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