serial: 8250_early: Use port->regshift

earlycon initializes struct uart_port::regshift to the correct
value for UPIO_MEM32 already. Use the port field rather than
hard-coded value.

This enables broader support for various i/o access methods in
8250 earlycon (eg., omap8250 earlycon).
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_early.c

@@ -39,15 +39,17 @@
 
 static unsigned int __init serial8250_early_in(struct uart_port *port, int offset)
 {
+	offset <<= port->regshift;
+
 	switch (port->iotype) {
 	case UPIO_MEM:
 		return readb(port->membase + offset);
 	case UPIO_MEM16:
-		return readw(port->membase + (offset << 1));
+		return readw(port->membase + offset);
 	case UPIO_MEM32:
-		return readl(port->membase + (offset << 2));
+		return readl(port->membase + offset);
 	case UPIO_MEM32BE:
-		return ioread32be(port->membase + (offset << 2));
+		return ioread32be(port->membase + offset);
 	case UPIO_PORT:
 		return inb(port->iobase + offset);
 	default:
@@ -57,18 +59,20 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
 
 static void __init serial8250_early_out(struct uart_port *port, int offset, int value)
 {
+	offset <<= port->regshift;
+
 	switch (port->iotype) {
 	case UPIO_MEM:
 		writeb(value, port->membase + offset);
 		break;
 	case UPIO_MEM16:
-		writew(value, port->membase + (offset << 1));
+		writew(value, port->membase + offset);
 		break;
 	case UPIO_MEM32:
-		writel(value, port->membase + (offset << 2));
+		writel(value, port->membase + offset);
 		break;
 	case UPIO_MEM32BE:
-		iowrite32be(value, port->membase + (offset << 2));
+		iowrite32be(value, port->membase + offset);
 		break;
 	case UPIO_PORT:
 		outb(value, port->iobase + offset);