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74ba9207 | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
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2 | /* |
3 | * posix-clock.h - support for dynamic clock devices | |
4 | * | |
5 | * Copyright (C) 2010 OMICRON electronics GmbH | |
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6 | */ |
7 | #ifndef _LINUX_POSIX_CLOCK_H_ | |
8 | #define _LINUX_POSIX_CLOCK_H_ | |
9 | ||
10 | #include <linux/cdev.h> | |
11 | #include <linux/fs.h> | |
12 | #include <linux/poll.h> | |
13 | #include <linux/posix-timers.h> | |
1791f881 | 14 | #include <linux/rwsem.h> |
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15 | |
16 | struct posix_clock; | |
17 | ||
18 | /** | |
19 | * struct posix_clock_operations - functional interface to the clock | |
20 | * | |
21 | * Every posix clock is represented by a character device. Drivers may | |
22 | * optionally offer extended capabilities by implementing the | |
23 | * character device methods. The character device file operations are | |
24 | * first handled by the clock device layer, then passed on to the | |
25 | * driver by calling these functions. | |
26 | * | |
27 | * @owner: The clock driver should set to THIS_MODULE | |
28 | * @clock_adjtime: Adjust the clock | |
29 | * @clock_gettime: Read the current time | |
30 | * @clock_getres: Get the clock resolution | |
31 | * @clock_settime: Set the current time value | |
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32 | * @open: Optional character device open method |
33 | * @release: Optional character device release method | |
34 | * @ioctl: Optional character device ioctl method | |
35 | * @read: Optional character device read method | |
36 | * @poll: Optional character device poll method | |
37 | */ | |
38 | struct posix_clock_operations { | |
39 | struct module *owner; | |
40 | ||
ead25417 | 41 | int (*clock_adjtime)(struct posix_clock *pc, struct __kernel_timex *tx); |
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d340266e | 43 | int (*clock_gettime)(struct posix_clock *pc, struct timespec64 *ts); |
0606f422 | 44 | |
d340266e | 45 | int (*clock_getres) (struct posix_clock *pc, struct timespec64 *ts); |
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46 | |
47 | int (*clock_settime)(struct posix_clock *pc, | |
d340266e | 48 | const struct timespec64 *ts); |
0606f422 | 49 | |
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50 | /* |
51 | * Optional character device methods: | |
52 | */ | |
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53 | long (*ioctl) (struct posix_clock *pc, |
54 | unsigned int cmd, unsigned long arg); | |
55 | ||
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56 | int (*open) (struct posix_clock *pc, fmode_t f_mode); |
57 | ||
a3f8683b | 58 | __poll_t (*poll) (struct posix_clock *pc, |
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59 | struct file *file, poll_table *wait); |
60 | ||
61 | int (*release) (struct posix_clock *pc); | |
62 | ||
63 | ssize_t (*read) (struct posix_clock *pc, | |
64 | uint flags, char __user *buf, size_t cnt); | |
65 | }; | |
66 | ||
67 | /** | |
68 | * struct posix_clock - represents a dynamic posix clock | |
69 | * | |
70 | * @ops: Functional interface to the clock | |
71 | * @cdev: Character device instance for this clock | |
72 | * @kref: Reference count. | |
1791f881 | 73 | * @rwsem: Protects the 'zombie' field from concurrent access. |
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74 | * @zombie: If 'zombie' is true, then the hardware has disappeared. |
75 | * @release: A function to free the structure when the reference count reaches | |
76 | * zero. May be NULL if structure is statically allocated. | |
77 | * | |
78 | * Drivers should embed their struct posix_clock within a private | |
79 | * structure, obtaining a reference to it during callbacks using | |
80 | * container_of(). | |
81 | */ | |
82 | struct posix_clock { | |
83 | struct posix_clock_operations ops; | |
84 | struct cdev cdev; | |
85 | struct kref kref; | |
1791f881 | 86 | struct rw_semaphore rwsem; |
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87 | bool zombie; |
88 | void (*release)(struct posix_clock *clk); | |
89 | }; | |
90 | ||
91 | /** | |
92 | * posix_clock_register() - register a new clock | |
93 | * @clk: Pointer to the clock. Caller must provide 'ops' and 'release' | |
94 | * @devid: Allocated device id | |
95 | * | |
96 | * A clock driver calls this function to register itself with the | |
97 | * clock device subsystem. If 'clk' points to dynamically allocated | |
98 | * memory, then the caller must provide a 'release' function to free | |
99 | * that memory. | |
100 | * | |
101 | * Returns zero on success, non-zero otherwise. | |
102 | */ | |
103 | int posix_clock_register(struct posix_clock *clk, dev_t devid); | |
104 | ||
105 | /** | |
106 | * posix_clock_unregister() - unregister a clock | |
107 | * @clk: Clock instance previously registered via posix_clock_register() | |
108 | * | |
109 | * A clock driver calls this function to remove itself from the clock | |
110 | * device subsystem. The posix_clock itself will remain (in an | |
111 | * inactive state) until its reference count drops to zero, at which | |
112 | * point it will be deallocated with its 'release' method. | |
113 | */ | |
114 | void posix_clock_unregister(struct posix_clock *clk); | |
115 | ||
116 | #endif |