nmhw21: improve support for tja1102 dual phy

- install filter driver for mdio read funtion
- remove ghost phy at address 0
- report phy type also for 2nd port

BugzId: 55131

board/nm/nmhw21/board.c

@@ -172,6 +172,8 @@ static struct module_pin_mux spi1_pin_mux[] = {
 #endif
 };
 
+static struct mii_dev olddev;	/* Backup of PHY driver structure for read function override */
+
 #endif
 
 
@@ -1084,6 +1086,38 @@ static void set_mac_address(int index, uchar mac[6])
 	}
 }
 
+static int read_tja1102(struct mii_dev *bus, int phy_id, int dev_addr, int phy_reg)
+{
+	/* Remove TJA1102 mirror(s) at address 0 from bus */
+	if (phy_id == 0) {
+		return -1;
+	}
+
+	/*
+	 * Also report ID registers 2&3 for 2nd PHY in TJA1102
+	 * Take values from 1st PHY (ID 2)
+	 */
+	if (phy_id == 3 && (phy_reg == 2 || phy_reg == 3)) {
+		phy_id = 2;
+	}
+
+	return olddev.read(bus, phy_id, dev_addr, phy_reg);
+}
+
+static void register_phy_hook(void)
+{
+	struct mii_dev* dev;
+
+	dev = miiphy_get_dev_by_name("cpsw");
+	if (dev != NULL) {
+		/* Remember original structure (read pointer) */
+		memcpy(&olddev, dev, sizeof(olddev));
+
+		/* Override read method with SJA1002 wrapper */
+		dev->read = read_tja1102;
+	}
+}
+
 /* TODO: Update doc */
 /*
  * This function will:
@@ -1137,8 +1171,11 @@ int board_eth_init(bd_t *bis)
 		}
 	}
 #endif
+	register_phy_hook();
+
 	/* Enable BroadR PHYs, set to slave mode */
 	configure_broadr_phys();
+
 	return n;
 }
 #endif