4 * Copyright (C) 1995-2001 Russell King
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
12 * This is the traditional way of passing data to the kernel at boot time. Rather
13 * than passing a fixed inflexible structure to the kernel, we pass a list
14 * of variable-sized tags to the kernel. The first tag must be a ATAG_CORE
15 * tag for the list to be recognised (to distinguish the tagged list from
16 * a param_struct). The list is terminated with a zero-length tag (this tag
17 * is not parsed in any way).
20 #include <linux/init.h>
21 #include <linux/kernel.h>
23 #include <linux/root_dev.h>
24 #include <linux/screen_info.h>
25 #include <linux/memblock.h>
27 #include <asm/setup.h>
28 #include <asm/system_info.h>
30 #include <asm/mach/arch.h>
34 static char default_command_line[COMMAND_LINE_SIZE] __initdata = CONFIG_CMDLINE;
37 #define MEM_SIZE (16*1024*1024)
41 struct tag_header hdr1;
43 struct tag_header hdr2;
45 struct tag_header hdr3;
46 } default_tags __initdata = {
47 { tag_size(tag_core), ATAG_CORE },
48 { 1, PAGE_SIZE, 0xff },
49 { tag_size(tag_mem32), ATAG_MEM },
54 static int __init parse_tag_core(const struct tag *tag)
56 if (tag->hdr.size > 2) {
57 if ((tag->u.core.flags & 1) == 0)
58 root_mountflags &= ~MS_RDONLY;
59 ROOT_DEV = old_decode_dev(tag->u.core.rootdev);
64 __tagtable(ATAG_CORE, parse_tag_core);
66 static int __init parse_tag_mem32(const struct tag *tag)
68 return arm_add_memory(tag->u.mem.start, tag->u.mem.size);
71 __tagtable(ATAG_MEM, parse_tag_mem32);
73 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
74 static int __init parse_tag_videotext(const struct tag *tag)
76 screen_info.orig_x = tag->u.videotext.x;
77 screen_info.orig_y = tag->u.videotext.y;
78 screen_info.orig_video_page = tag->u.videotext.video_page;
79 screen_info.orig_video_mode = tag->u.videotext.video_mode;
80 screen_info.orig_video_cols = tag->u.videotext.video_cols;
81 screen_info.orig_video_ega_bx = tag->u.videotext.video_ega_bx;
82 screen_info.orig_video_lines = tag->u.videotext.video_lines;
83 screen_info.orig_video_isVGA = tag->u.videotext.video_isvga;
84 screen_info.orig_video_points = tag->u.videotext.video_points;
88 __tagtable(ATAG_VIDEOTEXT, parse_tag_videotext);
91 #ifdef CONFIG_BLK_DEV_RAM
92 static int __init parse_tag_ramdisk(const struct tag *tag)
94 extern int rd_size, rd_image_start, rd_prompt, rd_doload;
96 rd_image_start = tag->u.ramdisk.start;
97 rd_doload = (tag->u.ramdisk.flags & 1) == 0;
98 rd_prompt = (tag->u.ramdisk.flags & 2) == 0;
100 if (tag->u.ramdisk.size)
101 rd_size = tag->u.ramdisk.size;
106 __tagtable(ATAG_RAMDISK, parse_tag_ramdisk);
109 static int __init parse_tag_serialnr(const struct tag *tag)
111 system_serial_low = tag->u.serialnr.low;
112 system_serial_high = tag->u.serialnr.high;
116 __tagtable(ATAG_SERIAL, parse_tag_serialnr);
118 static int __init parse_tag_revision(const struct tag *tag)
120 system_rev = tag->u.revision.rev;
124 __tagtable(ATAG_REVISION, parse_tag_revision);
126 static int __init parse_tag_cmdline(const struct tag *tag)
128 #if defined(CONFIG_CMDLINE_EXTEND)
129 strlcat(default_command_line, " ", COMMAND_LINE_SIZE);
130 strlcat(default_command_line, tag->u.cmdline.cmdline,
132 #elif defined(CONFIG_CMDLINE_FORCE)
133 pr_warn("Ignoring tag cmdline (using the default kernel command line)\n");
135 strlcpy(default_command_line, tag->u.cmdline.cmdline,
141 __tagtable(ATAG_CMDLINE, parse_tag_cmdline);
144 * Scan the tag table for this tag, and call its parse function.
145 * The tag table is built by the linker from all the __tagtable
148 static int __init parse_tag(const struct tag *tag)
150 extern struct tagtable __tagtable_begin, __tagtable_end;
153 for (t = &__tagtable_begin; t < &__tagtable_end; t++)
154 if (tag->hdr.tag == t->tag) {
159 return t < &__tagtable_end;
163 * Parse all tags in the list, checking both the global and architecture
164 * specific tag tables.
166 static void __init parse_tags(const struct tag *t)
168 for (; t->hdr.size; t = tag_next(t))
170 pr_warn("Ignoring unrecognised tag 0x%08x\n",
174 static void __init squash_mem_tags(struct tag *tag)
176 for (; tag->hdr.size; tag = tag_next(tag))
177 if (tag->hdr.tag == ATAG_MEM)
178 tag->hdr.tag = ATAG_NONE;
181 const struct machine_desc * __init
182 setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr)
184 struct tag *tags = (struct tag *)&default_tags;
185 const struct machine_desc *mdesc = NULL, *p;
186 char *from = default_command_line;
188 default_tags.mem.start = PHYS_OFFSET;
191 * locate machine in the list of supported machines.
193 for_each_machine_desc(p)
194 if (machine_nr == p->nr) {
195 pr_info("Machine: %s\n", p->name);
201 early_print("\nError: unrecognized/unsupported machine ID"
202 " (r1 = 0x%08x).\n\n", machine_nr);
203 dump_machine_table(); /* does not return */
207 tags = phys_to_virt(__atags_pointer);
208 else if (mdesc->atag_offset)
209 tags = (void *)(PAGE_OFFSET + mdesc->atag_offset);
211 #if defined(CONFIG_DEPRECATED_PARAM_STRUCT)
213 * If we have the old style parameters, convert them to
216 if (tags->hdr.tag != ATAG_CORE)
217 convert_to_tag_list(tags);
219 if (tags->hdr.tag != ATAG_CORE) {
220 early_print("Warning: Neither atags nor dtb found\n");
221 tags = (struct tag *)&default_tags;
225 mdesc->fixup(tags, &from);
227 if (tags->hdr.tag == ATAG_CORE) {
228 if (memblock_phys_mem_size())
229 squash_mem_tags(tags);
234 /* parse_early_param needs a boot_command_line */
235 strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);