serial: 8250_early: Add earlycon support for Palmchip UART

Define an OF early console for Palmchip UART, which can be enabled
by passing "earlycon" on the boot command line.
Signed-off-by: NMarc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -39,6 +39,7 @@
 
 static unsigned int __init serial8250_early_in(struct uart_port *port, int offset)
 {
+	int reg_offset = offset;
 	offset <<= port->regshift;
 
 	switch (port->iotype) {
@@ -52,6 +53,8 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
 		return ioread32be(port->membase + offset);
 	case UPIO_PORT:
 		return inb(port->iobase + offset);
+	case UPIO_AU:
+		return port->serial_in(port, reg_offset);
 	default:
 		return 0;
 	}
@@ -59,6 +62,7 @@ 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)
 {
+	int reg_offset = offset;
 	offset <<= port->regshift;
 
 	switch (port->iotype) {
@@ -77,6 +81,9 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
 	case UPIO_PORT:
 		outb(value, port->iobase + offset);
 		break;
+	case UPIO_AU:
+		port->serial_out(port, reg_offset, value);
+		break;
 	}
 }
 
@@ -172,3 +179,20 @@ OF_EARLYCON_DECLARE(omap8250, "ti,omap3-uart", early_omap8250_setup);
 OF_EARLYCON_DECLARE(omap8250, "ti,omap4-uart", early_omap8250_setup);
 
 #endif
+
+#ifdef CONFIG_SERIAL_8250_RT288X
+
+unsigned int au_serial_in(struct uart_port *p, int offset);
+void au_serial_out(struct uart_port *p, int offset, int value);
+
+static int __init early_au_setup(struct earlycon_device *dev, const char *opt)
+{
+	dev->port.serial_in = au_serial_in;
+	dev->port.serial_out = au_serial_out;
+	dev->port.iotype = UPIO_AU;
+	dev->con->write = early_serial8250_write;
+	return 0;
+}
+OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup);
+
+#endif

drivers/tty/serial/8250/8250_port.c

@@ -328,7 +328,7 @@ static const s8 au_io_out_map[8] = {
 	-1,	/* UART_SCR (unmapped) */
 };
 
-static unsigned int au_serial_in(struct uart_port *p, int offset)
+unsigned int au_serial_in(struct uart_port *p, int offset)
 {
 	if (offset >= ARRAY_SIZE(au_io_in_map))
 		return UINT_MAX;
@@ -338,7 +338,7 @@ static unsigned int au_serial_in(struct uart_port *p, int offset)
 	return __raw_readl(p->membase + (offset << p->regshift));
 }
 
-static void au_serial_out(struct uart_port *p, int offset, int value)
+void au_serial_out(struct uart_port *p, int offset, int value)
 {
 	if (offset >= ARRAY_SIZE(au_io_out_map))
 		return;