Merge branch 'side-mdio-support-for-lan937x-switches'

Oleksij Rempel says:

====================
Side MDIO Support for LAN937x Switches

This patch set introduces support for an internal MDIO bus in LAN937x
switches, enabling the use of a side MDIO channel for PHY management
while keeping SPI as the main interface for switch configuration.

other changelogs are added to separate patches.
====================

Link: https://patch.msgid.link/20241106075942.1636998-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml

@@ -81,6 +81,26 @@ properties:
   interrupts:
     maxItems: 1
 
+  mdio:
+    $ref: /schemas/net/mdio.yaml#
+    unevaluatedProperties: false
+    properties:
+      mdio-parent-bus:
+        $ref: /schemas/types.yaml#/definitions/phandle
+        description:
+          Phandle pointing to the MDIO bus controller connected to the
+          secondary MDIO interface. This property should be used when
+          the internal MDIO bus is accessed via a secondary MDIO
+          interface rather than the primary management interface.
+
+    patternProperties:
+      "^ethernet-phy@[0-9a-f]$":
+        type: object
+        $ref: /schemas/net/ethernet-phy.yaml#
+        unevaluatedProperties: false
+        description:
+          Integrated PHY node
+
 required:
   - compatible
   - reg

drivers/net/dsa/microchip/ksz_common.c

@@ -411,6 +411,8 @@ static const struct ksz_dev_ops lan937x_dev_ops = {
 	.flush_dyn_mac_table = ksz9477_flush_dyn_mac_table,
 	.port_setup = lan937x_port_setup,
 	.set_ageing_time = lan937x_set_ageing_time,
+	.mdio_bus_preinit = lan937x_mdio_bus_preinit,
+	.create_phy_addr_map = lan937x_create_phy_addr_map,
 	.r_phy = lan937x_r_phy,
 	.w_phy = lan937x_w_phy,
 	.r_mib_cnt = ksz9477_r_mib_cnt,
@@ -1762,6 +1764,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.num_tx_queues = 8,
 		.num_ipms = 8,
 		.tc_cbs_supported = true,
+		.phy_side_mdio_supported = true,
 		.ops = &lan937x_dev_ops,
 		.phylink_mac_ops = &lan937x_phylink_mac_ops,
 		.mib_names = ksz9477_mib_names,
@@ -1790,6 +1793,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.num_tx_queues = 8,
 		.num_ipms = 8,
 		.tc_cbs_supported = true,
+		.phy_side_mdio_supported = true,
 		.ops = &lan937x_dev_ops,
 		.phylink_mac_ops = &lan937x_phylink_mac_ops,
 		.mib_names = ksz9477_mib_names,
@@ -1818,6 +1822,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.num_tx_queues = 8,
 		.num_ipms = 8,
 		.tc_cbs_supported = true,
+		.phy_side_mdio_supported = true,
 		.ops = &lan937x_dev_ops,
 		.phylink_mac_ops = &lan937x_phylink_mac_ops,
 		.mib_names = ksz9477_mib_names,
@@ -1850,6 +1855,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.num_tx_queues = 8,
 		.num_ipms = 8,
 		.tc_cbs_supported = true,
+		.phy_side_mdio_supported = true,
 		.ops = &lan937x_dev_ops,
 		.phylink_mac_ops = &lan937x_phylink_mac_ops,
 		.mib_names = ksz9477_mib_names,
@@ -1882,6 +1888,7 @@ const struct ksz_chip_data ksz_switch_chips[] = {
 		.num_tx_queues = 8,
 		.num_ipms = 8,
 		.tc_cbs_supported = true,
+		.phy_side_mdio_supported = true,
 		.ops = &lan937x_dev_ops,
 		.phylink_mac_ops = &lan937x_phylink_mac_ops,
 		.mib_names = ksz9477_mib_names,
@@ -2236,16 +2243,100 @@ static int ksz_sw_mdio_write(struct mii_bus *bus, int addr, int regnum,
 	return dev->dev_ops->w_phy(dev, addr, regnum, val);
 }
 
+/**
+ * ksz_parent_mdio_read - Read data from a PHY register on the parent MDIO bus.
+ * @bus: MDIO bus structure.
+ * @addr: PHY address on the parent MDIO bus.
+ * @regnum: Register number to read.
+ *
+ * This function provides a direct read operation on the parent MDIO bus for
+ * accessing PHY registers. By bypassing SPI or I2C, it uses the parent MDIO bus
+ * to retrieve data from the PHY registers at the specified address and register
+ * number.
+ *
+ * Return: Value of the PHY register, or a negative error code on failure.
+ */
+static int ksz_parent_mdio_read(struct mii_bus *bus, int addr, int regnum)
+{
+	struct ksz_device *dev = bus->priv;
+
+	return mdiobus_read_nested(dev->parent_mdio_bus, addr, regnum);
+}
+
+/**
+ * ksz_parent_mdio_write - Write data to a PHY register on the parent MDIO bus.
+ * @bus: MDIO bus structure.
+ * @addr: PHY address on the parent MDIO bus.
+ * @regnum: Register number to write to.
+ * @val: Value to write to the PHY register.
+ *
+ * This function provides a direct write operation on the parent MDIO bus for
+ * accessing PHY registers. Bypassing SPI or I2C, it uses the parent MDIO bus
+ * to modify the PHY register values at the specified address.
+ *
+ * Return: 0 on success, or a negative error code on failure.
+ */
+static int ksz_parent_mdio_write(struct mii_bus *bus, int addr, int regnum,
+				 u16 val)
+{
+	struct ksz_device *dev = bus->priv;
+
+	return mdiobus_write_nested(dev->parent_mdio_bus, addr, regnum, val);
+}
+
+/**
+ * ksz_phy_addr_to_port - Map a PHY address to the corresponding switch port.
+ * @dev: Pointer to device structure.
+ * @addr: PHY address to map to a port.
+ *
+ * This function finds the corresponding switch port for a given PHY address by
+ * iterating over all user ports on the device. It checks if a port's PHY
+ * address in `phy_addr_map` matches the specified address and if the port
+ * contains an internal PHY. If a match is found, the index of the port is
+ * returned.
+ *
+ * Return: Port index on success, or -EINVAL if no matching port is found.
+ */
+static int ksz_phy_addr_to_port(struct ksz_device *dev, int addr)
+{
+	struct dsa_switch *ds = dev->ds;
+	struct dsa_port *dp;
+
+	dsa_switch_for_each_user_port(dp, ds) {
+		if (dev->info->internal_phy[dp->index] &&
+		    dev->phy_addr_map[dp->index] == addr)
+			return dp->index;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * ksz_irq_phy_setup - Configure IRQs for PHYs in the KSZ device.
+ * @dev: Pointer to the KSZ device structure.
+ *
+ * Sets up IRQs for each active PHY connected to the KSZ switch by mapping the
+ * appropriate IRQs for each PHY and assigning them to the `user_mii_bus` in
+ * the DSA switch structure. Each IRQ is mapped based on the port's IRQ domain.
+ *
+ * Return: 0 on success, or a negative error code on failure.
+ */
 static int ksz_irq_phy_setup(struct ksz_device *dev)
 {
 	struct dsa_switch *ds = dev->ds;
-	int phy;
+	int phy, port;
 	int irq;
 	int ret;
 
-	for (phy = 0; phy < KSZ_MAX_NUM_PORTS; phy++) {
+	for (phy = 0; phy < PHY_MAX_ADDR; phy++) {
 		if (BIT(phy) & ds->phys_mii_mask) {
-			irq = irq_find_mapping(dev->ports[phy].pirq.domain,
+			port = ksz_phy_addr_to_port(dev, phy);
+			if (port < 0) {
+				ret = port;
+				goto out;
+			}
+
+			irq = irq_find_mapping(dev->ports[port].pirq.domain,
 					       PORT_SRC_PHY_INT);
 			if (irq < 0) {
 				ret = irq;
@@ -2263,49 +2354,183 @@ static int ksz_irq_phy_setup(struct ksz_device *dev)
 	return ret;
 }
 
+/**
+ * ksz_irq_phy_free - Release IRQ mappings for PHYs in the KSZ device.
+ * @dev: Pointer to the KSZ device structure.
+ *
+ * Releases any IRQ mappings previously assigned to active PHYs in the KSZ
+ * switch by disposing of each mapped IRQ in the `user_mii_bus` structure.
+ */
 static void ksz_irq_phy_free(struct ksz_device *dev)
 {
 	struct dsa_switch *ds = dev->ds;
 	int phy;
 
-	for (phy = 0; phy < KSZ_MAX_NUM_PORTS; phy++)
+	for (phy = 0; phy < PHY_MAX_ADDR; phy++)
 		if (BIT(phy) & ds->phys_mii_mask)
 			irq_dispose_mapping(ds->user_mii_bus->irq[phy]);
 }
 
+/**
+ * ksz_parse_dt_phy_config - Parse and validate PHY configuration from DT
+ * @dev: pointer to the KSZ device structure
+ * @bus: pointer to the MII bus structure
+ * @mdio_np: pointer to the MDIO node in the device tree
+ *
+ * This function parses and validates PHY configurations for each user port
+ * defined in the device tree for a KSZ switch device. It verifies that the
+ * `phy-handle` properties are correctly set and that the internal PHYs match
+ * expected addresses and parent nodes. Sets up the PHY mask in the MII bus if
+ * all validations pass. Logs error messages for any mismatches or missing data.
+ *
+ * Return: 0 on success, or a negative error code on failure.
+ */
+static int ksz_parse_dt_phy_config(struct ksz_device *dev, struct mii_bus *bus,
+				   struct device_node *mdio_np)
+{
+	struct device_node *phy_node, *phy_parent_node;
+	bool phys_are_valid = true;
+	struct dsa_port *dp;
+	u32 phy_addr;
+	int ret;
+
+	dsa_switch_for_each_user_port(dp, dev->ds) {
+		if (!dev->info->internal_phy[dp->index])
+			continue;
+
+		phy_node = of_parse_phandle(dp->dn, "phy-handle", 0);
+		if (!phy_node) {
+			dev_err(dev->dev, "failed to parse phy-handle for port %d.\n",
+				dp->index);
+			phys_are_valid = false;
+			continue;
+		}
+
+		phy_parent_node = of_get_parent(phy_node);
+		if (!phy_parent_node) {
+			dev_err(dev->dev, "failed to get PHY-parent node for port %d\n",
+				dp->index);
+			phys_are_valid = false;
+		} else if (phy_parent_node != mdio_np) {
+			dev_err(dev->dev, "PHY-parent node mismatch for port %d, expected %pOF, got %pOF\n",
+				dp->index, mdio_np, phy_parent_node);
+			phys_are_valid = false;
+		} else {
+			ret = of_property_read_u32(phy_node, "reg", &phy_addr);
+			if (ret < 0) {
+				dev_err(dev->dev, "failed to read PHY address for port %d. Error %d\n",
+					dp->index, ret);
+				phys_are_valid = false;
+			} else if (phy_addr != dev->phy_addr_map[dp->index]) {
+				dev_err(dev->dev, "PHY address mismatch for port %d, expected 0x%x, got 0x%x\n",
+					dp->index, dev->phy_addr_map[dp->index],
+					phy_addr);
+				phys_are_valid = false;
+			} else {
+				bus->phy_mask |= BIT(phy_addr);
+			}
+		}
+
+		of_node_put(phy_node);
+		of_node_put(phy_parent_node);
+	}
+
+	if (!phys_are_valid)
+		return -EINVAL;
+
+	return 0;
+}
+
+/**
+ * ksz_mdio_register - Register and configure the MDIO bus for the KSZ device.
+ * @dev: Pointer to the KSZ device structure.
+ *
+ * This function sets up and registers an MDIO bus for the KSZ switch device,
+ * allowing access to its internal PHYs. If the device supports side MDIO,
+ * the function will configure the external MDIO controller specified by the
+ * "mdio-parent-bus" device tree property to directly manage internal PHYs.
+ * Otherwise, SPI or I2C access is set up for PHY access.
+ *
+ * Return: 0 on success, or a negative error code on failure.
+ */
 static int ksz_mdio_register(struct ksz_device *dev)
 {
+	struct device_node *parent_bus_node;
+	struct mii_bus *parent_bus = NULL;
 	struct dsa_switch *ds = dev->ds;
 	struct device_node *mdio_np;
 	struct mii_bus *bus;
-	int ret;
+	int ret, i;
 
 	mdio_np = of_get_child_by_name(dev->dev->of_node, "mdio");
 	if (!mdio_np)
 		return 0;
 
+	parent_bus_node = of_parse_phandle(mdio_np, "mdio-parent-bus", 0);
+	if (parent_bus_node && !dev->info->phy_side_mdio_supported) {
+		dev_err(dev->dev, "Side MDIO bus is not supported for this HW, ignoring 'mdio-parent-bus' property.\n");
+		ret = -EINVAL;
+
+		goto put_mdio_node;
+	} else if (parent_bus_node) {
+		parent_bus = of_mdio_find_bus(parent_bus_node);
+		if (!parent_bus) {
+			ret = -EPROBE_DEFER;
+
+			goto put_mdio_node;
+		}
+
+		dev->parent_mdio_bus = parent_bus;
+	}
+
 	bus = devm_mdiobus_alloc(ds->dev);
 	if (!bus) {
-		of_node_put(mdio_np);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto put_mdio_node;
+	}
+
+	if (dev->dev_ops->mdio_bus_preinit) {
+		ret = dev->dev_ops->mdio_bus_preinit(dev, !!parent_bus);
+		if (ret)
+			goto put_mdio_node;
+	}
+
+	if (dev->dev_ops->create_phy_addr_map) {
+		ret = dev->dev_ops->create_phy_addr_map(dev, !!parent_bus);
+		if (ret)
+			goto put_mdio_node;
+	} else {
+		for (i = 0; i < dev->info->port_cnt; i++)
+			dev->phy_addr_map[i] = i;
 	}
 
 	bus->priv = dev;
-	bus->read = ksz_sw_mdio_read;
-	bus->write = ksz_sw_mdio_write;
-	bus->name = "ksz user smi";
-	snprintf(bus->id, MII_BUS_ID_SIZE, "SMI-%d", ds->index);
+	if (parent_bus) {
+		bus->read = ksz_parent_mdio_read;
+		bus->write = ksz_parent_mdio_write;
+		bus->name = "KSZ side MDIO";
+		snprintf(bus->id, MII_BUS_ID_SIZE, "ksz-side-mdio-%d",
+			 ds->index);
+	} else {
+		bus->read = ksz_sw_mdio_read;
+		bus->write = ksz_sw_mdio_write;
+		bus->name = "ksz user smi";
+		snprintf(bus->id, MII_BUS_ID_SIZE, "SMI-%d", ds->index);
+	}
+
+	ret = ksz_parse_dt_phy_config(dev, bus, mdio_np);
+	if (ret)
+		goto put_mdio_node;
+
+	ds->phys_mii_mask = bus->phy_mask;
 	bus->parent = ds->dev;
-	bus->phy_mask = ~ds->phys_mii_mask;
 
 	ds->user_mii_bus = bus;
 
 	if (dev->irq > 0) {
 		ret = ksz_irq_phy_setup(dev);
-		if (ret) {
-			of_node_put(mdio_np);
-			return ret;
-		}
+		if (ret)
+			goto put_mdio_node;
 	}
 
 	ret = devm_of_mdiobus_register(ds->dev, bus, mdio_np);
@@ -2316,7 +2541,9 @@ static int ksz_mdio_register(struct ksz_device *dev)
 			ksz_irq_phy_free(dev);
 	}
 
+put_mdio_node:
 	of_node_put(mdio_np);
+	of_node_put(parent_bus_node);
 
 	return ret;
 }

drivers/net/dsa/microchip/ksz_common.h

@@ -65,6 +65,12 @@ struct ksz_chip_data {
 	u8 num_tx_queues;
 	u8 num_ipms; /* number of Internal Priority Maps */
 	bool tc_cbs_supported;
+
+	/**
+	 * @phy_side_mdio_supported: Indicates if the chip supports an additional
+	 * side MDIO channel for accessing integrated PHYs.
+	 */
+	bool phy_side_mdio_supported;
 	const struct ksz_dev_ops *ops;
 	const struct phylink_mac_ops *phylink_mac_ops;
 	bool phy_errata_9477;
@@ -191,6 +197,22 @@ struct ksz_device {
 	struct ksz_switch_macaddr *switch_macaddr;
 	struct net_device *hsr_dev;     /* HSR */
 	u8 hsr_ports;
+
+	/**
+	 * @phy_addr_map: Array mapping switch ports to their corresponding PHY
+	 * addresses.
+	 */
+	u8 phy_addr_map[KSZ_MAX_NUM_PORTS];
+
+	/**
+	 * @parent_mdio_bus: Pointer to the external MDIO bus controller.
+	 *
+	 * This points to an external MDIO bus controller that is used to access
+	 * the  PHYs integrated within the switch. Unlike an integrated MDIO
+	 * bus, this external controller provides a direct path for managing
+	 * the switch’s internal PHYs, bypassing the main SPI interface.
+	 */
+	struct mii_bus *parent_mdio_bus;
 };
 
 /* List of supported models */
@@ -326,6 +348,43 @@ struct ksz_dev_ops {
 	void (*port_cleanup)(struct ksz_device *dev, int port);
 	void (*port_setup)(struct ksz_device *dev, int port, bool cpu_port);
 	int (*set_ageing_time)(struct ksz_device *dev, unsigned int msecs);
+
+	/**
+	 * @mdio_bus_preinit: Function pointer to pre-initialize the MDIO bus
+	 *                    for accessing PHYs.
+	 * @dev: Pointer to device structure.
+	 * @side_mdio: Boolean indicating if the PHYs are accessed over a side
+	 *             MDIO bus.
+	 *
+	 * This function pointer is used to configure the MDIO bus for PHY
+	 * access before initiating regular PHY operations. It enables either
+	 * SPI/I2C or side MDIO access modes by unlocking necessary registers
+	 * and setting up access permissions for the selected mode.
+	 *
+	 * Return:
+	 *  - 0 on success.
+	 *  - Negative error code on failure.
+	 */
+	int (*mdio_bus_preinit)(struct ksz_device *dev, bool side_mdio);
+
+	/**
+	 * @create_phy_addr_map: Function pointer to create a port-to-PHY
+	 *                       address map.
+	 * @dev: Pointer to device structure.
+	 * @side_mdio: Boolean indicating if the PHYs are accessed over a side
+	 *             MDIO bus.
+	 *
+	 * This function pointer is responsible for mapping switch ports to PHY
+	 * addresses according to the configured access mode (SPI or side MDIO)
+	 * and the device’s strap configuration. The mapping setup may vary
+	 * depending on the chip variant and configuration. Ensures the correct
+	 * address mapping for PHY communication.
+	 *
+	 * Return:
+	 *  - 0 on success.
+	 *  - Negative error code on failure (e.g., invalid configuration).
+	 */
+	int (*create_phy_addr_map)(struct ksz_device *dev, bool side_mdio);
 	int (*r_phy)(struct ksz_device *dev, u16 phy, u16 reg, u16 *val);
 	int (*w_phy)(struct ksz_device *dev, u16 phy, u16 reg, u16 val);
 	void (*r_mib_cnt)(struct ksz_device *dev, int port, u16 addr,

drivers/net/dsa/microchip/lan937x.h

@@ -13,6 +13,8 @@ void lan937x_port_setup(struct ksz_device *dev, int port, bool cpu_port);
 void lan937x_config_cpu_port(struct dsa_switch *ds);
 int lan937x_switch_init(struct ksz_device *dev);
 void lan937x_switch_exit(struct ksz_device *dev);
+int lan937x_mdio_bus_preinit(struct ksz_device *dev, bool side_mdio);
+int lan937x_create_phy_addr_map(struct ksz_device *dev, bool side_mdio);
 int lan937x_r_phy(struct ksz_device *dev, u16 addr, u16 reg, u16 *data);
 int lan937x_w_phy(struct ksz_device *dev, u16 addr, u16 reg, u16 val);
 int lan937x_change_mtu(struct ksz_device *dev, int port, int new_mtu);

drivers/net/dsa/microchip/lan937x_main.c

@@ -18,6 +18,87 @@
 #include "ksz9477.h"
 #include "lan937x.h"
 
+/* marker for ports without built-in PHY */
+#define LAN937X_NO_PHY U8_MAX
+
+/*
+ * lan9370_phy_addr - Mapping of LAN9370 switch ports to PHY addresses.
+ *
+ * Each entry corresponds to a specific port on the LAN9370 switch,
+ * where ports 1-4 are connected to integrated 100BASE-T1 PHYs, and
+ * Port 5 is connected to an RGMII interface without a PHY. The values
+ * are based on the documentation (DS00003108E, section 3.3).
+ */
+static const u8 lan9370_phy_addr[] = {
+	[0] = 2, /* Port 1, T1 AFE0 */
+	[1] = 3, /* Port 2, T1 AFE1 */
+	[2] = 5, /* Port 3, T1 AFE3 */
+	[3] = 6, /* Port 4, T1 AFE4 */
+	[4] = LAN937X_NO_PHY, /* Port 5, RGMII 2 */
+};
+
+/*
+ * lan9371_phy_addr - Mapping of LAN9371 switch ports to PHY addresses.
+ *
+ * The values are based on the documentation (DS00003109E, section 3.3).
+ */
+static const u8 lan9371_phy_addr[] = {
+	[0] = 2, /* Port 1, T1 AFE0 */
+	[1] = 3, /* Port 2, T1 AFE1 */
+	[2] = 5, /* Port 3, T1 AFE3 */
+	[3] = 8, /* Port 4, TX PHY */
+	[4] = LAN937X_NO_PHY, /* Port 5, RGMII 2 */
+	[5] = LAN937X_NO_PHY, /* Port 6, RGMII 1 */
+};
+
+/*
+ * lan9372_phy_addr - Mapping of LAN9372 switch ports to PHY addresses.
+ *
+ * The values are based on the documentation (DS00003110F, section 3.3).
+ */
+static const u8 lan9372_phy_addr[] = {
+	[0] = 2, /* Port 1, T1 AFE0 */
+	[1] = 3, /* Port 2, T1 AFE1 */
+	[2] = 5, /* Port 3, T1 AFE3 */
+	[3] = 8, /* Port 4, TX PHY */
+	[4] = LAN937X_NO_PHY, /* Port 5, RGMII 2 */
+	[5] = LAN937X_NO_PHY, /* Port 6, RGMII 1 */
+	[6] = 6, /* Port 7, T1 AFE4 */
+	[7] = 4, /* Port 8, T1 AFE2 */
+};
+
+/*
+ * lan9373_phy_addr - Mapping of LAN9373 switch ports to PHY addresses.
+ *
+ * The values are based on the documentation (DS00003110F, section 3.3).
+ */
+static const u8 lan9373_phy_addr[] = {
+	[0] = 2, /* Port 1, T1 AFE0 */
+	[1] = 3, /* Port 2, T1 AFE1 */
+	[2] = 5, /* Port 3, T1 AFE3 */
+	[3] = LAN937X_NO_PHY, /* Port 4, SGMII */
+	[4] = LAN937X_NO_PHY, /* Port 5, RGMII 2 */
+	[5] = LAN937X_NO_PHY, /* Port 6, RGMII 1 */
+	[6] = 6, /* Port 7, T1 AFE4 */
+	[7] = 4, /* Port 8, T1 AFE2 */
+};
+
+/*
+ * lan9374_phy_addr - Mapping of LAN9374 switch ports to PHY addresses.
+ *
+ * The values are based on the documentation (DS00003110F, section 3.3).
+ */
+static const u8 lan9374_phy_addr[] = {
+	[0] = 2, /* Port 1, T1 AFE0 */
+	[1] = 3, /* Port 2, T1 AFE1 */
+	[2] = 5, /* Port 3, T1 AFE3 */
+	[3] = 7, /* Port 4, T1 AFE5 */
+	[4] = LAN937X_NO_PHY, /* Port 5, RGMII 2 */
+	[5] = LAN937X_NO_PHY, /* Port 6, RGMII 1 */
+	[6] = 6, /* Port 7, T1 AFE4 */
+	[7] = 4, /* Port 8, T1 AFE2 */
+};
+
 static int lan937x_cfg(struct ksz_device *dev, u32 addr, u8 bits, bool set)
 {
 	return regmap_update_bits(ksz_regmap_8(dev), addr, bits, set ? bits : 0);
@@ -30,24 +111,144 @@ static int lan937x_port_cfg(struct ksz_device *dev, int port, int offset,
 				  bits, set ? bits : 0);
 }
 
-static int lan937x_enable_spi_indirect_access(struct ksz_device *dev)
+/**
+ * lan937x_create_phy_addr_map - Create port-to-PHY address map for MDIO bus.
+ * @dev: Pointer to device structure.
+ * @side_mdio: Boolean indicating if the PHYs are accessed over a side MDIO bus.
+ *
+ * This function sets up the PHY address mapping for the LAN937x switches,
+ * which support two access modes for internal PHYs:
+ * 1. **SPI Access**: A straightforward one-to-one port-to-PHY address
+ *    mapping is applied.
+ * 2. **MDIO Access**: The PHY address mapping varies based on chip variant
+ *    and strap configuration. An offset is calculated based on strap settings
+ *    to ensure correct PHY addresses are assigned. The offset calculation logic
+ *    is based on Microchip's Article Number 000015828, available at:
+ *    https://microchip.my.site.com/s/article/LAN9374-Virtual-PHY-PHY-Address-Mapping
+ *
+ * The function first checks if side MDIO access is disabled, in which case a
+ * simple direct mapping (port number = PHY address) is applied. If side MDIO
+ * access is enabled, it reads the strap configuration to determine the correct
+ * offset for PHY addresses.
+ *
+ * The appropriate mapping table is selected based on the chip ID, and the
+ * `phy_addr_map` is populated with the correct addresses for each port. Any
+ * port with no PHY is assigned a `LAN937X_NO_PHY` marker.
+ *
+ * Return: 0 on success, error code on failure.
+ */
+int lan937x_create_phy_addr_map(struct ksz_device *dev, bool side_mdio)
+{
+	static const u8 *phy_addr_map;
+	u32 strap_val;
+	u8 offset = 0;
+	size_t size;
+	int ret, i;
+
+	if (!side_mdio) {
+		/* simple direct mapping */
+		for (i = 0; i < dev->info->port_cnt; i++)
+			dev->phy_addr_map[i] = i;
+
+		return 0;
+	}
+
+	ret = ksz_read32(dev, REG_SW_CFG_STRAP_VAL, &strap_val);
+	if (ret < 0)
+		return ret;
+
+	if (!(strap_val & SW_CASCADE_ID_CFG) && !(strap_val & SW_VPHY_ADD_CFG))
+		offset = 0;
+	else if (!(strap_val & SW_CASCADE_ID_CFG) && (strap_val & SW_VPHY_ADD_CFG))
+		offset = 7;
+	else if ((strap_val & SW_CASCADE_ID_CFG) && !(strap_val & SW_VPHY_ADD_CFG))
+		offset = 15;
+	else
+		offset = 22;
+
+	switch (dev->info->chip_id) {
+	case LAN9370_CHIP_ID:
+		phy_addr_map = lan9370_phy_addr;
+		size = ARRAY_SIZE(lan9370_phy_addr);
+		break;
+	case LAN9371_CHIP_ID:
+		phy_addr_map = lan9371_phy_addr;
+		size = ARRAY_SIZE(lan9371_phy_addr);
+		break;
+	case LAN9372_CHIP_ID:
+		phy_addr_map = lan9372_phy_addr;
+		size = ARRAY_SIZE(lan9372_phy_addr);
+		break;
+	case LAN9373_CHIP_ID:
+		phy_addr_map = lan9373_phy_addr;
+		size = ARRAY_SIZE(lan9373_phy_addr);
+		break;
+	case LAN9374_CHIP_ID:
+		phy_addr_map = lan9374_phy_addr;
+		size = ARRAY_SIZE(lan9374_phy_addr);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (size < dev->info->port_cnt)
+		return -EINVAL;
+
+	for (i = 0; i < dev->info->port_cnt; i++) {
+		if (phy_addr_map[i] == LAN937X_NO_PHY)
+			dev->phy_addr_map[i] = phy_addr_map[i];
+		else
+			dev->phy_addr_map[i] = phy_addr_map[i] + offset;
+	}
+
+	return 0;
+}
+
+/**
+ * lan937x_mdio_bus_preinit - Pre-initialize MDIO bus for accessing PHYs.
+ * @dev: Pointer to device structure.
+ * @side_mdio: Boolean indicating if the PHYs are accessed over a side MDIO bus.
+ *
+ * This function configures the LAN937x switch for PHY access either through
+ * SPI or the side MDIO bus, unlocking the necessary registers for each access
+ * mode.
+ *
+ * Operation Modes:
+ * 1. **SPI Access**: Enables SPI indirect access to address clock domain
+ *    crossing issues when SPI is used for PHY access.
+ * 2. **MDIO Access**: Grants access to internal PHYs over the side MDIO bus,
+ *    required when using the MDIO bus for PHY management.
+ *
+ * Return: 0 on success, error code on failure.
+ */
+int lan937x_mdio_bus_preinit(struct ksz_device *dev, bool side_mdio)
 {
 	u16 data16;
 	int ret;
 
-	/* Enable Phy access through SPI */
+	/* Unlock access to the PHYs, needed for SPI and side MDIO access */
 	ret = lan937x_cfg(dev, REG_GLOBAL_CTRL_0, SW_PHY_REG_BLOCK, false);
 	if (ret < 0)
-		return ret;
+		goto print_error;
 
-	ret = ksz_read16(dev, REG_VPHY_SPECIAL_CTRL__2, &data16);
+	if (side_mdio)
+		/* Allow access to internal PHYs over MDIO bus */
+		data16 = VPHY_MDIO_INTERNAL_ENABLE;
+	else
+		/* Enable SPI indirect access to address clock domain crossing
+		 * issue
+		 */
+		data16 = VPHY_SPI_INDIRECT_ENABLE;
+
+	ret = ksz_rmw16(dev, REG_VPHY_SPECIAL_CTRL__2,
+			VPHY_SPI_INDIRECT_ENABLE | VPHY_MDIO_INTERNAL_ENABLE,
+			data16);
+
+print_error:
 	if (ret < 0)
-		return ret;
+		dev_err(dev->dev, "failed to preinit the MDIO bus\n");
 
-	/* Allow SPI access */
-	data16 |= VPHY_SPI_INDIRECT_ENABLE;
-
-	return ksz_write16(dev, REG_VPHY_SPECIAL_CTRL__2, data16);
+	return ret;
 }
 
 static int lan937x_vphy_ind_addr_wr(struct ksz_device *dev, int addr, int reg)
@@ -363,13 +564,6 @@ int lan937x_setup(struct dsa_switch *ds)
 	struct ksz_device *dev = ds->priv;
 	int ret;
 
-	/* enable Indirect Access from SPI to the VPHY registers */
-	ret = lan937x_enable_spi_indirect_access(dev);
-	if (ret < 0) {
-		dev_err(dev->dev, "failed to enable spi indirect access");
-		return ret;
-	}
-
 	/* The VLAN aware is a global setting. Mixed vlan
 	 * filterings are not supported.
 	 */

drivers/net/dsa/microchip/lan937x_reg.h

@@ -37,6 +37,10 @@
 #define SW_CLK125_ENB			BIT(1)
 #define SW_CLK25_ENB			BIT(0)
 
+#define REG_SW_CFG_STRAP_VAL		0x0200
+#define SW_CASCADE_ID_CFG		BIT(15)
+#define SW_VPHY_ADD_CFG			BIT(0)
+
 /* 2 - PHY Control */
 #define REG_SW_CFG_STRAP_OVR		0x0214
 #define SW_VPHY_DISABLE			BIT(31)