Merge branch 'mini2440-dev-unlikely' into mini2440-dev
[linux-2.6/mini2440.git] / drivers / char / misc.c
blob07fa612a58d56efd23a24a3cb7f5ec61052b5190
1 /*
2 * linux/drivers/char/misc.c
4 * Generic misc open routine by Johan Myreen
6 * Based on code from Linus
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.
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.
16 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
18 * Fixed a failing symbol register to free the device registration
19 * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
21 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
23 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
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>
30 * Changes for kmod (from kerneld):
31 * Cyrus Durgin <cider@speakeasy.org>
33 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998
36 #include <linux/module.h>
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>
43 #include <linux/slab.h>
44 #include <linux/mutex.h>
45 #include <linux/proc_fs.h>
46 #include <linux/seq_file.h>
47 #include <linux/stat.h>
48 #include <linux/init.h>
49 #include <linux/device.h>
50 #include <linux/tty.h>
51 #include <linux/kmod.h>
52 #include <linux/smp_lock.h>
55 * Head entry for the doubly linked miscdevice list
57 static LIST_HEAD(misc_list);
58 static DEFINE_MUTEX(misc_mtx);
61 * Assigned numbers, used for dynamic minors
63 #define DYNAMIC_MINORS 64 /* like dynamic majors */
64 static unsigned char misc_minors[DYNAMIC_MINORS / 8];
66 extern int pmu_device_init(void);
68 #ifdef CONFIG_PROC_FS
69 static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
71 mutex_lock(&misc_mtx);
72 return seq_list_start(&misc_list, *pos);
75 static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
77 return seq_list_next(v, &misc_list, pos);
80 static void misc_seq_stop(struct seq_file *seq, void *v)
82 mutex_unlock(&misc_mtx);
85 static int misc_seq_show(struct seq_file *seq, void *v)
87 const struct miscdevice *p = list_entry(v, struct miscdevice, list);
89 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
90 return 0;
94 static const struct seq_operations misc_seq_ops = {
95 .start = misc_seq_start,
96 .next = misc_seq_next,
97 .stop = misc_seq_stop,
98 .show = misc_seq_show,
101 static int misc_seq_open(struct inode *inode, struct file *file)
103 return seq_open(file, &misc_seq_ops);
106 static const struct file_operations misc_proc_fops = {
107 .owner = THIS_MODULE,
108 .open = misc_seq_open,
109 .read = seq_read,
110 .llseek = seq_lseek,
111 .release = seq_release,
113 #endif
115 static int misc_open(struct inode * inode, struct file * file)
117 int minor = iminor(inode);
118 struct miscdevice *c;
119 int err = -ENODEV;
120 const struct file_operations *old_fops, *new_fops = NULL;
122 lock_kernel();
123 mutex_lock(&misc_mtx);
125 list_for_each_entry(c, &misc_list, list) {
126 if (c->minor == minor) {
127 new_fops = fops_get(c->fops);
128 break;
132 if (!new_fops) {
133 mutex_unlock(&misc_mtx);
134 request_module("char-major-%d-%d", MISC_MAJOR, minor);
135 mutex_lock(&misc_mtx);
137 list_for_each_entry(c, &misc_list, list) {
138 if (c->minor == minor) {
139 new_fops = fops_get(c->fops);
140 break;
143 if (!new_fops)
144 goto fail;
147 err = 0;
148 old_fops = file->f_op;
149 file->f_op = new_fops;
150 if (file->f_op->open) {
151 err=file->f_op->open(inode,file);
152 if (err) {
153 fops_put(file->f_op);
154 file->f_op = fops_get(old_fops);
157 fops_put(old_fops);
158 fail:
159 mutex_unlock(&misc_mtx);
160 unlock_kernel();
161 return err;
164 static struct class *misc_class;
166 static const struct file_operations misc_fops = {
167 .owner = THIS_MODULE,
168 .open = misc_open,
172 * misc_register - register a miscellaneous device
173 * @misc: device structure
175 * Register a miscellaneous device with the kernel. If the minor
176 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
177 * and placed in the minor field of the structure. For other cases
178 * the minor number requested is used.
180 * The structure passed is linked into the kernel and may not be
181 * destroyed until it has been unregistered.
183 * A zero is returned on success and a negative errno code for
184 * failure.
187 int misc_register(struct miscdevice * misc)
189 struct miscdevice *c;
190 dev_t dev;
191 int err = 0;
193 INIT_LIST_HEAD(&misc->list);
195 mutex_lock(&misc_mtx);
196 list_for_each_entry(c, &misc_list, list) {
197 if (c->minor == misc->minor) {
198 mutex_unlock(&misc_mtx);
199 return -EBUSY;
203 if (misc->minor == MISC_DYNAMIC_MINOR) {
204 int i = DYNAMIC_MINORS;
205 while (--i >= 0)
206 if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
207 break;
208 if (i<0) {
209 mutex_unlock(&misc_mtx);
210 return -EBUSY;
212 misc->minor = i;
215 if (misc->minor < DYNAMIC_MINORS)
216 misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
217 dev = MKDEV(MISC_MAJOR, misc->minor);
219 misc->this_device = device_create(misc_class, misc->parent, dev,
220 misc, "%s", misc->name);
221 if (IS_ERR(misc->this_device)) {
222 err = PTR_ERR(misc->this_device);
223 goto out;
227 * Add it to the front, so that later devices can "override"
228 * earlier defaults
230 list_add(&misc->list, &misc_list);
231 out:
232 mutex_unlock(&misc_mtx);
233 return err;
237 * misc_deregister - unregister a miscellaneous device
238 * @misc: device to unregister
240 * Unregister a miscellaneous device that was previously
241 * successfully registered with misc_register(). Success
242 * is indicated by a zero return, a negative errno code
243 * indicates an error.
246 int misc_deregister(struct miscdevice *misc)
248 int i = misc->minor;
250 if (list_empty(&misc->list))
251 return -EINVAL;
253 mutex_lock(&misc_mtx);
254 list_del(&misc->list);
255 device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
256 if (i < DYNAMIC_MINORS && i>0) {
257 misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
259 mutex_unlock(&misc_mtx);
260 return 0;
263 EXPORT_SYMBOL(misc_register);
264 EXPORT_SYMBOL(misc_deregister);
266 static char *misc_devnode(struct device *dev, mode_t *mode)
268 struct miscdevice *c = dev_get_drvdata(dev);
270 if (mode && c->mode)
271 *mode = c->mode;
272 if (c->nodename)
273 return kstrdup(c->nodename, GFP_KERNEL);
274 return NULL;
277 static int __init misc_init(void)
279 int err;
281 #ifdef CONFIG_PROC_FS
282 proc_create("misc", 0, NULL, &misc_proc_fops);
283 #endif
284 misc_class = class_create(THIS_MODULE, "misc");
285 err = PTR_ERR(misc_class);
286 if (IS_ERR(misc_class))
287 goto fail_remove;
289 err = -EIO;
290 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
291 goto fail_printk;
292 misc_class->devnode = misc_devnode;
293 return 0;
295 fail_printk:
296 printk("unable to get major %d for misc devices\n", MISC_MAJOR);
297 class_destroy(misc_class);
298 fail_remove:
299 remove_proc_entry("misc", NULL);
300 return err;
302 subsys_initcall(misc_init);