promlib.c

linux 内核源代码

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1996 David S. Miller ([e-mail])
 * Compability with board caches, Ulf Carlsson
 */
#include <linux/kernel.h>
#include <asm/sgialib.h>
#include <asm/bcache.h>

/*
 * IP22 boardcache is not compatible with board caches.  Thus we disable it
 * during romvec action.  Since r4xx0.c is always compiled and linked with your
 * kernel, this shouldn't cause any harm regardless what MIPS processor you
 * have.
 *
 * The ARC write and read functions seem to interfere with the serial lines
 * in some way. You should be careful with them.
 */

void prom_putchar(char c)
{
	ULONG cnt;
	CHAR it = c;

	bc_disable();
	ArcWrite(1, &it, 1, &cnt);
	bc_enable();
}

char prom_getchar(void)
{
	ULONG cnt;
	CHAR c;

	bc_disable();
	ArcRead(0, &c, 1, &cnt);
	bc_enable();

	return c;
}