74ba9207e1
Based on 1 normalized pattern(s): 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 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 441 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190520071858.739733335@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
117 lines
3.8 KiB
C
117 lines
3.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* posix-clock.h - 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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#ifndef _LINUX_POSIX_CLOCK_H_
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#define _LINUX_POSIX_CLOCK_H_
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#include <linux/cdev.h>
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#include <linux/fs.h>
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#include <linux/poll.h>
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#include <linux/posix-timers.h>
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#include <linux/rwsem.h>
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struct posix_clock;
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/**
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* struct posix_clock_operations - functional interface to the clock
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*
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* Every posix clock is represented by a character device. Drivers may
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* optionally offer extended capabilities by implementing the
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* character device methods. The character device file operations are
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* first handled by the clock device layer, then passed on to the
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* driver by calling these functions.
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*
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* @owner: The clock driver should set to THIS_MODULE
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* @clock_adjtime: Adjust the clock
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* @clock_gettime: Read the current time
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* @clock_getres: Get the clock resolution
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* @clock_settime: Set the current time value
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* @open: Optional character device open method
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* @release: Optional character device release method
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* @ioctl: Optional character device ioctl method
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* @read: Optional character device read method
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* @poll: Optional character device poll method
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*/
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struct posix_clock_operations {
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struct module *owner;
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int (*clock_adjtime)(struct posix_clock *pc, struct __kernel_timex *tx);
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int (*clock_gettime)(struct posix_clock *pc, struct timespec64 *ts);
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int (*clock_getres) (struct posix_clock *pc, struct timespec64 *ts);
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int (*clock_settime)(struct posix_clock *pc,
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const struct timespec64 *ts);
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/*
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* Optional character device methods:
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*/
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long (*ioctl) (struct posix_clock *pc,
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unsigned int cmd, unsigned long arg);
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int (*open) (struct posix_clock *pc, fmode_t f_mode);
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__poll_t (*poll) (struct posix_clock *pc,
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struct file *file, poll_table *wait);
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int (*release) (struct posix_clock *pc);
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ssize_t (*read) (struct posix_clock *pc,
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uint flags, char __user *buf, size_t cnt);
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};
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/**
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* struct posix_clock - represents a dynamic posix clock
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*
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* @ops: Functional interface to the clock
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* @cdev: Character device instance for this clock
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* @kref: Reference count.
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* @rwsem: Protects the 'zombie' field from concurrent access.
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* @zombie: If 'zombie' is true, then the hardware has disappeared.
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* @release: A function to free the structure when the reference count reaches
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* zero. May be NULL if structure is statically allocated.
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*
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* Drivers should embed their struct posix_clock within a private
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* structure, obtaining a reference to it during callbacks using
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* container_of().
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*/
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struct posix_clock {
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struct posix_clock_operations ops;
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struct cdev cdev;
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struct kref kref;
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struct rw_semaphore rwsem;
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bool zombie;
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void (*release)(struct posix_clock *clk);
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};
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/**
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* posix_clock_register() - register a new clock
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* @clk: Pointer to the clock. Caller must provide 'ops' and 'release'
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* @devid: Allocated device id
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*
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* A clock driver calls this function to register itself with the
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* clock device subsystem. If 'clk' points to dynamically allocated
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* memory, then the caller must provide a 'release' function to free
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* that memory.
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*
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* Returns zero on success, non-zero otherwise.
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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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* posix_clock_unregister() - unregister a clock
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* @clk: Clock instance previously registered via posix_clock_register()
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*
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* A clock driver calls this function to remove itself from the clock
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* device subsystem. The posix_clock itself will remain (in an
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* inactive state) until its reference count drops to zero, at which
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* point it will be deallocated with its 'release' method.
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*/
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void posix_clock_unregister(struct posix_clock *clk);
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#endif
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