1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Tag parsing. |
4 | * |
5 | * Copyright (C) 1995-2001 Russell King |
6 | */ |
7 | |
8 | /* |
9 | * This is the traditional way of passing data to the kernel at boot time. Rather |
10 | * than passing a fixed inflexible structure to the kernel, we pass a list |
11 | * of variable-sized tags to the kernel. The first tag must be a ATAG_CORE |
12 | * tag for the list to be recognised (to distinguish the tagged list from |
13 | * a param_struct). The list is terminated with a zero-length tag (this tag |
14 | * is not parsed in any way). |
15 | */ |
16 | |
17 | #include <linux/init.h> |
18 | #include <linux/initrd.h> |
19 | #include <linux/kernel.h> |
20 | #include <linux/fs.h> |
21 | #include <linux/root_dev.h> |
22 | #include <linux/screen_info.h> |
23 | #include <linux/memblock.h> |
24 | #include <uapi/linux/mount.h> |
25 | |
26 | #include <asm/setup.h> |
27 | #include <asm/system_info.h> |
28 | #include <asm/page.h> |
29 | #include <asm/mach/arch.h> |
30 | |
31 | #include "atags.h" |
32 | |
33 | static char default_command_line[COMMAND_LINE_SIZE] __initdata = CONFIG_CMDLINE; |
34 | |
35 | #ifndef MEM_SIZE |
36 | #define MEM_SIZE (16*1024*1024) |
37 | #endif |
38 | |
39 | static struct { |
40 | struct hdr1; |
41 | struct tag_core core; |
42 | struct tag_header hdr2; |
43 | struct tag_mem32 mem; |
44 | struct tag_header hdr3; |
45 | } default_tags __initdata = { |
46 | { tag_size(tag_core), ATAG_CORE }, |
47 | { 1, PAGE_SIZE, 0xff }, |
48 | { tag_size(tag_mem32), ATAG_MEM }, |
49 | { MEM_SIZE }, |
50 | { 0, ATAG_NONE } |
51 | }; |
52 | |
53 | static int __init parse_tag_core(const struct tag *tag) |
54 | { |
55 | if (tag->hdr.size > 2) { |
56 | if ((tag->u.core.flags & 1) == 0) |
57 | root_mountflags &= ~MS_RDONLY; |
58 | ROOT_DEV = old_decode_dev(val: tag->u.core.rootdev); |
59 | } |
60 | return 0; |
61 | } |
62 | |
63 | __tagtable(ATAG_CORE, parse_tag_core); |
64 | |
65 | static int __init parse_tag_mem32(const struct tag *tag) |
66 | { |
67 | return arm_add_memory(tag->u.mem.start, tag->u.mem.size); |
68 | } |
69 | |
70 | __tagtable(ATAG_MEM, parse_tag_mem32); |
71 | |
72 | #if defined(CONFIG_ARCH_FOOTBRIDGE) && defined(CONFIG_VGA_CONSOLE) |
73 | static int __init parse_tag_videotext(const struct tag *tag) |
74 | { |
75 | vgacon_screen_info.orig_x = tag->u.videotext.x; |
76 | vgacon_screen_info.orig_y = tag->u.videotext.y; |
77 | vgacon_screen_info.orig_video_page = tag->u.videotext.video_page; |
78 | vgacon_screen_info.orig_video_mode = tag->u.videotext.video_mode; |
79 | vgacon_screen_info.orig_video_cols = tag->u.videotext.video_cols; |
80 | vgacon_screen_info.orig_video_ega_bx = tag->u.videotext.video_ega_bx; |
81 | vgacon_screen_info.orig_video_lines = tag->u.videotext.video_lines; |
82 | vgacon_screen_info.orig_video_isVGA = tag->u.videotext.video_isvga; |
83 | vgacon_screen_info.orig_video_points = tag->u.videotext.video_points; |
84 | return 0; |
85 | } |
86 | |
87 | __tagtable(ATAG_VIDEOTEXT, parse_tag_videotext); |
88 | #endif |
89 | |
90 | #ifdef CONFIG_BLK_DEV_RAM |
91 | static int __init parse_tag_ramdisk(const struct tag *tag) |
92 | { |
93 | rd_image_start = tag->u.ramdisk.start; |
94 | |
95 | if (tag->u.ramdisk.size) |
96 | rd_size = tag->u.ramdisk.size; |
97 | |
98 | return 0; |
99 | } |
100 | |
101 | __tagtable(ATAG_RAMDISK, parse_tag_ramdisk); |
102 | #endif |
103 | |
104 | static int __init parse_tag_serialnr(const struct tag *tag) |
105 | { |
106 | system_serial_low = tag->u.serialnr.low; |
107 | system_serial_high = tag->u.serialnr.high; |
108 | return 0; |
109 | } |
110 | |
111 | __tagtable(ATAG_SERIAL, parse_tag_serialnr); |
112 | |
113 | static int __init parse_tag_revision(const struct tag *tag) |
114 | { |
115 | system_rev = tag->u.revision.rev; |
116 | return 0; |
117 | } |
118 | |
119 | __tagtable(ATAG_REVISION, parse_tag_revision); |
120 | |
121 | static int __init parse_tag_cmdline(const struct tag *tag) |
122 | { |
123 | #if defined(CONFIG_CMDLINE_EXTEND) |
124 | strlcat(default_command_line, " " , COMMAND_LINE_SIZE); |
125 | strlcat(default_command_line, tag->u.cmdline.cmdline, |
126 | COMMAND_LINE_SIZE); |
127 | #elif defined(CONFIG_CMDLINE_FORCE) |
128 | pr_warn("Ignoring tag cmdline (using the default kernel command line)\n" ); |
129 | #else |
130 | strscpy(default_command_line, tag->u.cmdline.cmdline, |
131 | COMMAND_LINE_SIZE); |
132 | #endif |
133 | return 0; |
134 | } |
135 | |
136 | __tagtable(ATAG_CMDLINE, parse_tag_cmdline); |
137 | |
138 | /* |
139 | * Scan the tag table for this tag, and call its parse function. |
140 | * The tag table is built by the linker from all the __tagtable |
141 | * declarations. |
142 | */ |
143 | static int __init parse_tag(const struct tag *tag) |
144 | { |
145 | extern struct tagtable __tagtable_begin, __tagtable_end; |
146 | struct tagtable *t; |
147 | |
148 | for (t = &__tagtable_begin; t < &__tagtable_end; t++) |
149 | if (tag->hdr.tag == t->tag) { |
150 | t->parse(tag); |
151 | break; |
152 | } |
153 | |
154 | return t < &__tagtable_end; |
155 | } |
156 | |
157 | /* |
158 | * Parse all tags in the list, checking both the global and architecture |
159 | * specific tag tables. |
160 | */ |
161 | static void __init parse_tags(const struct tag *t) |
162 | { |
163 | for (; t->hdr.size; t = tag_next(t)) |
164 | if (!parse_tag(tag: t)) |
165 | pr_warn("Ignoring unrecognised tag 0x%08x\n" , |
166 | t->hdr.tag); |
167 | } |
168 | |
169 | static void __init squash_mem_tags(struct tag *tag) |
170 | { |
171 | for (; tag->hdr.size; tag = tag_next(tag)) |
172 | if (tag->hdr.tag == ATAG_MEM) |
173 | tag->hdr.tag = ATAG_NONE; |
174 | } |
175 | |
176 | const struct machine_desc * __init |
177 | setup_machine_tags(void *atags_vaddr, unsigned int machine_nr) |
178 | { |
179 | struct tag *tags = (struct tag *)&default_tags; |
180 | const struct machine_desc *mdesc = NULL, *p; |
181 | char *from = default_command_line; |
182 | |
183 | default_tags.mem.start = PHYS_OFFSET; |
184 | |
185 | /* |
186 | * locate machine in the list of supported machines. |
187 | */ |
188 | for_each_machine_desc(p) |
189 | if (machine_nr == p->nr) { |
190 | pr_info("Machine: %s\n" , p->name); |
191 | mdesc = p; |
192 | break; |
193 | } |
194 | |
195 | if (!mdesc) |
196 | return NULL; |
197 | |
198 | if (atags_vaddr) |
199 | tags = atags_vaddr; |
200 | else if (mdesc->atag_offset) |
201 | tags = (void *)(PAGE_OFFSET + mdesc->atag_offset); |
202 | |
203 | #if defined(CONFIG_DEPRECATED_PARAM_STRUCT) |
204 | /* |
205 | * If we have the old style parameters, convert them to |
206 | * a tag list. |
207 | */ |
208 | if (tags->hdr.tag != ATAG_CORE) |
209 | convert_to_tag_list(tags); |
210 | #endif |
211 | if (tags->hdr.tag != ATAG_CORE) { |
212 | early_print("Warning: Neither atags nor dtb found\n" ); |
213 | tags = (struct tag *)&default_tags; |
214 | } |
215 | |
216 | if (mdesc->fixup) |
217 | mdesc->fixup(tags, &from); |
218 | |
219 | if (tags->hdr.tag == ATAG_CORE) { |
220 | if (memblock_phys_mem_size()) |
221 | squash_mem_tags(tag: tags); |
222 | save_atags(tags); |
223 | parse_tags(t: tags); |
224 | } |
225 | |
226 | /* parse_early_param needs a boot_command_line */ |
227 | strscpy(boot_command_line, from, COMMAND_LINE_SIZE); |
228 | |
229 | return mdesc; |
230 | } |
231 | |