1 // SPDX-License-Identifier: GPL-2.0+
3 * Support for dynamic clock devices
5 * Copyright (C) 2010 OMICRON electronics GmbH
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>
15 #include "posix-timers.h"
17 static void delete_clock(struct kref *kref);
20 * Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
22 static struct posix_clock *get_posix_clock(struct file *fp)
24 struct posix_clock *clk = fp->private_data;
26 down_read(&clk->rwsem);
36 static void put_posix_clock(struct posix_clock *clk)
41 static ssize_t posix_clock_read(struct file *fp, char __user *buf,
42 size_t count, loff_t *ppos)
44 struct posix_clock *clk = get_posix_clock(fp);
51 err = clk->ops.read(clk, fp->f_flags, buf, count);
58 static __poll_t posix_clock_poll(struct file *fp, poll_table *wait)
60 struct posix_clock *clk = get_posix_clock(fp);
67 result = clk->ops.poll(clk, fp, wait);
74 static long posix_clock_ioctl(struct file *fp,
75 unsigned int cmd, unsigned long arg)
77 struct posix_clock *clk = get_posix_clock(fp);
84 err = clk->ops.ioctl(clk, cmd, arg);
92 static long posix_clock_compat_ioctl(struct file *fp,
93 unsigned int cmd, unsigned long arg)
95 struct posix_clock *clk = get_posix_clock(fp);
102 err = clk->ops.ioctl(clk, cmd, arg);
104 put_posix_clock(clk);
110 static int posix_clock_open(struct inode *inode, struct file *fp)
113 struct posix_clock *clk =
114 container_of(inode->i_cdev, struct posix_clock, cdev);
116 down_read(&clk->rwsem);
123 err = clk->ops.open(clk, fp->f_mode);
128 kref_get(&clk->kref);
129 fp->private_data = clk;
132 up_read(&clk->rwsem);
136 static int posix_clock_release(struct inode *inode, struct file *fp)
138 struct posix_clock *clk = fp->private_data;
141 if (clk->ops.release)
142 err = clk->ops.release(clk);
144 kref_put(&clk->kref, delete_clock);
146 fp->private_data = NULL;
151 static const struct file_operations posix_clock_file_operations = {
152 .owner = THIS_MODULE,
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,
160 .compat_ioctl = posix_clock_compat_ioctl,
164 int posix_clock_register(struct posix_clock *clk, dev_t devid)
168 kref_init(&clk->kref);
169 init_rwsem(&clk->rwsem);
171 cdev_init(&clk->cdev, &posix_clock_file_operations);
172 clk->cdev.owner = clk->ops.owner;
173 err = cdev_add(&clk->cdev, devid, 1);
177 EXPORT_SYMBOL_GPL(posix_clock_register);
179 static void delete_clock(struct kref *kref)
181 struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
187 void posix_clock_unregister(struct posix_clock *clk)
189 cdev_del(&clk->cdev);
191 down_write(&clk->rwsem);
193 up_write(&clk->rwsem);
195 kref_put(&clk->kref, delete_clock);
197 EXPORT_SYMBOL_GPL(posix_clock_unregister);
199 struct posix_clock_desc {
201 struct posix_clock *clk;
204 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
206 struct file *fp = fget(clockid_to_fd(id));
212 if (fp->f_op->open != posix_clock_open || !fp->private_data)
216 cd->clk = get_posix_clock(fp);
218 err = cd->clk ? 0 : -ENODEV;
225 static void put_clock_desc(struct posix_clock_desc *cd)
227 put_posix_clock(cd->clk);
231 static int pc_clock_adjtime(clockid_t id, struct timex *tx)
233 struct posix_clock_desc cd;
236 err = get_clock_desc(id, &cd);
240 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
245 if (cd.clk->ops.clock_adjtime)
246 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
255 static int pc_clock_gettime(clockid_t id, struct timespec64 *ts)
257 struct posix_clock_desc cd;
260 err = get_clock_desc(id, &cd);
264 if (cd.clk->ops.clock_gettime)
265 err = cd.clk->ops.clock_gettime(cd.clk, ts);
274 static int pc_clock_getres(clockid_t id, struct timespec64 *ts)
276 struct posix_clock_desc cd;
279 err = get_clock_desc(id, &cd);
283 if (cd.clk->ops.clock_getres)
284 err = cd.clk->ops.clock_getres(cd.clk, ts);
293 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
295 struct posix_clock_desc cd;
298 err = get_clock_desc(id, &cd);
302 if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
307 if (cd.clk->ops.clock_settime)
308 err = cd.clk->ops.clock_settime(cd.clk, ts);
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,