1 /*
2 * Tag parsing.
3 *
4 * Copyright (C) 1995-2001 Russell King
5 *
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.
9 */
10
11 /*
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).
18 */
19
20 #include <linux/init.h>
21 #include <linux/kernel.h>
22 #include <linux/fs.h>
23 #include <linux/root_dev.h>
24 #include <linux/screen_info.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 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 {
93 extern int rd_size, rd_image_start, rd_prompt, rd_doload;
94
95 rd_image_start = tag->u.ramdisk.start;
96 rd_doload = (tag->u.ramdisk.flags & 1) == 0;
97 rd_prompt = (tag->u.ramdisk.flags & 2) == 0;
98
99 if (tag->u.ramdisk.size)
100 rd_size = tag->u.ramdisk.size;
101
102 return 0;
103 }
104
105 __tagtable(ATAG_RAMDISK, parse_tag_ramdisk);
106 #endif
107
108 static int __init parse_tag_serialnr(const struct tag *tag)
109 {
110 system_serial_low = tag->u.serialnr.low;
111 system_serial_high = tag->u.serialnr.high;
112 return 0;
113 }
114
115 __tagtable(ATAG_SERIAL, parse_tag_serialnr);
116
117 static int __init parse_tag_revision(const struct tag *tag)
118 {
119 system_rev = tag->u.revision.rev;
120 return 0;
121 }
122
123 __tagtable(ATAG_REVISION, parse_tag_revision);
124
125 static int __init parse_tag_cmdline(const struct tag *tag)
126 {
127 #if defined(CONFIG_CMDLINE_EXTEND)
128 strlcat(default_command_line, " ", COMMAND_LINE_SIZE);
129 strlcat(default_command_line, tag->u.cmdline.cmdline,
130 COMMAND_LINE_SIZE);
131 #elif defined(CONFIG_CMDLINE_FORCE)
132 pr_warning("Ignoring tag cmdline (using the default kernel command line)\n");
133 #else
134 strlcpy(default_command_line, tag->u.cmdline.cmdline,
135 COMMAND_LINE_SIZE);
136 #endif
137 return 0;
138 }
139
140 __tagtable(ATAG_CMDLINE, parse_tag_cmdline);
141
142 /*
143 * Scan the tag table for this tag, and call its parse function.
144 * The tag table is built by the linker from all the __tagtable
145 * declarations.
146 */
147 static int __init parse_tag(const struct tag *tag)
148 {
149 extern struct tagtable __tagtable_begin, __tagtable_end;
150 struct tagtable *t;
151
152 for (t = &__tagtable_begin; t < &__tagtable_end; t++)
153 if (tag->hdr.tag == t->tag) {
154 t->parse(tag);
155 break;
156 }
157
158 return t < &__tagtable_end;
159 }
160
161 /*
162 * Parse all tags in the list, checking both the global and architecture
163 * specific tag tables.
164 */
165 static void __init parse_tags(const struct tag *t)
166 {
167 for (; t->hdr.size; t = tag_next(t))
168 if (!parse_tag(t))
169 printk(KERN_WARNING
170 "Ignoring unrecognised tag 0x%08x\n",
171 t->hdr.tag);
172 }
173
174 static void __init squash_mem_tags(struct tag *tag)
175 {
176 for (; tag->hdr.size; tag = tag_next(tag))
177 if (tag->hdr.tag == ATAG_MEM)
178 tag->hdr.tag = ATAG_NONE;
179 }
180
181 const struct machine_desc * __init
182 setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr)
183 {
184 struct tag *tags = (struct tag *)&default_tags;
185 const struct machine_desc *mdesc = NULL, *p;
186 char *from = default_command_line;
187
188 default_tags.mem.start = PHYS_OFFSET;
189
190 /*
191 * locate machine in the list of supported machines.
192 */
193 for_each_machine_desc(p)
194 if (machine_nr == p->nr) {
195 printk("Machine: %s\n", p->name);
196 mdesc = p;
197 break;
198 }
199
200 if (!mdesc) {
201 early_print("\nError: unrecognized/unsupported machine ID"
202 " (r1 = 0x%08x).\n\n", machine_nr);
203 dump_machine_table(); /* does not return */
204 }
205
206 if (__atags_pointer)
207 tags = phys_to_virt(__atags_pointer);
208 else if (mdesc->atag_offset)
209 tags = (void *)(PAGE_OFFSET + mdesc->atag_offset);
210
211 #if defined(CONFIG_DEPRECATED_PARAM_STRUCT)
212 /*
213 * If we have the old style parameters, convert them to
214 * a tag list.
215 */
216 if (tags->hdr.tag != ATAG_CORE)
217 convert_to_tag_list(tags);
218 #endif
219 if (tags->hdr.tag != ATAG_CORE) {
220 early_print("Warning: Neither atags nor dtb found\n");
221 tags = (struct tag *)&default_tags;
222 }
223
224 if (mdesc->fixup)
225 mdesc->fixup(tags, &from, &meminfo);
226
227 if (tags->hdr.tag == ATAG_CORE) {
228 if (meminfo.nr_banks != 0)
229 squash_mem_tags(tags);
230 save_atags(tags);
231 parse_tags(tags);
232 }
233
234 /* parse_early_param needs a boot_command_line */
235 strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);
236
237 return mdesc;
238 }
239
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