MIPS: ralink: adds early_printk support

/*

 *  This program is free software; you can redistribute it and/or modify it

 *  under the terms of the GNU General Public License version 2 as published

 *  by the Free Software Foundation.

 *

 *  Copyright (C) 2011-2012 Gabor Juhos <juhosg@openwrt.org>

 */

#include <linux/io.h>

#include <linux/serial_reg.h>

#include <asm/addrspace.h>

#define EARLY_UART_BASE         0x10000c00

#define UART_REG_RX             0x00

#define UART_REG_TX             0x04

#define UART_REG_IER            0x08

#define UART_REG_IIR            0x0c

#define UART_REG_FCR            0x10

#define UART_REG_LCR            0x14

#define UART_REG_MCR            0x18

#define UART_REG_LSR            0x1c

static __iomem void *uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE);

static inline void uart_w32(u32 val, unsigned reg)

{

	__raw_writel(val, uart_membase + reg);

}

static inline u32 uart_r32(unsigned reg)

{

	return __raw_readl(uart_membase + reg);

}

void prom_putchar(unsigned char ch)

{

	while ((uart_r32(UART_REG_LSR) & UART_LSR_THRE) == 0)

		;

	uart_w32(ch, UART_REG_TX);

	while ((uart_r32(UART_REG_LSR) & UART_LSR_THRE) == 0)

		;

}