#define VENDOR_ID1_VAL 0x19
 #define VENDOR_ID2 0x24
 #define VENDOR_ID2_VAL 0x34
+#define IO_ADDR1 0x61
+#define IO_ADDR2 0x60
 #define LDN 0x7
 
 #define RS485  0xF0
        release_region(base_port + ADDR_PORT, 2);
 }
 
-static int fintek_8250_get_index(resource_size_t base_addr)
-{
-       resource_size_t base[] = {0x3f8, 0x2f8, 0x3e8, 0x2e8};
-       int i;
-
-       for (i = 0; i < ARRAY_SIZE(base); i++)
-               if (base_addr == base[i])
-                       return i;
-
-       return -ENODEV;
-}
-
 static int fintek_8250_check_id(u16 base_port)
 {
        u16 chip;
        return 0;
 }
 
-static int fintek_8250_base_port(u8 *key)
+static int fintek_8250_base_port(u16 io_address, u8 *key, u8 *index)
 {
        static const u16 addr[] = {0x4e, 0x2e};
        static const u8 keys[] = {0x77, 0xa0, 0x87, 0x67};
-       int i, j;
+       int i, j, k;
 
        for (i = 0; i < ARRAY_SIZE(addr); i++) {
                for (j = 0; j < ARRAY_SIZE(keys); j++) {
-                       int ret;
 
                        if (fintek_8250_enter_key(addr[i], keys[j]))
                                continue;
-                       ret = fintek_8250_check_id(addr[i]);
-                       fintek_8250_exit_key(addr[i]);
-                       if (!ret) {
+                       if (fintek_8250_check_id(addr[i])) {
+                               fintek_8250_exit_key(addr[i]);
+                               continue;
+                       }
+
+                       for (k = 0; k < 4; k++) {
+                               u16 aux;
+
+                               outb(LDN, addr[i] + ADDR_PORT);
+                               outb(k, addr[i] + DATA_PORT);
+
+                               outb(IO_ADDR1, addr[i] + ADDR_PORT);
+                               aux = inb(addr[i] + DATA_PORT);
+                               outb(IO_ADDR2, addr[i] + ADDR_PORT);
+                               aux |= inb(addr[i] + DATA_PORT) << 8;
+                               if (aux != io_address)
+                                       continue;
+
+                               fintek_8250_exit_key(addr[i]);
                                *key = keys[j];
+                               *index = k;
                                return addr[i];
                        }
+                       fintek_8250_exit_key(addr[i]);
                }
        }
 
 {
        struct uart_8250_port uart;
        struct fintek_8250 *pdata;
-       int index;
        int base_port;
        u8 key;
+       u8 index;
 
        if (!pnp_port_valid(dev, 0))
                return -ENODEV;
 
-       base_port = fintek_8250_base_port(&key);
+       base_port = fintek_8250_base_port(pnp_port_start(dev, 0), &key, &index);
        if (base_port < 0)
                return -ENODEV;
 
-       index = fintek_8250_get_index(pnp_port_start(dev, 0));
-       if (index < 0)
-               return -ENODEV;
-
        memset(&uart, 0, sizeof(uart));
 
        pdata = devm_kzalloc(&dev->dev, sizeof(*pdata), GFP_KERNEL);