MIPS: Malta: use generic 8250 early console

This patch switches Malta from using the MIPS implementation of early
printk with Malta's prom_putchar to using the generic 8250_early
implementation. This offers a couple of advantages:

  - We duplicate less generic code.

  - The UART can be initialised rather than being reliant upon
    inheriting a valid setup from the bootloader.

The Malta console_config function is extended to initialise the early
console if no earlycon= kernel parameter is provided, inheriting the
modetty0 bootloader environment if present and falling back to a
default 38400n8r setup if not. This matches the behaviour used for the
regular console= parameter.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6183/

arch/mips/Kconfig

@@ -320,7 +320,6 @@ config MIPS_MALTA
 	select SYS_HAS_CPU_MIPS64_R2
 	select SYS_HAS_CPU_NEVADA
 	select SYS_HAS_CPU_RM7000
-	select SYS_HAS_EARLY_PRINTK
 	select SYS_SUPPORTS_32BIT_KERNEL
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_BIG_ENDIAN

arch/mips/mti-malta/Makefile

@@ -9,7 +9,5 @@ obj-y				:= malta-amon.o malta-display.o malta-init.o \
 				   malta-int.o malta-memory.o malta-platform.o \
 				   malta-reset.o malta-setup.o malta-time.o
 
-obj-$(CONFIG_EARLY_PRINTK)	+= malta-console.o
-
 # FIXME FIXME FIXME
 obj-$(CONFIG_MIPS_MT_SMTC)	+= malta-smtc.o

arch/mips/mti-malta/malta-console.c

@@ -1,47 +0,0 @@
-/*
- * Carsten Langgaard, carstenl@mips.com
- * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
- *
- *  This program is free software; you can distribute it and/or modify it
- *  under the terms of the GNU General Public License (Version 2) as
- *  published by the Free Software Foundation.
- *
- *  This program is distributed in the hope it will be useful, but WITHOUT
- *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- *  for more details.
- *
- *  You should have received a copy of the GNU General Public License along
- *  with this program; if not, write to the Free Software Foundation, Inc.,
- *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
- *
- * Putting things on the screen/serial line using YAMONs facilities.
- */
-#include <linux/console.h>
-#include <linux/init.h>
-#include <linux/serial_reg.h>
-#include <asm/io.h>
-
-
-#define PORT(offset) (0x3f8 + (offset))
-
-
-static inline unsigned int serial_in(int offset)
-{
-	return inb(PORT(offset));
-}
-
-static inline void serial_out(int offset, int value)
-{
-	outb(value, PORT(offset));
-}
-
-int prom_putchar(char c)
-{
-	while ((serial_in(UART_LSR) & UART_LSR_THRE) == 0)
-		;
-
-	serial_out(UART_TX, c);
-
-	return 1;
-}

arch/mips/mti-malta/malta-init.c

@@ -14,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/serial_8250.h>
 
 #include <asm/cacheflush.h>
 #include <asm/smp-ops.h>
@@ -44,32 +45,39 @@ static void __init console_config(void)
 	char parity = '\0', bits = '\0', flow = '\0';
 	char *s;
 
-	if ((strstr(fw_getcmdline(), "console=")) == NULL) {
-		s = fw_getenv("modetty0");
-		if (s) {
-			while (*s >= '0' && *s <= '9')
-				baud = baud*10 + *s++ - '0';
-			if (*s == ',')
-				s++;
-			if (*s)
-				parity = *s++;
-			if (*s == ',')
-				s++;
-			if (*s)
-				bits = *s++;
-			if (*s == ',')
-				s++;
-			if (*s == 'h')
-				flow = 'r';
-		}
-		if (baud == 0)
-			baud = 38400;
-		if (parity != 'n' && parity != 'o' && parity != 'e')
-			parity = 'n';
-		if (bits != '7' && bits != '8')
-			bits = '8';
-		if (flow == '\0')
+	s = fw_getenv("modetty0");
+	if (s) {
+		while (*s >= '0' && *s <= '9')
+			baud = baud*10 + *s++ - '0';
+		if (*s == ',')
+			s++;
+		if (*s)
+			parity = *s++;
+		if (*s == ',')
+			s++;
+		if (*s)
+			bits = *s++;
+		if (*s == ',')
+			s++;
+		if (*s == 'h')
 			flow = 'r';
+	}
+	if (baud == 0)
+		baud = 38400;
+	if (parity != 'n' && parity != 'o' && parity != 'e')
+		parity = 'n';
+	if (bits != '7' && bits != '8')
+		bits = '8';
+	if (flow == '\0')
+		flow = 'r';
+
+	if ((strstr(fw_getcmdline(), "earlycon=")) == NULL) {
+		sprintf(console_string, "uart8250,io,0x3f8,%d%c%c", baud,
+			parity, bits);
+		setup_early_serial8250_console(console_string);
+	}
+
+	if ((strstr(fw_getcmdline(), "console=")) == NULL) {
 		sprintf(console_string, " console=ttyS0,%d%c%c%c", baud,
 			parity, bits, flow);
 		strcat(fw_getcmdline(), console_string);