167 lines
3.4 KiB
C
167 lines
3.4 KiB
C
/*
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* Telephony registration for Linux
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*
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* (c) Copyright 1999 Red Hat Software Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Author: Alan Cox, <alan@lxorguk.ukuu.org.uk>
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*
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* Fixes: Mar 01 2000 Thomas Sparr, <thomas.l.sparr@telia.com>
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* phone_register_device now works with unit!=PHONE_UNIT_ANY
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/phonedev.h>
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#include <linux/init.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <linux/kmod.h>
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#include <linux/sem.h>
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#include <linux/mutex.h>
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#define PHONE_NUM_DEVICES 256
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/*
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* Active devices
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*/
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static struct phone_device *phone_device[PHONE_NUM_DEVICES];
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static DEFINE_MUTEX(phone_lock);
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/*
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* Open a phone device.
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*/
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static int phone_open(struct inode *inode, struct file *file)
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{
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unsigned int minor = iminor(inode);
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int err = 0;
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struct phone_device *p;
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const struct file_operations *old_fops, *new_fops = NULL;
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if (minor >= PHONE_NUM_DEVICES)
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return -ENODEV;
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mutex_lock(&phone_lock);
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p = phone_device[minor];
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if (p)
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new_fops = fops_get(p->f_op);
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if (!new_fops) {
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mutex_unlock(&phone_lock);
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request_module("char-major-%d-%d", PHONE_MAJOR, minor);
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mutex_lock(&phone_lock);
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p = phone_device[minor];
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if (p == NULL || (new_fops = fops_get(p->f_op)) == NULL)
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{
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err=-ENODEV;
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goto end;
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}
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}
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old_fops = file->f_op;
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file->f_op = new_fops;
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if (p->open)
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err = p->open(p, file); /* Tell the device it is open */
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if (err) {
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fops_put(file->f_op);
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file->f_op = fops_get(old_fops);
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}
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fops_put(old_fops);
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end:
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mutex_unlock(&phone_lock);
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return err;
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}
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/*
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* Telephony For Linux device drivers request registration here.
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*/
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int phone_register_device(struct phone_device *p, int unit)
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{
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int base;
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int end;
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int i;
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base = 0;
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end = PHONE_NUM_DEVICES - 1;
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if (unit != PHONE_UNIT_ANY) {
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base = unit;
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end = unit + 1; /* enter the loop at least one time */
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}
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mutex_lock(&phone_lock);
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for (i = base; i < end; i++) {
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if (phone_device[i] == NULL) {
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phone_device[i] = p;
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p->minor = i;
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mutex_unlock(&phone_lock);
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return 0;
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}
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}
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mutex_unlock(&phone_lock);
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return -ENFILE;
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}
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/*
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* Unregister an unused Telephony for linux device
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*/
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void phone_unregister_device(struct phone_device *pfd)
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{
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mutex_lock(&phone_lock);
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if (likely(phone_device[pfd->minor] == pfd))
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phone_device[pfd->minor] = NULL;
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mutex_unlock(&phone_lock);
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}
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static const struct file_operations phone_fops =
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{
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.owner = THIS_MODULE,
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.open = phone_open,
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};
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/*
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* Board init functions
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*/
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/*
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* Initialise Telephony for linux
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*/
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static int __init telephony_init(void)
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{
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printk(KERN_INFO "Linux telephony interface: v1.00\n");
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if (register_chrdev(PHONE_MAJOR, "telephony", &phone_fops)) {
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printk("phonedev: unable to get major %d\n", PHONE_MAJOR);
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return -EIO;
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}
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return 0;
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}
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static void __exit telephony_exit(void)
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{
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unregister_chrdev(PHONE_MAJOR, "telephony");
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}
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module_init(telephony_init);
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module_exit(telephony_exit);
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MODULE_LICENSE("GPL");
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EXPORT_SYMBOL(phone_register_device);
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EXPORT_SYMBOL(phone_unregister_device);
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