Merge branch 'mini2440-dev-unlikely' into mini2440-dev
[linux-2.6/mini2440.git] / drivers / telephony / phonedev.c
blobf3873f650bb43f7f68f79ee87a8c8cdf13784b3a
1 /*
2 * Telephony registration for Linux
4 * (c) Copyright 1999 Red Hat Software Inc.
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.
11 * Author: Alan Cox, <alan@lxorguk.ukuu.org.uk>
13 * Fixes: Mar 01 2000 Thomas Sparr, <thomas.l.sparr@telia.com>
14 * phone_register_device now works with unit!=PHONE_UNIT_ANY
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>
29 #include <linux/kmod.h>
30 #include <linux/sem.h>
31 #include <linux/mutex.h>
33 #define PHONE_NUM_DEVICES 256
36 * Active devices
39 static struct phone_device *phone_device[PHONE_NUM_DEVICES];
40 static DEFINE_MUTEX(phone_lock);
43 * Open a phone device.
46 static int phone_open(struct inode *inode, struct file *file)
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;
53 if (minor >= PHONE_NUM_DEVICES)
54 return -ENODEV;
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)
67 err=-ENODEV;
68 goto end;
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);
79 fops_put(old_fops);
80 end:
81 mutex_unlock(&phone_lock);
82 return err;
86 * Telephony For Linux device drivers request registration here.
89 int phone_register_device(struct phone_device *p, int unit)
91 int base;
92 int end;
93 int i;
95 base = 0;
96 end = PHONE_NUM_DEVICES - 1;
98 if (unit != PHONE_UNIT_ANY) {
99 base = unit;
100 end = unit + 1; /* enter the loop at least one time */
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;
112 mutex_unlock(&phone_lock);
113 return -ENFILE;
117 * Unregister an unused Telephony for linux device
120 void phone_unregister_device(struct phone_device *pfd)
122 mutex_lock(&phone_lock);
123 if (likely(phone_device[pfd->minor] == pfd))
124 phone_device[pfd->minor] = NULL;
125 mutex_unlock(&phone_lock);
129 static const struct file_operations phone_fops =
131 .owner = THIS_MODULE,
132 .open = phone_open,
136 * Board init functions
141 * Initialise Telephony for linux
144 static int __init telephony_init(void)
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;
152 return 0;
155 static void __exit telephony_exit(void)
157 unregister_chrdev(PHONE_MAJOR, "telephony");
160 module_init(telephony_init);
161 module_exit(telephony_exit);
163 MODULE_LICENSE("GPL");
165 EXPORT_SYMBOL(phone_register_device);
166 EXPORT_SYMBOL(phone_unregister_device);