diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 0995430..5443fcd 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -299,6 +299,7 @@
 
 static unsigned int serial_in(struct uart_8250_port *up, int offset)
 {
+	unsigned int tmp;
 	offset = map_8250_in_reg(up, offset) << up->port.regshift;
 
 	switch (up->port.iotype) {
@@ -317,6 +318,13 @@
 		return __raw_readl(up->port.membase + offset);
 #endif
 
+	case UPIO_TSI:
+		if (offset == UART_IIR) {
+			tmp = readl((u32 *)(up->port.membase + UART_RX));
+			return (cpu_to_le32(tmp) >> 8) & 0xff;
+		} else
+			return readb(up->port.membase + offset);
+
 	default:
 		return inb(up->port.iobase + offset);
 	}
@@ -346,6 +354,10 @@
 		__raw_writel(value, up->port.membase + offset);
 		break;
 #endif
+	case UPIO_TSI:
+		if (!((offset == UART_IER) && (value & UART_IER_UUE)))
+			writeb(value, up->port.membase + offset);
+		break;
 
 	default:
 		outb(value, up->port.iobase + offset);