1 /*
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/version.h>
18 #include <linux/module.h>
19 #include <linux/types.h>
20 #include <linux/kernel.h>
21 #include <linux/sched.h>
22 #include <linux/mm.h>
23 #include <linux/string.h>
24 #include <linux/errno.h>
25 #include <linux/phonedev.h>
26 #include <linux/init.h>
27 #include <asm/uaccess.h>
28 #include <asm/system.h>
29
30 #include <linux/kmod.h>
31 #include <linux/sem.h>
32
33
34 #define PHONE_NUM_DEVICES 256
35
36 /*
37 * Active devices
38 */
39
40 static struct phone_device *phone_device[PHONE_NUM_DEVICES];
41 static DECLARE_MUTEX(phone_lock);
42
43 /*
44 * Open a phone device.
45 */
46
47 static int phone_open(struct inode *inode, struct file *file)
48 {
49 unsigned int minor = MINOR(inode->i_rdev);
50 int err = 0;
51 struct phone_device *p;
52 struct file_operations *old_fops, *new_fops = NULL;
53
54 if (minor >= PHONE_NUM_DEVICES)
55 return -ENODEV;
56
57 down(&phone_lock);
58 p = phone_device[minor];
59 if (p)
60 new_fops = fops_get(p->f_op);
61 if (!new_fops) {
62 char modname[32];
63
64 up(&phone_lock);
65 sprintf(modname, "char-major-%d-%d", PHONE_MAJOR, minor);
66 request_module(modname);
67 down(&phone_lock);
68 p = phone_device[minor];
69 if (p == NULL || (new_fops = fops_get(p->f_op)) == NULL)
70 {
71 err=-ENODEV;
72 goto end;
73 }
74 }
75 old_fops = file->f_op;
76 file->f_op = new_fops;
77 if (p->open)
78 err = p->open(p, file); /* Tell the device it is open */
79 if (err) {
80 fops_put(file->f_op);
81 file->f_op = fops_get(old_fops);
82 }
83 fops_put(old_fops);
84 end:
85 up(&phone_lock);
86 return err;
87 }
88
89 /*
90 * Telephony For Linux device drivers request registration here.
91 */
92
93 int phone_register_device(struct phone_device *p, int unit)
94 {
95 int base;
96 int end;
97 int i;
98
99 base = 0;
100 end = PHONE_NUM_DEVICES - 1;
101
102 if (unit != PHONE_UNIT_ANY) {
103 base = unit;
104 end = unit + 1; /* enter the loop at least one time */
105 }
106
107 down(&phone_lock);
108 for (i = base; i < end; i++) {
109 if (phone_device[i] == NULL) {
110 phone_device[i] = p;
111 p->minor = i;
112 MOD_INC_USE_COUNT;
113 up(&phone_lock);
114 return 0;
115 }
116 }
117 up(&phone_lock);
118 return -ENFILE;
119 }
120
121 /*
122 * Unregister an unused Telephony for linux device
123 */
124
125 void phone_unregister_device(struct phone_device *pfd)
126 {
127 down(&phone_lock);
128 if (phone_device[pfd->minor] != pfd)
129 panic("phone: bad unregister");
130 phone_device[pfd->minor] = NULL;
131 up(&phone_lock);
132 MOD_DEC_USE_COUNT;
133 }
134
135
136 static struct file_operations phone_fops =
137 {
138 owner: THIS_MODULE,
139 open: phone_open,
140 };
141
142 /*
143 * Board init functions
144 */
145
146
147 /*
148 * Initialise Telephony for linux
149 */
150
151 static int __init telephony_init(void)
152 {
153 printk(KERN_INFO "Linux telephony interface: v1.00\n");
154 if (register_chrdev(PHONE_MAJOR, "telephony", &phone_fops)) {
155 printk("phonedev: unable to get major %d\n", PHONE_MAJOR);
156 return -EIO;
157 }
158
159 return 0;
160 }
161
162 static void __exit telephony_exit(void)
163 {
164 unregister_chrdev(PHONE_MAJOR, "telephony");
165 }
166
167 module_init(telephony_init);
168 module_exit(telephony_exit);
169
170 EXPORT_SYMBOL(phone_register_device);
171 EXPORT_SYMBOL(phone_unregister_device);
172
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