net: phy: phy_port: Store information about a port's upstream

MII phy_ports are not meant to be connected directly to a link partner.
They are meant to feed into some media converter devices that will
expose an MDI phy_port, so far we only support SFP modules for that.

In the case an MDI phy_port is backed by an MII port (e.g. a SFP
module's port, backed by the SFP cage port), let's keep track of the
port id of the MII port backing it.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Aleksei Sviridkin <f@lex.la>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Tested-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20261016133107.54054-7-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 782d3ea2964e..21afc2082b17 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -616,6 +616,7 @@ struct phy_oatc14_sqi_capability {
  * @sfp_bus: SFP bus attached to this PHY's fiber port
  * @sfp_cage_port: The phy_port connected to the downstream SFP cage
  * @mod_port: phy_port representing the SFP module, if it is phy-less
+ * @upstream_port: phy_port this PHY's MII attaches to, if any
  * @attached_dev: The attached enet driver's device instance ptr
  * @adjust_link: Callback for the enet controller to respond to changes: in the
  *               link state.
@@ -811,6 +812,7 @@ struct phy_device {
 	struct sfp_bus *sfp_bus;
 	struct phy_port *sfp_cage_port;
 	struct phy_port *mod_port;
+	struct phy_port *upstream_port;
 	struct phylink *phylink;
 	struct net_device *attached_dev;
 	struct mii_timestamper *mii_ts;
@@ -2495,6 +2497,8 @@ int __phy_hwtstamp_set(struct phy_device *phydev,
 
 struct phy_port *phy_get_sfp_port(struct phy_device *phydev);
 
+void phy_set_upstream_port(struct phy_device *phydev, struct phy_port *port);
+
 /**
  * phy_module_driver() - Helper macro for registering PHY drivers
  * @__phy_drivers: array of PHY drivers to register
diff --git a/include/linux/phy_port.h b/include/linux/phy_port.h
index 4e2a3fdd2f2e..8f45c031cbc1 100644
--- a/include/linux/phy_port.h
+++ b/include/linux/phy_port.h
@@ -40,6 +40,8 @@ struct phy_port_ops {
  * @head: Used by the port's parent to list ports
  * @parent_type: The type of device this port is directly connected to
  * @phy: If the parent is PHY_PORT_PHYDEV, the PHY controlling that port
+ * @upstream_port: Indicates the MII port that feeds this port, if any,
+ *		   e.g. the SFP cage port for a SFP module port.
  * @ops: Callback ops implemented by the port controller
  * @pairs: The number of  pairs this port has, 0 if not applicable
  * @mediums: Bitmask of the physical mediums this port provides access to
@@ -59,6 +61,7 @@ struct phy_port {
 	union {
 		struct phy_device *phy;
 	};
+	struct phy_port *upstream_port;
 
 	const struct phy_port_ops *ops;