[RFC PATCH V2 7/8] xen: introduce interfaces to register N-level event channel

[Wei Liu <wei.liu2@citrix.com>]

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 drivers/xen/events.c |   46 +++++++++++++++++++++++++++++++++++-----------
 include/xen/events.h |    6 ++++++
 2 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index cbb10ed..76ff48c 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -2178,6 +2178,26 @@ static struct evtchn_ops evtchn_ops_l3 __read_mostly = {
 	.debug_interrupt   = debug_interrupt_l3,
 };
 
+void xen_set_event_channel_nlevel(unsigned int level)
+{
+	switch (level) {
+	case 2:
+		evtchn_level = 2;
+		nr_event_channels = NR_EVENT_CHANNELS_L2;
+		eops = &evtchn_ops_l2;
+		break;
+	case 3:
+		evtchn_level = 3;
+		nr_event_channels = NR_EVENT_CHANNELS_L3;
+		eops = &evtchn_ops_l3;
+		break;
+	default:
+		printk(KERN_EMERG "Trying to set unsupported %d-level event channel\n",
+		       level);
+		BUG();
+	}
+}
+
 static int xen_event_channel_register_3level(void)
 {
 	evtchn_register_nlevel_t reg;
@@ -2249,24 +2269,28 @@ out:
 	return rc;
 }
 
-void __init xen_init_IRQ(void)
+int xen_event_channel_register_nlevel(unsigned int level)
 {
-	int i, rc;
-	int cpu;
+	int rc;
 
-	switch (evtchn_level) {
-	case 2:
-		nr_event_channels = NR_EVENT_CHANNELS_L2;
-		eops = &evtchn_ops_l2;
-		break;
+	switch (level) {
 	case 3:
-		nr_event_channels = NR_EVENT_CHANNELS_L3;
-		eops = &evtchn_ops_l3;
+		rc = xen_event_channel_register_3level();
 		break;
 	default:
-		BUG();
+		printk(KERN_INFO "Trying to register unsupported %d-level event channel\n",
+		       level);
+		rc = -EINVAL;
 	}
 
+	return rc;
+}
+
+void __init xen_init_IRQ(void)
+{
+	int i, rc;
+	int cpu;
+
 	/* Setup 2-level event channel */
 	evtchn_to_irq = kcalloc(nr_event_channels, sizeof(*evtchn_to_irq),
 				GFP_KERNEL);
diff --git a/include/xen/events.h b/include/xen/events.h
index 04399b2..3c1708f 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -109,4 +109,10 @@ int xen_irq_from_gsi(unsigned gsi);
 /* Determine whether to ignore this IRQ if it is passed to a guest. */
 int xen_test_irq_shared(int irq);
 
+/* Register N-level event channel. */
+int xen_event_channel_register_nlevel(unsigned int level);
+
+/* Set event channel to N-level if registration succeed. */
+void xen_set_event_channel_nlevel(unsigned int level);
+
 #endif	/* _XEN_EVENTS_H */
-- 
1.7.10.4