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- /* SPDX-License-Identifier: GPL-2.0-or-later */
- /*
- * posix-clock.h - support for dynamic clock devices
- *
- * Copyright (C) 2010 OMICRON electronics GmbH
- */
- #ifndef _LINUX_POSIX_CLOCK_H_
- #define _LINUX_POSIX_CLOCK_H_
- #include <linux/cdev.h>
- #include <linux/fs.h>
- #include <linux/poll.h>
- #include <linux/posix-timers.h>
- #include <linux/rwsem.h>
- struct posix_clock;
- /**
- * struct posix_clock_operations - functional interface to the clock
- *
- * Every posix clock is represented by a character device. Drivers may
- * optionally offer extended capabilities by implementing the
- * character device methods. The character device file operations are
- * first handled by the clock device layer, then passed on to the
- * driver by calling these functions.
- *
- * @owner: The clock driver should set to THIS_MODULE
- * @clock_adjtime: Adjust the clock
- * @clock_gettime: Read the current time
- * @clock_getres: Get the clock resolution
- * @clock_settime: Set the current time value
- * @open: Optional character device open method
- * @release: Optional character device release method
- * @ioctl: Optional character device ioctl method
- * @read: Optional character device read method
- * @poll: Optional character device poll method
- */
- struct posix_clock_operations {
- struct module *owner;
- int (*clock_adjtime)(struct posix_clock *pc, struct __kernel_timex *tx);
- int (*clock_gettime)(struct posix_clock *pc, struct timespec64 *ts);
- int (*clock_getres) (struct posix_clock *pc, struct timespec64 *ts);
- int (*clock_settime)(struct posix_clock *pc,
- const struct timespec64 *ts);
- /*
- * Optional character device methods:
- */
- long (*ioctl) (struct posix_clock *pc,
- unsigned int cmd, unsigned long arg);
- int (*open) (struct posix_clock *pc, fmode_t f_mode);
- __poll_t (*poll) (struct posix_clock *pc,
- struct file *file, poll_table *wait);
- int (*release) (struct posix_clock *pc);
- ssize_t (*read) (struct posix_clock *pc,
- uint flags, char __user *buf, size_t cnt);
- };
- /**
- * struct posix_clock - represents a dynamic posix clock
- *
- * @ops: Functional interface to the clock
- * @cdev: Character device instance for this clock
- * @dev: Pointer to the clock's device.
- * @rwsem: Protects the 'zombie' field from concurrent access.
- * @zombie: If 'zombie' is true, then the hardware has disappeared.
- *
- * Drivers should embed their struct posix_clock within a private
- * structure, obtaining a reference to it during callbacks using
- * container_of().
- *
- * Drivers should supply an initialized but not exposed struct device
- * to posix_clock_register(). It is used to manage lifetime of the
- * driver's private structure. It's 'release' field should be set to
- * a release function for this private structure.
- */
- struct posix_clock {
- struct posix_clock_operations ops;
- struct cdev cdev;
- struct device *dev;
- struct rw_semaphore rwsem;
- bool zombie;
- };
- /**
- * posix_clock_register() - register a new clock
- * @clk: Pointer to the clock. Caller must provide 'ops' field
- * @dev: Pointer to the initialized device. Caller must provide
- * 'release' field
- *
- * A clock driver calls this function to register itself with the
- * clock device subsystem. If 'clk' points to dynamically allocated
- * memory, then the caller must provide a 'release' function to free
- * that memory.
- *
- * Returns zero on success, non-zero otherwise.
- */
- int posix_clock_register(struct posix_clock *clk, struct device *dev);
- /**
- * posix_clock_unregister() - unregister a clock
- * @clk: Clock instance previously registered via posix_clock_register()
- *
- * A clock driver calls this function to remove itself from the clock
- * device subsystem. The posix_clock itself will remain (in an
- * inactive state) until its reference count drops to zero, at which
- * point it will be deallocated with its 'release' method.
- */
- void posix_clock_unregister(struct posix_clock *clk);
- #endif
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