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Linux/kernel/time/posix-clock.c

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  1 /*
  2  * posix-clock.c - support for dynamic clock devices
  3  *
  4  * Copyright (C) 2010 OMICRON electronics GmbH
  5  *
  6  *  This program is free software; you can redistribute it and/or modify
  7  *  it under the terms of the GNU General Public License as published by
  8  *  the Free Software Foundation; either version 2 of the License, or
  9  *  (at your option) any later version.
 10  *
 11  *  This program is distributed in the hope that it will be useful,
 12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  *  GNU General Public License for more details.
 15  *
 16  *  You should have received a copy of the GNU General Public License
 17  *  along with this program; if not, write to the Free Software
 18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 19  */
 20 #include <linux/device.h>
 21 #include <linux/export.h>
 22 #include <linux/file.h>
 23 #include <linux/posix-clock.h>
 24 #include <linux/slab.h>
 25 #include <linux/syscalls.h>
 26 #include <linux/uaccess.h>
 27 
 28 static void delete_clock(struct kref *kref);
 29 
 30 /*
 31  * Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
 32  */
 33 static struct posix_clock *get_posix_clock(struct file *fp)
 34 {
 35         struct posix_clock *clk = fp->private_data;
 36 
 37         down_read(&clk->rwsem);
 38 
 39         if (!clk->zombie)
 40                 return clk;
 41 
 42         up_read(&clk->rwsem);
 43 
 44         return NULL;
 45 }
 46 
 47 static void put_posix_clock(struct posix_clock *clk)
 48 {
 49         up_read(&clk->rwsem);
 50 }
 51 
 52 static ssize_t posix_clock_read(struct file *fp, char __user *buf,
 53                                 size_t count, loff_t *ppos)
 54 {
 55         struct posix_clock *clk = get_posix_clock(fp);
 56         int err = -EINVAL;
 57 
 58         if (!clk)
 59                 return -ENODEV;
 60 
 61         if (clk->ops.read)
 62                 err = clk->ops.read(clk, fp->f_flags, buf, count);
 63 
 64         put_posix_clock(clk);
 65 
 66         return err;
 67 }
 68 
 69 static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
 70 {
 71         struct posix_clock *clk = get_posix_clock(fp);
 72         unsigned int result = 0;
 73 
 74         if (!clk)
 75                 return POLLERR;
 76 
 77         if (clk->ops.poll)
 78                 result = clk->ops.poll(clk, fp, wait);
 79 
 80         put_posix_clock(clk);
 81 
 82         return result;
 83 }
 84 
 85 static int posix_clock_fasync(int fd, struct file *fp, int on)
 86 {
 87         struct posix_clock *clk = get_posix_clock(fp);
 88         int err = 0;
 89 
 90         if (!clk)
 91                 return -ENODEV;
 92 
 93         if (clk->ops.fasync)
 94                 err = clk->ops.fasync(clk, fd, fp, on);
 95 
 96         put_posix_clock(clk);
 97 
 98         return err;
 99 }
100 
101 static int posix_clock_mmap(struct file *fp, struct vm_area_struct *vma)
102 {
103         struct posix_clock *clk = get_posix_clock(fp);
104         int err = -ENODEV;
105 
106         if (!clk)
107                 return -ENODEV;
108 
109         if (clk->ops.mmap)
110                 err = clk->ops.mmap(clk, vma);
111 
112         put_posix_clock(clk);
113 
114         return err;
115 }
116 
117 static long posix_clock_ioctl(struct file *fp,
118                               unsigned int cmd, unsigned long arg)
119 {
120         struct posix_clock *clk = get_posix_clock(fp);
121         int err = -ENOTTY;
122 
123         if (!clk)
124                 return -ENODEV;
125 
126         if (clk->ops.ioctl)
127                 err = clk->ops.ioctl(clk, cmd, arg);
128 
129         put_posix_clock(clk);
130 
131         return err;
132 }
133 
134 #ifdef CONFIG_COMPAT
135 static long posix_clock_compat_ioctl(struct file *fp,
136                                      unsigned int cmd, unsigned long arg)
137 {
138         struct posix_clock *clk = get_posix_clock(fp);
139         int err = -ENOTTY;
140 
141         if (!clk)
142                 return -ENODEV;
143 
144         if (clk->ops.ioctl)
145                 err = clk->ops.ioctl(clk, cmd, arg);
146 
147         put_posix_clock(clk);
148 
149         return err;
150 }
151 #endif
152 
153 static int posix_clock_open(struct inode *inode, struct file *fp)
154 {
155         int err;
156         struct posix_clock *clk =
157                 container_of(inode->i_cdev, struct posix_clock, cdev);
158 
159         down_read(&clk->rwsem);
160 
161         if (clk->zombie) {
162                 err = -ENODEV;
163                 goto out;
164         }
165         if (clk->ops.open)
166                 err = clk->ops.open(clk, fp->f_mode);
167         else
168                 err = 0;
169 
170         if (!err) {
171                 kref_get(&clk->kref);
172                 fp->private_data = clk;
173         }
174 out:
175         up_read(&clk->rwsem);
176         return err;
177 }
178 
179 static int posix_clock_release(struct inode *inode, struct file *fp)
180 {
181         struct posix_clock *clk = fp->private_data;
182         int err = 0;
183 
184         if (clk->ops.release)
185                 err = clk->ops.release(clk);
186 
187         kref_put(&clk->kref, delete_clock);
188 
189         fp->private_data = NULL;
190 
191         return err;
192 }
193 
194 static const struct file_operations posix_clock_file_operations = {
195         .owner          = THIS_MODULE,
196         .llseek         = no_llseek,
197         .read           = posix_clock_read,
198         .poll           = posix_clock_poll,
199         .unlocked_ioctl = posix_clock_ioctl,
200         .open           = posix_clock_open,
201         .release        = posix_clock_release,
202         .fasync         = posix_clock_fasync,
203         .mmap           = posix_clock_mmap,
204 #ifdef CONFIG_COMPAT
205         .compat_ioctl   = posix_clock_compat_ioctl,
206 #endif
207 };
208 
209 int posix_clock_register(struct posix_clock *clk, dev_t devid)
210 {
211         int err;
212 
213         kref_init(&clk->kref);
214         init_rwsem(&clk->rwsem);
215 
216         cdev_init(&clk->cdev, &posix_clock_file_operations);
217         clk->cdev.owner = clk->ops.owner;
218         err = cdev_add(&clk->cdev, devid, 1);
219 
220         return err;
221 }
222 EXPORT_SYMBOL_GPL(posix_clock_register);
223 
224 static void delete_clock(struct kref *kref)
225 {
226         struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
227 
228         if (clk->release)
229                 clk->release(clk);
230 }
231 
232 void posix_clock_unregister(struct posix_clock *clk)
233 {
234         cdev_del(&clk->cdev);
235 
236         down_write(&clk->rwsem);
237         clk->zombie = true;
238         up_write(&clk->rwsem);
239 
240         kref_put(&clk->kref, delete_clock);
241 }
242 EXPORT_SYMBOL_GPL(posix_clock_unregister);
243 
244 struct posix_clock_desc {
245         struct file *fp;
246         struct posix_clock *clk;
247 };
248 
249 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
250 {
251         struct file *fp = fget(CLOCKID_TO_FD(id));
252         int err = -EINVAL;
253 
254         if (!fp)
255                 return err;
256 
257         if (fp->f_op->open != posix_clock_open || !fp->private_data)
258                 goto out;
259 
260         cd->fp = fp;
261         cd->clk = get_posix_clock(fp);
262 
263         err = cd->clk ? 0 : -ENODEV;
264 out:
265         if (err)
266                 fput(fp);
267         return err;
268 }
269 
270 static void put_clock_desc(struct posix_clock_desc *cd)
271 {
272         put_posix_clock(cd->clk);
273         fput(cd->fp);
274 }
275 
276 static int pc_clock_adjtime(clockid_t id, struct timex *tx)
277 {
278         struct posix_clock_desc cd;
279         int err;
280 
281         err = get_clock_desc(id, &cd);
282         if (err)
283                 return err;
284 
285         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
286                 err = -EACCES;
287                 goto out;
288         }
289 
290         if (cd.clk->ops.clock_adjtime)
291                 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
292         else
293                 err = -EOPNOTSUPP;
294 out:
295         put_clock_desc(&cd);
296 
297         return err;
298 }
299 
300 static int pc_clock_gettime(clockid_t id, struct timespec *ts)
301 {
302         struct posix_clock_desc cd;
303         int err;
304 
305         err = get_clock_desc(id, &cd);
306         if (err)
307                 return err;
308 
309         if (cd.clk->ops.clock_gettime)
310                 err = cd.clk->ops.clock_gettime(cd.clk, ts);
311         else
312                 err = -EOPNOTSUPP;
313 
314         put_clock_desc(&cd);
315 
316         return err;
317 }
318 
319 static int pc_clock_getres(clockid_t id, struct timespec *ts)
320 {
321         struct posix_clock_desc cd;
322         int err;
323 
324         err = get_clock_desc(id, &cd);
325         if (err)
326                 return err;
327 
328         if (cd.clk->ops.clock_getres)
329                 err = cd.clk->ops.clock_getres(cd.clk, ts);
330         else
331                 err = -EOPNOTSUPP;
332 
333         put_clock_desc(&cd);
334 
335         return err;
336 }
337 
338 static int pc_clock_settime(clockid_t id, const struct timespec *ts)
339 {
340         struct posix_clock_desc cd;
341         int err;
342 
343         err = get_clock_desc(id, &cd);
344         if (err)
345                 return err;
346 
347         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
348                 err = -EACCES;
349                 goto out;
350         }
351 
352         if (cd.clk->ops.clock_settime)
353                 err = cd.clk->ops.clock_settime(cd.clk, ts);
354         else
355                 err = -EOPNOTSUPP;
356 out:
357         put_clock_desc(&cd);
358 
359         return err;
360 }
361 
362 static int pc_timer_create(struct k_itimer *kit)
363 {
364         clockid_t id = kit->it_clock;
365         struct posix_clock_desc cd;
366         int err;
367 
368         err = get_clock_desc(id, &cd);
369         if (err)
370                 return err;
371 
372         if (cd.clk->ops.timer_create)
373                 err = cd.clk->ops.timer_create(cd.clk, kit);
374         else
375                 err = -EOPNOTSUPP;
376 
377         put_clock_desc(&cd);
378 
379         return err;
380 }
381 
382 static int pc_timer_delete(struct k_itimer *kit)
383 {
384         clockid_t id = kit->it_clock;
385         struct posix_clock_desc cd;
386         int err;
387 
388         err = get_clock_desc(id, &cd);
389         if (err)
390                 return err;
391 
392         if (cd.clk->ops.timer_delete)
393                 err = cd.clk->ops.timer_delete(cd.clk, kit);
394         else
395                 err = -EOPNOTSUPP;
396 
397         put_clock_desc(&cd);
398 
399         return err;
400 }
401 
402 static void pc_timer_gettime(struct k_itimer *kit, struct itimerspec *ts)
403 {
404         clockid_t id = kit->it_clock;
405         struct posix_clock_desc cd;
406 
407         if (get_clock_desc(id, &cd))
408                 return;
409 
410         if (cd.clk->ops.timer_gettime)
411                 cd.clk->ops.timer_gettime(cd.clk, kit, ts);
412 
413         put_clock_desc(&cd);
414 }
415 
416 static int pc_timer_settime(struct k_itimer *kit, int flags,
417                             struct itimerspec *ts, struct itimerspec *old)
418 {
419         clockid_t id = kit->it_clock;
420         struct posix_clock_desc cd;
421         int err;
422 
423         err = get_clock_desc(id, &cd);
424         if (err)
425                 return err;
426 
427         if (cd.clk->ops.timer_settime)
428                 err = cd.clk->ops.timer_settime(cd.clk, kit, flags, ts, old);
429         else
430                 err = -EOPNOTSUPP;
431 
432         put_clock_desc(&cd);
433 
434         return err;
435 }
436 
437 struct k_clock clock_posix_dynamic = {
438         .clock_getres   = pc_clock_getres,
439         .clock_set      = pc_clock_settime,
440         .clock_get      = pc_clock_gettime,
441         .clock_adj      = pc_clock_adjtime,
442         .timer_create   = pc_timer_create,
443         .timer_set      = pc_timer_settime,
444         .timer_del      = pc_timer_delete,
445         .timer_get      = pc_timer_gettime,
446 };
447 

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