Add wake capability information to the IRQ resource. Wake capability is
assumed based on conventions provided in the devicetree wakeup-source
binding documentation. An interrupt is considered wake capable if the
following are true:
1. A wakeup-source property exits in the same device node as the
   interrupt.
2. The IRQ is marked as dedicated by setting its interrupt-name to
   "wakeup".

The wakeup-source documentation states that dedicated interrupts can use
device specific interrupt names and device drivers are still welcome to
use their own naming schemes. This API is provided as a helper if one is
willing to conform to the above conventions.

The ACPI subsystems already provides similar APIs that allow one to
query the wake capability of an IRQ. This brings closer feature parity
to the devicetree.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Hasemeyer <markhas@chromium.org>
---

Changes in v4:
-Add Rob's Reviewed-by tag from v2
-Ignored Andy's Reviewed-by tag per his request:
https://lore.kernel.org/all/ZYxgQn8L7ENkc0AJ@smile.fi.intel.com/

Changes in v3:
-Use DEFINE_RES_IRQ_NAMED_FLAGS macro

Changes in v2:
-Update logic to return true only if wakeup-source property and
 "wakeup" interrupt-name are defined
-irq->IRQ, api->API

 drivers/of/irq.c | 39 +++++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 174900072c18c..cdecdc3515f88 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -383,11 +383,39 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
 }
 EXPORT_SYMBOL_GPL(of_irq_parse_one);
 
+/**
+ * __of_irq_wake_capable - Determine whether a given IRQ index is wake capable
+ *
+ * The IRQ is considered wake capable if the following are true:
+ * 1. wakeup-source property exists
+ * 2. provided IRQ index is labelled as a dedicated wakeirq
+ *
+ * This logic assumes the provided IRQ index is valid.
+ *
+ * @dev: pointer to device tree node
+ * @index: zero-based index of the IRQ
+ * Return: True if provided IRQ index for #dev is wake capable. False otherwise.
+ */
+static bool __of_irq_wake_capable(const struct device_node *dev, int index)
+{
+	int wakeindex;
+
+	if (!of_property_read_bool(dev, "wakeup-source"))
+		return false;
+
+	wakeindex = of_property_match_string(dev, "interrupt-names", "wakeup");
+	return wakeindex >= 0 && wakeindex == index;
+}
+
 /**
  * of_irq_to_resource - Decode a node's IRQ and return it as a resource
  * @dev: pointer to device tree node
- * @index: zero-based index of the irq
+ * @index: zero-based index of the IRQ
  * @r: pointer to resource structure to return result into.
+ *
+ * Return: Linux IRQ number on success, or 0 on the IRQ mapping failure, or
+ * -EPROBE_DEFER if the IRQ domain is not yet created, or error code in case
+ * of any other failure.
  */
 int of_irq_to_resource(struct device_node *dev, int index, struct resource *r)
 {
@@ -399,6 +427,7 @@ 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) {
+		u32 irq_flags;
 		const char *name = NULL;
 
 		memset(r, 0, sizeof(*r));
@@ -409,9 +438,11 @@ int of_irq_to_resource(struct device_node *dev, int index, struct resource *r)
 		of_property_read_string_index(dev, "interrupt-names", index,
 					      &name);
 
-		r->start = r->end = irq;
-		r->flags = IORESOURCE_IRQ | irqd_get_trigger_type(irq_get_irq_data(irq));
-		r->name = name ? name : of_node_full_name(dev);
+		irq_flags = irqd_get_trigger_type(irq_get_irq_data(irq));
+		if (__of_irq_wake_capable(dev, index))
+			irq_flags |= IORESOURCE_IRQ_WAKECAPABLE;
+
+		*r = DEFINE_RES_IRQ_NAMED_FLAGS(irq, name ?: of_node_full_name(dev), irq_flags);
 	}
 
 	return irq;
-- 
2.43.0.472.g3155946c3a-goog