--- ztdummy.c	2007-03-23 10:15:40.000000000 +0100
+++ /home/karsten/src/zaptel-trunk/ztdummy.c	2007-03-23 09:26:20.000000000 +0100
@@ -82,6 +82,9 @@
 
 static int debug = 0;
 
+/* interrupt from extern module in use? */
+static int use_extern_interrupt = 0;
+
 #if defined(LINUX26) && defined(USE_RTC)
 static int rtc_rate = 0;
 static int current_rate = 0;
@@ -118,7 +121,6 @@
 
 #endif
 
-
 #ifdef LINUX26
 #ifdef USE_RTC
 static void update_rtc_rate(struct ztdummy *ztd)
@@ -215,7 +217,7 @@
 	return 0;
 }
 
-int init_module(void)
+int ztdummy_init_interrupts(void)
 {
 #ifdef LINUX26
 #ifdef USE_RTC
@@ -228,16 +230,6 @@
 #else
 	spinlock_t mylock = SPIN_LOCK_UNLOCKED;
 #endif
-	
-	if (uhci_devices==NULL) {
-		printk ("ztdummy: Uhci_devices pointer error.\n");
-		return -ENODEV;
-	}
-	s=*uhci_devices;	/* uhci device */
-	if (s==NULL) {
-		printk ("ztdummy: No uhci_device found.\n");
-		return -ENODEV;
-	}
 #endif
 
 	ztd = kmalloc(sizeof(struct ztdummy), GFP_KERNEL);
@@ -302,6 +294,102 @@
 #endif	
 
 	if (debug)
+		printk("ztdummy: Using internal time source\n");
+	return 0;
+}
+
+/* extern interrupt - called at 1000Hz for example from mISDN kernel module hfc_multi */
+static void ztdummy_extern_interrupt(void)
+{
+	zt_receive(&ztd->span);
+	zt_transmit(&ztd->span);
+}
+EXPORT_SYMBOL_GPL(ztdummy_extern_interrupt);
+
+/* function to register the interrupt from external module
+ * nothing more to do than to cancel the other interrupt routines */
+static void ztdummy_register_interrupt(void)
+{
+	/* to avoid second unregistration of old interrupts */
+	if(!use_extern_interrupt) {
+		use_extern_interrupt = 1;
+#ifdef LINUX26
+		try_module_get(THIS_MODULE);
+#ifdef USE_RTC
+		if (taskletpending) {
+			tasklet_disable(&ztd_tlet);
+			tasklet_kill(&ztd_tlet);
+		}
+		rtc_control(&ztd->rtc_task, RTC_PIE_OFF, 0);
+		rtc_unregister(&ztd->rtc_task);
+#else
+		del_timer(&timer);
+#endif
+#else
+		MOD_INC_USE_COUNT;
+		free_irq(s->irq, ztd);  /* disable interrupts */
+#endif
+		if(debug)
+			printk("ztdummy: Using external time source.\n");
+	}
+}
+EXPORT_SYMBOL_GPL(ztdummy_register_interrupt);
+
+/* function to unregister the interrupt from external module
+ * reactivate formerly used routines */
+static int ztdummy_unregister_interrupt(void)
+{
+	int err;
+
+	err = ztdummy_init_interrupts();
+	if(!err) {
+		use_extern_interrupt = 0;
+#ifdef LINUX26
+		module_put(THIS_MODULE);
+#else
+		MOD_DEC_USE_COUNT;
+#endif
+	}
+	
+	return err;
+}
+EXPORT_SYMBOL_GPL(ztdummy_unregister_interrupt);
+
+int init_module(void)
+{
+	int err;
+
+#ifndef LINUX26
+	if (uhci_devices==NULL) {
+		printk ("ztdummy: Uhci_devices pointer error.\n");
+		return -ENODEV;
+	}
+	s=*uhci_devices;	/* uhci device */
+	if (s==NULL) {
+		printk ("ztdummy: No uhci_device found.\n");
+		return -ENODEV;
+	}
+#endif
+
+	ztd = kmalloc(sizeof(struct ztdummy), GFP_KERNEL);
+	if (ztd == NULL) {
+		printk("ztdummy: Unable to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	memset(ztd, 0x0, sizeof(struct ztdummy));
+
+	if (ztdummy_initialize(ztd)) {
+		printk("ztdummy: Unable to intialize zaptel driver\n");
+		kfree(ztd);
+		return -ENODEV;
+	}
+	
+	/* unregister external interrupt means activate internal routines */
+	err = ztdummy_init_interrupts();
+	if (err) return err;
+
+	if (debug)
 		printk("ztdummy: init() finished\n");
 	return 0;
 }
@@ -309,20 +397,22 @@
 
 void cleanup_module(void)
 {
+	if(!use_extern_interrupt) {
 #ifdef LINUX26
 #ifdef USE_RTC
-	if (taskletpending) {
-		tasklet_disable(&ztd_tlet);
-		tasklet_kill(&ztd_tlet);
-	}
-	rtc_control(&ztd->rtc_task, RTC_PIE_OFF, 0);
-	rtc_unregister(&ztd->rtc_task);
+		if (taskletpending) {
+			tasklet_disable(&ztd_tlet);
+			tasklet_kill(&ztd_tlet);
+		}
+		rtc_control(&ztd->rtc_task, RTC_PIE_OFF, 0);
+		rtc_unregister(&ztd->rtc_task);
 #else
-	del_timer(&timer);
+		del_timer(&timer);
 #endif
 #else
-	free_irq(s->irq, ztd);  /* disable interrupts */
+		free_irq(s->irq, ztd);  /* disable interrupts */
 #endif
+	}
 	zt_unregister(&ztd->span);
 	kfree(ztd);
 #ifndef LINUX26