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/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>
31#include <linux/mutex.h>
32
33#define PHONE_NUM_DEVICES	256
34
35/*
36 *    Active devices
37 */
38
39static struct phone_device *phone_device[PHONE_NUM_DEVICES];
40static DEFINE_MUTEX(phone_lock);
41
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;
51	const struct file_operations *old_fops, *new_fops = NULL;
52
53	if (minor >= PHONE_NUM_DEVICES)
54		return -ENODEV;
55
56	mutex_lock(&phone_lock);
57	p = phone_device[minor];
58	if (p)
59		new_fops = fops_get(p->f_op);
60	if (!new_fops) {
61		mutex_unlock(&phone_lock);
62		request_module("char-major-%d-%d", PHONE_MAJOR, minor);
63		mutex_lock(&phone_lock);
64		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:
81	mutex_unlock(&phone_lock);
82	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
103	mutex_lock(&phone_lock);
104	for (i = base; i < end; i++) {
105		if (phone_device[i] == NULL) {
106			phone_device[i] = p;
107			p->minor = i;
108			mutex_unlock(&phone_lock);
109			return 0;
110		}
111	}
112	mutex_unlock(&phone_lock);
113	return -ENFILE;
114}
115
116/*
117 *    Unregister an unused Telephony for linux device
118 */
119
120void phone_unregister_device(struct phone_device *pfd)
121{
122	mutex_lock(&phone_lock);
123	if (phone_device[pfd->minor] != pfd)
124		panic("phone: bad unregister");
125	phone_device[pfd->minor] = NULL;
126	mutex_unlock(&phone_lock);
127}
128
129
130static const struct file_operations phone_fops =
131{
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);
168