+--- a/include/linux/serial_8250.h
++++ b/include/linux/serial_8250.h
+@@ -26,6 +26,7 @@ struct plat_serial8250_port {
+ void *private_data;
+ unsigned char regshift; /* register shift */
+ unsigned char iotype; /* UPIO_* */
++ unsigned int rw_delay; /* udelay for slower busses IXP4XX Expansion Bus */
+ unsigned char hub6;
+ upf_t flags; /* UPF_* flags */
+ };
+--- a/include/linux/serial_core.h
++++ b/include/linux/serial_core.h
+@@ -262,6 +262,7 @@ struct uart_port {
+ #define UPIO_TSI (5) /* Tsi108/109 type IO */
+ #define UPIO_DWAPB (6) /* DesignWare APB UART */
+ #define UPIO_RM9000 (7) /* RM9000 type IO */
++#define UPIO_MEM_DELAY (8)
+
+ unsigned int read_status_mask; /* driver specific */
+ unsigned int ignore_status_mask; /* driver specific */
+@@ -301,6 +302,7 @@ struct uart_port {
+
+ unsigned int mctrl; /* current modem ctrl settings */
+ unsigned int timeout; /* character-based timeout */
++ unsigned int rw_delay; /* udelay for slow busses, IXP4XX Expansion Bus */
+ unsigned int type; /* port type */
+ const struct uart_ops *ops;
+ unsigned int custom_divisor;
+--- a/drivers/serial/8250.c
++++ b/drivers/serial/8250.c
+@@ -373,6 +373,8 @@ static unsigned int serial_in(struct uar
+ outb(up->port.hub6 - 1 + offset, up->port.iobase);
+ return inb(up->port.iobase + 1);
+
++ case UPIO_MEM_DELAY:
++ udelay(up->port.rw_delay);
+ case UPIO_MEM:
+ case UPIO_DWAPB:
+ return readb(up->port.membase + offset);
+@@ -411,6 +413,8 @@ serial_out(struct uart_8250_port *up, in
+ outb(value, up->port.iobase + 1);
+ break;
+
++ case UPIO_MEM_DELAY:
++ udelay(up->port.rw_delay);
+ case UPIO_MEM:
+ writeb(value, up->port.membase + offset);
+ break;
+@@ -2823,6 +2827,7 @@ static int __devinit serial8250_probe(st
+ port.hub6 = p->hub6;
+ port.private_data = p->private_data;
+ port.dev = &dev->dev;
++ port.rw_delay = p->rw_delay;
+ if (share_irqs)
+ port.flags |= UPF_SHARE_IRQ;
+ ret = serial8250_register_port(&port);
+@@ -2972,6 +2977,7 @@ int serial8250_register_port(struct uart
+ uart->port.iotype = port->iotype;
+ uart->port.flags = port->flags | UPF_BOOT_AUTOCONF;
+ uart->port.mapbase = port->mapbase;
++ uart->port.rw_delay = port->rw_delay;
+ uart->port.private_data = port->private_data;
+ if (port->dev)
+ uart->port.dev = port->dev;
+--- a/drivers/serial/serial_core.c
++++ b/drivers/serial/serial_core.c
+@@ -2161,6 +2161,7 @@ uart_report_port(struct uart_driver *drv
+ snprintf(address, sizeof(address),
+ "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
+ break;
++ case UPIO_MEM_DELAY:
+ case UPIO_MEM:
+ case UPIO_MEM32:
+ case UPIO_AU:
+@@ -2577,6 +2578,7 @@ int uart_match_port(struct uart_port *po
+ case UPIO_HUB6:
+ return (port1->iobase == port2->iobase) &&
+ (port1->hub6 == port2->hub6);
++ case UPIO_MEM_DELAY:
+ case UPIO_MEM:
+ case UPIO_MEM32:
+ case UPIO_AU: