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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Telephony registration for Linux
3 *
4 * (c) Copyright 1999 Red Hat Software Inc.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * Author: Alan Cox, <alan@redhat.com>
12 *
13 * Fixes: Mar 01 2000 Thomas Sparr, <thomas.l.sparr@telia.com>
14 * phone_register_device now works with unit!=PHONE_UNIT_ANY
15 */
16
17#include <linux/module.h>
18#include <linux/types.h>
19#include <linux/kernel.h>
20#include <linux/fs.h>
21#include <linux/mm.h>
22#include <linux/string.h>
23#include <linux/errno.h>
24#include <linux/phonedev.h>
25#include <linux/init.h>
26#include <asm/uaccess.h>
27#include <asm/system.h>
28
29#include <linux/kmod.h>
30#include <linux/sem.h>
Ingo Molnar14cc3e22006-03-26 01:37:14 -080031#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33#define PHONE_NUM_DEVICES 256
34
35/*
36 * Active devices
37 */
38
39static struct phone_device *phone_device[PHONE_NUM_DEVICES];
Ingo Molnar14cc3e22006-03-26 01:37:14 -080040static DEFINE_MUTEX(phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
42/*
43 * Open a phone device.
44 */
45
46static int phone_open(struct inode *inode, struct file *file)
47{
48 unsigned int minor = iminor(inode);
49 int err = 0;
50 struct phone_device *p;
Arjan van de Ven99ac48f2006-03-28 01:56:41 -080051 const struct file_operations *old_fops, *new_fops = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53 if (minor >= PHONE_NUM_DEVICES)
54 return -ENODEV;
55
Ingo Molnar14cc3e22006-03-26 01:37:14 -080056 mutex_lock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 p = phone_device[minor];
58 if (p)
59 new_fops = fops_get(p->f_op);
60 if (!new_fops) {
Ingo Molnar14cc3e22006-03-26 01:37:14 -080061 mutex_unlock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 request_module("char-major-%d-%d", PHONE_MAJOR, minor);
Ingo Molnar14cc3e22006-03-26 01:37:14 -080063 mutex_lock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 p = phone_device[minor];
65 if (p == NULL || (new_fops = fops_get(p->f_op)) == NULL)
66 {
67 err=-ENODEV;
68 goto end;
69 }
70 }
71 old_fops = file->f_op;
72 file->f_op = new_fops;
73 if (p->open)
74 err = p->open(p, file); /* Tell the device it is open */
75 if (err) {
76 fops_put(file->f_op);
77 file->f_op = fops_get(old_fops);
78 }
79 fops_put(old_fops);
80end:
Ingo Molnar14cc3e22006-03-26 01:37:14 -080081 mutex_unlock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 return err;
83}
84
85/*
86 * Telephony For Linux device drivers request registration here.
87 */
88
89int phone_register_device(struct phone_device *p, int unit)
90{
91 int base;
92 int end;
93 int i;
94
95 base = 0;
96 end = PHONE_NUM_DEVICES - 1;
97
98 if (unit != PHONE_UNIT_ANY) {
99 base = unit;
100 end = unit + 1; /* enter the loop at least one time */
101 }
102
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800103 mutex_lock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 for (i = base; i < end; i++) {
105 if (phone_device[i] == NULL) {
106 phone_device[i] = p;
107 p->minor = i;
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800108 mutex_unlock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 return 0;
110 }
111 }
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800112 mutex_unlock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 return -ENFILE;
114}
115
116/*
117 * Unregister an unused Telephony for linux device
118 */
119
120void phone_unregister_device(struct phone_device *pfd)
121{
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800122 mutex_lock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 if (phone_device[pfd->minor] != pfd)
124 panic("phone: bad unregister");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 phone_device[pfd->minor] = NULL;
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800126 mutex_unlock(&phone_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127}
128
129
Arjan van de Ven00977a52007-02-12 00:55:34 -0800130static const struct file_operations phone_fops =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131{
132 .owner = THIS_MODULE,
133 .open = phone_open,
134};
135
136/*
137 * Board init functions
138 */
139
140
141/*
142 * Initialise Telephony for linux
143 */
144
145static int __init telephony_init(void)
146{
147 printk(KERN_INFO "Linux telephony interface: v1.00\n");
148 if (register_chrdev(PHONE_MAJOR, "telephony", &phone_fops)) {
149 printk("phonedev: unable to get major %d\n", PHONE_MAJOR);
150 return -EIO;
151 }
152
153 return 0;
154}
155
156static void __exit telephony_exit(void)
157{
158 unregister_chrdev(PHONE_MAJOR, "telephony");
159}
160
161module_init(telephony_init);
162module_exit(telephony_exit);
163
164MODULE_LICENSE("GPL");
165
166EXPORT_SYMBOL(phone_register_device);
167EXPORT_SYMBOL(phone_unregister_device);