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 a modified version of Erik Mouw's example proc
   8  * interface, so: thank you, Erik! He can be reached via email at
   9  * <J.A.K.Mouw@its.tudelft.nl>. It is based on an idea
  10  * provided by DEC^WCompaq^WIntel's "Jumpstart" CD. They
  11  * included a patch like this as well. Thanks for idea!
  12  *
  13  * This program is free software; you can redistribute
  14  * it and/or modify it under the terms of the GNU General
  15  * Public License version 2 as published by the Free Software
  16  * Foundation.
  17  *
  18  * This program is distributed in the hope that it will be
  19  * useful, but WITHOUT ANY WARRANTY; without even the implied
  20  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  21  * PURPOSE.  See the GNU General Public License for more
  22  * details.
  23  *
  24  * You should have received a copy of the GNU General Public
  25  * License along with this program; if not, write to the
  26  * Free Software Foundation, Inc., 59 Temple Place,
  27  * Suite 330, Boston, MA  02111-1307  USA
  28  *
  29  */
  30
  31 #include <linux/kernel.h>
  32 #include <linux/gfp.h>
  33 #include <linux/module.h>
  34 #include <linux/init.h>
  35 #include <linux/proc_fs.h>
  36 #include <linux/seq_file.h>
  37 #include <asm/console.h>
  38 #include <asm/uaccess.h>
  39 #include <asm/machvec.h>
  40
  41 #define BASE_DIR        "srm_environment"       /* Subdir in /proc/             */
  42 #define NAMED_DIR       "named_variables"       /* Subdir for known variables   */
  43 #define NUMBERED_DIR    "numbered_variables"    /* Subdir for all variables     */
  44 #define VERSION         "0.0.6"                 /* Module version               */
  45 #define NAME            "srm_env"               /* Module name                  */
  46
  47 MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
  48 MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
  49 MODULE_LICENSE("GPL");
  50
  51 typedef struct _srm_env {
  52         char                    *name;
  53         unsigned long           id;
  54 } srm_env_t;
  55
  56 static struct proc_dir_entry    *base_dir;
  57 static struct proc_dir_entry    *named_dir;
  58 static struct proc_dir_entry    *numbered_dir;
  59
  60 static srm_env_t        srm_named_entries[] = {
  61         { "auto_action",        ENV_AUTO_ACTION         },
  62         { "boot_dev",           ENV_BOOT_DEV            },
  63         { "bootdef_dev",        ENV_BOOTDEF_DEV         },
  64         { "booted_dev",         ENV_BOOTED_DEV          },
  65         { "boot_file",          ENV_BOOT_FILE           },
  66         { "booted_file",        ENV_BOOTED_FILE         },
  67         { "boot_osflags",       ENV_BOOT_OSFLAGS        },
  68         { "booted_osflags",     ENV_BOOTED_OSFLAGS      },
  69         { "boot_reset",         ENV_BOOT_RESET          },
  70         { "dump_dev",           ENV_DUMP_DEV            },
  71         { "enable_audit",       ENV_ENABLE_AUDIT        },
  72         { "license",            ENV_LICENSE             },
  73         { "char_set",           ENV_CHAR_SET            },
  74         { "language",           ENV_LANGUAGE            },
  75         { "tty_dev",            ENV_TTY_DEV             },
  76         { NULL,                 0                       },
  77 };
  78
  79 static int srm_env_proc_show(struct seq_file *m, void *v)
  80 {
  81         unsigned long   ret;
  82         unsigned long   id = (unsigned long)m->private;
  83         char            *page;
  84
  85         page = (char *)__get_free_page(GFP_USER);
  86         if (!page)
  87                 return -ENOMEM;
  88
  89         ret = callback_getenv(id, page, PAGE_SIZE);
  90
  91         if ((ret >> 61) == 0) {
  92                 seq_write(m, page, ret);
  93                 ret = 0;
  94         } else
  95                 ret = -EFAULT;
  96         free_page((unsigned long)page);
  97         return ret;
  98 }
  99
 100 static int srm_env_proc_open(struct inode *inode, struct file *file)
 101 {
 102         return single_open(file, srm_env_proc_show, PDE_DATA(inode));
 103 }
 104
 105 static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
 106                                   size_t count, loff_t *pos)
 107 {
 108         int res;
 109         unsigned long   id = (unsigned long)PDE_DATA(file_inode(file));
 110         char            *buf = (char *) __get_free_page(GFP_USER);
 111         unsigned long   ret1, ret2;
 112
 113         if (!buf)
 114                 return -ENOMEM;
 115
 116         res = -EINVAL;
 117         if (count >= PAGE_SIZE)
 118                 goto out;
 119
 120         res = -EFAULT;
 121         if (copy_from_user(buf, buffer, count))
 122                 goto out;
 123         buf[count] = '\0';
 124
 125         ret1 = callback_setenv(id, buf, count);
 126         if ((ret1 >> 61) == 0) {
 127                 do
 128                         ret2 = callback_save_env();
 129                 while((ret2 >> 61) == 1);
 130                 res = (int) ret1;
 131         }
 132
 133  out:
 134         free_page((unsigned long)buf);
 135         return res;
 136 }
 137
 138 static const struct file_operations srm_env_proc_fops = {
 139         .owner          = THIS_MODULE,
 140         .open           = srm_env_proc_open,
 141         .read           = seq_read,
 142         .llseek         = seq_lseek,
 143         .release        = single_release,
 144         .write          = srm_env_proc_write,
 145 };
 146
 147 static int __init
 148 srm_env_init(void)
 149 {
 150         srm_env_t       *entry;
 151         unsigned long   var_num;
 152
 153         /*
 154          * Check system
 155          */
 156         if (!alpha_using_srm) {
 157                 printk(KERN_INFO "%s: This Alpha system doesn't "
 158                                 "know about SRM (or you've booted "
 159                                 "SRM->MILO->Linux, which gets "
 160                                 "misdetected)...\n", __func__);
 161                 return -ENODEV;
 162         }
 163
 164         /*
 165          * Create base directory
 166          */
 167         base_dir = proc_mkdir(BASE_DIR, NULL);
 168         if (!base_dir) {
 169                 printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
 170                                 BASE_DIR);
 171                 return -ENOMEM;
 172         }
 173
 174         /*
 175          * Create per-name subdirectory
 176          */
 177         named_dir = proc_mkdir(NAMED_DIR, base_dir);
 178         if (!named_dir) {
 179                 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
 180                                 BASE_DIR, NAMED_DIR);
 181                 goto cleanup;
 182         }
 183
 184         /*
 185          * Create per-number subdirectory
 186          */
 187         numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
 188         if (!numbered_dir) {
 189                 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
 190                                 BASE_DIR, NUMBERED_DIR);
 191                 goto cleanup;
 192
 193         }
 194
 195         /*
 196          * Create all named nodes
 197          */
 198         entry = srm_named_entries;
 199         while (entry->name && entry->id) {
 200                 if (!proc_create_data(entry->name, 0644, named_dir,
 201                              &srm_env_proc_fops, (void *)entry->id))
 202                         goto cleanup;
 203                 entry++;
 204         }
 205
 206         /*
 207          * Create all numbered nodes
 208          */
 209         for (var_num = 0; var_num <= 255; var_num++) {
 210                 char name[4];
 211                 sprintf(name, "%ld", var_num);
 212                 if (!proc_create_data(name, 0644, numbered_dir,
 213                              &srm_env_proc_fops, (void *)var_num))
 214                         goto cleanup;
 215         }
 216
 217         printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
 218                         VERSION);
 219
 220         return 0;
 221
 222 cleanup:
 223         remove_proc_subtree(BASE_DIR, NULL);
 224         return -ENOMEM;
 225 }
 226
 227 static void __exit
 228 srm_env_exit(void)
 229 {
 230         remove_proc_subtree(BASE_DIR, NULL);
 231         printk(KERN_INFO "%s: unloaded successfully\n", NAME);
 232 }
 233
 234 module_init(srm_env_init);
 235 module_exit(srm_env_exit);