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