hvc_console: Add a hangup notifier for backends

I have added a hangup notifier that can be used by hvc console
backends to handle a tty hangup. The default irq hangup notifier
calls the notifier_del_irq() for compatibility.

Acked-by: Christian Borntraeger <[e-mail]>
Signed-off-by: Hendrik Brueckner <[e-mail]>
Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

drivers/char/hvc_console.c

···
 
 	spin_unlock_irqrestore(&hp->lock, flags);
 
-	if (hp->ops->notifier_del)
-			hp->ops->notifier_del(hp, hp->data);
+	if (hp->ops->notifier_hangup)
+			hp->ops->notifier_hangup(hp, hp->data);
 
 	while(temp_open_count) {
 		--temp_open_count;

drivers/char/hvc_console.h

···
 	int (*get_chars)(uint32_t vtermno, char *buf, int count);
 	int (*put_chars)(uint32_t vtermno, const char *buf, int count);
 
-	/* Callbacks for notification. Called in open and close */
+	/* Callbacks for notification. Called in open, close and hangup */
 	int (*notifier_add)(struct hvc_struct *hp, int irq);
 	void (*notifier_del)(struct hvc_struct *hp, int irq);
+	void (*notifier_hangup)(struct hvc_struct *hp, int irq);
 };
 
 /* Register a vterm and a slot index for use as a console (console_init) */
···
 /* default notifier for irq based notification */
 extern int notifier_add_irq(struct hvc_struct *hp, int data);
 extern void notifier_del_irq(struct hvc_struct *hp, int data);
+extern void notifier_hangup_irq(struct hvc_struct *hp, int data);
 
 
 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)

drivers/char/hvc_irq.c

···
 	free_irq(irq, hp);
 	hp->irq_requested = 0;
 }
+
+void notifier_hangup_irq(struct hvc_struct *hp, int irq)
+{
+	notifier_del_irq(hp, irq);
+}

drivers/char/hvc_iseries.c

···
 	.put_chars = put_chars,
 	.notifier_add = notifier_add_irq,
 	.notifier_del = notifier_del_irq,
+	.notifier_hangup = notifier_hangup_irq,
 };
 
 static int __devinit hvc_vio_probe(struct vio_dev *vdev,

drivers/char/hvc_vio.c

···
 	.put_chars = hvc_put_chars,
 	.notifier_add = notifier_add_irq,
 	.notifier_del = notifier_del_irq,
+	.notifier_hangup = notifier_hangup_irq,
 };
 
 static int __devinit hvc_vio_probe(struct vio_dev *vdev,

drivers/char/hvc_xen.c

···
 	.put_chars = write_console,
 	.notifier_add = notifier_add_irq,
 	.notifier_del = notifier_del_irq,
+	.notifier_hangup = notifier_hangup_irq,
 };
 
 static int __init xen_init(void)

drivers/char/virtio_console.c

···
 	virtio_cons.put_chars = put_chars;
 	virtio_cons.notifier_add = notifier_add_vio;
 	virtio_cons.notifier_del = notifier_del_vio;
+	virtio_cons.notifier_hangup = notifier_del_vio;
 
 	/* The first argument of hvc_alloc() is the virtual console number, so
 	 * we use zero.  The second argument is the parameter for the