1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * srm_env.c - Access to SRM environment
4 * variables through linux' procfs
5 *
6 * (C) 2001,2002,2006 by Jan-Benedict Glaw <jbglaw@lug-owl.de>
7 *
8 * This driver is a modified version of Erik Mouw's example proc
9 * interface, so: thank 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
15 #include <linux/kernel.h>
16 #include <linux/gfp.h>
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/proc_fs.h>
20 #include <linux/seq_file.h>
21 #include <asm/console.h>
22 #include <linux/uaccess.h>
23 #include <asm/machvec.h>
24
25 #define BASE_DIR "srm_environment" /* Subdir in /proc/ */
26 #define NAMED_DIR "named_variables" /* Subdir for known variables */
27 #define NUMBERED_DIR "numbered_variables" /* Subdir for all variables */
28 #define VERSION "0.0.6" /* Module version */
29 #define NAME "srm_env" /* Module name */
30
31 MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
32 MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
33 MODULE_LICENSE("GPL");
34
35 typedef struct _srm_env {
36 char *name;
37 unsigned long id;
38 } srm_env_t;
39
40 static struct proc_dir_entry *base_dir;
41 static struct proc_dir_entry *named_dir;
42 static struct proc_dir_entry *numbered_dir;
43
44 static srm_env_t srm_named_entries[] = {
45 { "auto_action", ENV_AUTO_ACTION },
46 { "boot_dev", ENV_BOOT_DEV },
47 { "bootdef_dev", ENV_BOOTDEF_DEV },
48 { "booted_dev", ENV_BOOTED_DEV },
49 { "boot_file", ENV_BOOT_FILE },
50 { "booted_file", ENV_BOOTED_FILE },
51 { "boot_osflags", ENV_BOOT_OSFLAGS },
52 { "booted_osflags", ENV_BOOTED_OSFLAGS },
53 { "boot_reset", ENV_BOOT_RESET },
54 { "dump_dev", ENV_DUMP_DEV },
55 { "enable_audit", ENV_ENABLE_AUDIT },
56 { "license", ENV_LICENSE },
57 { "char_set", ENV_CHAR_SET },
58 { "language", ENV_LANGUAGE },
59 { "tty_dev", ENV_TTY_DEV },
60 { NULL, 0 },
61 };
62
srm_env_proc_show(struct seq_file * m,void * v)63 static int srm_env_proc_show(struct seq_file *m, void *v)
64 {
65 unsigned long ret;
66 unsigned long id = (unsigned long)m->private;
67 char *page;
68
69 page = (char *)__get_free_page(GFP_USER);
70 if (!page)
71 return -ENOMEM;
72
73 ret = callback_getenv(id, page, PAGE_SIZE);
74
75 if ((ret >> 61) == 0) {
76 seq_write(m, page, ret);
77 ret = 0;
78 } else
79 ret = -EFAULT;
80 free_page((unsigned long)page);
81 return ret;
82 }
83
srm_env_proc_open(struct inode * inode,struct file * file)84 static int srm_env_proc_open(struct inode *inode, struct file *file)
85 {
86 return single_open(file, srm_env_proc_show, PDE_DATA(inode));
87 }
88
srm_env_proc_write(struct file * file,const char __user * buffer,size_t count,loff_t * pos)89 static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
90 size_t count, loff_t *pos)
91 {
92 int res;
93 unsigned long id = (unsigned long)PDE_DATA(file_inode(file));
94 char *buf = (char *) __get_free_page(GFP_USER);
95 unsigned long ret1, ret2;
96
97 if (!buf)
98 return -ENOMEM;
99
100 res = -EINVAL;
101 if (count >= PAGE_SIZE)
102 goto out;
103
104 res = -EFAULT;
105 if (copy_from_user(buf, buffer, count))
106 goto out;
107 buf[count] = '\0';
108
109 ret1 = callback_setenv(id, buf, count);
110 if ((ret1 >> 61) == 0) {
111 do
112 ret2 = callback_save_env();
113 while((ret2 >> 61) == 1);
114 res = (int) ret1;
115 }
116
117 out:
118 free_page((unsigned long)buf);
119 return res;
120 }
121
122 static const struct file_operations srm_env_proc_fops = {
123 .owner = THIS_MODULE,
124 .open = srm_env_proc_open,
125 .read = seq_read,
126 .llseek = seq_lseek,
127 .release = single_release,
128 .write = srm_env_proc_write,
129 };
130
131 static int __init
srm_env_init(void)132 srm_env_init(void)
133 {
134 srm_env_t *entry;
135 unsigned long var_num;
136
137 /*
138 * Check system
139 */
140 if (!alpha_using_srm) {
141 printk(KERN_INFO "%s: This Alpha system doesn't "
142 "know about SRM (or you've booted "
143 "SRM->MILO->Linux, which gets "
144 "misdetected)...\n", __func__);
145 return -ENODEV;
146 }
147
148 /*
149 * Create base directory
150 */
151 base_dir = proc_mkdir(BASE_DIR, NULL);
152 if (!base_dir) {
153 printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
154 BASE_DIR);
155 return -ENOMEM;
156 }
157
158 /*
159 * Create per-name subdirectory
160 */
161 named_dir = proc_mkdir(NAMED_DIR, base_dir);
162 if (!named_dir) {
163 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
164 BASE_DIR, NAMED_DIR);
165 goto cleanup;
166 }
167
168 /*
169 * Create per-number subdirectory
170 */
171 numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
172 if (!numbered_dir) {
173 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
174 BASE_DIR, NUMBERED_DIR);
175 goto cleanup;
176
177 }
178
179 /*
180 * Create all named nodes
181 */
182 entry = srm_named_entries;
183 while (entry->name && entry->id) {
184 if (!proc_create_data(entry->name, 0644, named_dir,
185 &srm_env_proc_fops, (void *)entry->id))
186 goto cleanup;
187 entry++;
188 }
189
190 /*
191 * Create all numbered nodes
192 */
193 for (var_num = 0; var_num <= 255; var_num++) {
194 char name[4];
195 sprintf(name, "%ld", var_num);
196 if (!proc_create_data(name, 0644, numbered_dir,
197 &srm_env_proc_fops, (void *)var_num))
198 goto cleanup;
199 }
200
201 printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
202 VERSION);
203
204 return 0;
205
206 cleanup:
207 remove_proc_subtree(BASE_DIR, NULL);
208 return -ENOMEM;
209 }
210
211 static void __exit
srm_env_exit(void)212 srm_env_exit(void)
213 {
214 remove_proc_subtree(BASE_DIR, NULL);
215 printk(KERN_INFO "%s: unloaded successfully\n", NAME);
216 }
217
218 module_init(srm_env_init);
219 module_exit(srm_env_exit);
220