[PATCH] pcmcia: embed dev_link_t into struct pcmcia_device
[linux-2.6.git] / drivers / telephony / phonedev.c
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/devfs_fs_kernel.h>
32 #include <linux/mutex.h>
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 DEFINE_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 = iminor(inode);
50         int err = 0;
51         struct phone_device *p;
52         const struct file_operations *old_fops, *new_fops = NULL;
53
54         if (minor >= PHONE_NUM_DEVICES)
55                 return -ENODEV;
56
57         mutex_lock(&phone_lock);
58         p = phone_device[minor];
59         if (p)
60                 new_fops = fops_get(p->f_op);
61         if (!new_fops) {
62                 mutex_unlock(&phone_lock);
63                 request_module("char-major-%d-%d", PHONE_MAJOR, minor);
64                 mutex_lock(&phone_lock);
65                 p = phone_device[minor];
66                 if (p == NULL || (new_fops = fops_get(p->f_op)) == NULL)
67                 {
68                         err=-ENODEV;
69                         goto end;
70                 }
71         }
72         old_fops = file->f_op;
73         file->f_op = new_fops;
74         if (p->open)
75                 err = p->open(p, file); /* Tell the device it is open */
76         if (err) {
77                 fops_put(file->f_op);
78                 file->f_op = fops_get(old_fops);
79         }
80         fops_put(old_fops);
81 end:
82         mutex_unlock(&phone_lock);
83         return err;
84 }
85
86 /*
87  *    Telephony For Linux device drivers request registration here.
88  */
89
90 int phone_register_device(struct phone_device *p, int unit)
91 {
92         int base;
93         int end;
94         int i;
95
96         base = 0;
97         end = PHONE_NUM_DEVICES - 1;
98
99         if (unit != PHONE_UNIT_ANY) {
100                 base = unit;
101                 end = unit + 1;  /* enter the loop at least one time */
102         }
103         
104         mutex_lock(&phone_lock);
105         for (i = base; i < end; i++) {
106                 if (phone_device[i] == NULL) {
107                         phone_device[i] = p;
108                         p->minor = i;
109                         devfs_mk_cdev(MKDEV(PHONE_MAJOR,i),
110                                 S_IFCHR|S_IRUSR|S_IWUSR, "phone/%d", i);
111                         mutex_unlock(&phone_lock);
112                         return 0;
113                 }
114         }
115         mutex_unlock(&phone_lock);
116         return -ENFILE;
117 }
118
119 /*
120  *    Unregister an unused Telephony for linux device
121  */
122
123 void phone_unregister_device(struct phone_device *pfd)
124 {
125         mutex_lock(&phone_lock);
126         if (phone_device[pfd->minor] != pfd)
127                 panic("phone: bad unregister");
128         devfs_remove("phone/%d", pfd->minor);
129         phone_device[pfd->minor] = NULL;
130         mutex_unlock(&phone_lock);
131 }
132
133
134 static struct file_operations phone_fops =
135 {
136         .owner          = THIS_MODULE,
137         .open           = phone_open,
138 };
139
140 /*
141  *      Board init functions
142  */
143  
144
145 /*
146  *    Initialise Telephony for linux
147  */
148
149 static int __init telephony_init(void)
150 {
151         printk(KERN_INFO "Linux telephony interface: v1.00\n");
152         if (register_chrdev(PHONE_MAJOR, "telephony", &phone_fops)) {
153                 printk("phonedev: unable to get major %d\n", PHONE_MAJOR);
154                 return -EIO;
155         }
156
157         return 0;
158 }
159
160 static void __exit telephony_exit(void)
161 {
162         unregister_chrdev(PHONE_MAJOR, "telephony");
163 }
164
165 module_init(telephony_init);
166 module_exit(telephony_exit);
167
168 MODULE_LICENSE("GPL");
169
170 EXPORT_SYMBOL(phone_register_device);
171 EXPORT_SYMBOL(phone_unregister_device);