+static u32
+qca8k_port_to_phy(int port)
+{
+ /* From Andrew Lunn:
+ * Port 0 has no internal phy.
+ * Port 1 has an internal PHY at MDIO address 0.
+ * Port 2 has an internal PHY at MDIO address 1.
+ * ...
+ * Port 5 has an internal PHY at MDIO address 4.
+ * Port 6 has no internal PHY.
+ */
+
+ return port - 1;
+}
+
+static int
+qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data)
+{
+ u32 phy, val;
+
+ if (regnum >= QCA8K_MDIO_MASTER_MAX_REG)
+ return -EINVAL;
+
+ /* callee is responsible for not passing bad ports,
+ * but we still would like to make spills impossible.
+ */
+ phy = qca8k_port_to_phy(port) % PHY_MAX_ADDR;
+ val = QCA8K_MDIO_MASTER_BUSY | QCA8K_MDIO_MASTER_EN |
+ QCA8K_MDIO_MASTER_WRITE | QCA8K_MDIO_MASTER_PHY_ADDR(phy) |
+ QCA8K_MDIO_MASTER_REG_ADDR(regnum) |
+ QCA8K_MDIO_MASTER_DATA(data);
+
+ qca8k_write(priv, QCA8K_MDIO_MASTER_CTRL, val);
+
+ return qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
+ QCA8K_MDIO_MASTER_BUSY);
+}
+
+static int
+qca8k_mdio_read(struct qca8k_priv *priv, int port, u32 regnum)
+{
+ u32 phy, val;
+
+ if (regnum >= QCA8K_MDIO_MASTER_MAX_REG)
+ return -EINVAL;
+
+ /* callee is responsible for not passing bad ports,
+ * but we still would like to make spills impossible.
+ */
+ phy = qca8k_port_to_phy(port) % PHY_MAX_ADDR;
+ val = QCA8K_MDIO_MASTER_BUSY | QCA8K_MDIO_MASTER_EN |
+ QCA8K_MDIO_MASTER_READ | QCA8K_MDIO_MASTER_PHY_ADDR(phy) |
+ QCA8K_MDIO_MASTER_REG_ADDR(regnum);
+
+ qca8k_write(priv, QCA8K_MDIO_MASTER_CTRL, val);
+
+ if (qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
+ QCA8K_MDIO_MASTER_BUSY))
+ return -ETIMEDOUT;
+
+ val = (qca8k_read(priv, QCA8K_MDIO_MASTER_CTRL) &
+ QCA8K_MDIO_MASTER_DATA_MASK);
+
+ return val;
+}
+
+static int
+qca8k_phy_write(struct dsa_switch *ds, int port, int regnum, u16 data)
+{
+ struct qca8k_priv *priv = ds->priv;
+
+ return qca8k_mdio_write(priv, port, regnum, data);
+}
+
+static int
+qca8k_phy_read(struct dsa_switch *ds, int port, int regnum)
+{
+ struct qca8k_priv *priv = ds->priv;
+ int ret;
+
+ ret = qca8k_mdio_read(priv, port, regnum);
+
+ if (ret < 0)
+ return 0xffff;
+
+ return ret;
+}
+
+static int
+qca8k_setup_mdio_bus(struct qca8k_priv *priv)
+{
+ u32 internal_mdio_mask = 0, external_mdio_mask = 0, reg;
+ struct device_node *ports, *port;
+ int err;
+
+ ports = of_get_child_by_name(priv->dev->of_node, "ports");
+ if (!ports)
+ return -EINVAL;
+
+ for_each_available_child_of_node(ports, port) {
+ err = of_property_read_u32(port, "reg", ®);
+ if (err)
+ return err;
+
+ if (!dsa_is_user_port(priv->ds, reg))
+ continue;
+
+ if (of_property_read_bool(port, "phy-handle"))
+ external_mdio_mask |= BIT(reg);
+ else
+ internal_mdio_mask |= BIT(reg);
+ }
+
+ if (!external_mdio_mask && !internal_mdio_mask) {
+ dev_err(priv->dev, "no PHYs are defined.\n");
+ return -EINVAL;
+ }
+
+ /* The QCA8K_MDIO_MASTER_EN Bit, which grants access to PHYs through
+ * the MDIO_MASTER register also _disconnects_ the external MDC
+ * passthrough to the internal PHYs. It's not possible to use both
+ * configurations at the same time!
+ *
+ * Because this came up during the review process:
+ * If the external mdio-bus driver is capable magically disabling
+ * the QCA8K_MDIO_MASTER_EN and mutex/spin-locking out the qca8k's
+ * accessors for the time being, it would be possible to pull this
+ * off.
+ */
+ if (!!external_mdio_mask && !!internal_mdio_mask) {
+ dev_err(priv->dev, "either internal or external mdio bus configuration is supported.\n");
+ return -EINVAL;
+ }
+
+ if (external_mdio_mask) {
+ /* Make sure to disable the internal mdio bus in cases
+ * a dt-overlay and driver reload changed the configuration
+ */
+
+ qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
+ QCA8K_MDIO_MASTER_EN);
+ return 0;
+ }
+
+ priv->ops.phy_read = qca8k_phy_read;
+ priv->ops.phy_write = qca8k_phy_write;
+ return 0;
+}
+