1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * general timer device for using in ISDN stacks
5 *
6 * Author	Karsten Keil <kkeil@novell.com>
7 *
8 * Copyright 2008  by Karsten Keil <kkeil@novell.com>
9 */
10
11#include <linux/poll.h>
12#include <linux/vmalloc.h>
13#include <linux/slab.h>
14#include <linux/timer.h>
15#include <linux/miscdevice.h>
16#include <linux/module.h>
17#include <linux/mISDNif.h>
18#include <linux/mutex.h>
19#include <linux/sched/signal.h>
20
21#include "core.h"
22
23static DEFINE_MUTEX(mISDN_mutex);
24static u_int	*debug;
25
26
27struct mISDNtimerdev {
28	int			next_id;
29	struct list_head	pending;
30	struct list_head	expired;
31	wait_queue_head_t	wait;
32	u_int			work;
33	spinlock_t		lock; /* protect lists */
34};
35
36struct mISDNtimer {
37	struct list_head	list;
38	struct  mISDNtimerdev	*dev;
39	struct timer_list	tl;
40	int			id;
41};
42
43static int
44mISDN_open(struct inode *ino, struct file *filep)
45{
46	struct mISDNtimerdev	*dev;
47
48	if (*debug & DEBUG_TIMER)
49		printk(KERN_DEBUG "%s(%p,%p)\n", __func__, ino, filep);
50	dev = kmalloc(sizeof(struct mISDNtimerdev) , GFP_KERNEL);
51	if (!dev)
52		return -ENOMEM;
53	dev->next_id = 1;
54	INIT_LIST_HEAD(&dev->pending);
55	INIT_LIST_HEAD(&dev->expired);
56	spin_lock_init(&dev->lock);
57	dev->work = 0;
58	init_waitqueue_head(&dev->wait);
59	filep->private_data = dev;
60	return nonseekable_open(ino, filep);
61}
62
63static int
64mISDN_close(struct inode *ino, struct file *filep)
65{
66	struct mISDNtimerdev	*dev = filep->private_data;
67	struct list_head	*list = &dev->pending;
68	struct mISDNtimer	*timer, *next;
69
70	if (*debug & DEBUG_TIMER)
71		printk(KERN_DEBUG "%s(%p,%p)\n", __func__, ino, filep);
72
73	spin_lock_irq(&dev->lock);
74	while (!list_empty(list)) {
75		timer = list_first_entry(list, struct mISDNtimer, list);
76		spin_unlock_irq(&dev->lock);
77		timer_shutdown_sync(&timer->tl);
78		spin_lock_irq(&dev->lock);
79		/* it might have been moved to ->expired */
80		list_del(&timer->list);
81		kfree(timer);
82	}
83	spin_unlock_irq(&dev->lock);
84
85	list_for_each_entry_safe(timer, next, &dev->expired, list) {
86		kfree(timer);
87	}
88	kfree(dev);
89	return 0;
90}
91
92static ssize_t
93mISDN_read(struct file *filep, char __user *buf, size_t count, loff_t *off)
94{
95	struct mISDNtimerdev	*dev = filep->private_data;
96	struct list_head *list = &dev->expired;
97	struct mISDNtimer	*timer;
98	int	ret = 0;
99
100	if (*debug & DEBUG_TIMER)
101		printk(KERN_DEBUG "%s(%p, %p, %d, %p)\n", __func__,
102		       filep, buf, (int)count, off);
103
104	if (count < sizeof(int))
105		return -ENOSPC;
106
107	spin_lock_irq(&dev->lock);
108	while (list_empty(list) && (dev->work == 0)) {
109		spin_unlock_irq(&dev->lock);
110		if (filep->f_flags & O_NONBLOCK)
111			return -EAGAIN;
112		wait_event_interruptible(dev->wait, (dev->work ||
113						     !list_empty(list)));
114		if (signal_pending(current))
115			return -ERESTARTSYS;
116		spin_lock_irq(&dev->lock);
117	}
118	if (dev->work)
119		dev->work = 0;
120	if (!list_empty(list)) {
121		timer = list_first_entry(list, struct mISDNtimer, list);
122		list_del(&timer->list);
123		spin_unlock_irq(&dev->lock);
124		if (put_user(timer->id, (int __user *)buf))
125			ret = -EFAULT;
126		else
127			ret = sizeof(int);
128		kfree(timer);
129	} else {
130		spin_unlock_irq(&dev->lock);
131	}
132	return ret;
133}
134
135static __poll_t
136mISDN_poll(struct file *filep, poll_table *wait)
137{
138	struct mISDNtimerdev	*dev = filep->private_data;
139	__poll_t		mask = EPOLLERR;
140
141	if (*debug & DEBUG_TIMER)
142		printk(KERN_DEBUG "%s(%p, %p)\n", __func__, filep, wait);
143	if (dev) {
144		poll_wait(filep, &dev->wait, wait);
145		mask = 0;
146		if (dev->work || !list_empty(&dev->expired))
147			mask |= (EPOLLIN | EPOLLRDNORM);
148		if (*debug & DEBUG_TIMER)
149			printk(KERN_DEBUG "%s work(%d) empty(%d)\n", __func__,
150			       dev->work, list_empty(&dev->expired));
151	}
152	return mask;
153}
154
155static void
156dev_expire_timer(struct timer_list *t)
157{
158	struct mISDNtimer *timer = from_timer(timer, t, tl);
159	u_long			flags;
160
161	spin_lock_irqsave(&timer->dev->lock, flags);
162	if (timer->id >= 0)
163		list_move_tail(&timer->list, &timer->dev->expired);
164	wake_up_interruptible(&timer->dev->wait);
165	spin_unlock_irqrestore(&timer->dev->lock, flags);
166}
167
168static int
169misdn_add_timer(struct mISDNtimerdev *dev, int timeout)
170{
171	int			id;
172	struct mISDNtimer	*timer;
173
174	if (!timeout) {
175		dev->work = 1;
176		wake_up_interruptible(&dev->wait);
177		id = 0;
178	} else {
179		timer = kzalloc(sizeof(struct mISDNtimer), GFP_KERNEL);
180		if (!timer)
181			return -ENOMEM;
182		timer->dev = dev;
183		timer_setup(&timer->tl, dev_expire_timer, 0);
184		spin_lock_irq(&dev->lock);
185		id = timer->id = dev->next_id++;
186		if (dev->next_id < 0)
187			dev->next_id = 1;
188		list_add_tail(&timer->list, &dev->pending);
189		timer->tl.expires = jiffies + ((HZ * (u_long)timeout) / 1000);
190		add_timer(&timer->tl);
191		spin_unlock_irq(&dev->lock);
192	}
193	return id;
194}
195
196static int
197misdn_del_timer(struct mISDNtimerdev *dev, int id)
198{
199	struct mISDNtimer	*timer;
200
201	spin_lock_irq(&dev->lock);
202	list_for_each_entry(timer, &dev->pending, list) {
203		if (timer->id == id) {
204			list_del_init(&timer->list);
205			timer->id = -1;
206			spin_unlock_irq(&dev->lock);
207			timer_shutdown_sync(&timer->tl);
208			kfree(timer);
209			return id;
210		}
211	}
212	spin_unlock_irq(&dev->lock);
213	return 0;
214}
215
216static long
217mISDN_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
218{
219	struct mISDNtimerdev	*dev = filep->private_data;
220	int			id, tout, ret = 0;
221
222
223	if (*debug & DEBUG_TIMER)
224		printk(KERN_DEBUG "%s(%p, %x, %lx)\n", __func__,
225		       filep, cmd, arg);
226	mutex_lock(&mISDN_mutex);
227	switch (cmd) {
228	case IMADDTIMER:
229		if (get_user(tout, (int __user *)arg)) {
230			ret = -EFAULT;
231			break;
232		}
233		id = misdn_add_timer(dev, tout);
234		if (*debug & DEBUG_TIMER)
235			printk(KERN_DEBUG "%s add %d id %d\n", __func__,
236			       tout, id);
237		if (id < 0) {
238			ret = id;
239			break;
240		}
241		if (put_user(id, (int __user *)arg))
242			ret = -EFAULT;
243		break;
244	case IMDELTIMER:
245		if (get_user(id, (int __user *)arg)) {
246			ret = -EFAULT;
247			break;
248		}
249		if (*debug & DEBUG_TIMER)
250			printk(KERN_DEBUG "%s del id %d\n", __func__, id);
251		id = misdn_del_timer(dev, id);
252		if (put_user(id, (int __user *)arg))
253			ret = -EFAULT;
254		break;
255	default:
256		ret = -EINVAL;
257	}
258	mutex_unlock(&mISDN_mutex);
259	return ret;
260}
261
262static const struct file_operations mISDN_fops = {
263	.owner		= THIS_MODULE,
264	.read		= mISDN_read,
265	.poll		= mISDN_poll,
266	.unlocked_ioctl	= mISDN_ioctl,
267	.open		= mISDN_open,
268	.release	= mISDN_close,
269	.llseek		= no_llseek,
270};
271
272static struct miscdevice mISDNtimer = {
273	.minor	= MISC_DYNAMIC_MINOR,
274	.name	= "mISDNtimer",
275	.fops	= &mISDN_fops,
276};
277
278int
279mISDN_inittimer(u_int *deb)
280{
281	int	err;
282
283	debug = deb;
284	err = misc_register(&mISDNtimer);
285	if (err)
286		printk(KERN_WARNING "mISDN: Could not register timer device\n");
287	return err;
288}
289
290void mISDN_timer_cleanup(void)
291{
292	misc_deregister(&mISDNtimer);
293}
294