genirq: Move non-irqdomain handle_domain_irq() handling into ARM's handle_IRQ()

Despite the name, handle_domain_irq() deals with non-irqdomain
handling for the sake of a handful of legacy ARM platforms.

Move such handling into ARM's handle_IRQ(), allowing for better
code generation for everyone else. This allows us get rid of
some complexity, and to rearrange the guards on the various helpers
in a more logical way.

Signed-off-by: Marc Zyngier <[e-mail]>

arch/arm/kernel/irq.c

···
  */
 void handle_IRQ(unsigned int irq, struct pt_regs *regs)
 {
-	__handle_domain_irq(NULL, irq, false, regs);
+	struct pt_regs *old_regs = set_irq_regs(regs);
+	struct irq_desc *desc;
+
+	irq_enter();
+
+	/*
+	 * Some hardware gives randomly wrong interrupts.  Rather
+	 * than crashing, do something sensible.
+	 */
+	if (unlikely(!irq || irq >= nr_irqs))
+		desc = NULL;
+	else
+		desc = irq_to_desc(irq);
+
+	if (likely(desc))
+		handle_irq_desc(desc);
+	else
+		ack_bad_irq(irq);
+
+	irq_exit();
+	set_irq_regs(old_regs);
 }
 
 /*

include/linux/irqdesc.h

···
 int handle_irq_desc(struct irq_desc *desc);
 int generic_handle_irq(unsigned int irq);
 
-#ifdef CONFIG_HANDLE_DOMAIN_IRQ
+#ifdef CONFIG_IRQ_DOMAIN
 /*
  * Convert a HW interrupt number to a logical one using a IRQ domain,
  * and handle the result interrupt number. Return -EINVAL if
  * conversion failed.
  */
-int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
-			bool lookup, struct pt_regs *regs);
-
 int generic_handle_domain_irq(struct irq_domain *domain, unsigned int hwirq);
 
-static inline int handle_domain_irq(struct irq_domain *domain,
-				    unsigned int hwirq, struct pt_regs *regs)
-{
-	return __handle_domain_irq(domain, hwirq, true, regs);
-}
+#ifdef CONFIG_HANDLE_DOMAIN_IRQ
+int handle_domain_irq(struct irq_domain *domain,
+		      unsigned int hwirq, struct pt_regs *regs);
 
-#ifdef CONFIG_IRQ_DOMAIN
 int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
 		      struct pt_regs *regs);
 #endif

kernel/irq/irqdesc.c

···
 }
 EXPORT_SYMBOL_GPL(generic_handle_irq);
 
-#ifdef CONFIG_HANDLE_DOMAIN_IRQ
+#ifdef CONFIG_IRQ_DOMAIN
 /**
  * generic_handle_domain_irq - Invoke the handler for a HW irq belonging
  *                             to a domain, usually for a non-root interrupt
···
 }
 EXPORT_SYMBOL_GPL(generic_handle_domain_irq);
 
+#ifdef CONFIG_HANDLE_DOMAIN_IRQ
 /**
- * __handle_domain_irq - Invoke the handler for a HW irq belonging to a domain,
- *                       usually for a root interrupt controller
+ * handle_domain_irq - Invoke the handler for a HW irq belonging to a domain,
+ *                     usually for a root interrupt controller
  * @domain:	The domain where to perform the lookup
  * @hwirq:	The HW irq number to convert to a logical one
  * @lookup:	Whether to perform the domain lookup or not
···
  *
  * Returns:	0 on success, or -EINVAL if conversion has failed
  */
-int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
-			bool lookup, struct pt_regs *regs)
+int handle_domain_irq(struct irq_domain *domain,
+		      unsigned int hwirq, struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
 	struct irq_desc *desc;
···
 
 	irq_enter();
 
-	if (likely(IS_ENABLED(CONFIG_IRQ_DOMAIN) && lookup)) {
-		/* The irqdomain code provides boundary checks */
-		desc = irq_resolve_mapping(domain, hwirq);
-	} else {
-		/*
-		 * Some hardware gives randomly wrong interrupts.  Rather
-		 * than crashing, do something sensible.
-		 */
-		if (unlikely(!hwirq || hwirq >= nr_irqs)) {
-			ack_bad_irq(hwirq);
-			desc = NULL;
-		} else {
-			desc = irq_to_desc(hwirq);
-		}
-	}
-
+	/* The irqdomain code provides boundary checks */
+	desc = irq_resolve_mapping(domain, hwirq);
 	if (likely(desc))
 		handle_irq_desc(desc);
 	else
···
 	return ret;
 }
 
-#ifdef CONFIG_IRQ_DOMAIN
 /**
  * handle_domain_nmi - Invoke the handler for a HW irq belonging to a domain
  * @domain:	The domain where to perform the lookup