[PATCH v4 1/3] device property: Add fwnode_irq_get_byname

[Akhil R <akhilrajeev@nvidia.com>]

Add fwnode_irq_get_byname() to get an interrupt by name from either
ACPI table or Device Tree, whichever is used for enumeration.

In the ACPI case, this allow us to use 'interrupt-names' in
_DSD which can be mapped to Interrupt() resource by index.
The implementation is similar to 'interrupt-names' in the
Device Tree.

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
 drivers/base/property.c  | 29 +++++++++++++++++++++++++++++
 include/linux/property.h |  1 +
 2 files changed, 30 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index e6497f6..fc59e0f 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -936,6 +936,35 @@ void __iomem *fwnode_iomap(struct fwnode_handle *fwnode, int index)
 EXPORT_SYMBOL(fwnode_iomap);
 
 /**
+ * fwnode_irq_get_byname - Get IRQ from a fwnode using its name
+ * @fwnode:	Pointer to the firmware node
+ * @name:	IRQ name
+ *
+ * Description:
+ * Find a match to the string @name in the 'interrupt-names' string array
+ * in _DSD for ACPI, or of_node for Device Tree. Then get the Linux IRQ
+ * number of the IRQ resource corresponding to the index of the matched
+ * string.
+ *
+ * Return:
+ * Linux IRQ number on success, or negative errno otherwise.
+ */
+int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name)
+{
+	int index;
+
+	if (!name)
+		return -EINVAL;
+
+	index = fwnode_property_match_string(fwnode, "interrupt-names",  name);
+	if (index < 0)
+		return index;
+
+	return fwnode_irq_get(fwnode, index);
+}
+EXPORT_SYMBOL(fwnode_irq_get_byname);
+
+/**
  * fwnode_graph_get_next_endpoint - Get next endpoint firmware node
  * @fwnode: Pointer to the parent firmware node
  * @prev: Previous endpoint node or %NULL to get the first
diff --git a/include/linux/property.h b/include/linux/property.h
index 7399a0b..95d56a5 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -121,6 +121,7 @@ struct fwnode_handle *fwnode_handle_get(struct fwnode_handle *fwnode);
 void fwnode_handle_put(struct fwnode_handle *fwnode);
 
 int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index);
+int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
 
 void __iomem *fwnode_iomap(struct fwnode_handle *fwnode, int index);
 
-- 
2.7.4