[PATCH] Make serial console work for any port

From: Bjorn Helgaas <bjorn.helgaas@hp.com>

The current serial console code only works for ports that are either
defined in SERIAL_PORT_DFNS (and set up by serial8250_isa_init_ports()) or
registered by early_serial_setup().

On ia64, SERIAL_PORT_DFNS is empty because we discover everything via ACPI
and PCI.  And we only use early_serial_setup() for one port described by
the HCDP firmware table.

This patch against 2.6.3-rc2 makes it work for any valid port.  If we don't
know about the port early, we just return -ENODEV from the setup()
function, which leaves the serial console disabled.  After the driver has
found all the ports, we try to register the serial console again if it
hasn't been enabled already.

I think the "port->type == PORT_UNKNOWN" test is cleaner than the
"port->ops" test -- it more clearly gets to the point of "do we know about
this port".

drivers/serial/8250.c

@@ -1976,6 +1976,8 @@ static int __init serial8250_console_setup(struct console *co, char *options)
 	if (co->index >= UART_NR)
 		co->index = 0;
 	port = &serial8250_ports[co->index].port;
+	if (port->type == PORT_UNKNOWN)
+		return -ENODEV;
 
 	/*
 	 * Temporary fix.
@@ -2007,6 +2009,14 @@ static int __init serial8250_console_init(void)
 }
 console_initcall(serial8250_console_init);
 
+static int __init serial8250_late_console_init(void)
+{
+	if (!(serial8250_console.flags & CON_ENABLED))
+		register_console(&serial8250_console);
+	return 0;
+}
+late_initcall(serial8250_late_console_init);
+
 #define SERIAL8250_CONSOLE	&serial8250_console
 #else
 #define SERIAL8250_CONSOLE	NULL

drivers/serial/serial_core.c

@@ -1871,9 +1871,6 @@ uart_set_options(struct uart_port *port, struct console *co,
 	if (flow == 'r')
 		termios.c_cflag |= CRTSCTS;
 
-	if (!port->ops)
-		return 0;	/* "console=" on ia64 */
-
 	port->ops->set_termios(port, &termios, NULL);
 	co->cflag = termios.c_cflag;