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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/drivers/char/misc.c | |
3 | * | |
4 | * Generic misc open routine by Johan Myreen | |
5 | * | |
6 | * Based on code from Linus | |
7 | * | |
8 | * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's | |
9 | * changes incorporated into 0.97pl4 | |
10 | * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92) | |
11 | * See busmouse.c for particulars. | |
12 | * | |
13 | * Made things a lot mode modular - easy to compile in just one or two | |
14 | * of the misc drivers, as they are now completely independent. Linus. | |
15 | * | |
16 | * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk> | |
17 | * | |
18 | * Fixed a failing symbol register to free the device registration | |
19 | * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96 | |
20 | * | |
21 | * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96 | |
22 | * | |
23 | * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96 | |
24 | * | |
25 | * Handling of mouse minor numbers for kerneld: | |
26 | * Idea by Jacques Gelinas <jack@solucorp.qc.ca>, | |
27 | * adapted by Bjorn Ekwall <bj0rn@blox.se> | |
28 | * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk> | |
29 | * | |
30 | * Changes for kmod (from kerneld): | |
31 | * Cyrus Durgin <cider@speakeasy.org> | |
32 | * | |
33 | * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998 | |
34 | */ | |
35 | ||
36 | #include <linux/module.h> | |
1da177e4 LT |
37 | |
38 | #include <linux/fs.h> | |
39 | #include <linux/errno.h> | |
40 | #include <linux/miscdevice.h> | |
41 | #include <linux/kernel.h> | |
42 | #include <linux/major.h> | |
0e82d5b6 | 43 | #include <linux/mutex.h> |
1da177e4 LT |
44 | #include <linux/proc_fs.h> |
45 | #include <linux/seq_file.h> | |
1da177e4 LT |
46 | #include <linux/stat.h> |
47 | #include <linux/init.h> | |
48 | #include <linux/device.h> | |
49 | #include <linux/tty.h> | |
50 | #include <linux/kmod.h> | |
5a0e3ad6 | 51 | #include <linux/gfp.h> |
1da177e4 LT |
52 | |
53 | /* | |
54 | * Head entry for the doubly linked miscdevice list | |
55 | */ | |
56 | static LIST_HEAD(misc_list); | |
0e82d5b6 | 57 | static DEFINE_MUTEX(misc_mtx); |
1da177e4 LT |
58 | |
59 | /* | |
60 | * Assigned numbers, used for dynamic minors | |
61 | */ | |
62 | #define DYNAMIC_MINORS 64 /* like dynamic majors */ | |
1f2f38d8 | 63 | static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS); |
1da177e4 | 64 | |
1da177e4 LT |
65 | #ifdef CONFIG_PROC_FS |
66 | static void *misc_seq_start(struct seq_file *seq, loff_t *pos) | |
67 | { | |
0e82d5b6 | 68 | mutex_lock(&misc_mtx); |
46c65b71 | 69 | return seq_list_start(&misc_list, *pos); |
1da177e4 LT |
70 | } |
71 | ||
72 | static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos) | |
73 | { | |
46c65b71 | 74 | return seq_list_next(v, &misc_list, pos); |
1da177e4 LT |
75 | } |
76 | ||
77 | static void misc_seq_stop(struct seq_file *seq, void *v) | |
78 | { | |
0e82d5b6 | 79 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
80 | } |
81 | ||
82 | static int misc_seq_show(struct seq_file *seq, void *v) | |
83 | { | |
46c65b71 | 84 | const struct miscdevice *p = list_entry(v, struct miscdevice, list); |
1da177e4 LT |
85 | |
86 | seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : ""); | |
87 | return 0; | |
88 | } | |
89 | ||
90 | ||
88e9d34c | 91 | static const struct seq_operations misc_seq_ops = { |
1da177e4 LT |
92 | .start = misc_seq_start, |
93 | .next = misc_seq_next, | |
94 | .stop = misc_seq_stop, | |
95 | .show = misc_seq_show, | |
96 | }; | |
97 | ||
98 | static int misc_seq_open(struct inode *inode, struct file *file) | |
99 | { | |
100 | return seq_open(file, &misc_seq_ops); | |
101 | } | |
102 | ||
62322d25 | 103 | static const struct file_operations misc_proc_fops = { |
1da177e4 LT |
104 | .owner = THIS_MODULE, |
105 | .open = misc_seq_open, | |
106 | .read = seq_read, | |
107 | .llseek = seq_lseek, | |
108 | .release = seq_release, | |
109 | }; | |
110 | #endif | |
111 | ||
112 | static int misc_open(struct inode * inode, struct file * file) | |
113 | { | |
114 | int minor = iminor(inode); | |
115 | struct miscdevice *c; | |
116 | int err = -ENODEV; | |
99ac48f5 | 117 | const struct file_operations *old_fops, *new_fops = NULL; |
40b798ef | 118 | |
0e82d5b6 | 119 | mutex_lock(&misc_mtx); |
1da177e4 LT |
120 | |
121 | list_for_each_entry(c, &misc_list, list) { | |
122 | if (c->minor == minor) { | |
123 | new_fops = fops_get(c->fops); | |
124 | break; | |
125 | } | |
126 | } | |
127 | ||
128 | if (!new_fops) { | |
0e82d5b6 | 129 | mutex_unlock(&misc_mtx); |
1da177e4 | 130 | request_module("char-major-%d-%d", MISC_MAJOR, minor); |
0e82d5b6 | 131 | mutex_lock(&misc_mtx); |
1da177e4 LT |
132 | |
133 | list_for_each_entry(c, &misc_list, list) { | |
134 | if (c->minor == minor) { | |
135 | new_fops = fops_get(c->fops); | |
136 | break; | |
137 | } | |
138 | } | |
139 | if (!new_fops) | |
140 | goto fail; | |
141 | } | |
142 | ||
143 | err = 0; | |
144 | old_fops = file->f_op; | |
145 | file->f_op = new_fops; | |
146 | if (file->f_op->open) { | |
147 | err=file->f_op->open(inode,file); | |
148 | if (err) { | |
149 | fops_put(file->f_op); | |
150 | file->f_op = fops_get(old_fops); | |
151 | } | |
152 | } | |
153 | fops_put(old_fops); | |
154 | fail: | |
0e82d5b6 | 155 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
156 | return err; |
157 | } | |
158 | ||
ca8eca68 | 159 | static struct class *misc_class; |
1da177e4 | 160 | |
62322d25 | 161 | static const struct file_operations misc_fops = { |
1da177e4 LT |
162 | .owner = THIS_MODULE, |
163 | .open = misc_open, | |
164 | }; | |
165 | ||
1da177e4 LT |
166 | /** |
167 | * misc_register - register a miscellaneous device | |
168 | * @misc: device structure | |
169 | * | |
170 | * Register a miscellaneous device with the kernel. If the minor | |
171 | * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned | |
172 | * and placed in the minor field of the structure. For other cases | |
173 | * the minor number requested is used. | |
174 | * | |
175 | * The structure passed is linked into the kernel and may not be | |
176 | * destroyed until it has been unregistered. | |
177 | * | |
178 | * A zero is returned on success and a negative errno code for | |
179 | * failure. | |
180 | */ | |
181 | ||
182 | int misc_register(struct miscdevice * misc) | |
183 | { | |
184 | struct miscdevice *c; | |
185 | dev_t dev; | |
7c69ef79 | 186 | int err = 0; |
1da177e4 | 187 | |
5d469ec0 NH |
188 | INIT_LIST_HEAD(&misc->list); |
189 | ||
0e82d5b6 | 190 | mutex_lock(&misc_mtx); |
1da177e4 LT |
191 | list_for_each_entry(c, &misc_list, list) { |
192 | if (c->minor == misc->minor) { | |
0e82d5b6 | 193 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
194 | return -EBUSY; |
195 | } | |
196 | } | |
197 | ||
198 | if (misc->minor == MISC_DYNAMIC_MINOR) { | |
1f2f38d8 TLSC |
199 | int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS); |
200 | if (i >= DYNAMIC_MINORS) { | |
0e82d5b6 | 201 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
202 | return -EBUSY; |
203 | } | |
1f2f38d8 TLSC |
204 | misc->minor = DYNAMIC_MINORS - i - 1; |
205 | set_bit(i, misc_minors); | |
1da177e4 LT |
206 | } |
207 | ||
1da177e4 LT |
208 | dev = MKDEV(MISC_MAJOR, misc->minor); |
209 | ||
d4056405 KS |
210 | misc->this_device = device_create(misc_class, misc->parent, dev, |
211 | misc, "%s", misc->name); | |
94fbcded | 212 | if (IS_ERR(misc->this_device)) { |
1f2f38d8 | 213 | int i = DYNAMIC_MINORS - misc->minor - 1; |
4ae717da | 214 | if (i < DYNAMIC_MINORS && i >= 0) |
1f2f38d8 | 215 | clear_bit(i, misc_minors); |
94fbcded | 216 | err = PTR_ERR(misc->this_device); |
1da177e4 LT |
217 | goto out; |
218 | } | |
219 | ||
1da177e4 LT |
220 | /* |
221 | * Add it to the front, so that later devices can "override" | |
222 | * earlier defaults | |
223 | */ | |
224 | list_add(&misc->list, &misc_list); | |
225 | out: | |
0e82d5b6 | 226 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
227 | return err; |
228 | } | |
229 | ||
230 | /** | |
b844eba2 | 231 | * misc_deregister - unregister a miscellaneous device |
1da177e4 LT |
232 | * @misc: device to unregister |
233 | * | |
234 | * Unregister a miscellaneous device that was previously | |
235 | * successfully registered with misc_register(). Success | |
236 | * is indicated by a zero return, a negative errno code | |
237 | * indicates an error. | |
238 | */ | |
239 | ||
b844eba2 | 240 | int misc_deregister(struct miscdevice *misc) |
1da177e4 | 241 | { |
1f2f38d8 | 242 | int i = DYNAMIC_MINORS - misc->minor - 1; |
1da177e4 LT |
243 | |
244 | if (list_empty(&misc->list)) | |
245 | return -EINVAL; | |
246 | ||
0e82d5b6 | 247 | mutex_lock(&misc_mtx); |
1da177e4 | 248 | list_del(&misc->list); |
b844eba2 | 249 | device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); |
4ae717da | 250 | if (i < DYNAMIC_MINORS && i >= 0) |
1f2f38d8 | 251 | clear_bit(i, misc_minors); |
0e82d5b6 | 252 | mutex_unlock(&misc_mtx); |
1da177e4 LT |
253 | return 0; |
254 | } | |
255 | ||
256 | EXPORT_SYMBOL(misc_register); | |
b844eba2 | 257 | EXPORT_SYMBOL(misc_deregister); |
1da177e4 | 258 | |
e454cea2 | 259 | static char *misc_devnode(struct device *dev, mode_t *mode) |
d4056405 KS |
260 | { |
261 | struct miscdevice *c = dev_get_drvdata(dev); | |
262 | ||
e454cea2 KS |
263 | if (mode && c->mode) |
264 | *mode = c->mode; | |
265 | if (c->nodename) | |
266 | return kstrdup(c->nodename, GFP_KERNEL); | |
d4056405 KS |
267 | return NULL; |
268 | } | |
269 | ||
1da177e4 LT |
270 | static int __init misc_init(void) |
271 | { | |
1b502217 | 272 | int err; |
1da177e4 | 273 | |
1b502217 DL |
274 | #ifdef CONFIG_PROC_FS |
275 | proc_create("misc", 0, NULL, &misc_proc_fops); | |
1da177e4 | 276 | #endif |
ca8eca68 | 277 | misc_class = class_create(THIS_MODULE, "misc"); |
1b502217 | 278 | err = PTR_ERR(misc_class); |
1da177e4 | 279 | if (IS_ERR(misc_class)) |
1b502217 | 280 | goto fail_remove; |
573fc113 | 281 | |
1b502217 DL |
282 | err = -EIO; |
283 | if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) | |
284 | goto fail_printk; | |
e454cea2 | 285 | misc_class->devnode = misc_devnode; |
1da177e4 | 286 | return 0; |
1b502217 DL |
287 | |
288 | fail_printk: | |
289 | printk("unable to get major %d for misc devices\n", MISC_MAJOR); | |
290 | class_destroy(misc_class); | |
291 | fail_remove: | |
292 | remove_proc_entry("misc", NULL); | |
293 | return err; | |
1da177e4 LT |
294 | } |
295 | subsys_initcall(misc_init); |