iommu/vt-d: Make intr-remapping initialization generic

This patch introduces irq_remap_ops to hold implementation
specific function pointer to handle interrupt remapping. As
the first part the initialization functions for VT-d are
converted to these ops.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index edc2448..1db6f63 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -35,6 +35,7 @@
 #include <linux/smp.h>
 #include <linux/mm.h>
 
+#include <asm/intr_remapping.h>
 #include <asm/perf_event.h>
 #include <asm/x86_init.h>
 #include <asm/pgalloc.h>
@@ -1528,7 +1529,7 @@
 		return -1;
 	}
 
-	return enable_intr_remapping();
+	return intr_hardware_enable();
 #endif
 	return -1;
 }
@@ -1537,10 +1538,13 @@
 {
 	unsigned long flags;
 	int ret, x2apic_enabled = 0;
-	int dmar_table_init_ret;
+	int hardware_init_ret;
 
-	dmar_table_init_ret = dmar_table_init();
-	if (dmar_table_init_ret && !x2apic_supported())
+	/* Make sure irq_remap_ops are initialized */
+	setup_intr_remapping();
+
+	hardware_init_ret = intr_hardware_init();
+	if (hardware_init_ret && !x2apic_supported())
 		return;
 
 	ret = save_ioapic_entries();
@@ -1556,7 +1560,7 @@
 	if (x2apic_preenabled && nox2apic)
 		disable_x2apic();
 
-	if (dmar_table_init_ret)
+	if (hardware_init_ret)
 		ret = -1;
 	else
 		ret = enable_IR();