[PATCH v2 2/2] dt/irq: add irq_domain_generate_simple() helper

[Grant Likely]

irq_domain_generate_simple() is an easy way to generate an irq translation
domain for simple irq controllers.  It assumes a flat 1:1 mapping from
hardware irq number to an offset of the first linux irq number assigned
to the controller

Signed-off-by: Grant Likely <grant.likely at secretlab.ca>
---
 include/linux/irq.h    |   11 ++++++++++
 kernel/irq/irqdomain.c |   55 +++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 65 insertions(+), 1 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index a103c01..3e5c35f 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -797,6 +797,17 @@ extern unsigned int irq_domain_map(struct irq_domain *domain,
 				   irq_hw_number_t hwirq);
 extern void irq_domain_unmap(struct irq_domain *domain, irq_hw_number_t hw);
 
+struct of_device_id;
+#ifdef CONFIG_OF
+extern void irq_domain_add_simple(struct device_node *controller, int irq_base);
+extern void irq_domain_generate_simple(const struct of_device_id *match,
+					u64 phys_base, unsigned int irq_start);
+#else
+static inline void irq_domain_generate_simple(const struct of_device_id *match,
+					u64 phys_base, unsigned int irq_start) { }
+#endif
+
+
 #endif /* !CONFIG_S390 */
 
 #endif /* _LINUX_IRQ_H */
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index a7cc910..7e251cd 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1,8 +1,9 @@
-
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
 
 static LIST_HEAD(irq_domain_list);
 static DEFINE_MUTEX(irq_domain_mutex);
@@ -159,4 +160,56 @@ void irq_dispose_mapping(unsigned int irq)
 }
 EXPORT_SYMBOL_GPL(irq_dispose_mapping);
 
+int irq_domain_simple_dt_translate(struct irq_domain *d,
+			    struct device_node *controller,
+			    const u32 *intspec, unsigned int intsize,
+			    irq_hw_number_t *out_hwirq, unsigned int *out_type)
+{
+	if (d->of_node != controller)
+		return -EINVAL;
+	if (intsize != 1)
+		return -EINVAL;
+
+	*out_hwirq = intspec[0];
+	*out_type = IRQ_TYPE_NONE;
+	return 0;
+}
+
+struct irq_domain_ops irq_domain_simple_ops = {
+	.dt_translate = irq_domain_simple_dt_translate,
+};
+
+/**
+ * irq_domain_create_simple() - Set up a 'simple' translation range
+ */
+void irq_domain_add_simple(struct device_node *controller, int irq_base)
+{
+	struct irq_domain *domain;
+
+	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+	if (!domain) {
+		WARN_ON(1);
+		return;
+	}
+
+	domain->irq_base = irq_base;
+	domain->of_node = of_node_get(controller);
+	domain->ops = &irq_domain_simple_ops;
+	irq_domain_add(domain);
+}
+EXPORT_SYMBOL_GPL(irq_domain_add_simple);
+
+void irq_domain_generate_simple(const struct of_device_id *match,
+				u64 phys_base, unsigned int irq_start)
+{
+	struct device_node *node;
+	pr_info("looking for phys_base=%llx, irq_start=%i\n",
+		(unsigned long long) phys_base, (int) irq_start);
+	node = of_find_matching_node_by_address(NULL, match, phys_base);
+	if (node)
+		irq_domain_add_simple(node, irq_start);
+	else
+		pr_info("no node found\n");
+}
+EXPORT_SYMBOL_GPL(irq_domain_generate_simple);
 #endif