1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Support for dynamic clock devices
4 *
5 * Copyright (C) 2010 OMICRON electronics GmbH
6 */
7 #include <linux/device.h>
8 #include <linux/export.h>
9 #include <linux/file.h>
10 #include <linux/posix-clock.h>
11 #include <linux/slab.h>
12 #include <linux/syscalls.h>
13 #include <linux/uaccess.h>
14
15 #include "posix-timers.h"
16
17 static void delete_clock(struct kref *kref);
18
19 /*
20 * Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
21 */
get_posix_clock(struct file * fp)22 static struct posix_clock *get_posix_clock(struct file *fp)
23 {
24 struct posix_clock *clk = fp->private_data;
25
26 down_read(&clk->rwsem);
27
28 if (!clk->zombie)
29 return clk;
30
31 up_read(&clk->rwsem);
32
33 return NULL;
34 }
35
put_posix_clock(struct posix_clock * clk)36 static void put_posix_clock(struct posix_clock *clk)
37 {
38 up_read(&clk->rwsem);
39 }
40
posix_clock_read(struct file * fp,char __user * buf,size_t count,loff_t * ppos)41 static ssize_t posix_clock_read(struct file *fp, char __user *buf,
42 size_t count, loff_t *ppos)
43 {
44 struct posix_clock *clk = get_posix_clock(fp);
45 int err = -EINVAL;
46
47 if (!clk)
48 return -ENODEV;
49
50 if (clk->ops.read)
51 err = clk->ops.read(clk, fp->f_flags, buf, count);
52
53 put_posix_clock(clk);
54
55 return err;
56 }
57
posix_clock_poll(struct file * fp,poll_table * wait)58 static __poll_t posix_clock_poll(struct file *fp, poll_table *wait)
59 {
60 struct posix_clock *clk = get_posix_clock(fp);
61 __poll_t result = 0;
62
63 if (!clk)
64 return EPOLLERR;
65
66 if (clk->ops.poll)
67 result = clk->ops.poll(clk, fp, wait);
68
69 put_posix_clock(clk);
70
71 return result;
72 }
73
posix_clock_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)74 static long posix_clock_ioctl(struct file *fp,
75 unsigned int cmd, unsigned long arg)
76 {
77 struct posix_clock *clk = get_posix_clock(fp);
78 int err = -ENOTTY;
79
80 if (!clk)
81 return -ENODEV;
82
83 if (clk->ops.ioctl)
84 err = clk->ops.ioctl(clk, cmd, arg);
85
86 put_posix_clock(clk);
87
88 return err;
89 }
90
91 #ifdef CONFIG_COMPAT
posix_clock_compat_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)92 static long posix_clock_compat_ioctl(struct file *fp,
93 unsigned int cmd, unsigned long arg)
94 {
95 struct posix_clock *clk = get_posix_clock(fp);
96 int err = -ENOTTY;
97
98 if (!clk)
99 return -ENODEV;
100
101 if (clk->ops.ioctl)
102 err = clk->ops.ioctl(clk, cmd, arg);
103
104 put_posix_clock(clk);
105
106 return err;
107 }
108 #endif
109
posix_clock_open(struct inode * inode,struct file * fp)110 static int posix_clock_open(struct inode *inode, struct file *fp)
111 {
112 int err;
113 struct posix_clock *clk =
114 container_of(inode->i_cdev, struct posix_clock, cdev);
115
116 down_read(&clk->rwsem);
117
118 if (clk->zombie) {
119 err = -ENODEV;
120 goto out;
121 }
122 if (clk->ops.open)
123 err = clk->ops.open(clk, fp->f_mode);
124 else
125 err = 0;
126
127 if (!err) {
128 kref_get(&clk->kref);
129 fp->private_data = clk;
130 }
131 out:
132 up_read(&clk->rwsem);
133 return err;
134 }
135
posix_clock_release(struct inode * inode,struct file * fp)136 static int posix_clock_release(struct inode *inode, struct file *fp)
137 {
138 struct posix_clock *clk = fp->private_data;
139 int err = 0;
140
141 if (clk->ops.release)
142 err = clk->ops.release(clk);
143
144 kref_put(&clk->kref, delete_clock);
145
146 fp->private_data = NULL;
147
148 return err;
149 }
150
151 static const struct file_operations posix_clock_file_operations = {
152 .owner = THIS_MODULE,
153 .llseek = no_llseek,
154 .read = posix_clock_read,
155 .poll = posix_clock_poll,
156 .unlocked_ioctl = posix_clock_ioctl,
157 .open = posix_clock_open,
158 .release = posix_clock_release,
159 #ifdef CONFIG_COMPAT
160 .compat_ioctl = posix_clock_compat_ioctl,
161 #endif
162 };
163
posix_clock_register(struct posix_clock * clk,dev_t devid)164 int posix_clock_register(struct posix_clock *clk, dev_t devid)
165 {
166 int err;
167
168 kref_init(&clk->kref);
169 init_rwsem(&clk->rwsem);
170
171 cdev_init(&clk->cdev, &posix_clock_file_operations);
172 clk->cdev.owner = clk->ops.owner;
173 err = cdev_add(&clk->cdev, devid, 1);
174
175 return err;
176 }
177 EXPORT_SYMBOL_GPL(posix_clock_register);
178
delete_clock(struct kref * kref)179 static void delete_clock(struct kref *kref)
180 {
181 struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
182
183 if (clk->release)
184 clk->release(clk);
185 }
186
posix_clock_unregister(struct posix_clock * clk)187 void posix_clock_unregister(struct posix_clock *clk)
188 {
189 cdev_del(&clk->cdev);
190
191 down_write(&clk->rwsem);
192 clk->zombie = true;
193 up_write(&clk->rwsem);
194
195 kref_put(&clk->kref, delete_clock);
196 }
197 EXPORT_SYMBOL_GPL(posix_clock_unregister);
198
199 struct posix_clock_desc {
200 struct file *fp;
201 struct posix_clock *clk;
202 };
203
get_clock_desc(const clockid_t id,struct posix_clock_desc * cd)204 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
205 {
206 struct file *fp = fget(clockid_to_fd(id));
207 int err = -EINVAL;
208
209 if (!fp)
210 return err;
211
212 if (fp->f_op->open != posix_clock_open || !fp->private_data)
213 goto out;
214
215 cd->fp = fp;
216 cd->clk = get_posix_clock(fp);
217
218 err = cd->clk ? 0 : -ENODEV;
219 out:
220 if (err)
221 fput(fp);
222 return err;
223 }
224
put_clock_desc(struct posix_clock_desc * cd)225 static void put_clock_desc(struct posix_clock_desc *cd)
226 {
227 put_posix_clock(cd->clk);
228 fput(cd->fp);
229 }
230
pc_clock_adjtime(clockid_t id,struct __kernel_timex * tx)231 static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx)
232 {
233 struct posix_clock_desc cd;
234 int err;
235
236 err = get_clock_desc(id, &cd);
237 if (err)
238 return err;
239
240 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
241 err = -EACCES;
242 goto out;
243 }
244
245 if (cd.clk->ops.clock_adjtime)
246 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
247 else
248 err = -EOPNOTSUPP;
249 out:
250 put_clock_desc(&cd);
251
252 return err;
253 }
254
pc_clock_gettime(clockid_t id,struct timespec64 * ts)255 static int pc_clock_gettime(clockid_t id, struct timespec64 *ts)
256 {
257 struct posix_clock_desc cd;
258 int err;
259
260 err = get_clock_desc(id, &cd);
261 if (err)
262 return err;
263
264 if (cd.clk->ops.clock_gettime)
265 err = cd.clk->ops.clock_gettime(cd.clk, ts);
266 else
267 err = -EOPNOTSUPP;
268
269 put_clock_desc(&cd);
270
271 return err;
272 }
273
pc_clock_getres(clockid_t id,struct timespec64 * ts)274 static int pc_clock_getres(clockid_t id, struct timespec64 *ts)
275 {
276 struct posix_clock_desc cd;
277 int err;
278
279 err = get_clock_desc(id, &cd);
280 if (err)
281 return err;
282
283 if (cd.clk->ops.clock_getres)
284 err = cd.clk->ops.clock_getres(cd.clk, ts);
285 else
286 err = -EOPNOTSUPP;
287
288 put_clock_desc(&cd);
289
290 return err;
291 }
292
pc_clock_settime(clockid_t id,const struct timespec64 * ts)293 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
294 {
295 struct posix_clock_desc cd;
296 int err;
297
298 err = get_clock_desc(id, &cd);
299 if (err)
300 return err;
301
302 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
303 err = -EACCES;
304 goto out;
305 }
306
307 if (cd.clk->ops.clock_settime)
308 err = cd.clk->ops.clock_settime(cd.clk, ts);
309 else
310 err = -EOPNOTSUPP;
311 out:
312 put_clock_desc(&cd);
313
314 return err;
315 }
316
317 const struct k_clock clock_posix_dynamic = {
318 .clock_getres = pc_clock_getres,
319 .clock_set = pc_clock_settime,
320 .clock_get = pc_clock_gettime,
321 .clock_adj = pc_clock_adjtime,
322 };
323
