152 lines
5.3 KiB
C
Executable File
152 lines
5.3 KiB
C
Executable File
/*
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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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* 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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#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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* @timer_create: Create a new timer
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* @timer_delete: Remove a previously created timer
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* @timer_gettime: Get remaining time and interval of a timer
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* @timer_settime: Set a timer's initial expiration and interval
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* @fasync: Optional character device fasync method
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* @mmap: Optional character device mmap method
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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 timex *tx);
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int (*clock_gettime)(struct posix_clock *pc, struct timespec *ts);
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int (*clock_getres) (struct posix_clock *pc, struct timespec *ts);
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int (*clock_settime)(struct posix_clock *pc,
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const struct timespec *ts);
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int (*timer_create) (struct posix_clock *pc, struct k_itimer *kit);
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int (*timer_delete) (struct posix_clock *pc, struct k_itimer *kit);
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void (*timer_gettime)(struct posix_clock *pc,
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struct k_itimer *kit, struct itimerspec *tsp);
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int (*timer_settime)(struct posix_clock *pc,
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struct k_itimer *kit, int flags,
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struct itimerspec *tsp, struct itimerspec *old);
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/*
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* Optional character device methods:
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*/
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int (*fasync) (struct posix_clock *pc,
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int fd, struct file *file, int on);
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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 (*mmap) (struct posix_clock *pc,
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struct vm_area_struct *vma);
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int (*open) (struct posix_clock *pc, fmode_t f_mode);
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uint (*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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