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1 | /* |
2 | * posix-clock.h - support for dynamic clock devices | |
3 | * | |
4 | * Copyright (C) 2010 OMICRON electronics GmbH | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | #ifndef _LINUX_POSIX_CLOCK_H_ | |
21 | #define _LINUX_POSIX_CLOCK_H_ | |
22 | ||
23 | #include <linux/cdev.h> | |
24 | #include <linux/fs.h> | |
25 | #include <linux/poll.h> | |
26 | #include <linux/posix-timers.h> | |
1791f881 | 27 | #include <linux/rwsem.h> |
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28 | |
29 | struct posix_clock; | |
30 | ||
31 | /** | |
32 | * struct posix_clock_operations - functional interface to the clock | |
33 | * | |
34 | * Every posix clock is represented by a character device. Drivers may | |
35 | * optionally offer extended capabilities by implementing the | |
36 | * character device methods. The character device file operations are | |
37 | * first handled by the clock device layer, then passed on to the | |
38 | * driver by calling these functions. | |
39 | * | |
40 | * @owner: The clock driver should set to THIS_MODULE | |
41 | * @clock_adjtime: Adjust the clock | |
42 | * @clock_gettime: Read the current time | |
43 | * @clock_getres: Get the clock resolution | |
44 | * @clock_settime: Set the current time value | |
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45 | * @open: Optional character device open method |
46 | * @release: Optional character device release method | |
47 | * @ioctl: Optional character device ioctl method | |
48 | * @read: Optional character device read method | |
49 | * @poll: Optional character device poll method | |
50 | */ | |
51 | struct posix_clock_operations { | |
52 | struct module *owner; | |
53 | ||
54 | int (*clock_adjtime)(struct posix_clock *pc, struct timex *tx); | |
55 | ||
d340266e | 56 | int (*clock_gettime)(struct posix_clock *pc, struct timespec64 *ts); |
0606f422 | 57 | |
d340266e | 58 | int (*clock_getres) (struct posix_clock *pc, struct timespec64 *ts); |
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59 | |
60 | int (*clock_settime)(struct posix_clock *pc, | |
d340266e | 61 | const struct timespec64 *ts); |
0606f422 | 62 | |
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63 | /* |
64 | * Optional character device methods: | |
65 | */ | |
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66 | long (*ioctl) (struct posix_clock *pc, |
67 | unsigned int cmd, unsigned long arg); | |
68 | ||
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69 | int (*open) (struct posix_clock *pc, fmode_t f_mode); |
70 | ||
a3f8683b | 71 | __poll_t (*poll) (struct posix_clock *pc, |
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72 | struct file *file, poll_table *wait); |
73 | ||
74 | int (*release) (struct posix_clock *pc); | |
75 | ||
76 | ssize_t (*read) (struct posix_clock *pc, | |
77 | uint flags, char __user *buf, size_t cnt); | |
78 | }; | |
79 | ||
80 | /** | |
81 | * struct posix_clock - represents a dynamic posix clock | |
82 | * | |
83 | * @ops: Functional interface to the clock | |
84 | * @cdev: Character device instance for this clock | |
85 | * @kref: Reference count. | |
1791f881 | 86 | * @rwsem: Protects the 'zombie' field from concurrent access. |
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87 | * @zombie: If 'zombie' is true, then the hardware has disappeared. |
88 | * @release: A function to free the structure when the reference count reaches | |
89 | * zero. May be NULL if structure is statically allocated. | |
90 | * | |
91 | * Drivers should embed their struct posix_clock within a private | |
92 | * structure, obtaining a reference to it during callbacks using | |
93 | * container_of(). | |
94 | */ | |
95 | struct posix_clock { | |
96 | struct posix_clock_operations ops; | |
97 | struct cdev cdev; | |
98 | struct kref kref; | |
1791f881 | 99 | struct rw_semaphore rwsem; |
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100 | bool zombie; |
101 | void (*release)(struct posix_clock *clk); | |
102 | }; | |
103 | ||
104 | /** | |
105 | * posix_clock_register() - register a new clock | |
106 | * @clk: Pointer to the clock. Caller must provide 'ops' and 'release' | |
107 | * @devid: Allocated device id | |
108 | * | |
109 | * A clock driver calls this function to register itself with the | |
110 | * clock device subsystem. If 'clk' points to dynamically allocated | |
111 | * memory, then the caller must provide a 'release' function to free | |
112 | * that memory. | |
113 | * | |
114 | * Returns zero on success, non-zero otherwise. | |
115 | */ | |
116 | int posix_clock_register(struct posix_clock *clk, dev_t devid); | |
117 | ||
118 | /** | |
119 | * posix_clock_unregister() - unregister a clock | |
120 | * @clk: Clock instance previously registered via posix_clock_register() | |
121 | * | |
122 | * A clock driver calls this function to remove itself from the clock | |
123 | * device subsystem. The posix_clock itself will remain (in an | |
124 | * inactive state) until its reference count drops to zero, at which | |
125 | * point it will be deallocated with its 'release' method. | |
126 | */ | |
127 | void posix_clock_unregister(struct posix_clock *clk); | |
128 | ||
129 | #endif |