[PATCH RFC net-next 03/13] net: eth: Add helpers to find DPLL pin firmware node

[Ivan Vecera <ivecera@redhat.com>]

Add helper functions to retrieve a DPLL pin's firmware node handle
based on the "dpll-pins" and "dpll-pin-names" device tree properties.

* fwnode_get_dpll_pin_node(): matches the given name against the
  "dpll-pin-names" property to find the correct index, then retrieves
  the reference from "dpll-pins".
* device_get_dpll_pin_node(): a wrapper around the fwnode helper for
  convenience when using a `struct device`.

These helpers simplify the process for Ethernet drivers to look up
their associated DPLL pins defined in the Device Tree, which can then
be passed to the DPLL subsystem to acquire the pin object.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
 include/linux/etherdevice.h |  4 ++++
 net/ethernet/eth.c          | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 9a1eacf35d370..e342e522ea0e8 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -35,6 +35,10 @@ int nvmem_get_mac_address(struct device *dev, void *addrbuf);
 int device_get_mac_address(struct device *dev, char *addr);
 int device_get_ethdev_address(struct device *dev, struct net_device *netdev);
 int fwnode_get_mac_address(struct fwnode_handle *fwnode, char *addr);
+struct fwnode_handle *fwnode_get_dpll_pin_node(struct fwnode_handle *fwnode,
+					       const char *name);
+struct fwnode_handle *device_get_dpll_pin_node(struct device *dev,
+					       const char *name);
 
 u32 eth_get_headlen(const struct net_device *dev, const void *data, u32 len);
 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 13a63b48b7eeb..9081dc02ba91e 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -639,3 +639,23 @@ int device_get_ethdev_address(struct device *dev, struct net_device *netdev)
 	return ret;
 }
 EXPORT_SYMBOL(device_get_ethdev_address);
+
+struct fwnode_handle *fwnode_get_dpll_pin_node(struct fwnode_handle *fwnode,
+					       const char *name)
+{
+	int index = 0;
+
+	if (name)
+		index = fwnode_property_match_string(fwnode, "dpll-pin-names",
+						     name);
+
+	return fwnode_find_reference(fwnode, "dpll-pins", index);
+}
+EXPORT_SYMBOL(fwnode_get_dpll_pin_node);
+
+struct fwnode_handle *device_get_dpll_pin_node(struct device *dev,
+					       const char *name)
+{
+	return fwnode_get_dpll_pin_node(dev_fwnode(dev), name);
+}
+EXPORT_SYMBOL(device_get_dpll_pin_node);
-- 
2.51.2