irq_domain/mips: Allow irq_domain on MIPS

This patch makes IRQ_DOMAIN usable on MIPS.  It uses an ugly workaround
to preserve current behaviour so that MIPS has time to add irq_domain
registration to the irq controller drivers.  The workaround will be
removed in Linux v3.6
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org

arch/mips/Kconfig

@@ -2327,6 +2327,7 @@ config USE_OF
 	bool "Flattened Device Tree support"
 	select OF
 	select OF_EARLY_FLATTREE
+	select IRQ_DOMAIN
 	help
 	  Include support for flattened device tree machine descriptions.
 

arch/mips/include/asm/irq.h

@@ -11,15 +11,12 @@
 
 #include <linux/linkage.h>
 #include <linux/smp.h>
+#include <linux/irqdomain.h>
 
 #include <asm/mipsmtregs.h>
 
 #include <irq.h>
 
-static inline void irq_dispose_mapping(unsigned int virq)
-{
-}
-
 #ifdef CONFIG_I8259
 static inline int irq_canonicalize(int irq)
 {

arch/mips/kernel/prom.c

@@ -60,20 +60,6 @@ void __init early_init_dt_setup_initrd_arch(unsigned long start,
 }
 #endif
 
-/*
- * irq_create_of_mapping - Hook to resolve OF irq specifier into a Linux irq#
- *
- * Currently the mapping mechanism is trivial; simple flat hwirq numbers are
- * mapped 1:1 onto Linux irq numbers.  Cascaded irq controllers are not
- * supported.
- */
-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);
-
 void __init early_init_devtree(void *params)
 {
 	/* Setup flat device-tree pointer */

kernel/irq/irqdomain.c

@@ -411,6 +411,18 @@ unsigned int irq_create_of_mapping(struct device_node *controller,
 
 	domain = controller ? irq_find_host(controller) : irq_default_domain;
 	if (!domain) {
+#ifdef CONFIG_MIPS
+		/*
+		 * Workaround to avoid breaking interrupt controller drivers
+		 * that don't yet register an irq_domain.  This is temporary
+		 * code. ~~~gcl, Feb 24, 2012
+		 *
+		 * Scheduled for removal in Linux v3.6.  That should be enough
+		 * time.
+		 */
+		if (intsize > 0)
+			return intspec[0];
+#endif
 		printk(KERN_WARNING "irq: no irq domain found for %s !\n",
 		       controller->full_name);
 		return 0;