linux.c

blob2.0.4.tar,Blob的源码,完整

/*
 * linux.c: support functions for booting a kernel
 *
 * Copyright (C) 2001  Erik Mouw ([e-mail])
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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
 *
 */

#ident "$Id: linux.c,v 1.3 2001/08/30 08:39:49 erikm Exp $"

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "linux.h"
#include "main.h"
#include "flash.h"
#include "memory.h"
#include "serial.h"
#include "util.h"

#include <asm-arm/setup.h>


static void setup_start_tag(void);
static void setup_memory_tags(void);
static void setup_commandline_tag(char *commandline);
static void setup_ramdisk_tag(void);
static void setup_initrd_tag(void);
static void setup_end_tag(void);


static struct tag *params;


void boot_linux(char *commandline)
{
	register u32 i;
	void (*theKernel)(int zero, int arch) = (void (*)(int, int))KERNEL_RAM_BASE;

	setup_start_tag();
	setup_memory_tags();
	setup_commandline_tag(commandline);
  	setup_initrd_tag();
	setup_ramdisk_tag();
	setup_end_tag();

	/* we assume that the kernel is in place */
	SerialOutputString("\nStarting kernel ...\n\n");

	/* turn off I-cache */
	asm ("mrc p15, 0, %0, c1, c0, 0": "=r" (i));
	i &= ~0x1000;
	asm ("mcr p15, 0, %0, c1, c0, 0": : "r" (i));

	/* flush I-cache */
	asm ("mcr p15, 0, %0, c7, c5, 0": : "r" (i));

	theKernel(0, ARCH_NUMBER);

	SerialOutputString("Hey, the kernel returned! This should not happen.\n");
}


static void setup_start_tag(void)
{
	params = (struct tag *)BOOT_PARAMS;

	params->hdr.tag = ATAG_CORE;
	params->hdr.size = tag_size(tag_core);

	params->u.core.flags = 0;
	params->u.core.pagesize = 0;
	params->u.core.rootdev = 0;

	params = tag_next(params);
}


static void setup_memory_tags(void)
{
	int i;

	for(i = 0; i < NUM_MEM_AREAS; i++) {
		if(memory_map[i].used) {
			params->hdr.tag = ATAG_MEM;
			params->hdr.size = tag_size(tag_mem32);

			params->u.mem.start = memory_map[i].start;
			params->u.mem.size = memory_map[i].len;
			
			params = tag_next(params);
		}
	}
}


static void setup_commandline_tag(char *commandline)
{
	char *p;

	/* eat leading white space */
	for(p = commandline; *p == ' '; p++)
		;

	/* skip non-existent command lines so the kernel will still
         * use its default command line.
	 */
	if(*p == '\0')
		return;

	params->hdr.tag = ATAG_CMDLINE;
	params->hdr.size = (sizeof(struct tag_header) + strlen(p) + 1 + 4) >> 2;

	strcpy(params->u.cmdline.cmdline, p);

	params = tag_next(params);
}


static void setup_initrd_tag(void)
{
	/* an ATAG_INITRD node tells the kernel where the compressed
         * ramdisk can be found. ATAG_RDIMG is a better name, actually.
	 */
	params->hdr.tag = ATAG_INITRD;
	params->hdr.size = tag_size(tag_initrd);
	
	params->u.initrd.start = RAMDISK_RAM_BASE;
	params->u.initrd.size = INITRD_LEN;
	
	params = tag_next(params);
}


static void setup_ramdisk_tag(void)
{
	/* an ATAG_RAMDISK node tells the kernel how large the
         * decompressed ramdisk will become.
	 */
	params->hdr.tag = ATAG_RAMDISK;
	params->hdr.size = tag_size(tag_ramdisk);
	
	params->u.ramdisk.start = 0;
	params->u.ramdisk.size = RAMDISK_SIZE;
	params->u.ramdisk.flags = 1;	/* automatically load ramdisk */
	
	params = tag_next(params);
}


static void setup_end_tag(void)
{
	params->hdr.tag = ATAG_NONE;
	params->hdr.size = 0;
}