[PATCH 6/8] irqdomain: Support identity mapped VIRQ allocation.

[Paul Mundt <lethal@linux-sh.org>]

This adds a new irq_create_identity_mapping() routine to permit platforms
to utilize 1:1 identity mapping between hardware and linux IRQs for
domain population. The same semantics as irq_create_mapping() apply,
though in this case we only support irqdesc allocation at a static
location, rather than falling back on dynamic lookup.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
---
 include/linux/irqdomain.h |    2 ++
 kernel/irq/irqdomain.c    |   41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 0 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 5abb533..e32d2e7 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -149,6 +149,8 @@ extern unsigned int irq_create_mapping(struct irq_domain *host,
 extern void irq_dispose_mapping(unsigned int virq);
 extern unsigned int irq_find_mapping(struct irq_domain *host,
 				     irq_hw_number_t hwirq);
+extern unsigned int irq_create_identity_mapping(struct irq_domain *host,
+						irq_hw_number_t hwirq);
 extern unsigned int irq_create_direct_mapping(struct irq_domain *host);
 extern void irq_radix_revmap_insert(struct irq_domain *host, unsigned int virq,
 				    irq_hw_number_t hwirq);
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 5f0ca52..ac44781 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -459,6 +459,47 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
 }
 EXPORT_SYMBOL_GPL(irq_create_mapping);
 
+/**
+ * irq_create_identity_mapping() - Allocate an identity mapped irq
+ * @domain: domain owning this hardware interrupt or NULL for default domain
+ * @hwirq: hardware irq number in that domain space
+ *
+ * This routine is used to allocate IRQs with a 1:1 identity mapping
+ * between the hardware and linux irq.
+ */
+unsigned int irq_create_identity_mapping(struct irq_domain *domain,
+					 irq_hw_number_t hwirq)
+{
+	int virq;
+
+	pr_debug("irq: irq_create_identity_mapping(0x%p, 0x%lx)\n",
+		 domain, hwirq);
+
+	if (domain == NULL)
+		domain = irq_default_domain;
+	if (domain == NULL) {
+		WARN_ON(1);
+		return 0;
+	}
+
+	virq = irq_alloc_desc_at(hwirq, irq_domain_nid(domain->of_node));
+	if (virq < 0) {
+		pr_debug("irq: -> virq allocation failed\n");
+		return 0;
+	}
+
+	if (irq_setup_virq(domain, virq, hwirq)) {
+		if (domain->revmap_type != IRQ_DOMAIN_MAP_LEGACY)
+			irq_free_desc(virq);
+		return 0;
+	}
+
+	pr_debug("irq: irq %lu identity mapped\n", hwirq);
+
+	return virq;
+}
+EXPORT_SYMBOL_GPL(irq_create_identity_mapping);
+
 unsigned int irq_create_of_mapping(struct device_node *controller,
 				   const u32 *intspec, unsigned int intsize)
 {
-- 
1.7.9.rc0.28.g0e1cf