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 #include "posix-timers.h"
29
30 static void delete_clock(struct kref *kref);
31
32 /*
33 * Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
34 */
get_posix_clock(struct file * fp)35 static struct posix_clock *get_posix_clock(struct file *fp)
36 {
37 struct posix_clock *clk = fp->private_data;
38
39 down_read(&clk->rwsem);
40
41 if (!clk->zombie)
42 return clk;
43
44 up_read(&clk->rwsem);
45
46 return NULL;
47 }
48
put_posix_clock(struct posix_clock * clk)49 static void put_posix_clock(struct posix_clock *clk)
50 {
51 up_read(&clk->rwsem);
52 }
53
posix_clock_read(struct file * fp,char __user * buf,size_t count,loff_t * ppos)54 static ssize_t posix_clock_read(struct file *fp, char __user *buf,
55 size_t count, loff_t *ppos)
56 {
57 struct posix_clock *clk = get_posix_clock(fp);
58 int err = -EINVAL;
59
60 if (!clk)
61 return -ENODEV;
62
63 if (clk->ops.read)
64 err = clk->ops.read(clk, fp->f_flags, buf, count);
65
66 put_posix_clock(clk);
67
68 return err;
69 }
70
posix_clock_poll(struct file * fp,poll_table * wait)71 static __poll_t posix_clock_poll(struct file *fp, poll_table *wait)
72 {
73 struct posix_clock *clk = get_posix_clock(fp);
74 __poll_t result = 0;
75
76 if (!clk)
77 return EPOLLERR;
78
79 if (clk->ops.poll)
80 result = clk->ops.poll(clk, fp, wait);
81
82 put_posix_clock(clk);
83
84 return result;
85 }
86
posix_clock_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)87 static long posix_clock_ioctl(struct file *fp,
88 unsigned int cmd, unsigned long arg)
89 {
90 struct posix_clock *clk = get_posix_clock(fp);
91 int err = -ENOTTY;
92
93 if (!clk)
94 return -ENODEV;
95
96 if (clk->ops.ioctl)
97 err = clk->ops.ioctl(clk, cmd, arg);
98
99 put_posix_clock(clk);
100
101 return err;
102 }
103
104 #ifdef CONFIG_COMPAT
posix_clock_compat_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)105 static long posix_clock_compat_ioctl(struct file *fp,
106 unsigned int cmd, unsigned long arg)
107 {
108 struct posix_clock *clk = get_posix_clock(fp);
109 int err = -ENOTTY;
110
111 if (!clk)
112 return -ENODEV;
113
114 if (clk->ops.ioctl)
115 err = clk->ops.ioctl(clk, cmd, arg);
116
117 put_posix_clock(clk);
118
119 return err;
120 }
121 #endif
122
posix_clock_open(struct inode * inode,struct file * fp)123 static int posix_clock_open(struct inode *inode, struct file *fp)
124 {
125 int err;
126 struct posix_clock *clk =
127 container_of(inode->i_cdev, struct posix_clock, cdev);
128
129 down_read(&clk->rwsem);
130
131 if (clk->zombie) {
132 err = -ENODEV;
133 goto out;
134 }
135 if (clk->ops.open)
136 err = clk->ops.open(clk, fp->f_mode);
137 else
138 err = 0;
139
140 if (!err) {
141 kref_get(&clk->kref);
142 fp->private_data = clk;
143 }
144 out:
145 up_read(&clk->rwsem);
146 return err;
147 }
148
posix_clock_release(struct inode * inode,struct file * fp)149 static int posix_clock_release(struct inode *inode, struct file *fp)
150 {
151 struct posix_clock *clk = fp->private_data;
152 int err = 0;
153
154 if (clk->ops.release)
155 err = clk->ops.release(clk);
156
157 kref_put(&clk->kref, delete_clock);
158
159 fp->private_data = NULL;
160
161 return err;
162 }
163
164 static const struct file_operations posix_clock_file_operations = {
165 .owner = THIS_MODULE,
166 .llseek = no_llseek,
167 .read = posix_clock_read,
168 .poll = posix_clock_poll,
169 .unlocked_ioctl = posix_clock_ioctl,
170 .open = posix_clock_open,
171 .release = posix_clock_release,
172 #ifdef CONFIG_COMPAT
173 .compat_ioctl = posix_clock_compat_ioctl,
174 #endif
175 };
176
posix_clock_register(struct posix_clock * clk,dev_t devid)177 int posix_clock_register(struct posix_clock *clk, dev_t devid)
178 {
179 int err;
180
181 kref_init(&clk->kref);
182 init_rwsem(&clk->rwsem);
183
184 cdev_init(&clk->cdev, &posix_clock_file_operations);
185 clk->cdev.owner = clk->ops.owner;
186 err = cdev_add(&clk->cdev, devid, 1);
187
188 return err;
189 }
190 EXPORT_SYMBOL_GPL(posix_clock_register);
191
delete_clock(struct kref * kref)192 static void delete_clock(struct kref *kref)
193 {
194 struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
195
196 if (clk->release)
197 clk->release(clk);
198 }
199
posix_clock_unregister(struct posix_clock * clk)200 void posix_clock_unregister(struct posix_clock *clk)
201 {
202 cdev_del(&clk->cdev);
203
204 down_write(&clk->rwsem);
205 clk->zombie = true;
206 up_write(&clk->rwsem);
207
208 kref_put(&clk->kref, delete_clock);
209 }
210 EXPORT_SYMBOL_GPL(posix_clock_unregister);
211
212 struct posix_clock_desc {
213 struct file *fp;
214 struct posix_clock *clk;
215 };
216
get_clock_desc(const clockid_t id,struct posix_clock_desc * cd)217 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
218 {
219 struct file *fp = fget(clockid_to_fd(id));
220 int err = -EINVAL;
221
222 if (!fp)
223 return err;
224
225 if (fp->f_op->open != posix_clock_open || !fp->private_data)
226 goto out;
227
228 cd->fp = fp;
229 cd->clk = get_posix_clock(fp);
230
231 err = cd->clk ? 0 : -ENODEV;
232 out:
233 if (err)
234 fput(fp);
235 return err;
236 }
237
put_clock_desc(struct posix_clock_desc * cd)238 static void put_clock_desc(struct posix_clock_desc *cd)
239 {
240 put_posix_clock(cd->clk);
241 fput(cd->fp);
242 }
243
pc_clock_adjtime(clockid_t id,struct timex * tx)244 static int pc_clock_adjtime(clockid_t id, struct timex *tx)
245 {
246 struct posix_clock_desc cd;
247 int err;
248
249 err = get_clock_desc(id, &cd);
250 if (err)
251 return err;
252
253 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
254 err = -EACCES;
255 goto out;
256 }
257
258 if (cd.clk->ops.clock_adjtime)
259 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
260 else
261 err = -EOPNOTSUPP;
262 out:
263 put_clock_desc(&cd);
264
265 return err;
266 }
267
pc_clock_gettime(clockid_t id,struct timespec64 * ts)268 static int pc_clock_gettime(clockid_t id, struct timespec64 *ts)
269 {
270 struct posix_clock_desc cd;
271 int err;
272
273 err = get_clock_desc(id, &cd);
274 if (err)
275 return err;
276
277 if (cd.clk->ops.clock_gettime)
278 err = cd.clk->ops.clock_gettime(cd.clk, ts);
279 else
280 err = -EOPNOTSUPP;
281
282 put_clock_desc(&cd);
283
284 return err;
285 }
286
pc_clock_getres(clockid_t id,struct timespec64 * ts)287 static int pc_clock_getres(clockid_t id, struct timespec64 *ts)
288 {
289 struct posix_clock_desc cd;
290 int err;
291
292 err = get_clock_desc(id, &cd);
293 if (err)
294 return err;
295
296 if (cd.clk->ops.clock_getres)
297 err = cd.clk->ops.clock_getres(cd.clk, ts);
298 else
299 err = -EOPNOTSUPP;
300
301 put_clock_desc(&cd);
302
303 return err;
304 }
305
pc_clock_settime(clockid_t id,const struct timespec64 * ts)306 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
307 {
308 struct posix_clock_desc cd;
309 int err;
310
311 err = get_clock_desc(id, &cd);
312 if (err)
313 return err;
314
315 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
316 err = -EACCES;
317 goto out;
318 }
319
320 if (cd.clk->ops.clock_settime)
321 err = cd.clk->ops.clock_settime(cd.clk, ts);
322 else
323 err = -EOPNOTSUPP;
324 out:
325 put_clock_desc(&cd);
326
327 return err;
328 }
329
330 const struct k_clock clock_posix_dynamic = {
331 .clock_getres = pc_clock_getres,
332 .clock_set = pc_clock_settime,
333 .clock_get = pc_clock_gettime,
334 .clock_adj = pc_clock_adjtime,
335 };
336
