net: mdio-ipq4019: add Clause 45 support

While up-streaming the IPQ4019 driver it was thought that the controller had no Clause 45 support,
but it actually does and its activated by writing a bit to the mode register.

So lets add it as newer SoC-s use the same controller and Clause 45 compliant PHY-s.
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/mdio/mdio-ipq4019.c

@@ -12,6 +12,7 @@
 #include <linux/phy.h>
 #include <linux/platform_device.h>
 
+#define MDIO_MODE_REG				0x40
 #define MDIO_ADDR_REG				0x44
 #define MDIO_DATA_WRITE_REG			0x48
 #define MDIO_DATA_READ_REG			0x4c
@@ -20,6 +21,12 @@
 #define MDIO_CMD_ACCESS_START		BIT(8)
 #define MDIO_CMD_ACCESS_CODE_READ	0
 #define MDIO_CMD_ACCESS_CODE_WRITE	1
+#define MDIO_CMD_ACCESS_CODE_C45_ADDR	0
+#define MDIO_CMD_ACCESS_CODE_C45_WRITE	1
+#define MDIO_CMD_ACCESS_CODE_C45_READ	2
+
+/* 0 = Clause 22, 1 = Clause 45 */
+#define MDIO_MODE_C45				BIT(8)
 
 #define IPQ4019_MDIO_TIMEOUT	10000
 #define IPQ4019_MDIO_SLEEP		10
@@ -41,19 +48,44 @@ static int ipq4019_mdio_wait_busy(struct mii_bus *bus)
 static int ipq4019_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
 {
 	struct ipq4019_mdio_data *priv = bus->priv;
+	unsigned int data;
 	unsigned int cmd;
 
-	/* Reject clause 45 */
-	if (regnum & MII_ADDR_C45)
-		return -EOPNOTSUPP;
-
 	if (ipq4019_mdio_wait_busy(bus))
 		return -ETIMEDOUT;
 
-	/* issue the phy address and reg */
-	writel((mii_id << 8) | regnum, priv->membase + MDIO_ADDR_REG);
+	/* Clause 45 support */
+	if (regnum & MII_ADDR_C45) {
+		unsigned int mmd = (regnum >> 16) & 0x1F;
+		unsigned int reg = regnum & 0xFFFF;
+
+		/* Enter Clause 45 mode */
+		data = readl(priv->membase + MDIO_MODE_REG);
+
+		data |= MDIO_MODE_C45;
+
+		writel(data, priv->membase + MDIO_MODE_REG);
+
+		/* issue the phy address and mmd */
+		writel((mii_id << 8) | mmd, priv->membase + MDIO_ADDR_REG);
+
+		/* issue reg */
+		writel(reg, priv->membase + MDIO_DATA_WRITE_REG);
+
+		cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_C45_ADDR;
+	} else {
+		/* Enter Clause 22 mode */
+		data = readl(priv->membase + MDIO_MODE_REG);
 
-	cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_READ;
+		data &= ~MDIO_MODE_C45;
+
+		writel(data, priv->membase + MDIO_MODE_REG);
+
+		/* issue the phy address and reg */
+		writel((mii_id << 8) | regnum, priv->membase + MDIO_ADDR_REG);
+
+		cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_READ;
+	}
 
 	/* issue read command */
 	writel(cmd, priv->membase + MDIO_CMD_REG);
@@ -62,6 +94,15 @@ static int ipq4019_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
 	if (ipq4019_mdio_wait_busy(bus))
 		return -ETIMEDOUT;
 
+	if (regnum & MII_ADDR_C45) {
+		cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_C45_READ;
+
+		writel(cmd, priv->membase + MDIO_CMD_REG);
+
+		if (ipq4019_mdio_wait_busy(bus))
+			return -ETIMEDOUT;
+	}
+
 	/* Read and return data */
 	return readl(priv->membase + MDIO_DATA_READ_REG);
 }
@@ -70,23 +111,57 @@ static int ipq4019_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
 							 u16 value)
 {
 	struct ipq4019_mdio_data *priv = bus->priv;
+	unsigned int data;
 	unsigned int cmd;
 
-	/* Reject clause 45 */
-	if (regnum & MII_ADDR_C45)
-		return -EOPNOTSUPP;
-
 	if (ipq4019_mdio_wait_busy(bus))
 		return -ETIMEDOUT;
 
-	/* issue the phy address and reg */
-	writel((mii_id << 8) | regnum, priv->membase + MDIO_ADDR_REG);
+	/* Clause 45 support */
+	if (regnum & MII_ADDR_C45) {
+		unsigned int mmd = (regnum >> 16) & 0x1F;
+		unsigned int reg = regnum & 0xFFFF;
+
+		/* Enter Clause 45 mode */
+		data = readl(priv->membase + MDIO_MODE_REG);
+
+		data |= MDIO_MODE_C45;
+
+		writel(data, priv->membase + MDIO_MODE_REG);
+
+		/* issue the phy address and mmd */
+		writel((mii_id << 8) | mmd, priv->membase + MDIO_ADDR_REG);
+
+		/* issue reg */
+		writel(reg, priv->membase + MDIO_DATA_WRITE_REG);
+
+		cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_C45_ADDR;
+
+		writel(cmd, priv->membase + MDIO_CMD_REG);
+
+		if (ipq4019_mdio_wait_busy(bus))
+			return -ETIMEDOUT;
+	} else {
+		/* Enter Clause 22 mode */
+		data = readl(priv->membase + MDIO_MODE_REG);
+
+		data &= ~MDIO_MODE_C45;
+
+		writel(data, priv->membase + MDIO_MODE_REG);
+
+		/* issue the phy address and reg */
+		writel((mii_id << 8) | regnum, priv->membase + MDIO_ADDR_REG);
+	}
 
 	/* issue write data */
 	writel(value, priv->membase + MDIO_DATA_WRITE_REG);
 
-	cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_WRITE;
 	/* issue write command */
+	if (regnum & MII_ADDR_C45)
+		cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_C45_WRITE;
+	else
+		cmd = MDIO_CMD_ACCESS_START | MDIO_CMD_ACCESS_CODE_WRITE;
+
 	writel(cmd, priv->membase + MDIO_CMD_REG);
 
 	/* Wait write complete */