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>
 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>
 43#include <linux/mutex.h>
 44#include <linux/proc_fs.h>
 45#include <linux/seq_file.h>
 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>
 51#include <linux/gfp.h>
 52
 53/*
 54 * Head entry for the doubly linked miscdevice list
 55 */
 56static LIST_HEAD(misc_list);
 57static DEFINE_MUTEX(misc_mtx);
 58
 59/*
 60 * Assigned numbers, used for dynamic minors
 61 */
 62#define DYNAMIC_MINORS 64 /* like dynamic majors */
 63static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
 64
 65#ifdef CONFIG_PROC_FS
 66static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
 67{
 68	mutex_lock(&misc_mtx);
 69	return seq_list_start(&misc_list, *pos);
 70}
 71
 72static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 73{
 74	return seq_list_next(v, &misc_list, pos);
 75}
 76
 77static void misc_seq_stop(struct seq_file *seq, void *v)
 78{
 79	mutex_unlock(&misc_mtx);
 80}
 81
 82static int misc_seq_show(struct seq_file *seq, void *v)
 83{
 84	const struct miscdevice *p = list_entry(v, struct miscdevice, list);
 85
 86	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
 87	return 0;
 88}
 89
 90
 91static const struct seq_operations misc_seq_ops = {
 92	.start = misc_seq_start,
 93	.next  = misc_seq_next,
 94	.stop  = misc_seq_stop,
 95	.show  = misc_seq_show,
 96};
 97
 98static int misc_seq_open(struct inode *inode, struct file *file)
 99{
100	return seq_open(file, &misc_seq_ops);
101}
102
103static const struct file_operations misc_proc_fops = {
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
112static int misc_open(struct inode * inode, struct file * file)
113{
114	int minor = iminor(inode);
115	struct miscdevice *c;
116	int err = -ENODEV;
117	const struct file_operations *old_fops, *new_fops = NULL;
118
119	mutex_lock(&misc_mtx);
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) {
129		mutex_unlock(&misc_mtx);
130		request_module("char-major-%d-%d", MISC_MAJOR, minor);
131		mutex_lock(&misc_mtx);
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		file->private_data = c;
148		err=file->f_op->open(inode,file);
149		if (err) {
150			fops_put(file->f_op);
151			file->f_op = fops_get(old_fops);
152		}
153	}
154	fops_put(old_fops);
155fail:
156	mutex_unlock(&misc_mtx);
157	return err;
158}
159
160static struct class *misc_class;
161
162static const struct file_operations misc_fops = {
163	.owner		= THIS_MODULE,
164	.open		= misc_open,
165	.llseek		= noop_llseek,
166};
167
168/**
169 *	misc_register	-	register a miscellaneous device
170 *	@misc: device structure
171 *	
172 *	Register a miscellaneous device with the kernel. If the minor
173 *	number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
174 *	and placed in the minor field of the structure. For other cases
175 *	the minor number requested is used.
176 *
177 *	The structure passed is linked into the kernel and may not be
178 *	destroyed until it has been unregistered.
 
 
179 *
180 *	A zero is returned on success and a negative errno code for
181 *	failure.
182 */
183 
184int misc_register(struct miscdevice * misc)
185{
186	struct miscdevice *c;
187	dev_t dev;
188	int err = 0;
 
189
190	INIT_LIST_HEAD(&misc->list);
191
192	mutex_lock(&misc_mtx);
193	list_for_each_entry(c, &misc_list, list) {
194		if (c->minor == misc->minor) {
195			mutex_unlock(&misc_mtx);
196			return -EBUSY;
197		}
198	}
199
200	if (misc->minor == MISC_DYNAMIC_MINOR) {
201		int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
202		if (i >= DYNAMIC_MINORS) {
203			mutex_unlock(&misc_mtx);
204			return -EBUSY;
205		}
206		misc->minor = DYNAMIC_MINORS - i - 1;
207		set_bit(i, misc_minors);
 
 
 
 
 
 
 
 
 
208	}
209
210	dev = MKDEV(MISC_MAJOR, misc->minor);
211
212	misc->this_device = device_create(misc_class, misc->parent, dev,
213					  misc, "%s", misc->name);
 
214	if (IS_ERR(misc->this_device)) {
215		int i = DYNAMIC_MINORS - misc->minor - 1;
216		if (i < DYNAMIC_MINORS && i >= 0)
217			clear_bit(i, misc_minors);
 
 
 
 
218		err = PTR_ERR(misc->this_device);
219		goto out;
220	}
221
222	/*
223	 * Add it to the front, so that later devices can "override"
224	 * earlier defaults
225	 */
226	list_add(&misc->list, &misc_list);
227 out:
228	mutex_unlock(&misc_mtx);
229	return err;
230}
231
232/**
233 *	misc_deregister - unregister a miscellaneous device
234 *	@misc: device to unregister
235 *
236 *	Unregister a miscellaneous device that was previously
237 *	successfully registered with misc_register(). Success
238 *	is indicated by a zero return, a negative errno code
239 *	indicates an error.
240 */
241
242int misc_deregister(struct miscdevice *misc)
243{
244	int i = DYNAMIC_MINORS - misc->minor - 1;
245
246	if (WARN_ON(list_empty(&misc->list)))
247		return -EINVAL;
248
249	mutex_lock(&misc_mtx);
250	list_del(&misc->list);
251	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
252	if (i < DYNAMIC_MINORS && i >= 0)
253		clear_bit(i, misc_minors);
254	mutex_unlock(&misc_mtx);
255	return 0;
256}
257
258EXPORT_SYMBOL(misc_register);
259EXPORT_SYMBOL(misc_deregister);
260
261static char *misc_devnode(struct device *dev, mode_t *mode)
262{
263	struct miscdevice *c = dev_get_drvdata(dev);
264
265	if (mode && c->mode)
266		*mode = c->mode;
267	if (c->nodename)
268		return kstrdup(c->nodename, GFP_KERNEL);
269	return NULL;
270}
271
272static int __init misc_init(void)
273{
274	int err;
 
275
276#ifdef CONFIG_PROC_FS
277	proc_create("misc", 0, NULL, &misc_proc_fops);
278#endif
279	misc_class = class_create(THIS_MODULE, "misc");
280	err = PTR_ERR(misc_class);
281	if (IS_ERR(misc_class))
282		goto fail_remove;
283
284	err = -EIO;
285	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
286		goto fail_printk;
287	misc_class->devnode = misc_devnode;
288	return 0;
289
290fail_printk:
291	printk("unable to get major %d for misc devices\n", MISC_MAJOR);
292	class_destroy(misc_class);
293fail_remove:
294	remove_proc_entry("misc", NULL);
 
295	return err;
296}
297subsys_initcall(misc_init);

  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>
 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>
 43#include <linux/mutex.h>
 44#include <linux/proc_fs.h>
 45#include <linux/seq_file.h>
 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>
 51#include <linux/gfp.h>
 52
 53/*
 54 * Head entry for the doubly linked miscdevice list
 55 */
 56static LIST_HEAD(misc_list);
 57static DEFINE_MUTEX(misc_mtx);
 58
 59/*
 60 * Assigned numbers, used for dynamic minors
 61 */
 62#define DYNAMIC_MINORS 64 /* like dynamic majors */
 63static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
 64
 65#ifdef CONFIG_PROC_FS
 66static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
 67{
 68	mutex_lock(&misc_mtx);
 69	return seq_list_start(&misc_list, *pos);
 70}
 71
 72static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 73{
 74	return seq_list_next(v, &misc_list, pos);
 75}
 76
 77static void misc_seq_stop(struct seq_file *seq, void *v)
 78{
 79	mutex_unlock(&misc_mtx);
 80}
 81
 82static int misc_seq_show(struct seq_file *seq, void *v)
 83{
 84	const struct miscdevice *p = list_entry(v, struct miscdevice, list);
 85
 86	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
 87	return 0;
 88}
 89
 90
 91static const struct seq_operations misc_seq_ops = {
 92	.start = misc_seq_start,
 93	.next  = misc_seq_next,
 94	.stop  = misc_seq_stop,
 95	.show  = misc_seq_show,
 96};
 97
 98static int misc_seq_open(struct inode *inode, struct file *file)
 99{
100	return seq_open(file, &misc_seq_ops);
101}
102
103static const struct file_operations misc_proc_fops = {
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
112static int misc_open(struct inode * inode, struct file * file)
113{
114	int minor = iminor(inode);
115	struct miscdevice *c;
116	int err = -ENODEV;
117	const struct file_operations *new_fops = NULL;
118
119	mutex_lock(&misc_mtx);
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) {
129		mutex_unlock(&misc_mtx);
130		request_module("char-major-%d-%d", MISC_MAJOR, minor);
131		mutex_lock(&misc_mtx);
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	/*
144	 * Place the miscdevice in the file's
145	 * private_data so it can be used by the
146	 * file operations, including f_op->open below
147	 */
148	file->private_data = c;
149
150	err = 0;
151	replace_fops(file, new_fops);
152	if (file->f_op->open)
153		err = file->f_op->open(inode,file);
 
 
 
 
 
 
 
 
154fail:
155	mutex_unlock(&misc_mtx);
156	return err;
157}
158
159static struct class *misc_class;
160
161static const struct file_operations misc_fops = {
162	.owner		= THIS_MODULE,
163	.open		= misc_open,
164	.llseek		= noop_llseek,
165};
166
167/**
168 *	misc_register	-	register a miscellaneous device
169 *	@misc: device structure
170 *
171 *	Register a miscellaneous device with the kernel. If the minor
172 *	number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
173 *	and placed in the minor field of the structure. For other cases
174 *	the minor number requested is used.
175 *
176 *	The structure passed is linked into the kernel and may not be
177 *	destroyed until it has been unregistered. By default, an open()
178 *	syscall to the device sets file->private_data to point to the
179 *	structure. Drivers don't need open in fops for this.
180 *
181 *	A zero is returned on success and a negative errno code for
182 *	failure.
183 */
184
185int misc_register(struct miscdevice * misc)
186{
 
187	dev_t dev;
188	int err = 0;
189	bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR);
190
191	INIT_LIST_HEAD(&misc->list);
192
193	mutex_lock(&misc_mtx);
 
 
 
 
 
 
194
195	if (is_dynamic) {
196		int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
197		if (i >= DYNAMIC_MINORS) {
198			err = -EBUSY;
199			goto out;
200		}
201		misc->minor = DYNAMIC_MINORS - i - 1;
202		set_bit(i, misc_minors);
203	} else {
204		struct miscdevice *c;
205
206		list_for_each_entry(c, &misc_list, list) {
207			if (c->minor == misc->minor) {
208				err = -EBUSY;
209				goto out;
210			}
211		}
212	}
213
214	dev = MKDEV(MISC_MAJOR, misc->minor);
215
216	misc->this_device =
217		device_create_with_groups(misc_class, misc->parent, dev,
218					  misc, misc->groups, "%s", misc->name);
219	if (IS_ERR(misc->this_device)) {
220		if (is_dynamic) {
221			int i = DYNAMIC_MINORS - misc->minor - 1;
222
223			if (i < DYNAMIC_MINORS && i >= 0)
224				clear_bit(i, misc_minors);
225			misc->minor = MISC_DYNAMIC_MINOR;
226		}
227		err = PTR_ERR(misc->this_device);
228		goto out;
229	}
230
231	/*
232	 * Add it to the front, so that later devices can "override"
233	 * earlier defaults
234	 */
235	list_add(&misc->list, &misc_list);
236 out:
237	mutex_unlock(&misc_mtx);
238	return err;
239}
240
241/**
242 *	misc_deregister - unregister a miscellaneous device
243 *	@misc: device to unregister
244 *
245 *	Unregister a miscellaneous device that was previously
246 *	successfully registered with misc_register().
 
 
247 */
248
249void misc_deregister(struct miscdevice *misc)
250{
251	int i = DYNAMIC_MINORS - misc->minor - 1;
252
253	if (WARN_ON(list_empty(&misc->list)))
254		return;
255
256	mutex_lock(&misc_mtx);
257	list_del(&misc->list);
258	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
259	if (i < DYNAMIC_MINORS && i >= 0)
260		clear_bit(i, misc_minors);
261	mutex_unlock(&misc_mtx);
 
262}
263
264EXPORT_SYMBOL(misc_register);
265EXPORT_SYMBOL(misc_deregister);
266
267static char *misc_devnode(struct device *dev, umode_t *mode)
268{
269	struct miscdevice *c = dev_get_drvdata(dev);
270
271	if (mode && c->mode)
272		*mode = c->mode;
273	if (c->nodename)
274		return kstrdup(c->nodename, GFP_KERNEL);
275	return NULL;
276}
277
278static int __init misc_init(void)
279{
280	int err;
281	struct proc_dir_entry *ret;
282
283	ret = proc_create("misc", 0, NULL, &misc_proc_fops);
 
 
284	misc_class = class_create(THIS_MODULE, "misc");
285	err = PTR_ERR(misc_class);
286	if (IS_ERR(misc_class))
287		goto fail_remove;
288
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;
294
295fail_printk:
296	printk("unable to get major %d for misc devices\n", MISC_MAJOR);
297	class_destroy(misc_class);
298fail_remove:
299	if (ret)
300		remove_proc_entry("misc", NULL);
301	return err;
302}
303subsys_initcall(misc_init);