x86, of: Define irq functions to allow drivers/of/* to build on x86

- Define a stub irq_create_of_mapping for x86 as a stop-gap solution until
   drivers/of/irq is further along.
 - Define irq_dispose_mapping for x86 to appease of_i2c.c

These are needed to allow stuff in drivers/of/ to build on x86.  This stuff
will eventually get replaced; quoting Grant,

"The long term plan is to have the drivers/of/ code handling the mapping
intelligently like powerpc currently does."  But for now, just provide
these functions.

Signed-off-by: Andres Salomon <dilinger@queued.net>
LKML-Reference: <20101111214526.5de7121b@queued.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/irq.h

@@ -10,6 +10,9 @@
 #include <asm/apicdef.h>
 #include <asm/irq_vectors.h>
 
+/* Even though we don't support this, supply it to appease OF */
+static inline void irq_dispose_mapping(unsigned int virq) { }
+
 static inline int irq_canonicalize(int irq)
 {
 	return ((irq == 2) ? 9 : irq);

arch/x86/kernel/irq.c

@@ -4,6 +4,7 @@
 #include <linux/cpu.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
+#include <linux/of.h>
 #include <linux/seq_file.h>
 #include <linux/smp.h>
 #include <linux/ftrace.h>
@@ -275,6 +276,15 @@ void smp_x86_platform_ipi(struct pt_regs *regs)
 
 EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
 
+#ifdef CONFIG_OF
+unsigned int irq_create_of_mapping(struct device_node *controller,
+		const u32 *intspec, unsigned int intsize)
+{
+	return intspec[0];
+}
+EXPORT_SYMBOL_GPL(irq_create_of_mapping);
+#endif
+
 #ifdef CONFIG_HOTPLUG_CPU
 /* A cpu has been removed from cpu_online_mask.  Reset irq affinities. */
 void fixup_irqs(void)