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 */
get_posix_clock(struct file * fp)20 static 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(&clk->rwsem);
26
27 if (!clk->zombie)
28 return clk;
29
30 up_read(&clk->rwsem);
31
32 return NULL;
33 }
34
put_posix_clock(struct posix_clock * clk)35 static void put_posix_clock(struct posix_clock *clk)
36 {
37 up_read(&clk->rwsem);
38 }
39
posix_clock_read(struct file * fp,char __user * buf,size_t count,loff_t * ppos)40 static 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
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_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
posix_clock_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)75 static 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
posix_clock_compat_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)94 static 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
posix_clock_open(struct inode * inode,struct file * fp)113 static 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(&clk->rwsem);
121
122 if (clk->zombie) {
123 err = -ENODEV;
124 goto out;
125 }
126 pccontext = kzalloc(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(pccontext);
136 goto out;
137 }
138 }
139
140 fp->private_data = pccontext;
141 get_device(clk->dev);
142 err = 0;
143 out:
144 up_read(&clk->rwsem);
145 return err;
146 }
147
posix_clock_release(struct inode * inode,struct file * fp)148 static 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(clk->dev);
162
163 kfree(pccontext);
164 fp->private_data = NULL;
165
166 return err;
167 }
168
169 static const struct file_operations posix_clock_file_operations = {
170 .owner = THIS_MODULE,
171 .read = posix_clock_read,
172 .poll = posix_clock_poll,
173 .unlocked_ioctl = posix_clock_ioctl,
174 .open = posix_clock_open,
175 .release = posix_clock_release,
176 #ifdef CONFIG_COMPAT
177 .compat_ioctl = posix_clock_compat_ioctl,
178 #endif
179 };
180
posix_clock_register(struct posix_clock * clk,struct device * dev)181 int posix_clock_register(struct posix_clock *clk, struct device *dev)
182 {
183 int err;
184
185 init_rwsem(&clk->rwsem);
186
187 cdev_init(&clk->cdev, &posix_clock_file_operations);
188 err = cdev_device_add(&clk->cdev, dev);
189 if (err) {
190 pr_err("%s unable to add device %d:%d\n",
191 dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt));
192 return err;
193 }
194 clk->cdev.owner = clk->ops.owner;
195 clk->dev = dev;
196
197 return 0;
198 }
199 EXPORT_SYMBOL_GPL(posix_clock_register);
200
posix_clock_unregister(struct posix_clock * clk)201 void posix_clock_unregister(struct posix_clock *clk)
202 {
203 cdev_device_del(&clk->cdev, clk->dev);
204
205 down_write(&clk->rwsem);
206 clk->zombie = true;
207 up_write(&clk->rwsem);
208
209 put_device(clk->dev);
210 }
211 EXPORT_SYMBOL_GPL(posix_clock_unregister);
212
213 struct posix_clock_desc {
214 struct file *fp;
215 struct posix_clock *clk;
216 };
217
get_clock_desc(const clockid_t id,struct posix_clock_desc * cd)218 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
219 {
220 struct file *fp = fget(clockid_to_fd(id));
221 int err = -EINVAL;
222
223 if (!fp)
224 return err;
225
226 if (fp->f_op->open != posix_clock_open || !fp->private_data)
227 goto out;
228
229 cd->fp = fp;
230 cd->clk = get_posix_clock(fp);
231
232 err = cd->clk ? 0 : -ENODEV;
233 out:
234 if (err)
235 fput(fp);
236 return err;
237 }
238
put_clock_desc(struct posix_clock_desc * cd)239 static void put_clock_desc(struct posix_clock_desc *cd)
240 {
241 put_posix_clock(cd->clk);
242 fput(cd->fp);
243 }
244
pc_clock_adjtime(clockid_t id,struct __kernel_timex * tx)245 static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx)
246 {
247 struct posix_clock_desc cd;
248 int err;
249
250 err = get_clock_desc(id, &cd);
251 if (err)
252 return err;
253
254 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
255 err = -EACCES;
256 goto out;
257 }
258
259 if (cd.clk->ops.clock_adjtime)
260 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
261 else
262 err = -EOPNOTSUPP;
263 out:
264 put_clock_desc(&cd);
265
266 return err;
267 }
268
pc_clock_gettime(clockid_t id,struct timespec64 * ts)269 static int pc_clock_gettime(clockid_t id, struct timespec64 *ts)
270 {
271 struct posix_clock_desc cd;
272 int err;
273
274 err = get_clock_desc(id, &cd);
275 if (err)
276 return err;
277
278 if (cd.clk->ops.clock_gettime)
279 err = cd.clk->ops.clock_gettime(cd.clk, ts);
280 else
281 err = -EOPNOTSUPP;
282
283 put_clock_desc(&cd);
284
285 return err;
286 }
287
pc_clock_getres(clockid_t id,struct timespec64 * ts)288 static int pc_clock_getres(clockid_t id, struct timespec64 *ts)
289 {
290 struct posix_clock_desc cd;
291 int err;
292
293 err = get_clock_desc(id, &cd);
294 if (err)
295 return err;
296
297 if (cd.clk->ops.clock_getres)
298 err = cd.clk->ops.clock_getres(cd.clk, ts);
299 else
300 err = -EOPNOTSUPP;
301
302 put_clock_desc(&cd);
303
304 return err;
305 }
306
pc_clock_settime(clockid_t id,const struct timespec64 * ts)307 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
308 {
309 struct posix_clock_desc cd;
310 int err;
311
312 if (!timespec64_valid_strict(ts))
313 return -EINVAL;
314
315 err = get_clock_desc(id, &cd);
316 if (err)
317 return err;
318
319 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
320 err = -EACCES;
321 goto out;
322 }
323
324 if (cd.clk->ops.clock_settime)
325 err = cd.clk->ops.clock_settime(cd.clk, ts);
326 else
327 err = -EOPNOTSUPP;
328 out:
329 put_clock_desc(&cd);
330
331 return err;
332 }
333
334 const struct k_clock clock_posix_dynamic = {
335 .clock_getres = pc_clock_getres,
336 .clock_set = pc_clock_settime,
337 .clock_get_timespec = pc_clock_gettime,
338 .clock_adj = pc_clock_adjtime,
339 };
340