arch/mips/loongson64/common/early_printk.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

// SPDX-License-Identifier: GPL-2.0-or-later
/*  early printk support
 *
 *  Copyright (c) 2009 Philippe Vachon <philippe@cowpig.ca>
 *  Copyright (c) 2009 Lemote Inc.
 *  Author: Wu Zhangjin, wuzhangjin@gmail.com
 */
#include <linux/serial_reg.h>
#include <asm/setup.h>

#include <loongson.h>

#define PORT(base, offset) (u8 *)(base + offset)

static inline unsigned int serial_in(unsigned char *base, int offset)
{
	return readb(PORT(base, offset));
}

static inline void serial_out(unsigned char *base, int offset, int value)
{
	writeb(value, PORT(base, offset));
}

void prom_putchar(char c)
{
	int timeout;
	unsigned char *uart_base;

	uart_base = (unsigned char *)_loongson_uart_base[0];
	timeout = 1024;

	while (((serial_in(uart_base, UART_LSR) & UART_LSR_THRE) == 0) &&
			(timeout-- > 0))
		;

	serial_out(uart_base, UART_TX, c);
}