--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2021, NXP Semiconductors
+ */
+#include <linux/of_mdio.h>
+#include "sja1105.h"
+
+enum sja1105_mdio_opcode {
+       SJA1105_C45_ADDR = 0,
+       SJA1105_C22 = 1,
+       SJA1105_C45_DATA = 2,
+       SJA1105_C45_DATA_AUTOINC = 3,
+};
+
+static u64 sja1105_base_t1_encode_addr(struct sja1105_private *priv,
+                                      int phy, enum sja1105_mdio_opcode op,
+                                      int xad)
+{
+       const struct sja1105_regs *regs = priv->info->regs;
+
+       return regs->mdio_100base_t1 | (phy << 7) | (op << 5) | (xad << 0);
+}
+
+static int sja1105_base_t1_mdio_read(struct mii_bus *bus, int phy, int reg)
+{
+       struct sja1105_mdio_private *mdio_priv = bus->priv;
+       struct sja1105_private *priv = mdio_priv->priv;
+       u64 addr;
+       u32 tmp;
+       int rc;
+
+       if (reg & MII_ADDR_C45) {
+               u16 mmd = (reg >> MII_DEVADDR_C45_SHIFT) & 0x1f;
+
+               addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_ADDR,
+                                                  mmd);
+
+               tmp = reg & MII_REGADDR_C45_MASK;
+
+               rc = sja1105_xfer_u32(priv, SPI_WRITE, addr, &tmp, NULL);
+               if (rc < 0)
+                       return rc;
+
+               addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_DATA,
+                                                  mmd);
+
+               rc = sja1105_xfer_u32(priv, SPI_READ, addr, &tmp, NULL);
+               if (rc < 0)
+                       return rc;
+
+               return tmp & 0xffff;
+       }
+
+       /* Clause 22 read */
+       addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C22, reg & 0x1f);
+
+       rc = sja1105_xfer_u32(priv, SPI_READ, addr, &tmp, NULL);
+       if (rc < 0)
+               return rc;
+
+       return tmp & 0xffff;
+}
+
+static int sja1105_base_t1_mdio_write(struct mii_bus *bus, int phy, int reg,
+                                     u16 val)
+{
+       struct sja1105_mdio_private *mdio_priv = bus->priv;
+       struct sja1105_private *priv = mdio_priv->priv;
+       u64 addr;
+       u32 tmp;
+       int rc;
+
+       if (reg & MII_ADDR_C45) {
+               u16 mmd = (reg >> MII_DEVADDR_C45_SHIFT) & 0x1f;
+
+               addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_ADDR,
+                                                  mmd);
+
+               tmp = reg & MII_REGADDR_C45_MASK;
+
+               rc = sja1105_xfer_u32(priv, SPI_WRITE, addr, &tmp, NULL);
+               if (rc < 0)
+                       return rc;
+
+               addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_DATA,
+                                                  mmd);
+
+               tmp = val & 0xffff;
+
+               rc = sja1105_xfer_u32(priv, SPI_WRITE, addr, &tmp, NULL);
+               if (rc < 0)
+                       return rc;
+
+               return 0;
+       }
+
+       /* Clause 22 write */
+       addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C22, reg & 0x1f);
+
+       tmp = val & 0xffff;
+
+       return sja1105_xfer_u32(priv, SPI_WRITE, addr, &tmp, NULL);
+}
+
+static int sja1105_base_tx_mdio_read(struct mii_bus *bus, int phy, int reg)
+{
+       struct sja1105_mdio_private *mdio_priv = bus->priv;
+       struct sja1105_private *priv = mdio_priv->priv;
+       const struct sja1105_regs *regs = priv->info->regs;
+       u32 tmp;
+       int rc;
+
+       rc = sja1105_xfer_u32(priv, SPI_READ, regs->mdio_100base_tx + reg,
+                             &tmp, NULL);
+       if (rc < 0)
+               return rc;
+
+       return tmp & 0xffff;
+}
+
+static int sja1105_base_tx_mdio_write(struct mii_bus *bus, int phy, int reg,
+                                     u16 val)
+{
+       struct sja1105_mdio_private *mdio_priv = bus->priv;
+       struct sja1105_private *priv = mdio_priv->priv;
+       const struct sja1105_regs *regs = priv->info->regs;
+       u32 tmp = val;
+
+       return sja1105_xfer_u32(priv, SPI_WRITE, regs->mdio_100base_tx + reg,
+                               &tmp, NULL);
+}
+
+static int sja1105_mdiobus_base_tx_register(struct sja1105_private *priv,
+                                           struct device_node *mdio_node)
+{
+       struct sja1105_mdio_private *mdio_priv;
+       struct device_node *np;
+       struct mii_bus *bus;
+       int rc = 0;
+
+       np = of_find_compatible_node(mdio_node, NULL,
+                                    "nxp,sja1110-base-tx-mdio");
+       if (!np)
+               return 0;
+
+       if (!of_device_is_available(np))
+               goto out_put_np;
+
+       bus = mdiobus_alloc_size(sizeof(*mdio_priv));
+       if (!bus) {
+               rc = -ENOMEM;
+               goto out_put_np;
+       }
+
+       bus->name = "SJA1110 100base-TX MDIO bus";
+       snprintf(bus->id, MII_BUS_ID_SIZE, "%s-base-tx",
+                dev_name(priv->ds->dev));
+       bus->read = sja1105_base_tx_mdio_read;
+       bus->write = sja1105_base_tx_mdio_write;
+       bus->parent = priv->ds->dev;
+       mdio_priv = bus->priv;
+       mdio_priv->priv = priv;
+
+       rc = of_mdiobus_register(bus, np);
+       if (rc) {
+               mdiobus_free(bus);
+               goto out_put_np;
+       }
+
+       priv->mdio_base_tx = bus;
+
+out_put_np:
+       of_node_put(np);
+
+       return 0;
+}
+
+static void sja1105_mdiobus_base_tx_unregister(struct sja1105_private *priv)
+{
+       if (!priv->mdio_base_tx)
+               return;
+
+       mdiobus_unregister(priv->mdio_base_tx);
+       mdiobus_free(priv->mdio_base_tx);
+       priv->mdio_base_tx = NULL;
+}
+
+static int sja1105_mdiobus_base_t1_register(struct sja1105_private *priv,
+                                           struct device_node *mdio_node)
+{
+       struct sja1105_mdio_private *mdio_priv;
+       struct device_node *np;
+       struct mii_bus *bus;
+       int rc = 0;
+
+       np = of_find_compatible_node(mdio_node, NULL,
+                                    "nxp,sja1110-base-t1-mdio");
+       if (!np)
+               return 0;
+
+       if (!of_device_is_available(np))
+               goto out_put_np;
+
+       bus = mdiobus_alloc_size(sizeof(*mdio_priv));
+       if (!bus) {
+               rc = -ENOMEM;
+               goto out_put_np;
+       }
+
+       bus->name = "SJA1110 100base-T1 MDIO bus";
+       snprintf(bus->id, MII_BUS_ID_SIZE, "%s-base-t1",
+                dev_name(priv->ds->dev));
+       bus->read = sja1105_base_t1_mdio_read;
+       bus->write = sja1105_base_t1_mdio_write;
+       bus->parent = priv->ds->dev;
+       mdio_priv = bus->priv;
+       mdio_priv->priv = priv;
+
+       rc = of_mdiobus_register(bus, np);
+       if (rc) {
+               mdiobus_free(bus);
+               goto out_put_np;
+       }
+
+       priv->mdio_base_t1 = bus;
+
+out_put_np:
+       of_node_put(np);
+
+       return rc;
+}
+
+static void sja1105_mdiobus_base_t1_unregister(struct sja1105_private *priv)
+{
+       if (!priv->mdio_base_t1)
+               return;
+
+       mdiobus_unregister(priv->mdio_base_t1);
+       mdiobus_free(priv->mdio_base_t1);
+       priv->mdio_base_t1 = NULL;
+}
+
+int sja1105_mdiobus_register(struct dsa_switch *ds)
+{
+       struct sja1105_private *priv = ds->priv;
+       const struct sja1105_regs *regs = priv->info->regs;
+       struct device_node *switch_node = ds->dev->of_node;
+       struct device_node *mdio_node;
+       int rc;
+
+       mdio_node = of_get_child_by_name(switch_node, "mdios");
+       if (!mdio_node)
+               return 0;
+
+       if (!of_device_is_available(mdio_node))
+               goto out_put_mdio_node;
+
+       if (regs->mdio_100base_tx != SJA1105_RSV_ADDR) {
+               rc = sja1105_mdiobus_base_tx_register(priv, mdio_node);
+               if (rc)
+                       goto err_put_mdio_node;
+       }
+
+       if (regs->mdio_100base_t1 != SJA1105_RSV_ADDR) {
+               rc = sja1105_mdiobus_base_t1_register(priv, mdio_node);
+               if (rc)
+                       goto err_free_base_tx_mdiobus;
+       }
+
+out_put_mdio_node:
+       of_node_put(mdio_node);
+
+       return 0;
+
+err_free_base_tx_mdiobus:
+       sja1105_mdiobus_base_tx_unregister(priv);
+err_put_mdio_node:
+       of_node_put(mdio_node);
+
+       return rc;
+}
+
+void sja1105_mdiobus_unregister(struct dsa_switch *ds)
+{
+       struct sja1105_private *priv = ds->priv;
+
+       sja1105_mdiobus_base_t1_unregister(priv);
+       sja1105_mdiobus_base_tx_unregister(priv);
+}
 
        .ptpclkval = 0x18, /* Spans 0x18 to 0x19 */
        .ptpclkrate = 0x1A,
        .ptpclkcorp = 0x1D,
+       .mdio_100base_tx = SJA1105_RSV_ADDR,
+       .mdio_100base_t1 = SJA1105_RSV_ADDR,
 };
 
 static struct sja1105_regs sja1105pqrs_regs = {
        .ptpclkrate = 0x1B,
        .ptpclkcorp = 0x1E,
        .ptpsyncts = 0x1F,
+       .mdio_100base_tx = SJA1105_RSV_ADDR,
+       .mdio_100base_t1 = SJA1105_RSV_ADDR,
 };
 
 static struct sja1105_regs sja1110_regs = {
        .ptpclkrate = SJA1110_SPI_ADDR(0x74),
        .ptpclkcorp = SJA1110_SPI_ADDR(0x80),
        .ptpsyncts = SJA1110_SPI_ADDR(0x84),
+       .mdio_100base_tx = 0x1c2400,
+       .mdio_100base_t1 = 0x1c1000,
 };
 
 const struct sja1105_info sja1105e_info = {
                                   false, false, false, false, false, false},
        .supports_2500basex     = {false, false, false, true, true,
                                   false, false, false, false, false, false},
+       .internal_phy           = {SJA1105_NO_PHY, SJA1105_PHY_BASE_TX,
+                                  SJA1105_NO_PHY, SJA1105_NO_PHY,
+                                  SJA1105_NO_PHY, SJA1105_PHY_BASE_T1,
+                                  SJA1105_PHY_BASE_T1, SJA1105_PHY_BASE_T1,
+                                  SJA1105_PHY_BASE_T1, SJA1105_PHY_BASE_T1,
+                                  SJA1105_PHY_BASE_T1},
        .name                   = "SJA1110A",
 };
 
                                   false, false, false, false, false, false},
        .supports_2500basex     = {false, false, false, true, true,
                                   false, false, false, false, false, false},
+       .internal_phy           = {SJA1105_NO_PHY, SJA1105_PHY_BASE_TX,
+                                  SJA1105_NO_PHY, SJA1105_NO_PHY,
+                                  SJA1105_NO_PHY, SJA1105_PHY_BASE_T1,
+                                  SJA1105_PHY_BASE_T1, SJA1105_PHY_BASE_T1,
+                                  SJA1105_PHY_BASE_T1, SJA1105_PHY_BASE_T1,
+                                  SJA1105_NO_PHY},
        .name                   = "SJA1110B",
 };
 
                                   false, false, false, false, false, false},
        .supports_2500basex     = {false, false, false, false, true,
                                   false, false, false, false, false, false},
+       .internal_phy           = {SJA1105_NO_PHY, SJA1105_PHY_BASE_TX,
+                                  SJA1105_NO_PHY, SJA1105_NO_PHY,
+                                  SJA1105_NO_PHY, SJA1105_PHY_BASE_T1,
+                                  SJA1105_PHY_BASE_T1, SJA1105_PHY_BASE_T1,
+                                  SJA1105_NO_PHY, SJA1105_NO_PHY,
+                                  SJA1105_NO_PHY},
        .name                   = "SJA1110C",
 };
 
                                   false, false, false, false, false, false},
        .supports_sgmii         = {false, true, true, true, true,
                                   false, false, false, false, false, false},
+       .internal_phy           = {SJA1105_NO_PHY, SJA1105_NO_PHY,
+                                  SJA1105_NO_PHY, SJA1105_NO_PHY,
+                                  SJA1105_NO_PHY, SJA1105_PHY_BASE_T1,
+                                  SJA1105_PHY_BASE_T1, SJA1105_PHY_BASE_T1,
+                                  SJA1105_NO_PHY, SJA1105_NO_PHY,
+                                  SJA1105_NO_PHY},
        .name                   = "SJA1110D",
 };