct k_clock alarm_clock = {
@@ -793,11 +800,25 @@ static int __init alarmtimer_init(void)
 		alarm_bases[i].timer.function = alarmtimer_fired;
 	}
 
-	alarmtimer_rtc_interface_setup();
+	error = alarmtimer_rtc_interface_setup();
+	if (error)
+		return error;
+
 	error = platform_driver_register(&alarmtimer_driver);
-	platform_device_register_simple("alarmtimer", -1, NULL, 0);
+	if (error)
+		goto out_if;
 
+	pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
+	if (IS_ERR(pdev)) {
+		error = PTR_ERR(pdev);
+		goto out_drv;
+	}
+	return 0;
+
+out_drv:
+	platform_driver_unregister(&alarmtimer_driver);
+out_if:
+	alarmtimer_rtc_interface_remove();
 	return error;
 }
 device_initcall(alarmtimer_init);
-