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 fp->private_data = pccontext;
133 if (clk->ops.open)
134 err = clk->ops.open(pccontext, fp->f_mode);
135 else
136 err = 0;
137
138 if (!err) {
139 get_device(dev: clk->dev);
140 }
141out:
142 up_read(sem: &clk->rwsem);
143 return err;
144}
145
146static int posix_clock_release(struct inode *inode, struct file *fp)
147{
148 struct posix_clock_context *pccontext = fp->private_data;
149 struct posix_clock *clk;
150 int err = 0;
151
152 if (!pccontext)
153 return -ENODEV;
154 clk = pccontext->clk;
155
156 if (clk->ops.release)
157 err = clk->ops.release(pccontext);
158
159 put_device(dev: clk->dev);
160
161 kfree(objp: pccontext);
162 fp->private_data = NULL;
163
164 return err;
165}
166
167static const struct file_operations posix_clock_file_operations = {
168 .owner = THIS_MODULE,
169 .llseek = no_llseek,
170 .read = posix_clock_read,
171 .poll = posix_clock_poll,
172 .unlocked_ioctl = posix_clock_ioctl,
173 .open = posix_clock_open,
174 .release = posix_clock_release,
175#ifdef CONFIG_COMPAT
176 .compat_ioctl = posix_clock_compat_ioctl,
177#endif
178};
179
180int posix_clock_register(struct posix_clock *clk, struct device *dev)
181{
182 int err;
183
184 init_rwsem(&clk->rwsem);
185
186 cdev_init(&clk->cdev, &posix_clock_file_operations);
187 err = cdev_device_add(cdev: &clk->cdev, dev);
188 if (err) {
189 pr_err("%s unable to add device %d:%d\n",
190 dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt));
191 return err;
192 }
193 clk->cdev.owner = clk->ops.owner;
194 clk->dev = dev;
195
196 return 0;
197}
198EXPORT_SYMBOL_GPL(posix_clock_register);
199
200void posix_clock_unregister(struct posix_clock *clk)
201{
202 cdev_device_del(cdev: &clk->cdev, dev: clk->dev);
203
204 down_write(sem: &clk->rwsem);
205 clk->zombie = true;
206 up_write(sem: &clk->rwsem);
207
208 put_device(dev: clk->dev);
209}
210EXPORT_SYMBOL_GPL(posix_clock_unregister);
211
212struct posix_clock_desc {
213 struct file *fp;
214 struct posix_clock *clk;
215};
216
217static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
218{
219 struct file *fp = fget(fd: clockid_to_fd(clk: 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;
232out:
233 if (err)
234 fput(fp);
235 return err;
236}
237
238static void put_clock_desc(struct posix_clock_desc *cd)
239{
240 put_posix_clock(clk: cd->clk);
241 fput(cd->fp);
242}
243
244static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx)
245{
246 struct posix_clock_desc cd;
247 int err;
248
249 err = get_clock_desc(id, cd: &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;
262out:
263 put_clock_desc(cd: &cd);
264
265 return err;
266}
267
268static 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: &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: &cd);
283
284 return err;
285}
286
287static 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: &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: &cd);
302
303 return err;
304}
305
306static 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: &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;
324out:
325 put_clock_desc(cd: &cd);
326
327 return err;
328}
329
330const struct k_clock clock_posix_dynamic = {
331 .clock_getres = pc_clock_getres,
332 .clock_set = pc_clock_settime,
333 .clock_get_timespec = pc_clock_gettime,
334 .clock_adj = pc_clock_adjtime,
335};
336

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