[PATCH net-next v3 2/4] net: mdio: link PHY package suppliers to member PHYs

[James Hilliard <james.hilliard1@gmail.com>]

Ethernet PHY package nodes describe resources shared by their member
PHYs, but a package node is not instantiated as a device. Its
firmware-node supplier links therefore cannot become normal device links
for the PHY members without help from the MDIO layer.

When registering an OF-backed PHY whose parent is an
ethernet-phy-package node, copy the package supplier links onto the
member's firmware node before the PHY device is added. The ordinary
fw_devlink path then creates managed links after the PHY device has been
initialized for link registration and before its driver can probe.

Apply this to both ordinary OF discovery and the exported registration
path for a pre-created PHY device. Leave the package links intact so
every member, including one registered later, can acquire the same
dependencies. This preserves probe, unbind and runtime-PM ordering
without adding PHY-package policy to generic firmware parsing.

Fixes: 385ef48f4686 ("net: phy: add support for scanning PHY in PHY packages nodes")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>

---
Changes v2 -> v3:
  - Move PHY-package handling out of generic OF property parsing and into
    OF MDIO registration, as suggested by Saravana Kannan
  - Copy package supplier links before device_add() so the normal
    fw_devlink path creates real member links at the correct stage
  - Cover both normal OF discovery and pre-created PHY registration
---
 drivers/net/mdio/of_mdio.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/net/mdio/of_mdio.c b/drivers/net/mdio/of_mdio.c
index b8d298c04d3f..ff540049b847 100644
--- a/drivers/net/mdio/of_mdio.c
+++ b/drivers/net/mdio/of_mdio.c
@@ -10,6 +10,7 @@
 
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/fwnode.h>
 #include <linux/fwnode_mdio.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -34,9 +35,26 @@ static int of_get_phy_id(struct device_node *device, u32 *phy_id)
 	return fwnode_get_phy_id(of_fwnode_handle(device), phy_id);
 }
 
+static int of_mdiobus_link_phy_package(struct device_node *child)
+{
+	struct device_node *package __free(device_node) = of_get_parent(child);
+
+	if (!package || !of_node_name_eq(package, "ethernet-phy-package"))
+		return 0;
+
+	return fw_devlink_copy_suppliers(of_fwnode_handle(child),
+					 of_fwnode_handle(package));
+}
+
 int of_mdiobus_phy_device_register(struct mii_bus *mdio, struct phy_device *phy,
 				   struct device_node *child, u32 addr)
 {
+	int ret;
+
+	ret = of_mdiobus_link_phy_package(child);
+	if (ret)
+		return ret;
+
 	return fwnode_mdiobus_phy_device_register(mdio, phy,
 						  of_fwnode_handle(child),
 						  addr);
@@ -46,6 +64,12 @@ EXPORT_SYMBOL(of_mdiobus_phy_device_register);
 static int of_mdiobus_register_phy(struct mii_bus *mdio,
 				    struct device_node *child, u32 addr)
 {
+	int ret;
+
+	ret = of_mdiobus_link_phy_package(child);
+	if (ret)
+		return ret;
+
 	return fwnode_mdiobus_register_phy(mdio, of_fwnode_handle(child), addr);
 }
 

-- 
2.53.0