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Linux/arch/arm/kernel/atags_parse.c

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  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/initrd.h>
 22 #include <linux/kernel.h>
 23 #include <linux/fs.h>
 24 #include <linux/root_dev.h>
 25 #include <linux/screen_info.h>
 26 #include <linux/memblock.h>
 27 
 28 #include <asm/setup.h>
 29 #include <asm/system_info.h>
 30 #include <asm/page.h>
 31 #include <asm/mach/arch.h>
 32 
 33 #include "atags.h"
 34 
 35 static char default_command_line[COMMAND_LINE_SIZE] __initdata = CONFIG_CMDLINE;
 36 
 37 #ifndef MEM_SIZE
 38 #define MEM_SIZE        (16*1024*1024)
 39 #endif
 40 
 41 static struct {
 42         struct tag_header hdr1;
 43         struct tag_core   core;
 44         struct tag_header hdr2;
 45         struct tag_mem32  mem;
 46         struct tag_header hdr3;
 47 } default_tags __initdata = {
 48         { tag_size(tag_core), ATAG_CORE },
 49         { 1, PAGE_SIZE, 0xff },
 50         { tag_size(tag_mem32), ATAG_MEM },
 51         { MEM_SIZE },
 52         { 0, ATAG_NONE }
 53 };
 54 
 55 static int __init parse_tag_core(const struct tag *tag)
 56 {
 57         if (tag->hdr.size > 2) {
 58                 if ((tag->u.core.flags & 1) == 0)
 59                         root_mountflags &= ~MS_RDONLY;
 60                 ROOT_DEV = old_decode_dev(tag->u.core.rootdev);
 61         }
 62         return 0;
 63 }
 64 
 65 __tagtable(ATAG_CORE, parse_tag_core);
 66 
 67 static int __init parse_tag_mem32(const struct tag *tag)
 68 {
 69         return arm_add_memory(tag->u.mem.start, tag->u.mem.size);
 70 }
 71 
 72 __tagtable(ATAG_MEM, parse_tag_mem32);
 73 
 74 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
 75 static int __init parse_tag_videotext(const struct tag *tag)
 76 {
 77         screen_info.orig_x            = tag->u.videotext.x;
 78         screen_info.orig_y            = tag->u.videotext.y;
 79         screen_info.orig_video_page   = tag->u.videotext.video_page;
 80         screen_info.orig_video_mode   = tag->u.videotext.video_mode;
 81         screen_info.orig_video_cols   = tag->u.videotext.video_cols;
 82         screen_info.orig_video_ega_bx = tag->u.videotext.video_ega_bx;
 83         screen_info.orig_video_lines  = tag->u.videotext.video_lines;
 84         screen_info.orig_video_isVGA  = tag->u.videotext.video_isvga;
 85         screen_info.orig_video_points = tag->u.videotext.video_points;
 86         return 0;
 87 }
 88 
 89 __tagtable(ATAG_VIDEOTEXT, parse_tag_videotext);
 90 #endif
 91 
 92 #ifdef CONFIG_BLK_DEV_RAM
 93 static int __init parse_tag_ramdisk(const struct tag *tag)
 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_warn("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                         pr_warn("Ignoring unrecognised tag 0x%08x\n",
170                                 t->hdr.tag);
171 }
172 
173 static void __init squash_mem_tags(struct tag *tag)
174 {
175         for (; tag->hdr.size; tag = tag_next(tag))
176                 if (tag->hdr.tag == ATAG_MEM)
177                         tag->hdr.tag = ATAG_NONE;
178 }
179 
180 const struct machine_desc * __init
181 setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr)
182 {
183         struct tag *tags = (struct tag *)&default_tags;
184         const struct machine_desc *mdesc = NULL, *p;
185         char *from = default_command_line;
186 
187         default_tags.mem.start = PHYS_OFFSET;
188 
189         /*
190          * locate machine in the list of supported machines.
191          */
192         for_each_machine_desc(p)
193                 if (machine_nr == p->nr) {
194                         pr_info("Machine: %s\n", p->name);
195                         mdesc = p;
196                         break;
197                 }
198 
199         if (!mdesc)
200                 return NULL;
201 
202         if (__atags_pointer)
203                 tags = phys_to_virt(__atags_pointer);
204         else if (mdesc->atag_offset)
205                 tags = (void *)(PAGE_OFFSET + mdesc->atag_offset);
206 
207 #if defined(CONFIG_DEPRECATED_PARAM_STRUCT)
208         /*
209          * If we have the old style parameters, convert them to
210          * a tag list.
211          */
212         if (tags->hdr.tag != ATAG_CORE)
213                 convert_to_tag_list(tags);
214 #endif
215         if (tags->hdr.tag != ATAG_CORE) {
216                 early_print("Warning: Neither atags nor dtb found\n");
217                 tags = (struct tag *)&default_tags;
218         }
219 
220         if (mdesc->fixup)
221                 mdesc->fixup(tags, &from);
222 
223         if (tags->hdr.tag == ATAG_CORE) {
224                 if (memblock_phys_mem_size())
225                         squash_mem_tags(tags);
226                 save_atags(tags);
227                 parse_tags(tags);
228         }
229 
230         /* parse_early_param needs a boot_command_line */
231         strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);
232 
233         return mdesc;
234 }
235 

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