diff --git a/drivers/net/dsa/b53/b53_mmap.c b/drivers/net/dsa/b53/b53_mmap.c
index 706df04b6cee..7deca1c557c5 100644
--- a/drivers/net/dsa/b53/b53_mmap.c
+++ b/drivers/net/dsa/b53/b53_mmap.c
@@ -19,14 +19,25 @@
 #include <linux/bits.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of_mdio.h>
 #include <linux/io.h>
 #include <linux/platform_device.h>
 #include <linux/platform_data/b53.h>
 
 #include "b53_priv.h"
 
+#define REG_MDIOC		0xb0
+#define  REG_MDIOC_EXT_MASK	BIT(16)
+#define  REG_MDIOC_REG_SHIFT	20
+#define  REG_MDIOC_PHYID_SHIFT	25
+#define  REG_MDIOC_RD_MASK	BIT(30)
+#define  REG_MDIOC_WR_MASK	BIT(31)
+
+#define REG_MDIOD		0xb4
+
 struct b53_mmap_priv {
 	void __iomem *regs;
+	struct mii_bus *bus;
 };
 
 static int b53_mmap_read8(struct b53_device *dev, u8 page, u8 reg, u8 *val)
@@ -216,6 +227,69 @@ static int b53_mmap_write64(struct b53_device *dev, u8 page, u8 reg,
 	return 0;
 }
 
+static inline void b53_mmap_mdio_read(struct b53_device *dev, int phy_id,
+				      int loc, u16 *val)
+{
+	uint32_t reg;
+
+	b53_mmap_write32(dev, 0, REG_MDIOC, 0);
+
+	reg = REG_MDIOC_RD_MASK |
+	      (phy_id << REG_MDIOC_PHYID_SHIFT) |
+	      (loc << REG_MDIOC_REG_SHIFT);
+
+	b53_mmap_write32(dev, 0, REG_MDIOC, reg);
+	udelay(50);
+	b53_mmap_read16(dev, 0, REG_MDIOD, val);
+}
+
+static inline int b53_mmap_mdio_write(struct b53_device *dev, int phy_id,
+				      int loc, u16 val)
+{
+	uint32_t reg;
+
+	b53_mmap_write32(dev, 0, REG_MDIOC, 0);
+
+	reg = REG_MDIOC_WR_MASK |
+	      (phy_id << REG_MDIOC_PHYID_SHIFT) |
+	      (loc << REG_MDIOC_REG_SHIFT) |
+	      val;
+
+	b53_mmap_write32(dev, 0, REG_MDIOC, reg);
+	udelay(50);
+
+	return 0;
+}
+
+static int b53_mmap_phy_read16(struct b53_device *dev, int addr, int reg,
+			       u16 *value)
+{
+	struct b53_mmap_priv *priv = dev->priv;
+	struct mii_bus *bus = priv->bus;
+
+	if (bus)
+		*value = mdiobus_read_nested(bus, addr, reg);
+	else
+		b53_mmap_mdio_read(dev, addr, reg, value);
+
+	return 0;
+}
+
+static int b53_mmap_phy_write16(struct b53_device *dev, int addr, int reg,
+				u16 value)
+{
+	struct b53_mmap_priv *priv = dev->priv;
+	struct mii_bus *bus = priv->bus;
+	int ret;
+
+	if (bus)
+		ret = mdiobus_write_nested(bus, addr, reg, value);
+	else
+		ret = b53_mmap_mdio_write(dev, addr, reg, value);
+
+	return ret;
+}
+
 static const struct b53_io_ops b53_mmap_ops = {
 	.read8 = b53_mmap_read8,
 	.read16 = b53_mmap_read16,
@@ -227,6 +301,8 @@ static const struct b53_io_ops b53_mmap_ops = {
 	.write32 = b53_mmap_write32,
 	.write48 = b53_mmap_write48,
 	.write64 = b53_mmap_write64,
+	.phy_read16 = b53_mmap_phy_read16,
+	.phy_write16 = b53_mmap_phy_write16,
 };
 
 static int b53_mmap_probe_of(struct platform_device *pdev,
@@ -234,6 +310,7 @@ static int b53_mmap_probe_of(struct platform_device *pdev,
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct device_node *of_ports, *of_port;
+	struct device_node *mdio;
 	struct device *dev = &pdev->dev;
 	struct b53_platform_data *pdata;
 	void __iomem *mem;
@@ -251,6 +328,14 @@ static int b53_mmap_probe_of(struct platform_device *pdev,
 	pdata->chip_id = (u32)device_get_match_data(dev);
 	pdata->big_endian = of_property_read_bool(np, "big-endian");
 
+	mdio = of_parse_phandle(np, "mii-bus", 0);
+	if (!mdio)
+		return -EINVAL;
+
+	pdata->bus = of_mdio_find_bus(mdio);
+	if (!pdata->bus)
+		return -EPROBE_DEFER;
+
 	of_ports = of_get_child_by_name(np, "ports");
 	if (!of_ports) {
 		dev_err(dev, "no ports child node found\n");
@@ -297,6 +382,7 @@ static int b53_mmap_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	priv->regs = pdata->regs;
+	priv->bus = pdata->bus;
 
 	dev = b53_switch_alloc(&pdev->dev, &b53_mmap_ops, priv);
 	if (!dev)
diff --git a/include/linux/platform_data/b53.h b/include/linux/platform_data/b53.h
index 6f6fed2b171d..be0c5bfdedad 100644
--- a/include/linux/platform_data/b53.h
+++ b/include/linux/platform_data/b53.h
@@ -32,6 +32,7 @@ struct b53_platform_data {
 	/* only used by MMAP'd driver */
 	unsigned big_endian:1;
 	void __iomem *regs;
+	struct mii_bus *bus;
 };
 
 #endif
