net: pcs: xpcs: add specific vendor supoprt for Wangxun 10Gb NICs

Since Wangxun 10Gb NICs require some special configuration on the IP of
Synopsys Designware XPCS, introduce dev_flag for different vendors. Read
OUI from device identifier registers, to detect Wangxun devices.

And xpcs_soft_reset() is skipped to avoid the reset of device identifier
registers.

Signed-off-by: Jiawen Wu <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/pcs/pcs-xpcs.c

···
 	return xpcs_write_vendor(xpcs, MDIO_MMD_PCS, reg, val);
 }
 
+static int xpcs_dev_flag(struct dw_xpcs *xpcs)
+{
+	int ret, oui;
+
+	ret = xpcs_read(xpcs, MDIO_MMD_PMAPMD, MDIO_DEVID1);
+	if (ret < 0)
+		return ret;
+
+	oui = ret;
+
+	ret = xpcs_read(xpcs, MDIO_MMD_PMAPMD, MDIO_DEVID2);
+	if (ret < 0)
+		return ret;
+
+	ret = (ret >> 10) & 0x3F;
+	oui |= ret << 16;
+
+	if (oui == DW_OUI_WX)
+		xpcs->dev_flag = DW_DEV_TXGBE;
+
+	return 0;
+}
+
 static int xpcs_poll_reset(struct dw_xpcs *xpcs, int dev)
 {
 	/* Poll until the reset bit clears (50ms per retry == 0.6 sec) */
···
 			goto out;
 		}
 
+		ret = xpcs_dev_flag(xpcs);
+		if (ret)
+			goto out;
+
 		xpcs->pcs.ops = &xpcs_phylink_ops;
 		xpcs->pcs.neg_mode = true;
 		if (compat->an_mode == DW_10GBASER)
···
 
 		xpcs->pcs.poll = true;
 
-		ret = xpcs_soft_reset(xpcs, compat);
-		if (ret)
-			goto out;
+		if (xpcs->dev_flag != DW_DEV_TXGBE) {
+			ret = xpcs_soft_reset(xpcs, compat);
+			if (ret)
+				goto out;
+		}
 
 		return xpcs;
 	}

include/linux/pcs/pcs-xpcs.h

···
 #define DW_AN_C37_1000BASEX		4
 #define DW_10GBASER			5
 
+/* device vendor OUI */
+#define DW_OUI_WX			0x0018fc80
+
+/* dev_flag */
+#define DW_DEV_TXGBE			BIT(0)
+
 struct xpcs_id;
 
 struct dw_xpcs {
 	struct mdio_device *mdiodev;
 	const struct xpcs_id *id;
 	struct phylink_pcs pcs;
+	int dev_flag;
 };
 
 int xpcs_get_an_mode(struct dw_xpcs *xpcs, phy_interface_t interface);