[RFC PATCH 2/4] device property: Introduce helper device_get_reference_node()

Kefeng Wang
2015-12-02T09:12:21Z

With of_parse_phandle() and acpi_dev_get_reference_device(), we can introduce
a universal helper device_get_reference_node() to read and parse a device
property and return a pointer to the resulting firmware node.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
drivers/base/property.c | 40 ++++++++++++++++++++++++++++++++++++++++
include/linux/property.h | 6 ++++++
2 files changed, 46 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 1325ff2..6517140 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -568,6 +568,46 @@ struct fwnode_handle *device_get_next_child_node(struct device *dev,
EXPORT_SYMBOL_GPL(device_get_next_child_node);

/**
+ * fwnode_get_reference_node - Find the firmware node referenced
+ * @fwnode: Firmware node to get the property from.
+ * @propname: Name of the property
+ * @index: Index of the reference
+ *
+ * Returns referenced fwnode handler pointer, or an NULL if not found
+ */
+struct fwnode_handle *fwnode_get_reference_node(struct fwnode_handle *fwnode,
+ const char *propname, int index)
+{
+ if (is_of_node(fwnode)) {
+ struct device_node *np;
+ np = of_parse_phandle(to_of_node(fwnode), propname, index);
+ return np ? &np->fwnode : NULL;
+ } else if (is_acpi_node(fwnode)) {
+ struct acpi_device *adev;
+ adev = acpi_dev_get_reference_device(to_acpi_device_node(fwnode),
+ propname, index);
+ return adev ? acpi_fwnode_handle(adev) : NULL;
+ }
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_reference_node);
+
+/**
+ * dev_get_reference_node - Find the firmware node referenced
+ * @dev: Device to get the property from.
+ * @propname: Name of the property
+ * @index: Index of the reference
+ *
+ * Returns referenced fwnode handler pointer, or an NULL if not found
+ */
+struct fwnode_handle *device_get_reference_node(struct device *dev,
+ const char *propname, int index)
+{
+ return fwnode_get_reference_node(dev_fwnode(dev), propname, index);
+}
+EXPORT_SYMBOL_GPL(device_get_reference_node);
+
+/**
* fwnode_handle_put - Drop reference to a device node
* @fwnode: Pointer to the device node to drop the reference to.
*
diff --git a/include/linux/property.h b/include/linux/property.h
index 0a3705a..d77e6a2 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -70,6 +70,12 @@ int fwnode_property_read_string(struct fwnode_handle *fwnode,
int fwnode_property_match_string(struct fwnode_handle *fwnode,
const char *propname, const char *string);

+struct fwnode_handle *fwnode_get_reference_node(struct fwnode_handle *fwnode,
+ const char *propname, int index);
+
+struct fwnode_handle *device_get_reference_node(struct device *dev,
+ const char *propname, int index);
+
struct fwnode_handle *device_get_next_child_node(struct device *dev,
struct fwnode_handle *child);

--
1.7.12.4