serial: convert early_uart to earlycon for 8250

Beacuse SERIAL_PORT_DFNS is removed from include/asm-i386/serial.h and
include/asm-x86_64/serial.h.  the serial8250_ports need to be probed late in
serial initializing stage.  the console_init=>serial8250_console_init=>
register_console=>serial8250_console_setup will return -ENDEV, and console
ttyS0 can not be enabled at that time.  need to wait till uart_add_one_port in
drivers/serial/serial_core.c to call register_console to get console ttyS0.
that is too late.

Make early_uart to use early_param, so uart console can be used earlier.  Make
it to be bootconsole with CON_BOOT flag, so can use console handover feature.
and it will switch to corresponding normal serial console automatically.

new command line will be:
	console=uart8250,io,0x3f8,9600n8
	console=uart8250,mmio,0xff5e0000,115200n8
or
	earlycon=uart8250,io,0x3f8,9600n8
	earlycon=uart8250,mmio,0xff5e0000,115200n8

it will print in very early stage:
	Early serial console at I/O port 0x3f8 (options '9600n8')
	console [uart0] enabled
later for console it will print:
	console handover: boot [uart0] -> real [ttyS0]

Signed-off-by: <yinghai.lu@sun.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/firmware/pcdp.c b/drivers/firmware/pcdp.c
index 2b4b76e8bd72..58e9f8e457f8 100644
--- a/drivers/firmware/pcdp.c
+++ b/drivers/firmware/pcdp.c
@@ -15,6 +15,7 @@
 #include <linux/console.h>
 #include <linux/efi.h>
 #include <linux/serial.h>
+#include <linux/serial_8250.h>
 #include <asm/vga.h>
 #include "pcdp.h"
 
@@ -27,7 +28,7 @@ setup_serial_console(struct pcdp_uart *uart)
         char parity;
 
         mmio = (uart->addr.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY);
-        p += sprintf(p, "console=uart,%s,0x%lx",
+        p += sprintf(p, "uart8250,%s,0x%lx",
                 mmio ? "mmio" : "io", uart->addr.address);
         if (uart->baud) {
                 p += sprintf(p, ",%lu", uart->baud);
@@ -41,7 +42,8 @@ setup_serial_console(struct pcdp_uart *uart)
                 }
         }
 
-        return early_serial_console_init(options);
+        add_preferred_console("uart", 8250, &options[9]);
+        return setup_early_serial8250_console(options);
 #else
         return -ENODEV;
 #endif