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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> |
27 | #include <linux/rwsem.h> |
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 |
48 | * @timer_settime: Set a timer's initial expiration and interval |
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. |
108 | * @rwsem: Protects the 'zombie' field from concurrent access. |
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; |
121 | struct rw_semaphore rwsem; |
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 |
152 |
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