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   1 /*
   2  * srm_env.c - Access to SRM environment
   3  *             variables through linux' procfs
   4  *
   5  * Copyright (C) 2001-2002 Jan-Benedict Glaw <jbglaw@lug-owl.de>
   6  *
   7  * This driver is at all a modified version of Erik Mouw's
   8  * Documentation/DocBook/procfs_example.c, so: thank
   9  * you, Erik! He can be reached via email at
  10  * <J.A.K.Mouw@its.tudelft.nl>. It is based on an idea
  11  * provided by DEC^WCompaq^WIntel's "Jumpstart" CD. They
  12  * included a patch like this as well. Thanks for idea!
  13  *
  14  * This program is free software; you can redistribute
  15  * it and/or modify it under the terms of the GNU General
  16  * Public License version 2 as published by the Free Software
  17  * Foundation.
  18  *
  19  * This program is distributed in the hope that it will be
  20  * useful, but WITHOUT ANY WARRANTY; without even the implied
  21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  22  * PURPOSE.  See the GNU General Public License for more
  23  * details.
  24  *
  25  * You should have received a copy of the GNU General Public
  26  * License along with this program; if not, write to the
  27  * Free Software Foundation, Inc., 59 Temple Place,
  28  * Suite 330, Boston, MA  02111-1307  USA
  29  *
  30  */
  31
  32 /*
  33  * Changelog
  34  * ~~~~~~~~~
  35  *
  36  * Thu, 22 Aug 2002 15:10:43 +0200
  37  *      - Update Config.help entry. I got a number of emails asking
  38  *        me to tell their senders if they could make use of this
  39  *        piece of code... So: "SRM is something like BIOS for your
  40  *        Alpha"
  41  *      - Update code formatting a bit to better conform CodingStyle
  42  *        rules.
  43  *      - So this is v0.0.5, with no changes (except formatting)
  44  *
  45  * Wed, 22 May 2002 00:11:21 +0200
  46  *      - Fix typo on comment (SRC -> SRM)
  47  *      - Call this "Version 0.0.4"
  48  *
  49  * Tue,  9 Apr 2002 18:44:40 +0200
  50  *      - Implement access by variable name and additionally
  51  *        by number. This is done by creating two subdirectories
  52  *        where one holds all names (like the old directory
  53  *        did) and the other holding 256 files named like "0",
  54  *        "1" and so on.
  55  *      - Call this "Version 0.0.3"
  56  *
  57  */
  58
  59 #include <linux/kernel.h>
  60 #include <linux/module.h>
  61 #include <linux/init.h>
  62 #include <linux/proc_fs.h>
  63 #include <asm/console.h>
  64 #include <asm/uaccess.h>
  65 #include <asm/machvec.h>
  66
  67 #define BASE_DIR        "srm_environment"       /* Subdir in /proc/             */
  68 #define NAMED_DIR       "named_variables"       /* Subdir for known variables   */
  69 #define NUMBERED_DIR    "numbered_variables"    /* Subdir for all variables     */
  70 #define VERSION         "0.0.5"                 /* Module version               */
  71 #define NAME            "srm_env"               /* Module name                  */
  72
  73 MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
  74 MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
  75 MODULE_LICENSE("GPL");
  76
  77 typedef struct _srm_env {
  78         char                    *name;
  79         unsigned long           id;
  80         struct proc_dir_entry   *proc_entry;
  81 } srm_env_t;
  82
  83 static struct proc_dir_entry    *base_dir;
  84 static struct proc_dir_entry    *named_dir;
  85 static struct proc_dir_entry    *numbered_dir;
  86 static char                     number[256][4];
  87
  88 static srm_env_t        srm_named_entries[] = {
  89         { "auto_action",        ENV_AUTO_ACTION         },
  90         { "boot_dev",           ENV_BOOT_DEV            },
  91         { "bootdef_dev",        ENV_BOOTDEF_DEV         },
  92         { "booted_dev",         ENV_BOOTED_DEV          },
  93         { "boot_file",          ENV_BOOT_FILE           },
  94         { "booted_file",        ENV_BOOTED_FILE         },
  95         { "boot_osflags",       ENV_BOOT_OSFLAGS        },
  96         { "booted_osflags",     ENV_BOOTED_OSFLAGS      },
  97         { "boot_reset",         ENV_BOOT_RESET          },
  98         { "dump_dev",           ENV_DUMP_DEV            },
  99         { "enable_audit",       ENV_ENABLE_AUDIT        },
 100         { "license",            ENV_LICENSE             },
 101         { "char_set",           ENV_CHAR_SET            },
 102         { "language",           ENV_LANGUAGE            },
 103         { "tty_dev",            ENV_TTY_DEV             },
 104         { NULL,                 0                       },
 105 };
 106 static srm_env_t        srm_numbered_entries[256];
 107
 108
 109
 110 static int
 111 srm_env_read(char *page, char **start, off_t off, int count, int *eof,
 112                 void *data)
 113 {
 114         int             nbytes;
 115         unsigned long   ret;
 116         srm_env_t       *entry;
 117
 118         if(off != 0)
 119                 return -EFAULT;
 120
 121         entry   = (srm_env_t *) data;
 122         ret     = callback_getenv(entry->id, page, count);
 123
 124         if((ret >> 61) == 0)
 125                 nbytes = (int) ret;
 126         else
 127                 nbytes = -EFAULT;
 128
 129         return nbytes;
 130 }
 131
 132
 133 static int
 134 srm_env_write(struct file *file, const char __user *buffer, unsigned long count,
 135                 void *data)
 136 {
 137         int res;
 138         srm_env_t       *entry;
 139         char            *buf = (char *) __get_free_page(GFP_USER);
 140         unsigned long   ret1, ret2;
 141
 142         entry = (srm_env_t *) data;
 143
 144         if (!buf)
 145                 return -ENOMEM;
 146
 147         res = -EINVAL;
 148         if (count >= PAGE_SIZE)
 149                 goto out;
 150
 151         res = -EFAULT;
 152         if (copy_from_user(buf, buffer, count))
 153                 goto out;
 154         buf[count] = '\0';
 155
 156         ret1 = callback_setenv(entry->id, buf, count);
 157         if ((ret1 >> 61) == 0) {
 158                 do
 159                         ret2 = callback_save_env();
 160                 while((ret2 >> 61) == 1);
 161                 res = (int) ret1;
 162         }
 163
 164  out:
 165         free_page((unsigned long)buf);
 166         return res;
 167 }
 168
 169 static void
 170 srm_env_cleanup(void)
 171 {
 172         srm_env_t       *entry;
 173         unsigned long   var_num;
 174
 175         if(base_dir) {
 176                 /*
 177                  * Remove named entries
 178                  */
 179                 if(named_dir) {
 180                         entry = srm_named_entries;
 181                         while(entry->name != NULL && entry->id != 0) {
 182                                 if(entry->proc_entry) {
 183                                         remove_proc_entry(entry->name,
 184                                                         named_dir);
 185                                         entry->proc_entry = NULL;
 186                                 }
 187                                 entry++;
 188                         }
 189                         remove_proc_entry(NAMED_DIR, base_dir);
 190                 }
 191
 192                 /*
 193                  * Remove numbered entries
 194                  */
 195                 if(numbered_dir) {
 196                         for(var_num = 0; var_num <= 255; var_num++) {
 197                                 entry = &srm_numbered_entries[var_num];
 198
 199                                 if(entry->proc_entry) {
 200                                         remove_proc_entry(entry->name,
 201                                                         numbered_dir);
 202                                         entry->proc_entry       = NULL;
 203                                         entry->name             = NULL;
 204                                 }
 205                         }
 206                         remove_proc_entry(NUMBERED_DIR, base_dir);
 207                 }
 208
 209                 remove_proc_entry(BASE_DIR, NULL);
 210         }
 211
 212         return;
 213 }
 214
 215
 216 static int __init
 217 srm_env_init(void)
 218 {
 219         srm_env_t       *entry;
 220         unsigned long   var_num;
 221
 222         /*
 223          * Check system
 224          */
 225         if(!alpha_using_srm) {
 226                 printk(KERN_INFO "%s: This Alpha system doesn't "
 227                                 "know about SRM (or you've booted "
 228                                 "SRM->MILO->Linux, which gets "
 229                                 "misdetected)...\n", __FUNCTION__);
 230                 return -ENODEV;
 231         }
 232
 233         /*
 234          * Init numbers
 235          */
 236         for(var_num = 0; var_num <= 255; var_num++)
 237                 sprintf(number[var_num], "%ld", var_num);
 238
 239         /*
 240          * Create base directory
 241          */
 242         base_dir = proc_mkdir(BASE_DIR, NULL);
 243         if(base_dir == NULL) {
 244                 printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
 245                                 BASE_DIR);
 246                 goto cleanup;
 247         }
 248         base_dir->owner = THIS_MODULE;
 249
 250         /*
 251          * Create per-name subdirectory
 252          */
 253         named_dir = proc_mkdir(NAMED_DIR, base_dir);
 254         if(named_dir == NULL) {
 255                 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
 256                                 BASE_DIR, NAMED_DIR);
 257                 goto cleanup;
 258         }
 259         named_dir->owner = THIS_MODULE;
 260
 261         /*
 262          * Create per-number subdirectory
 263          */
 264         numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
 265         if(numbered_dir == NULL) {
 266                 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
 267                                 BASE_DIR, NUMBERED_DIR);
 268                 goto cleanup;
 269
 270         }
 271         numbered_dir->owner = THIS_MODULE;
 272
 273         /*
 274          * Create all named nodes
 275          */
 276         entry = srm_named_entries;
 277         while(entry->name != NULL && entry->id != 0) {
 278                 entry->proc_entry = create_proc_entry(entry->name,
 279                                 0644, named_dir);
 280                 if(entry->proc_entry == NULL)
 281                         goto cleanup;
 282
 283                 entry->proc_entry->data         = (void *) entry;
 284                 entry->proc_entry->owner        = THIS_MODULE;
 285                 entry->proc_entry->read_proc    = srm_env_read;
 286                 entry->proc_entry->write_proc   = srm_env_write;
 287
 288                 entry++;
 289         }
 290
 291         /*
 292          * Create all numbered nodes
 293          */
 294         for(var_num = 0; var_num <= 255; var_num++) {
 295                 entry = &srm_numbered_entries[var_num];
 296                 entry->name = number[var_num];
 297
 298                 entry->proc_entry = create_proc_entry(entry->name,
 299                                 0644, numbered_dir);
 300                 if(entry->proc_entry == NULL)
 301                         goto cleanup;
 302
 303                 entry->id                       = var_num;
 304                 entry->proc_entry->data         = (void *) entry;
 305                 entry->proc_entry->owner        = THIS_MODULE;
 306                 entry->proc_entry->read_proc    = srm_env_read;
 307                 entry->proc_entry->write_proc   = srm_env_write;
 308         }
 309
 310         printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
 311                         VERSION);
 312
 313         return 0;
 314
 315 cleanup:
 316         srm_env_cleanup();
 317
 318         return -ENOMEM;
 319 }
 320
 321
 322 static void __exit
 323 srm_env_exit(void)
 324 {
 325         srm_env_cleanup();
 326         printk(KERN_INFO "%s: unloaded successfully\n", NAME);
 327
 328         return;
 329 }
 330
 331
 332 module_init(srm_env_init);
 333 module_exit(srm_env_exit);
 334