drivers/isdn/mISDN/timerdev.c

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