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151 lines
5.3 KiB
151 lines
5.3 KiB
/* |
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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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