of: Add of_property_read_u16_index

There is an of_property_read_u32_index and of_property_read_u64_index.
This patch adds a similar helper for u16.

Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250319142059.46692-2-francesco@dolcini.it
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Ernest Van Hoecke

drivers/of/property.c

@@ -147,6 +147,39 @@ static void *of_find_property_value_of_size(const struct device_node *np,
 	return prop->value;
 }
 
+/**
+ * of_property_read_u16_index - Find and read a u16 from a multi-value property.
+ *
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @index:	index of the u16 in the list of values
+ * @out_value:	pointer to return value, modified only if no error.
+ *
+ * Search for a property in a device node and read nth 16-bit value from
+ * it.
+ *
+ * Return: 0 on success, -EINVAL if the property does not exist,
+ * -ENODATA if property does not have a value, and -EOVERFLOW if the
+ * property data isn't large enough.
+ *
+ * The out_value is modified only if a valid u16 value can be decoded.
+ */
+int of_property_read_u16_index(const struct device_node *np,
+				       const char *propname,
+				       u32 index, u16 *out_value)
+{
+	const u16 *val = of_find_property_value_of_size(np, propname,
+					((index + 1) * sizeof(*out_value)),
+					0, NULL);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	*out_value = be16_to_cpup(((__be16 *)val) + index);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_property_read_u16_index);
+
 /**
  * of_property_read_u32_index - Find and read a u32 from a multi-value property.
  *

include/linux/of.h

@@ -314,6 +314,9 @@ extern struct property *of_find_property(const struct device_node *np,
 extern bool of_property_read_bool(const struct device_node *np, const char *propname);
 extern int of_property_count_elems_of_size(const struct device_node *np,
 				const char *propname, int elem_size);
+extern int of_property_read_u16_index(const struct device_node *np,
+				       const char *propname,
+				       u32 index, u16 *out_value);
 extern int of_property_read_u32_index(const struct device_node *np,
 				       const char *propname,
 				       u32 index, u32 *out_value);
@@ -627,6 +630,12 @@ static inline int of_property_count_elems_of_size(const struct device_node *np,
 	return -ENOSYS;
 }
 
+static inline int of_property_read_u16_index(const struct device_node *np,
+			const char *propname, u32 index, u16 *out_value)
+{
+	return -ENOSYS;
+}
+
 static inline int of_property_read_u32_index(const struct device_node *np,
 			const char *propname, u32 index, u32 *out_value)
 {