net: dsa: microchip: Refactor MDIO handling for side MDIO access

Add support for accessing PHYs via a side MDIO interface in LAN937x
switches. The existing code already supports accessing PHYs via main
management interfaces, which can be SPI, I2C, or MDIO, depending on the
chip variant. This patch enables using a side MDIO bus, where SPI is
used for the main switch configuration and MDIO for managing the
integrated PHYs. On LAN937x, this is optional, allowing them to operate
in both configurations: SPI only, or SPI + MDIO. Typically, the SPI
interface is used for switch configuration, while MDIO handles PHY
management.

Additionally, update interrupt controller code to support non-linear
port to PHY address mapping, enabling correct interrupt handling for
configurations where PHY addresses do not directly correspond to port
indexes. This change ensures that the interrupt mechanism properly
aligns with the new, flexible PHY address mappings introduced by side
MDIO support.

Signed-off-by: Oleksij Rempel <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

1 files changed, 59 insertions, 0 deletions

diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index bec846e20682..bbb548af201e 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/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,