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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/kernel.h>
 22 #include <linux/fs.h>
 23 #include <linux/root_dev.h>
 24 #include <linux/screen_info.h>
 25 #include <linux/memblock.h>
 26 
 27 #include <asm/setup.h>
 28 #include <asm/system_info.h>
 29 #include <asm/page.h>
 30 #include <asm/mach/arch.h>
 31 
 32 #include "atags.h"
 33 
 34 static char default_command_line[COMMAND_LINE_SIZE] __initdata = CONFIG_CMDLINE;
 35 
 36 #ifndef MEM_SIZE
 37 #define MEM_SIZE        (16*1024*1024)
 38 #endif
 39 
 40 static struct {
 41         struct tag_header hdr1;
 42         struct tag_core   core;
 43         struct tag_header hdr2;
 44         struct tag_mem32  mem;
 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 },
 50         { MEM_SIZE },
 51         { 0, ATAG_NONE }
 52 };
 53 
 54 static int __init parse_tag_core(const struct tag *tag)
 55 {
 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);
 60         }
 61         return 0;
 62 }
 63 
 64 __tagtable(ATAG_CORE, parse_tag_core);
 65 
 66 static int __init parse_tag_mem32(const struct tag *tag)
 67 {
 68         return arm_add_memory(tag->u.mem.start, tag->u.mem.size);
 69 }
 70 
 71 __tagtable(ATAG_MEM, parse_tag_mem32);
 72 
 73 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
 74 static int __init parse_tag_videotext(const struct tag *tag)
 75 {
 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;
 85         return 0;
 86 }
 87 
 88 __tagtable(ATAG_VIDEOTEXT, parse_tag_videotext);
 89 #endif
 90 
 91 #ifdef CONFIG_BLK_DEV_RAM
 92 static int __init parse_tag_ramdisk(const struct tag *tag)
 93 {
 94         extern int rd_size, rd_image_start, rd_prompt, rd_doload;
 95 
 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;
 99 
100         if (tag->u.ramdisk.size)
101                 rd_size = tag->u.ramdisk.size;
102 
103         return 0;
104 }
105 
106 __tagtable(ATAG_RAMDISK, parse_tag_ramdisk);
107 #endif
108 
109 static int __init parse_tag_serialnr(const struct tag *tag)
110 {
111         system_serial_low = tag->u.serialnr.low;
112         system_serial_high = tag->u.serialnr.high;
113         return 0;
114 }
115 
116 __tagtable(ATAG_SERIAL, parse_tag_serialnr);
117 
118 static int __init parse_tag_revision(const struct tag *tag)
119 {
120         system_rev = tag->u.revision.rev;
121         return 0;
122 }
123 
124 __tagtable(ATAG_REVISION, parse_tag_revision);
125 
126 static int __init parse_tag_cmdline(const struct tag *tag)
127 {
128 #if defined(CONFIG_CMDLINE_EXTEND)
129         strlcat(default_command_line, " ", COMMAND_LINE_SIZE);
130         strlcat(default_command_line, tag->u.cmdline.cmdline,
131                 COMMAND_LINE_SIZE);
132 #elif defined(CONFIG_CMDLINE_FORCE)
133         pr_warn("Ignoring tag cmdline (using the default kernel command line)\n");
134 #else
135         strlcpy(default_command_line, tag->u.cmdline.cmdline,
136                 COMMAND_LINE_SIZE);
137 #endif
138         return 0;
139 }
140 
141 __tagtable(ATAG_CMDLINE, parse_tag_cmdline);
142 
143 /*
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
146  * declarations.
147  */
148 static int __init parse_tag(const struct tag *tag)
149 {
150         extern struct tagtable __tagtable_begin, __tagtable_end;
151         struct tagtable *t;
152 
153         for (t = &__tagtable_begin; t < &__tagtable_end; t++)
154                 if (tag->hdr.tag == t->tag) {
155                         t->parse(tag);
156                         break;
157                 }
158 
159         return t < &__tagtable_end;
160 }
161 
162 /*
163  * Parse all tags in the list, checking both the global and architecture
164  * specific tag tables.
165  */
166 static void __init parse_tags(const struct tag *t)
167 {
168         for (; t->hdr.size; t = tag_next(t))
169                 if (!parse_tag(t))
170                         pr_warn("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                         pr_info("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);
226 
227         if (tags->hdr.tag == ATAG_CORE) {
228                 if (memblock_phys_mem_size())
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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