net: phy: introduce genphy_match_phy_device()

Introduce new API, genphy_match_phy_device(), to provide a way to check
to match a PHY driver for a PHY device based on the info stored in the
PHY device struct.

The function generalize the logic used in phy_bus_match() to check the
PHY ID whether if C45 or C22 ID should be used for matching.

This is useful for custom .match_phy_device function that wants to use
the generic logic under some condition. (example a PHY is already setup
and provide the correct PHY ID)

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Link: https://patch.msgid.link/20250517201353.5137-5-ansuelsmth@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 40 insertions, 15 deletions

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 6006cff1a73e..0f6f86252622 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -543,20 +543,26 @@ static int phy_scan_fixups(struct phy_device *phydev)
 	return 0;
 }
 
-static int phy_bus_match(struct device *dev, const struct device_driver *drv)
+/**
+ * genphy_match_phy_device - match a PHY device with a PHY driver
+ * @phydev: target phy_device struct
+ * @phydrv: target phy_driver struct
+ *
+ * Description: Checks whether the given PHY device matches the specified
+ * PHY driver. For Clause 45 PHYs, iterates over the available device
+ * identifiers and compares them against the driver's expected PHY ID,
+ * applying the provided mask. For Clause 22 PHYs, a direct ID comparison
+ * is performed.
+ *
+ * Return: 1 if the PHY device matches the driver, 0 otherwise.
+ */
+int genphy_match_phy_device(struct phy_device *phydev,
+			    const struct phy_driver *phydrv)
 {
-	struct phy_device *phydev = to_phy_device(dev);
-	const struct phy_driver *phydrv = to_phy_driver(drv);
-	const int num_ids = ARRAY_SIZE(phydev->c45_ids.device_ids);
-	int i;
-
-	if (!(phydrv->mdiodrv.flags & MDIO_DEVICE_IS_PHY))
-		return 0;
-
-	if (phydrv->match_phy_device)
-		return phydrv->match_phy_device(phydev, phydrv);
-
 	if (phydev->is_c45) {
+		const int num_ids = ARRAY_SIZE(phydev->c45_ids.device_ids);
+		int i;
+
 		for (i = 1; i < num_ids; i++) {
 			if (phydev->c45_ids.device_ids[i] == 0xffffffff)
 				continue;
@@ -565,11 +571,27 @@ static int phy_bus_match(struct device *dev, const struct device_driver *drv)
 					   phydrv->phy_id, phydrv->phy_id_mask))
 				return 1;
 		}
+
 		return 0;
-	} else {
-		return phy_id_compare(phydev->phy_id, phydrv->phy_id,
-				      phydrv->phy_id_mask);
 	}
+
+	return phy_id_compare(phydev->phy_id, phydrv->phy_id,
+			      phydrv->phy_id_mask);
+}
+EXPORT_SYMBOL_GPL(genphy_match_phy_device);
+
+static int phy_bus_match(struct device *dev, const struct device_driver *drv)
+{
+	struct phy_device *phydev = to_phy_device(dev);
+	const struct phy_driver *phydrv = to_phy_driver(drv);
+
+	if (!(phydrv->mdiodrv.flags & MDIO_DEVICE_IS_PHY))
+		return 0;
+
+	if (phydrv->match_phy_device)
+		return phydrv->match_phy_device(phydev, phydrv);
+
+	return genphy_match_phy_device(phydev, phydrv);
 }
 
 static ssize_t
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 10e66d45a8e8..32b9da274115 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1868,6 +1868,9 @@ char *phy_attached_info_irq(struct phy_device *phydev)
 	__malloc;
 void phy_attached_info(struct phy_device *phydev);
 
+int genphy_match_phy_device(struct phy_device *phydev,
+			    const struct phy_driver *phydrv);
+
 /* Clause 22 PHY */
 int genphy_read_abilities(struct phy_device *phydev);
 int genphy_setup_forced(struct phy_device *phydev);