tty/hvc_opal: Kick the HVC thread on OPAL console events

The firmware can notify us when new input data is available, so
let's make sure we wakeup the HVC thread in that case.

Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

drivers/tty/hvc/hvc_opal.c

···
 /* For early boot console */
 static struct hvc_opal_priv hvc_opal_boot_priv;
 static u32 hvc_opal_boot_termno;
+static bool hvc_opal_event_registered;
 
 static const struct hv_ops hvc_opal_raw_ops = {
 	.get_chars = opal_get_chars,
···
 	.tiocmset = hvc_opal_hvsi_tiocmset,
 };
 
+static int hvc_opal_console_event(struct notifier_block *nb,
+				  unsigned long events, void *change)
+{
+	if (events & OPAL_EVENT_CONSOLE_INPUT)
+		hvc_kick();
+	return 0;
+}
+
+static struct notifier_block hvc_opal_console_nb = {
+	.notifier_call	= hvc_opal_console_event,
+};
+
 static int hvc_opal_probe(struct platform_device *dev)
 {
 	const struct hv_ops *ops;
···
 	hv_protocol_t proto;
 	unsigned int termno, boot = 0;
 	const __be32 *reg;
+
 
 	if (of_device_is_compatible(dev->dev.of_node, "ibm,opal-console-raw")) {
 		proto = HV_PROTOCOL_RAW;
···
 		dev->dev.of_node->full_name,
 		boot ? " (boot console)" : "");
 
-	/* We don't do IRQ yet */
+	/* We don't do IRQ ... */
 	hp = hvc_alloc(termno, 0, ops, MAX_VIO_PUT_CHARS);
 	if (IS_ERR(hp))
 		return PTR_ERR(hp);
 	dev_set_drvdata(&dev->dev, hp);
+
+	/* ...  but we use OPAL event to kick the console */
+	if (!hvc_opal_event_registered) {
+		opal_notifier_register(&hvc_opal_console_nb);
+		hvc_opal_event_registered = true;
+	}
 
 	return 0;
 }