336 lines
6.4 KiB
C
336 lines
6.4 KiB
C
/*
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* posix-clock.c - support for dynamic clock devices
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*
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* Copyright (C) 2010 OMICRON electronics GmbH
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/device.h>
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#include <linux/export.h>
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#include <linux/file.h>
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#include <linux/posix-clock.h>
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#include <linux/slab.h>
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#include <linux/syscalls.h>
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#include <linux/uaccess.h>
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#include "posix-timers.h"
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static void delete_clock(struct kref *kref);
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/*
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* Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
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*/
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static struct posix_clock *get_posix_clock(struct file *fp)
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{
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struct posix_clock *clk = fp->private_data;
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down_read(&clk->rwsem);
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if (!clk->zombie)
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return clk;
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up_read(&clk->rwsem);
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return NULL;
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}
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static void put_posix_clock(struct posix_clock *clk)
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{
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up_read(&clk->rwsem);
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}
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static ssize_t posix_clock_read(struct file *fp, char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct posix_clock *clk = get_posix_clock(fp);
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int err = -EINVAL;
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if (!clk)
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return -ENODEV;
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if (clk->ops.read)
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err = clk->ops.read(clk, fp->f_flags, buf, count);
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put_posix_clock(clk);
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return err;
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}
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static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
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{
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struct posix_clock *clk = get_posix_clock(fp);
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unsigned int result = 0;
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if (!clk)
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return POLLERR;
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if (clk->ops.poll)
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result = clk->ops.poll(clk, fp, wait);
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put_posix_clock(clk);
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return result;
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}
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static long posix_clock_ioctl(struct file *fp,
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unsigned int cmd, unsigned long arg)
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{
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struct posix_clock *clk = get_posix_clock(fp);
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int err = -ENOTTY;
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if (!clk)
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return -ENODEV;
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if (clk->ops.ioctl)
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err = clk->ops.ioctl(clk, cmd, arg);
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put_posix_clock(clk);
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return err;
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}
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#ifdef CONFIG_COMPAT
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static long posix_clock_compat_ioctl(struct file *fp,
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unsigned int cmd, unsigned long arg)
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{
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struct posix_clock *clk = get_posix_clock(fp);
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int err = -ENOTTY;
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if (!clk)
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return -ENODEV;
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if (clk->ops.ioctl)
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err = clk->ops.ioctl(clk, cmd, arg);
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put_posix_clock(clk);
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return err;
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}
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#endif
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static int posix_clock_open(struct inode *inode, struct file *fp)
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{
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int err;
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struct posix_clock *clk =
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container_of(inode->i_cdev, struct posix_clock, cdev);
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down_read(&clk->rwsem);
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if (clk->zombie) {
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err = -ENODEV;
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goto out;
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}
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if (clk->ops.open)
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err = clk->ops.open(clk, fp->f_mode);
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else
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err = 0;
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if (!err) {
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kref_get(&clk->kref);
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fp->private_data = clk;
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}
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out:
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up_read(&clk->rwsem);
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return err;
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}
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static int posix_clock_release(struct inode *inode, struct file *fp)
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{
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struct posix_clock *clk = fp->private_data;
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int err = 0;
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if (clk->ops.release)
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err = clk->ops.release(clk);
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kref_put(&clk->kref, delete_clock);
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fp->private_data = NULL;
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return err;
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}
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static const struct file_operations posix_clock_file_operations = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.read = posix_clock_read,
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.poll = posix_clock_poll,
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.unlocked_ioctl = posix_clock_ioctl,
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.open = posix_clock_open,
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.release = posix_clock_release,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = posix_clock_compat_ioctl,
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#endif
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};
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int posix_clock_register(struct posix_clock *clk, dev_t devid)
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{
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int err;
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kref_init(&clk->kref);
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init_rwsem(&clk->rwsem);
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cdev_init(&clk->cdev, &posix_clock_file_operations);
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clk->cdev.owner = clk->ops.owner;
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err = cdev_add(&clk->cdev, devid, 1);
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return err;
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}
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EXPORT_SYMBOL_GPL(posix_clock_register);
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static void delete_clock(struct kref *kref)
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{
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struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
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if (clk->release)
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clk->release(clk);
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}
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void posix_clock_unregister(struct posix_clock *clk)
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{
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cdev_del(&clk->cdev);
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down_write(&clk->rwsem);
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clk->zombie = true;
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up_write(&clk->rwsem);
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kref_put(&clk->kref, delete_clock);
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}
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EXPORT_SYMBOL_GPL(posix_clock_unregister);
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struct posix_clock_desc {
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struct file *fp;
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struct posix_clock *clk;
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};
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static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
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{
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struct file *fp = fget(CLOCKID_TO_FD(id));
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int err = -EINVAL;
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if (!fp)
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return err;
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if (fp->f_op->open != posix_clock_open || !fp->private_data)
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goto out;
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cd->fp = fp;
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cd->clk = get_posix_clock(fp);
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err = cd->clk ? 0 : -ENODEV;
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out:
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if (err)
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fput(fp);
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return err;
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}
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static void put_clock_desc(struct posix_clock_desc *cd)
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{
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put_posix_clock(cd->clk);
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fput(cd->fp);
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}
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static int pc_clock_adjtime(clockid_t id, struct timex *tx)
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{
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struct posix_clock_desc cd;
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int err;
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err = get_clock_desc(id, &cd);
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if (err)
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return err;
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if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
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err = -EACCES;
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goto out;
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}
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if (cd.clk->ops.clock_adjtime)
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err = cd.clk->ops.clock_adjtime(cd.clk, tx);
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else
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err = -EOPNOTSUPP;
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out:
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put_clock_desc(&cd);
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return err;
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}
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static int pc_clock_gettime(clockid_t id, struct timespec64 *ts)
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{
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struct posix_clock_desc cd;
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int err;
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err = get_clock_desc(id, &cd);
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if (err)
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return err;
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if (cd.clk->ops.clock_gettime)
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err = cd.clk->ops.clock_gettime(cd.clk, ts);
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else
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err = -EOPNOTSUPP;
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put_clock_desc(&cd);
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return err;
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}
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static int pc_clock_getres(clockid_t id, struct timespec64 *ts)
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{
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struct posix_clock_desc cd;
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int err;
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err = get_clock_desc(id, &cd);
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if (err)
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return err;
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if (cd.clk->ops.clock_getres)
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err = cd.clk->ops.clock_getres(cd.clk, ts);
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else
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err = -EOPNOTSUPP;
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put_clock_desc(&cd);
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return err;
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}
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static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
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{
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struct posix_clock_desc cd;
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int err;
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err = get_clock_desc(id, &cd);
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if (err)
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return err;
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if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
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err = -EACCES;
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goto out;
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}
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if (cd.clk->ops.clock_settime)
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err = cd.clk->ops.clock_settime(cd.clk, ts);
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else
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err = -EOPNOTSUPP;
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out:
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put_clock_desc(&cd);
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return err;
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}
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const struct k_clock clock_posix_dynamic = {
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.clock_getres = pc_clock_getres,
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.clock_set = pc_clock_settime,
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.clock_get = pc_clock_gettime,
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.clock_adj = pc_clock_adjtime,
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};
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