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 */
get_posix_clock(struct file * fp)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
put_posix_clock(struct posix_clock * clk)47 static void put_posix_clock(struct posix_clock *clk)
48 {
49 up_read(&clk->rwsem);
50 }
51
posix_clock_read(struct file * fp,char __user * buf,size_t count,loff_t * ppos)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
posix_clock_poll(struct file * fp,poll_table * wait)69 static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
70 {
71 struct posix_clock *clk = get_posix_clock(fp);
72 int result = 0;
73
74 if (!clk)
75 return -ENODEV;
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
posix_clock_fasync(int fd,struct file * fp,int on)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
posix_clock_mmap(struct file * fp,struct vm_area_struct * vma)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
posix_clock_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)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
posix_clock_compat_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)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
posix_clock_open(struct inode * inode,struct file * fp)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
posix_clock_release(struct inode * inode,struct file * fp)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
posix_clock_register(struct posix_clock * clk,dev_t devid)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
delete_clock(struct kref * kref)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
posix_clock_unregister(struct posix_clock * clk)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
get_clock_desc(const clockid_t id,struct posix_clock_desc * cd)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
put_clock_desc(struct posix_clock_desc * cd)270 static void put_clock_desc(struct posix_clock_desc *cd)
271 {
272 put_posix_clock(cd->clk);
273 fput(cd->fp);
274 }
275
pc_clock_adjtime(clockid_t id,struct timex * tx)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
pc_clock_gettime(clockid_t id,struct timespec * ts)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
pc_clock_getres(clockid_t id,struct timespec * ts)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
pc_clock_settime(clockid_t id,const struct timespec * ts)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
pc_timer_create(struct k_itimer * kit)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
pc_timer_delete(struct k_itimer * kit)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
pc_timer_gettime(struct k_itimer * kit,struct itimerspec * ts)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
pc_timer_settime(struct k_itimer * kit,int flags,struct itimerspec * ts,struct itimerspec * old)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