of/irq: Add interrupts-names property to name an irq resource

Add a interrupts-names property to allow the possibility to provide a name
to any interrupts entries.  If the name is available, use it to name the
resource, otherwise keep the device full name.
Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
[grant.likely: use "interrupt-names" and tidy documentation]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Documentation/devicetree/bindings/resource-names.txt

@@ -32,6 +32,8 @@ l4-abe {
 		      <1 0x10 0x10>, <1 0x20 0x10>;
 		reg-names = "mpu", "dat",
 			    "dma", "dma_dat";
+		interrupts = <11>, <12>;
+		interrupt-names = "rx", "tx";
 	};
 
 	timer {
@@ -47,4 +49,6 @@ usb {
 	reg = <0x4a064000 0x800>, <0x4a064800 0x200>,
 	      <0x4a064c00 0x200>;
 	reg-names = "config", "ohci", "ehci";
+	interrupts = <14>, <15>;
+	interrupt-names = "ohci", "ehci";
 };

drivers/of/irq.c

@@ -341,9 +341,18 @@ int of_irq_to_resource(struct device_node *dev, int index, struct resource *r)
 	/* Only dereference the resource if both the
 	 * resource and the irq are valid. */
 	if (r && irq) {
+		const char *name = NULL;
+
+		/*
+		 * Get optional "interrupts-names" property to add a name
+		 * to the resource.
+		 */
+		of_property_read_string_index(dev, "interrupt-names", index,
+					      &name);
+
 		r->start = r->end = irq;
 		r->flags = IORESOURCE_IRQ;
-		r->name = dev->full_name;
+		r->name = name ? name : dev->full_name;
 	}
 
 	return irq;