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// SPDX-License-Identifier: GPL-2.0-only
/*
* Tag parsing.
*
* Copyright (C) 1995-2001 Russell King
*/
/*
* This is the traditional way of passing data to the kernel at boot time. Rather
* than passing a fixed inflexible structure to the kernel, we pass a list
* of variable-sized tags to the kernel. The first tag must be a ATAG_CORE
* tag for the list to be recognised (to distinguish the tagged list from
* a param_struct). The list is terminated with a zero-length tag (this tag
* is not parsed in any way).
*/
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/root_dev.h>
#include <linux/screen_info.h>
#include <linux/memblock.h>
#include <uapi/linux/mount.h>
#include <asm/setup.h>
#include <asm/system_info.h>
#include <asm/page.h>
#include <asm/mach/arch.h>
#include "atags.h"
static char default_command_line[COMMAND_LINE_SIZE] __initdata = CONFIG_CMDLINE;
#ifndef MEM_SIZE
#define MEM_SIZE (16*1024*1024)
#endif
static struct {
struct tag_header hdr1;
struct tag_core core;
struct tag_header hdr2;
struct tag_mem32 mem;
struct tag_header hdr3;
} default_tags __initdata = {
{ tag_size(tag_core), ATAG_CORE },
{ 1, PAGE_SIZE, 0xff },
{ tag_size(tag_mem32), ATAG_MEM },
{ MEM_SIZE },
{ 0, ATAG_NONE }
};
static int __init parse_tag_core(const struct tag *tag)
{
if (tag->hdr.size > 2) {
if ((tag->u.core.flags & 1) == 0)
root_mountflags &= ~MS_RDONLY;
ROOT_DEV = old_decode_dev(tag->u.core.rootdev);
}
return 0;
}
__tagtable(ATAG_CORE, parse_tag_core);
static int __init parse_tag_mem32(const struct tag *tag)
{
return arm_add_memory(tag->u.mem.start, tag->u.mem.size);
}
__tagtable(ATAG_MEM, parse_tag_mem32);
#if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
static int __init parse_tag_videotext(const struct tag *tag)
{
screen_info.orig_x = tag->u.videotext.x;
screen_info.orig_y = tag->u.videotext.y;
screen_info.orig_video_page = tag->u.videotext.video_page;
screen_info.orig_video_mode = tag->u.videotext.video_mode;
screen_info.orig_video_cols = tag->u.videotext.video_cols;
screen_info.orig_video_ega_bx = tag->u.videotext.video_ega_bx;
screen_info.orig_video_lines = tag->u.videotext.video_lines;
screen_info.orig_video_isVGA = tag->u.videotext.video_isvga;
screen_info.orig_video_points = tag->u.videotext.video_points;
return 0;
}
__tagtable(ATAG_VIDEOTEXT, parse_tag_videotext);
#endif
#ifdef CONFIG_BLK_DEV_RAM
static int __init parse_tag_ramdisk(const struct tag *tag)
{
rd_image_start = tag->u.ramdisk.start;
if (tag->u.ramdisk.size)
rd_size = tag->u.ramdisk.size;
return 0;
}
__tagtable(ATAG_RAMDISK, parse_tag_ramdisk);
#endif
static int __init parse_tag_serialnr(const struct tag *tag)
{
system_serial_low = tag->u.serialnr.low;
system_serial_high = tag->u.serialnr.high;
return 0;
}
__tagtable(ATAG_SERIAL, parse_tag_serialnr);
static int __init parse_tag_revision(const struct tag *tag)
{
system_rev = tag->u.revision.rev;
return 0;
}
__tagtable(ATAG_REVISION, parse_tag_revision);
static int __init parse_tag_cmdline(const struct tag *tag)
{
#if defined(CONFIG_CMDLINE_EXTEND)
strlcat(default_command_line, " ", COMMAND_LINE_SIZE);
strlcat(default_command_line, tag->u.cmdline.cmdline,
COMMAND_LINE_SIZE);
#elif defined(CONFIG_CMDLINE_FORCE)
pr_warn("Ignoring tag cmdline (using the default kernel command line)\n");
#else
strlcpy(default_command_line, tag->u.cmdline.cmdline,
COMMAND_LINE_SIZE);
#endif
return 0;
}
__tagtable(ATAG_CMDLINE, parse_tag_cmdline);
/*
* Scan the tag table for this tag, and call its parse function.
* The tag table is built by the linker from all the __tagtable
* declarations.
*/
static int __init parse_tag(const struct tag *tag)
{
extern struct tagtable __tagtable_begin, __tagtable_end;
struct tagtable *t;
for (t = &__tagtable_begin; t < &__tagtable_end; t++)
if (tag->hdr.tag == t->tag) {
t->parse(tag);
break;
}
return t < &__tagtable_end;
}
/*
* Parse all tags in the list, checking both the global and architecture
* specific tag tables.
*/
static void __init parse_tags(const struct tag *t)
{
for (; t->hdr.size; t = tag_next(t))
if (!parse_tag(t))
pr_warn("Ignoring unrecognised tag 0x%08x\n",
t->hdr.tag);
}
static void __init squash_mem_tags(struct tag *tag)
{
for (; tag->hdr.size; tag = tag_next(tag))
if (tag->hdr.tag == ATAG_MEM)
tag->hdr.tag = ATAG_NONE;
}
const struct machine_desc * __init
setup_machine_tags(void *atags_vaddr, unsigned int machine_nr)
{
struct tag *tags = (struct tag *)&default_tags;
const struct machine_desc *mdesc = NULL, *p;
char *from = default_command_line;
default_tags.mem.start = PHYS_OFFSET;
/*
* locate machine in the list of supported machines.
*/
for_each_machine_desc(p)
if (machine_nr == p->nr) {
pr_info("Machine: %s\n", p->name);
mdesc = p;
break;
}
if (!mdesc)
return NULL;
if (atags_vaddr)
tags = atags_vaddr;
else if (mdesc->atag_offset)
tags = (void *)(PAGE_OFFSET + mdesc->atag_offset);
#if defined(CONFIG_DEPRECATED_PARAM_STRUCT)
/*
* If we have the old style parameters, convert them to
* a tag list.
*/
if (tags->hdr.tag != ATAG_CORE)
convert_to_tag_list(tags);
#endif
if (tags->hdr.tag != ATAG_CORE) {
early_print("Warning: Neither atags nor dtb found\n");
tags = (struct tag *)&default_tags;
}
if (mdesc->fixup)
mdesc->fixup(tags, &from);
if (tags->hdr.tag == ATAG_CORE) {
if (memblock_phys_mem_size())
squash_mem_tags(tags);
save_atags(tags);
parse_tags(tags);
}
/* parse_early_param needs a boot_command_line */
strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);
return mdesc;
}
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