net: phy: adin: add {write,read}_mmd hooks

Both ADIN1200 & ADIN1300 support Clause 45 access for some registers.
The Extended Management Interface (EMI) registers are accessible via both
Clause 45 (at register MDIO_MMD_VEND1) and using Clause 22.

The Clause 22 access for MMD regs differs from the standard one defined by
802.3. The ADIN PHYs  use registers ExtRegPtr (0x0010) and ExtRegData
(0x0011) to access Clause 45 & EMI registers.

The indirect access is done via the following mechanism (for both R/W):
1. Write the address of the register in the ExtRegPtr
2. Read/write the value of the register via reg ExtRegData

This mechanism is needed to manage configuration of chip settings and to
access EEE registers via Clause 22.

Since Clause 45 access will likely never be used, it is not implemented via
this hook.
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/adin.c

@@ -14,6 +14,9 @@
 #define PHY_ID_ADIN1200				0x0283bc20
 #define PHY_ID_ADIN1300				0x0283bc30
 
+#define ADIN1300_MII_EXT_REG_PTR		0x0010
+#define ADIN1300_MII_EXT_REG_DATA		0x0011
+
 #define ADIN1300_INT_MASK_REG			0x0018
 #define   ADIN1300_INT_MDIO_SYNC_EN		BIT(9)
 #define   ADIN1300_INT_ANEG_STAT_CHNG_EN	BIT(8)
@@ -51,6 +54,33 @@ static int adin_phy_config_intr(struct phy_device *phydev)
 			      ADIN1300_INT_MASK_EN);
 }
 
+static int adin_read_mmd(struct phy_device *phydev, int devad, u16 regnum)
+{
+	struct mii_bus *bus = phydev->mdio.bus;
+	int phy_addr = phydev->mdio.addr;
+	int err;
+
+	err = __mdiobus_write(bus, phy_addr, ADIN1300_MII_EXT_REG_PTR, regnum);
+	if (err)
+		return err;
+
+	return __mdiobus_read(bus, phy_addr, ADIN1300_MII_EXT_REG_DATA);
+}
+
+static int adin_write_mmd(struct phy_device *phydev, int devad, u16 regnum,
+			  u16 val)
+{
+	struct mii_bus *bus = phydev->mdio.bus;
+	int phy_addr = phydev->mdio.addr;
+	int err;
+
+	err = __mdiobus_write(bus, phy_addr, ADIN1300_MII_EXT_REG_PTR, regnum);
+	if (err)
+		return err;
+
+	return __mdiobus_write(bus, phy_addr, ADIN1300_MII_EXT_REG_DATA, val);
+}
+
 static struct phy_driver adin_driver[] = {
 	{
 		PHY_ID_MATCH_MODEL(PHY_ID_ADIN1200),
@@ -62,6 +92,8 @@ static struct phy_driver adin_driver[] = {
 		.config_intr	= adin_phy_config_intr,
 		.resume		= genphy_resume,
 		.suspend	= genphy_suspend,
+		.read_mmd	= adin_read_mmd,
+		.write_mmd	= adin_write_mmd,
 	},
 	{
 		PHY_ID_MATCH_MODEL(PHY_ID_ADIN1300),
@@ -73,6 +105,8 @@ static struct phy_driver adin_driver[] = {
 		.config_intr	= adin_phy_config_intr,
 		.resume		= genphy_resume,
 		.suspend	= genphy_suspend,
+		.read_mmd	= adin_read_mmd,
+		.write_mmd	= adin_write_mmd,
 	},
 };