arch/alpha/kernel/srm_env.c

   1 /*
   2  * srm_env.c - Access to SRM environment
   3  *             variables through linux' procfs
   4  *
   5  * (C) 2001,2002,2006 by 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 #include <linux/kernel.h>
  33 #include <linux/gfp.h>
  34 #include <linux/module.h>
  35 #include <linux/init.h>
  36 #include <linux/proc_fs.h>
  37 #include <linux/seq_file.h>
  38 #include <asm/console.h>
  39 #include <asm/uaccess.h>
  40 #include <asm/machvec.h>
  41
  42 #define BASE_DIR        "srm_environment"       /* Subdir in /proc/             */
  43 #define NAMED_DIR       "named_variables"       /* Subdir for known variables   */
  44 #define NUMBERED_DIR    "numbered_variables"    /* Subdir for all variables     */
  45 #define VERSION         "0.0.6"                 /* Module version               */
  46 #define NAME            "srm_env"               /* Module name                  */
  47
  48 MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
  49 MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
  50 MODULE_LICENSE("GPL");
  51
  52 typedef struct _srm_env {
  53         char                    *name;
  54         unsigned long           id;
  55         struct proc_dir_entry   *proc_entry;
  56 } srm_env_t;
  57
  58 static struct proc_dir_entry    *base_dir;
  59 static struct proc_dir_entry    *named_dir;
  60 static struct proc_dir_entry    *numbered_dir;
  61 static char                     number[256][4];
  62
  63 static srm_env_t        srm_named_entries[] = {
  64         { "auto_action",        ENV_AUTO_ACTION         },
  65         { "boot_dev",           ENV_BOOT_DEV            },
  66         { "bootdef_dev",        ENV_BOOTDEF_DEV         },
  67         { "booted_dev",         ENV_BOOTED_DEV          },
  68         { "boot_file",          ENV_BOOT_FILE           },
  69         { "booted_file",        ENV_BOOTED_FILE         },
  70         { "boot_osflags",       ENV_BOOT_OSFLAGS        },
  71         { "booted_osflags",     ENV_BOOTED_OSFLAGS      },
  72         { "boot_reset",         ENV_BOOT_RESET          },
  73         { "dump_dev",           ENV_DUMP_DEV            },
  74         { "enable_audit",       ENV_ENABLE_AUDIT        },
  75         { "license",            ENV_LICENSE             },
  76         { "char_set",           ENV_CHAR_SET            },
  77         { "language",           ENV_LANGUAGE            },
  78         { "tty_dev",            ENV_TTY_DEV             },
  79         { NULL,                 0                       },
  80 };
  81 static srm_env_t        srm_numbered_entries[256];
  82
  83
  84 static int srm_env_proc_show(struct seq_file *m, void *v)
  85 {
  86         unsigned long   ret;
  87         srm_env_t       *entry;
  88         char            *page;
  89
  90         entry = m->private;
  91         page = (char *)__get_free_page(GFP_USER);
  92         if (!page)
  93                 return -ENOMEM;
  94
  95         ret = callback_getenv(entry->id, page, PAGE_SIZE);
  96
  97         if ((ret >> 61) == 0) {
  98                 seq_write(m, page, ret);
  99                 ret = 0;
 100         } else
 101                 ret = -EFAULT;
 102         free_page((unsigned long)page);
 103         return ret;
 104 }
 105
 106 static int srm_env_proc_open(struct inode *inode, struct file *file)
 107 {
 108         return single_open(file, srm_env_proc_show, PDE(inode)->data);
 109 }
 110
 111 static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
 112                                   size_t count, loff_t *pos)
 113 {
 114         int res;
 115         srm_env_t       *entry = PDE(file->f_path.dentry->d_inode)->data;
 116         char            *buf = (char *) __get_free_page(GFP_USER);
 117         unsigned long   ret1, ret2;
 118
 119         if (!buf)
 120                 return -ENOMEM;
 121
 122         res = -EINVAL;
 123         if (count >= PAGE_SIZE)
 124                 goto out;
 125
 126         res = -EFAULT;
 127         if (copy_from_user(buf, buffer, count))
 128                 goto out;
 129         buf[count] = '\0';
 130
 131         ret1 = callback_setenv(entry->id, buf, count);
 132         if ((ret1 >> 61) == 0) {
 133                 do
 134                         ret2 = callback_save_env();
 135                 while((ret2 >> 61) == 1);
 136                 res = (int) ret1;
 137         }
 138
 139  out:
 140         free_page((unsigned long)buf);
 141         return res;
 142 }
 143
 144 static const struct file_operations srm_env_proc_fops = {
 145         .owner          = THIS_MODULE,
 146         .open           = srm_env_proc_open,
 147         .read           = seq_read,
 148         .llseek         = seq_lseek,
 149         .release        = single_release,
 150         .write          = srm_env_proc_write,
 151 };
 152
 153 static void
 154 srm_env_cleanup(void)
 155 {
 156         srm_env_t       *entry;
 157         unsigned long   var_num;
 158
 159         if (base_dir) {
 160                 /*
 161                  * Remove named entries
 162                  */
 163                 if (named_dir) {
 164                         entry = srm_named_entries;
 165                         while (entry->name != NULL && entry->id != 0) {
 166                                 if (entry->proc_entry) {
 167                                         remove_proc_entry(entry->name,
 168                                                         named_dir);
 169                                         entry->proc_entry = NULL;
 170                                 }
 171                                 entry++;
 172                         }
 173                         remove_proc_entry(NAMED_DIR, base_dir);
 174                 }
 175
 176                 /*
 177                  * Remove numbered entries
 178                  */
 179                 if (numbered_dir) {
 180                         for (var_num = 0; var_num <= 255; var_num++) {
 181                                 entry = &srm_numbered_entries[var_num];
 182
 183                                 if (entry->proc_entry) {
 184                                         remove_proc_entry(entry->name,
 185                                                         numbered_dir);
 186                                         entry->proc_entry       = NULL;
 187                                         entry->name             = NULL;
 188                                 }
 189                         }
 190                         remove_proc_entry(NUMBERED_DIR, base_dir);
 191                 }
 192
 193                 remove_proc_entry(BASE_DIR, NULL);
 194         }
 195
 196         return;
 197 }
 198
 199 static int __init
 200 srm_env_init(void)
 201 {
 202         srm_env_t       *entry;
 203         unsigned long   var_num;
 204
 205         /*
 206          * Check system
 207          */
 208         if (!alpha_using_srm) {
 209                 printk(KERN_INFO "%s: This Alpha system doesn't "
 210                                 "know about SRM (or you've booted "
 211                                 "SRM->MILO->Linux, which gets "
 212                                 "misdetected)...\n", __func__);
 213                 return -ENODEV;
 214         }
 215
 216         /*
 217          * Init numbers
 218          */
 219         for (var_num = 0; var_num <= 255; var_num++)
 220                 sprintf(number[var_num], "%ld", var_num);
 221
 222         /*
 223          * Create base directory
 224          */
 225         base_dir = proc_mkdir(BASE_DIR, NULL);
 226         if (!base_dir) {
 227                 printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
 228                                 BASE_DIR);
 229                 goto cleanup;
 230         }
 231
 232         /*
 233          * Create per-name subdirectory
 234          */
 235         named_dir = proc_mkdir(NAMED_DIR, base_dir);
 236         if (!named_dir) {
 237                 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
 238                                 BASE_DIR, NAMED_DIR);
 239                 goto cleanup;
 240         }
 241
 242         /*
 243          * Create per-number subdirectory
 244          */
 245         numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
 246         if (!numbered_dir) {
 247                 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
 248                                 BASE_DIR, NUMBERED_DIR);
 249                 goto cleanup;
 250
 251         }
 252
 253         /*
 254          * Create all named nodes
 255          */
 256         entry = srm_named_entries;
 257         while (entry->name && entry->id) {
 258                 entry->proc_entry = proc_create_data(entry->name, 0644, named_dir,
 259                                                      &srm_env_proc_fops, entry);
 260                 if (!entry->proc_entry)
 261                         goto cleanup;
 262                 entry++;
 263         }
 264
 265         /*
 266          * Create all numbered nodes
 267          */
 268         for (var_num = 0; var_num <= 255; var_num++) {
 269                 entry = &srm_numbered_entries[var_num];
 270                 entry->name = number[var_num];
 271
 272                 entry->proc_entry = proc_create_data(entry->name, 0644, numbered_dir,
 273                                                      &srm_env_proc_fops, entry);
 274                 if (!entry->proc_entry)
 275                         goto cleanup;
 276
 277                 entry->id                       = var_num;
 278         }
 279
 280         printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
 281                         VERSION);
 282
 283         return 0;
 284
 285 cleanup:
 286         srm_env_cleanup();
 287
 288         return -ENOMEM;
 289 }
 290
 291 static void __exit
 292 srm_env_exit(void)
 293 {
 294         srm_env_cleanup();
 295         printk(KERN_INFO "%s: unloaded successfully\n", NAME);
 296
 297         return;
 298 }
 299
 300 module_init(srm_env_init);
 301 module_exit(srm_env_exit);