/drivers/char/misc.c

  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#include <linux/config.h>
 38
 39#include <linux/fs.h>
 40#include <linux/errno.h>
 41#include <linux/miscdevice.h>
 42#include <linux/kernel.h>
 43#include <linux/major.h>
 44#include <linux/slab.h>
 45#include <linux/proc_fs.h>
 46#include <linux/seq_file.h>
 47#include <linux/devfs_fs_kernel.h>
 48#include <linux/stat.h>
 49#include <linux/init.h>
 50#include <linux/device.h>
 51#include <linux/tty.h>
 52#include <linux/kmod.h>
 53
 54/*
 55 * Head entry for the doubly linked miscdevice list
 56 */
 57static LIST_HEAD(misc_list);
 58static DECLARE_MUTEX(misc_sem);
 59
 60/*
 61 * Assigned numbers, used for dynamic minors
 62 */
 63#define DYNAMIC_MINORS 64 /* like dynamic majors */
 64static unsigned char misc_minors[DYNAMIC_MINORS / 8];
 65
 66extern int rtc_DP8570A_init(void);
 67extern int rtc_MK48T08_init(void);
 68extern int pmu_device_init(void);
 69extern int tosh_init(void);
 70extern int i8k_init(void);
 71
 72#ifdef CONFIG_PROC_FS
 73static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
 74{
 75	struct miscdevice *p;
 76	loff_t off = 0;
 77
 78	down(&misc_sem);
 79	list_for_each_entry(p, &misc_list, list) {
 80		if (*pos == off++) 
 81			return p;
 82	}
 83	return NULL;
 84}
 85
 86static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 87{
 88	struct list_head *n = ((struct miscdevice *)v)->list.next;
 89
 90	++*pos;
 91
 92	return (n != &misc_list) ? list_entry(n, struct miscdevice, list)
 93		 : NULL;
 94}
 95
 96static void misc_seq_stop(struct seq_file *seq, void *v)
 97{
 98	up(&misc_sem);
 99}
100
101static int misc_seq_show(struct seq_file *seq, void *v)
102{
103	const struct miscdevice *p = v;
104
105	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
106	return 0;
107}
108
109
110static struct seq_operations misc_seq_ops = {
111	.start = misc_seq_start,
112	.next  = misc_seq_next,
113	.stop  = misc_seq_stop,
114	.show  = misc_seq_show,
115};
116
117static int misc_seq_open(struct inode *inode, struct file *file)
118{
119	return seq_open(file, &misc_seq_ops);
120}
121
122static struct file_operations misc_proc_fops = {
123	.owner	 = THIS_MODULE,
124	.open    = misc_seq_open,
125	.read    = seq_read,
126	.llseek  = seq_lseek,
127	.release = seq_release,
128};
129#endif
130
131static int misc_open(struct inode * inode, struct file * file)
132{
133	int minor = iminor(inode);
134	struct miscdevice *c;
135	int err = -ENODEV;
136	struct file_operations *old_fops, *new_fops = NULL;
137	
138	down(&misc_sem);
139	
140	list_for_each_entry(c, &misc_list, list) {
141		if (c->minor == minor) {
142			new_fops = fops_get(c->fops);		
143			break;
144		}
145	}
146		
147	if (!new_fops) {
148		up(&misc_sem);
149		request_module("char-major-%d-%d", MISC_MAJOR, minor);
150		down(&misc_sem);
151
152		list_for_each_entry(c, &misc_list, list) {
153			if (c->minor == minor) {
154				new_fops = fops_get(c->fops);
155				break;
156			}
157		}
158		if (!new_fops)
159			goto fail;
160	}
161
162	err = 0;
163	old_fops = file->f_op;
164	file->f_op = new_fops;
165	if (file->f_op->open) {
166		err=file->f_op->open(inode,file);
167		if (err) {
168			fops_put(file->f_op);
169			file->f_op = fops_get(old_fops);
170		}
171	}
172	fops_put(old_fops);
173fail:
174	up(&misc_sem);
175	return err;
176}
177
178/* 
179 * TODO for 2.7:
180 *  - add a struct class_device to struct miscdevice and make all usages of
181 *    them dynamic.
182 */
183static struct class_simple *misc_class;
184
185static struct file_operations misc_fops = {
186	.owner		= THIS_MODULE,
187	.open		= misc_open,
188};
189
190
191/**
192 *	misc_register	-	register a miscellaneous device
193 *	@misc: device structure
194 *	
195 *	Register a miscellaneous device with the kernel. If the minor
196 *	number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
197 *	and placed in the minor field of the structure. For other cases
198 *	the minor number requested is used.
199 *
200 *	The structure passed is linked into the kernel and may not be
201 *	destroyed until it has been unregistered.
202 *
203 *	A zero is returned on success and a negative errno code for
204 *	failure.
205 */
206 
207int misc_register(struct miscdevice * misc)
208{
209	struct miscdevice *c;
210	dev_t dev;
211	int err;
212
213	down(&misc_sem);
214	list_for_each_entry(c, &misc_list, list) {
215		if (c->minor == misc->minor) {
216			up(&misc_sem);
217			return -EBUSY;
218		}
219	}
220
221	if (misc->minor == MISC_DYNAMIC_MINOR) {
222		int i = DYNAMIC_MINORS;
223		while (--i >= 0)
224			if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
225				break;
226		if (i<0) {
227			up(&misc_sem);
228			return -EBUSY;
229		}
230		misc->minor = i;
231	}
232
233	if (misc->minor < DYNAMIC_MINORS)
234		misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
235	if (misc->devfs_name[0] == '\0') {
236		snprintf(misc->devfs_name, sizeof(misc->devfs_name),
237				"misc/%s", misc->name);
238	}
239	dev = MKDEV(MISC_MAJOR, misc->minor);
240
241	misc->class = class_simple_device_add(misc_class, dev,
242					      misc->dev, misc->name);
243	if (IS_ERR(misc->class)) {
244		err = PTR_ERR(misc->class);
245		goto out;
246	}
247
248	err = devfs_mk_cdev(dev, S_IFCHR|S_IRUSR|S_IWUSR|S_IRGRP, 
249			    misc->devfs_name);
250	if (err) {
251		class_simple_device_remove(dev);
252		goto out;
253	}
254
255	/*
256	 * Add it to the front, so that later devices can "override"
257	 * earlier defaults
258	 */
259	list_add(&misc->list, &misc_list);
260 out:
261	up(&misc_sem);
262	return err;
263}
264
265/**
266 *	misc_deregister - unregister a miscellaneous device
267 *	@misc: device to unregister
268 *
269 *	Unregister a miscellaneous device that was previously
270 *	successfully registered with misc_register(). Success
271 *	is indicated by a zero return, a negative errno code
272 *	indicates an error.
273 */
274
275int misc_deregister(struct miscdevice * misc)
276{
277	int i = misc->minor;
278
279	if (list_empty(&misc->list))
280		return -EINVAL;
281
282	down(&misc_sem);
283	list_del(&misc->list);
284	class_simple_device_remove(MKDEV(MISC_MAJOR, misc->minor));
285	devfs_remove(misc->devfs_name);
286	if (i < DYNAMIC_MINORS && i>0) {
287		misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
288	}
289	up(&misc_sem);
290	return 0;
291}
292
293EXPORT_SYMBOL(misc_register);
294EXPORT_SYMBOL(misc_deregister);
295
296static int __init misc_init(void)
297{
298#ifdef CONFIG_PROC_FS
299	struct proc_dir_entry *ent;
300
301	ent = create_proc_entry("misc", 0, NULL);
302	if (ent)
303		ent->proc_fops = &misc_proc_fops;
304#endif
305	misc_class = class_simple_create(THIS_MODULE, "misc");
306	if (IS_ERR(misc_class))
307		return PTR_ERR(misc_class);
308#ifdef CONFIG_MVME16x
309	rtc_MK48T08_init();
310#endif
311#ifdef CONFIG_BVME6000
312	rtc_DP8570A_init();
313#endif
314#ifdef CONFIG_PMAC_PBOOK
315	pmu_device_init();
316#endif
317#ifdef CONFIG_TOSHIBA
318	tosh_init();
319#endif
320#ifdef CONFIG_I8K
321	i8k_init();
322#endif
323	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) {
324		printk("unable to get major %d for misc devices\n",
325		       MISC_MAJOR);
326		class_simple_destroy(misc_class);
327		return -EIO;
328	}
329	return 0;
330}
331subsys_initcall(misc_init);