of: base: Add of_property_read_u8_index

Add support for of_property_read_u8_index(), simillar to others
u16 and u32 variants. Having this helper makes the code more tidy in
isome cases, specially when we are parsing multiple of these into
data structures.

Signed-off-by: Srinivas Kandagatla <[e-mail]>
Reviewed-by: Rob Herring (Arm) <[e-mail]>
Tested-by: Alexey Klimov <[e-mail]> # sm8550
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/of/property.c

···
 }
 
 /**
+ * of_property_read_u8_index - Find and read a u8 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 u8 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 8-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 u8 value can be decoded.
+ */
+int of_property_read_u8_index(const struct device_node *np,
+				       const char *propname,
+				       u32 index, u8 *out_value)
+{
+	const u8 *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 = val[index];
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_property_read_u8_index);
+
+/**
  * 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.

include/linux/of.h

···
 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_u8_index(const struct device_node *np,
+				       const char *propname,
+				       u32 index, u8 *out_value);
 extern int of_property_read_u16_index(const struct device_node *np,
 				       const char *propname,
 				       u32 index, u16 *out_value);
···
 
 static inline int of_property_count_elems_of_size(const struct device_node *np,
 			const char *propname, int elem_size)
+{
+	return -ENOSYS;
+}
+
+static inline int of_property_read_u8_index(const struct device_node *np,
+			const char *propname, u32 index, u8 *out_value)
 {
 	return -ENOSYS;
 }