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