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/*
18 * Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
19 */
20static struct posix_clock *get_posix_clock(struct file *fp)
21{
22 struct posix_clock_context *pccontext = fp->private_data;
23 struct posix_clock *clk = pccontext->clk;
24
25 down_read(sem: &clk->rwsem);
26
27 if (!clk->zombie)
28 return clk;
29
30 up_read(sem: &clk->rwsem);
31
32 return NULL;
33}
34
35static void put_posix_clock(struct posix_clock *clk)
36{
37 up_read(sem: &clk->rwsem);
38}
39
40static ssize_t posix_clock_read(struct file *fp, char __user *buf,
41 size_t count, loff_t *ppos)
42{
43 struct posix_clock_context *pccontext = fp->private_data;
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(pccontext, fp->f_flags, buf, count);
52
53 put_posix_clock(clk);
54
55 return err;
56}
57
58static __poll_t posix_clock_poll(struct file *fp, poll_table *wait)
59{
60 struct posix_clock_context *pccontext = fp->private_data;
61 struct posix_clock *clk = get_posix_clock(fp);
62 __poll_t result = 0;
63
64 if (!clk)
65 return EPOLLERR;
66
67 if (clk->ops.poll)
68 result = clk->ops.poll(pccontext, fp, wait);
69
70 put_posix_clock(clk);
71
72 return result;
73}
74
75static long posix_clock_ioctl(struct file *fp,
76 unsigned int cmd, unsigned long arg)
77{
78 struct posix_clock_context *pccontext = fp->private_data;
79 struct posix_clock *clk = get_posix_clock(fp);
80 int err = -ENOTTY;
81
82 if (!clk)
83 return -ENODEV;
84
85 if (clk->ops.ioctl)
86 err = clk->ops.ioctl(pccontext, cmd, arg);
87
88 put_posix_clock(clk);
89
90 return err;
91}
92
93#ifdef CONFIG_COMPAT
94static long posix_clock_compat_ioctl(struct file *fp,
95 unsigned int cmd, unsigned long arg)
96{
97 struct posix_clock_context *pccontext = fp->private_data;
98 struct posix_clock *clk = get_posix_clock(fp);
99 int err = -ENOTTY;
100
101 if (!clk)
102 return -ENODEV;
103
104 if (clk->ops.ioctl)
105 err = clk->ops.ioctl(pccontext, cmd, arg);
106
107 put_posix_clock(clk);
108
109 return err;
110}
111#endif
112
113static int posix_clock_open(struct inode *inode, struct file *fp)
114{
115 int err;
116 struct posix_clock *clk =
117 container_of(inode->i_cdev, struct posix_clock, cdev);
118 struct posix_clock_context *pccontext;
119
120 down_read(sem: &clk->rwsem);
121
122 if (clk->zombie) {
123 err = -ENODEV;
124 goto out;
125 }
126 pccontext = kzalloc(size: sizeof(*pccontext), GFP_KERNEL);
127 if (!pccontext) {
128 err = -ENOMEM;
129 goto out;
130 }
131 pccontext->clk = clk;
132 if (clk->ops.open) {
133 err = clk->ops.open(pccontext, fp->f_mode);
134 if (err) {
135 kfree(objp: pccontext);
136 goto out;
137 }
138 }
139
140 fp->private_data = pccontext;
141 get_device(dev: clk->dev);
142 err = 0;
143out:
144 up_read(sem: &clk->rwsem);
145 return err;
146}
147
148static int posix_clock_release(struct inode *inode, struct file *fp)
149{
150 struct posix_clock_context *pccontext = fp->private_data;
151 struct posix_clock *clk;
152 int err = 0;
153
154 if (!pccontext)
155 return -ENODEV;
156 clk = pccontext->clk;
157
158 if (clk->ops.release)
159 err = clk->ops.release(pccontext);
160
161 put_device(dev: clk->dev);
162
163 kfree(objp: pccontext);
164 fp->private_data = NULL;
165
166 return err;
167}
168
169static const struct file_operations posix_clock_file_operations = {
170 .owner = THIS_MODULE,
171 .llseek = no_llseek,
172 .read = posix_clock_read,
173 .poll = posix_clock_poll,
174 .unlocked_ioctl = posix_clock_ioctl,
175 .open = posix_clock_open,
176 .release = posix_clock_release,
177#ifdef CONFIG_COMPAT
178 .compat_ioctl = posix_clock_compat_ioctl,
179#endif
180};
181
182int posix_clock_register(struct posix_clock *clk, struct device *dev)
183{
184 int err;
185
186 init_rwsem(&clk->rwsem);
187
188 cdev_init(&clk->cdev, &posix_clock_file_operations);
189 err = cdev_device_add(cdev: &clk->cdev, dev);
190 if (err) {
191 pr_err("%s unable to add device %d:%d\n",
192 dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt));
193 return err;
194 }
195 clk->cdev.owner = clk->ops.owner;
196 clk->dev = dev;
197
198 return 0;
199}
200EXPORT_SYMBOL_GPL(posix_clock_register);
201
202void posix_clock_unregister(struct posix_clock *clk)
203{
204 cdev_device_del(cdev: &clk->cdev, dev: clk->dev);
205
206 down_write(sem: &clk->rwsem);
207 clk->zombie = true;
208 up_write(sem: &clk->rwsem);
209
210 put_device(dev: clk->dev);
211}
212EXPORT_SYMBOL_GPL(posix_clock_unregister);
213
214struct posix_clock_desc {
215 struct file *fp;
216 struct posix_clock *clk;
217};
218
219static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
220{
221 struct file *fp = fget(fd: clockid_to_fd(clk: id));
222 int err = -EINVAL;
223
224 if (!fp)
225 return err;
226
227 if (fp->f_op->open != posix_clock_open || !fp->private_data)
228 goto out;
229
230 cd->fp = fp;
231 cd->clk = get_posix_clock(fp);
232
233 err = cd->clk ? 0 : -ENODEV;
234out:
235 if (err)
236 fput(fp);
237 return err;
238}
239
240static void put_clock_desc(struct posix_clock_desc *cd)
241{
242 put_posix_clock(clk: cd->clk);
243 fput(cd->fp);
244}
245
246static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx)
247{
248 struct posix_clock_desc cd;
249 int err;
250
251 err = get_clock_desc(id, cd: &cd);
252 if (err)
253 return err;
254
255 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
256 err = -EACCES;
257 goto out;
258 }
259
260 if (cd.clk->ops.clock_adjtime)
261 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
262 else
263 err = -EOPNOTSUPP;
264out:
265 put_clock_desc(cd: &cd);
266
267 return err;
268}
269
270static int pc_clock_gettime(clockid_t id, struct timespec64 *ts)
271{
272 struct posix_clock_desc cd;
273 int err;
274
275 err = get_clock_desc(id, cd: &cd);
276 if (err)
277 return err;
278
279 if (cd.clk->ops.clock_gettime)
280 err = cd.clk->ops.clock_gettime(cd.clk, ts);
281 else
282 err = -EOPNOTSUPP;
283
284 put_clock_desc(cd: &cd);
285
286 return err;
287}
288
289static int pc_clock_getres(clockid_t id, struct timespec64 *ts)
290{
291 struct posix_clock_desc cd;
292 int err;
293
294 err = get_clock_desc(id, cd: &cd);
295 if (err)
296 return err;
297
298 if (cd.clk->ops.clock_getres)
299 err = cd.clk->ops.clock_getres(cd.clk, ts);
300 else
301 err = -EOPNOTSUPP;
302
303 put_clock_desc(cd: &cd);
304
305 return err;
306}
307
308static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
309{
310 struct posix_clock_desc cd;
311 int err;
312
313 err = get_clock_desc(id, cd: &cd);
314 if (err)
315 return err;
316
317 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
318 err = -EACCES;
319 goto out;
320 }
321
322 if (cd.clk->ops.clock_settime)
323 err = cd.clk->ops.clock_settime(cd.clk, ts);
324 else
325 err = -EOPNOTSUPP;
326out:
327 put_clock_desc(cd: &cd);
328
329 return err;
330}
331
332const struct k_clock clock_posix_dynamic = {
333 .clock_getres = pc_clock_getres,
334 .clock_set = pc_clock_settime,
335 .clock_get_timespec = pc_clock_gettime,
336 .clock_adj = pc_clock_adjtime,
337};
338

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source code of linux/kernel/time/posix-clock.c