amd-xgbe: Fix mdio access for non-zero ports and clause 45 PHYs

The XGBE hardware has support for performing MDIO operations using an
MDIO command request. The driver mistakenly uses the mdio port address
as the MDIO command request device address instead of the MDIO command
request port address. Additionally, the driver does not properly check
for and create a clause 45 MDIO command.

Check the supplied MDIO register to determine if the request is a clause
45 operation (MII_ADDR_C45). For a clause 45 operation, extract the device
address and register number from the supplied MDIO register and use them
to set the MDIO command request device address and register number fields.
For a clause 22 operation, the MDIO request device address is set to zero
and the MDIO command request register number is set to the supplied MDIO
register. In either case, the supplied MDIO port address is used as the
MDIO command request port address.

Fixes: 732f2ab7af ("amd-xgbe: Add support for MDIO attached PHYs")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/amd/xgbe/xgbe-common.h

@@ -431,8 +431,6 @@
 #define MAC_MDIOSCAR_PA_WIDTH		5
 #define MAC_MDIOSCAR_RA_INDEX		0
 #define MAC_MDIOSCAR_RA_WIDTH		16
-#define MAC_MDIOSCAR_REG_INDEX		0
-#define MAC_MDIOSCAR_REG_WIDTH		21
 #define MAC_MDIOSCCDR_BUSY_INDEX	22
 #define MAC_MDIOSCCDR_BUSY_WIDTH	1
 #define MAC_MDIOSCCDR_CMD_INDEX		16

drivers/net/ethernet/amd/xgbe/xgbe-dev.c

@@ -1284,6 +1284,20 @@ static void xgbe_write_mmd_regs(struct xgbe_prv_data *pdata, int prtad,
 	}
 }
 
+static unsigned int xgbe_create_mdio_sca(int port, int reg)
+{
+	unsigned int mdio_sca, da;
+
+	da = (reg & MII_ADDR_C45) ? reg >> 16 : 0;
+
+	mdio_sca = 0;
+	XGMAC_SET_BITS(mdio_sca, MAC_MDIOSCAR, RA, reg);
+	XGMAC_SET_BITS(mdio_sca, MAC_MDIOSCAR, PA, port);
+	XGMAC_SET_BITS(mdio_sca, MAC_MDIOSCAR, DA, da);
+
+	return mdio_sca;
+}
+
 static int xgbe_write_ext_mii_regs(struct xgbe_prv_data *pdata, int addr,
 				   int reg, u16 val)
 {
@@ -1291,9 +1305,7 @@ static int xgbe_write_ext_mii_regs(struct xgbe_prv_data *pdata, int addr,
 
 	reinit_completion(&pdata->mdio_complete);
 
-	mdio_sca = 0;
+	mdio_sca = xgbe_create_mdio_sca(addr, reg);
-	XGMAC_SET_BITS(mdio_sca, MAC_MDIOSCAR, REG, reg);
-	XGMAC_SET_BITS(mdio_sca, MAC_MDIOSCAR, DA, addr);
 	XGMAC_IOWRITE(pdata, MAC_MDIOSCAR, mdio_sca);
 
 	mdio_sccd = 0;
@@ -1317,9 +1329,7 @@ static int xgbe_read_ext_mii_regs(struct xgbe_prv_data *pdata, int addr,
 
 	reinit_completion(&pdata->mdio_complete);
 
-	mdio_sca = 0;
+	mdio_sca = xgbe_create_mdio_sca(addr, reg);
-	XGMAC_SET_BITS(mdio_sca, MAC_MDIOSCAR, REG, reg);
-	XGMAC_SET_BITS(mdio_sca, MAC_MDIOSCAR, DA, addr);
 	XGMAC_IOWRITE(pdata, MAC_MDIOSCAR, mdio_sca);
 
 	mdio_sccd = 0;