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/module.h>
34#include <linux/init.h>
35#include <linux/proc_fs.h>
36#include <asm/console.h>
37#include <asm/uaccess.h>
38#include <asm/machvec.h>
39
40#define BASE_DIR	"srm_environment"	/* Subdir in /proc/		*/
41#define NAMED_DIR	"named_variables"	/* Subdir for known variables	*/
42#define NUMBERED_DIR	"numbered_variables"	/* Subdir for all variables	*/
43#define VERSION		"0.0.6"			/* Module version		*/
44#define NAME		"srm_env"		/* Module name			*/
45
46MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
47MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
48MODULE_LICENSE("GPL");
49
50typedef struct _srm_env {
51	char			*name;
52	unsigned long		id;
53	struct proc_dir_entry	*proc_entry;
54} srm_env_t;
55
56static struct proc_dir_entry	*base_dir;
57static struct proc_dir_entry	*named_dir;
58static struct proc_dir_entry	*numbered_dir;
59static char			number[256][4];
60
61static srm_env_t	srm_named_entries[] = {
62	{ "auto_action",	ENV_AUTO_ACTION		},
63	{ "boot_dev",		ENV_BOOT_DEV		},
64	{ "bootdef_dev",	ENV_BOOTDEF_DEV		},
65	{ "booted_dev",		ENV_BOOTED_DEV		},
66	{ "boot_file",		ENV_BOOT_FILE		},
67	{ "booted_file",	ENV_BOOTED_FILE		},
68	{ "boot_osflags",	ENV_BOOT_OSFLAGS	},
69	{ "booted_osflags",	ENV_BOOTED_OSFLAGS	},
70	{ "boot_reset",		ENV_BOOT_RESET		},
71	{ "dump_dev",		ENV_DUMP_DEV		},
72	{ "enable_audit",	ENV_ENABLE_AUDIT	},
73	{ "license",		ENV_LICENSE		},
74	{ "char_set",		ENV_CHAR_SET		},
75	{ "language",		ENV_LANGUAGE		},
76	{ "tty_dev",		ENV_TTY_DEV		},
77	{ NULL,			0			},
78};
79static srm_env_t	srm_numbered_entries[256];
80
81
82static int
83srm_env_read(char *page, char **start, off_t off, int count, int *eof,
84		void *data)
85{
86	int		nbytes;
87	unsigned long	ret;
88	srm_env_t	*entry;
89
90	if (off != 0) {
91		*eof = 1;
92		return 0;
93	}
94
95	entry	= (srm_env_t *) data;
96	ret	= callback_getenv(entry->id, page, count);
97
98	if ((ret >> 61) == 0) {
99		nbytes = (int) ret;
100		*eof = 1;
101	} else
102		nbytes = -EFAULT;
103
104	return nbytes;
105}
106
107static int
108srm_env_write(struct file *file, const char __user *buffer, unsigned long count,
109		void *data)
110{
111	int res;
112	srm_env_t	*entry;
113	char		*buf = (char *) __get_free_page(GFP_USER);
114	unsigned long	ret1, ret2;
115
116	entry = (srm_env_t *) data;
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
143static void
144srm_env_cleanup(void)
145{
146	srm_env_t	*entry;
147	unsigned long	var_num;
148
149	if (base_dir) {
150		/*
151		 * Remove named entries
152		 */
153		if (named_dir) {
154			entry = srm_named_entries;
155			while (entry->name != NULL && entry->id != 0) {
156				if (entry->proc_entry) {
157					remove_proc_entry(entry->name,
158							named_dir);
159					entry->proc_entry = NULL;
160				}
161				entry++;
162			}
163			remove_proc_entry(NAMED_DIR, base_dir);
164		}
165
166		/*
167		 * Remove numbered entries
168		 */
169		if (numbered_dir) {
170			for (var_num = 0; var_num <= 255; var_num++) {
171				entry =	&srm_numbered_entries[var_num];
172
173				if (entry->proc_entry) {
174					remove_proc_entry(entry->name,
175							numbered_dir);
176					entry->proc_entry	= NULL;
177					entry->name		= NULL;
178				}
179			}
180			remove_proc_entry(NUMBERED_DIR, base_dir);
181		}
182
183		remove_proc_entry(BASE_DIR, NULL);
184	}
185
186	return;
187}
188
189static int __init
190srm_env_init(void)
191{
192	srm_env_t	*entry;
193	unsigned long	var_num;
194
195	/*
196	 * Check system
197	 */
198	if (!alpha_using_srm) {
199		printk(KERN_INFO "%s: This Alpha system doesn't "
200				"know about SRM (or you've booted "
201				"SRM->MILO->Linux, which gets "
202				"misdetected)...\n", __FUNCTION__);
203		return -ENODEV;
204	}
205
206	/*
207	 * Init numbers
208	 */
209	for (var_num = 0; var_num <= 255; var_num++)
210		sprintf(number[var_num], "%ld", var_num);
211
212	/*
213	 * Create base directory
214	 */
215	base_dir = proc_mkdir(BASE_DIR, NULL);
216	if (!base_dir) {
217		printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
218				BASE_DIR);
219		goto cleanup;
220	}
221	base_dir->owner = THIS_MODULE;
222
223	/*
224	 * Create per-name subdirectory
225	 */
226	named_dir = proc_mkdir(NAMED_DIR, base_dir);
227	if (!named_dir) {
228		printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
229				BASE_DIR, NAMED_DIR);
230		goto cleanup;
231	}
232	named_dir->owner = THIS_MODULE;
233
234	/*
235	 * Create per-number subdirectory
236	 */
237	numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
238	if (!numbered_dir) {
239		printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
240				BASE_DIR, NUMBERED_DIR);
241		goto cleanup;
242
243	}
244	numbered_dir->owner = THIS_MODULE;
245
246	/*
247	 * Create all named nodes
248	 */
249	entry = srm_named_entries;
250	while (entry->name && entry->id) {
251		entry->proc_entry = create_proc_entry(entry->name,
252				0644, named_dir);
253		if (!entry->proc_entry)
254			goto cleanup;
255
256		entry->proc_entry->data		= (void *) entry;
257		entry->proc_entry->owner	= THIS_MODULE;
258		entry->proc_entry->read_proc	= srm_env_read;
259		entry->proc_entry->write_proc	= srm_env_write;
260
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 = create_proc_entry(entry->name,
272				0644, numbered_dir);
273		if (!entry->proc_entry)
274			goto cleanup;
275
276		entry->id			= var_num;
277		entry->proc_entry->data		= (void *) entry;
278		entry->proc_entry->owner	= THIS_MODULE;
279		entry->proc_entry->read_proc	= srm_env_read;
280		entry->proc_entry->write_proc	= srm_env_write;
281	}
282
283	printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
284			VERSION);
285
286	return 0;
287
288cleanup:
289	srm_env_cleanup();
290
291	return -ENOMEM;
292}
293
294static void __exit
295srm_env_exit(void)
296{
297	srm_env_cleanup();
298	printk(KERN_INFO "%s: unloaded successfully\n", NAME);
299
300	return;
301}
302
303module_init(srm_env_init);
304module_exit(srm_env_exit);
305