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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 | |
45 | * @timer_create: Create a new timer | |
46 | * @timer_delete: Remove a previously created timer | |
47 | * @timer_gettime: Get remaining time and interval of a timer | |
70f23fd6 | 48 | * @timer_settime: Set a timer's initial expiration and interval |
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49 | * @fasync: Optional character device fasync method |
50 | * @mmap: Optional character device mmap method | |
51 | * @open: Optional character device open method | |
52 | * @release: Optional character device release method | |
53 | * @ioctl: Optional character device ioctl method | |
54 | * @read: Optional character device read method | |
55 | * @poll: Optional character device poll method | |
56 | */ | |
57 | struct posix_clock_operations { | |
58 | struct module *owner; | |
59 | ||
60 | int (*clock_adjtime)(struct posix_clock *pc, struct timex *tx); | |
61 | ||
62 | int (*clock_gettime)(struct posix_clock *pc, struct timespec *ts); | |
63 | ||
64 | int (*clock_getres) (struct posix_clock *pc, struct timespec *ts); | |
65 | ||
66 | int (*clock_settime)(struct posix_clock *pc, | |
67 | const struct timespec *ts); | |
68 | ||
69 | int (*timer_create) (struct posix_clock *pc, struct k_itimer *kit); | |
70 | ||
71 | int (*timer_delete) (struct posix_clock *pc, struct k_itimer *kit); | |
72 | ||
73 | void (*timer_gettime)(struct posix_clock *pc, | |
74 | struct k_itimer *kit, struct itimerspec *tsp); | |
75 | ||
76 | int (*timer_settime)(struct posix_clock *pc, | |
77 | struct k_itimer *kit, int flags, | |
78 | struct itimerspec *tsp, struct itimerspec *old); | |
79 | /* | |
80 | * Optional character device methods: | |
81 | */ | |
82 | int (*fasync) (struct posix_clock *pc, | |
83 | int fd, struct file *file, int on); | |
84 | ||
85 | long (*ioctl) (struct posix_clock *pc, | |
86 | unsigned int cmd, unsigned long arg); | |
87 | ||
88 | int (*mmap) (struct posix_clock *pc, | |
89 | struct vm_area_struct *vma); | |
90 | ||
91 | int (*open) (struct posix_clock *pc, fmode_t f_mode); | |
92 | ||
93 | uint (*poll) (struct posix_clock *pc, | |
94 | struct file *file, poll_table *wait); | |
95 | ||
96 | int (*release) (struct posix_clock *pc); | |
97 | ||
98 | ssize_t (*read) (struct posix_clock *pc, | |
99 | uint flags, char __user *buf, size_t cnt); | |
100 | }; | |
101 | ||
102 | /** | |
103 | * struct posix_clock - represents a dynamic posix clock | |
104 | * | |
105 | * @ops: Functional interface to the clock | |
106 | * @cdev: Character device instance for this clock | |
107 | * @kref: Reference count. | |
1791f881 | 108 | * @rwsem: Protects the 'zombie' field from concurrent access. |
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109 | * @zombie: If 'zombie' is true, then the hardware has disappeared. |
110 | * @release: A function to free the structure when the reference count reaches | |
111 | * zero. May be NULL if structure is statically allocated. | |
112 | * | |
113 | * Drivers should embed their struct posix_clock within a private | |
114 | * structure, obtaining a reference to it during callbacks using | |
115 | * container_of(). | |
116 | */ | |
117 | struct posix_clock { | |
118 | struct posix_clock_operations ops; | |
119 | struct cdev cdev; | |
120 | struct kref kref; | |
1791f881 | 121 | struct rw_semaphore rwsem; |
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122 | bool zombie; |
123 | void (*release)(struct posix_clock *clk); | |
124 | }; | |
125 | ||
126 | /** | |
127 | * posix_clock_register() - register a new clock | |
128 | * @clk: Pointer to the clock. Caller must provide 'ops' and 'release' | |
129 | * @devid: Allocated device id | |
130 | * | |
131 | * A clock driver calls this function to register itself with the | |
132 | * clock device subsystem. If 'clk' points to dynamically allocated | |
133 | * memory, then the caller must provide a 'release' function to free | |
134 | * that memory. | |
135 | * | |
136 | * Returns zero on success, non-zero otherwise. | |
137 | */ | |
138 | int posix_clock_register(struct posix_clock *clk, dev_t devid); | |
139 | ||
140 | /** | |
141 | * posix_clock_unregister() - unregister a clock | |
142 | * @clk: Clock instance previously registered via posix_clock_register() | |
143 | * | |
144 | * A clock driver calls this function to remove itself from the clock | |
145 | * device subsystem. The posix_clock itself will remain (in an | |
146 | * inactive state) until its reference count drops to zero, at which | |
147 | * point it will be deallocated with its 'release' method. | |
148 | */ | |
149 | void posix_clock_unregister(struct posix_clock *clk); | |
150 | ||
151 | #endif |