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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
aa783b6f NP |
2 | /* |
3 | * Tag parsing. | |
4 | * | |
5 | * Copyright (C) 1995-2001 Russell King | |
aa783b6f NP |
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> | |
287f3ca5 | 18 | #include <linux/initrd.h> |
aa783b6f NP |
19 | #include <linux/kernel.h> |
20 | #include <linux/fs.h> | |
21 | #include <linux/root_dev.h> | |
22 | #include <linux/screen_info.h> | |
1c2f87c2 | 23 | #include <linux/memblock.h> |
e262e32d | 24 | #include <uapi/linux/mount.h> |
aa783b6f NP |
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 tag_header 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(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_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE) | |
73 | static int __init parse_tag_videotext(const struct tag *tag) | |
74 | { | |
75 | screen_info.orig_x = tag->u.videotext.x; | |
76 | screen_info.orig_y = tag->u.videotext.y; | |
77 | screen_info.orig_video_page = tag->u.videotext.video_page; | |
78 | screen_info.orig_video_mode = tag->u.videotext.video_mode; | |
79 | screen_info.orig_video_cols = tag->u.videotext.video_cols; | |
80 | screen_info.orig_video_ega_bx = tag->u.videotext.video_ega_bx; | |
81 | screen_info.orig_video_lines = tag->u.videotext.video_lines; | |
82 | screen_info.orig_video_isVGA = tag->u.videotext.video_isvga; | |
83 | 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 | { | |
aa783b6f | 93 | rd_image_start = tag->u.ramdisk.start; |
aa783b6f NP |
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) | |
8b521cb2 | 128 | pr_warn("Ignoring tag cmdline (using the default kernel command line)\n"); |
aa783b6f NP |
129 | #else |
130 | strlcpy(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(t)) | |
4ed89f22 | 165 | pr_warn("Ignoring unrecognised tag 0x%08x\n", |
aa783b6f NP |
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 | ||
ff69a4c8 RK |
176 | const struct machine_desc * __init |
177 | setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr) | |
aa783b6f NP |
178 | { |
179 | struct tag *tags = (struct tag *)&default_tags; | |
ff69a4c8 | 180 | const struct machine_desc *mdesc = NULL, *p; |
aa783b6f NP |
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) { | |
4ed89f22 | 190 | pr_info("Machine: %s\n", p->name); |
aa783b6f NP |
191 | mdesc = p; |
192 | break; | |
193 | } | |
194 | ||
99cf8f90 RK |
195 | if (!mdesc) |
196 | return NULL; | |
aa783b6f NP |
197 | |
198 | if (__atags_pointer) | |
199 | tags = phys_to_virt(__atags_pointer); | |
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) | |
1c2f87c2 | 217 | mdesc->fixup(tags, &from); |
aa783b6f NP |
218 | |
219 | if (tags->hdr.tag == ATAG_CORE) { | |
1c2f87c2 | 220 | if (memblock_phys_mem_size()) |
aa783b6f NP |
221 | squash_mem_tags(tags); |
222 | save_atags(tags); | |
223 | parse_tags(tags); | |
224 | } | |
225 | ||
226 | /* parse_early_param needs a boot_command_line */ | |
227 | strlcpy(boot_command_line, from, COMMAND_LINE_SIZE); | |
228 | ||
229 | return mdesc; | |
230 | } |