| /* 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 |