1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
|
/*
* Copyright 2008 by Andreas Eversberg <andreas@eversberg.eu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Quick API description:
*
* A clock source registers using mISDN_register_clock:
* name = text string to name clock source
* priority = value to priorize clock sources (0 = default)
* ctl = callback function to enable/disable clock source
* priv = private pointer of clock source
* return = pointer to clock source structure;
*
* Note: Callback 'ctl' can be called before mISDN_register_clock returns!
* Also it can be called during mISDN_unregister_clock.
*
* A clock source calls mISDN_clock_update with given samples elapsed, if
* enabled. If function call is delayed, tv must be set with the timestamp
* of the actual event.
*
* A clock source unregisters using mISDN_unregister_clock.
*
* To get current clock, call mISDN_clock_get. The signed short value
* counts the number of samples since. Time since last clock event is added.
*
*/
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <linux/mISDNif.h>
#include <linux/export.h>
#include "core.h"
static u_int *debug;
static LIST_HEAD(iclock_list);
static DEFINE_RWLOCK(iclock_lock);
static u16 iclock_count; /* counter of last clock */
static struct timeval iclock_tv; /* time stamp of last clock */
static int iclock_tv_valid; /* already received one timestamp */
static struct mISDNclock *iclock_current;
void
mISDN_init_clock(u_int *dp)
{
debug = dp;
do_gettimeofday(&iclock_tv);
}
static void
select_iclock(void)
{
struct mISDNclock *iclock, *bestclock = NULL, *lastclock = NULL;
int pri = -128;
list_for_each_entry(iclock, &iclock_list, list) {
if (iclock->pri > pri) {
pri = iclock->pri;
bestclock = iclock;
}
if (iclock_current == iclock)
lastclock = iclock;
}
if (lastclock && bestclock != lastclock) {
/* last used clock source still exists but changes, disable */
if (*debug & DEBUG_CLOCK)
printk(KERN_DEBUG "Old clock source '%s' disable.\n",
lastclock->name);
lastclock->ctl(lastclock->priv, 0);
}
if (bestclock && bestclock != iclock_current) {
/* new clock source selected, enable */
if (*debug & DEBUG_CLOCK)
printk(KERN_DEBUG "New clock source '%s' enable.\n",
bestclock->name);
bestclock->ctl(bestclock->priv, 1);
}
if (bestclock != iclock_current) {
/* no clock received yet */
iclock_tv_valid = 0;
}
iclock_current = bestclock;
}
struct mISDNclock
*mISDN_register_clock(char *name, int pri, clockctl_func_t *ctl, void *priv)
{
u_long flags;
struct mISDNclock *iclock;
if (*debug & (DEBUG_CORE | DEBUG_CLOCK))
printk(KERN_DEBUG "%s: %s %d\n", __func__, name, pri);
iclock = kzalloc(sizeof(struct mISDNclock), GFP_ATOMIC);
if (!iclock) {
printk(KERN_ERR "%s: No memory for clock entry.\n", __func__);
return NULL;
}
strncpy(iclock->name, name, sizeof(iclock->name)-1);
iclock->pri = pri;
iclock->priv = priv;
iclock->ctl = ctl;
write_lock_irqsave(&iclock_lock, flags);
list_add_tail(&iclock->list, &iclock_list);
select_iclock();
write_unlock_irqrestore(&iclock_lock, flags);
return iclock;
}
EXPORT_SYMBOL(mISDN_register_clock);
void
mISDN_unregister_clock(struct mISDNclock *iclock)
{
u_long flags;
if (*debug & (DEBUG_CORE | DEBUG_CLOCK))
printk(KERN_DEBUG "%s: %s %d\n", __func__, iclock->name,
iclock->pri);
write_lock_irqsave(&iclock_lock, flags);
if (iclock_current == iclock) {
if (*debug & DEBUG_CLOCK)
printk(KERN_DEBUG
"Current clock source '%s' unregisters.\n",
iclock->name);
iclock->ctl(iclock->priv, 0);
}
list_del(&iclock->list);
select_iclock();
write_unlock_irqrestore(&iclock_lock, flags);
}
EXPORT_SYMBOL(mISDN_unregister_clock);
void
mISDN_clock_update(struct mISDNclock *iclock, int samples, struct timeval *tv)
{
u_long flags;
struct timeval tv_now;
time_t elapsed_sec;
int elapsed_8000th;
write_lock_irqsave(&iclock_lock, flags);
if (iclock_current != iclock) {
printk(KERN_ERR "%s: '%s' sends us clock updates, but we do "
"listen to '%s'. This is a bug!\n", __func__,
iclock->name,
iclock_current ? iclock_current->name : "nothing");
iclock->ctl(iclock->priv, 0);
write_unlock_irqrestore(&iclock_lock, flags);
return;
}
if (iclock_tv_valid) {
/* increment sample counter by given samples */
iclock_count += samples;
if (tv) { /* tv must be set, if function call is delayed */
iclock_tv.tv_sec = tv->tv_sec;
iclock_tv.tv_usec = tv->tv_usec;
} else
do_gettimeofday(&iclock_tv);
} else {
/* calc elapsed time by system clock */
if (tv) { /* tv must be set, if function call is delayed */
tv_now.tv_sec = tv->tv_sec;
tv_now.tv_usec = tv->tv_usec;
} else
do_gettimeofday(&tv_now);
elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
elapsed_8000th = (tv_now.tv_usec / 125)
- (iclock_tv.tv_usec / 125);
if (elapsed_8000th < 0) {
elapsed_sec -= 1;
elapsed_8000th += 8000;
}
/* add elapsed time to counter and set new timestamp */
iclock_count += elapsed_sec * 8000 + elapsed_8000th;
iclock_tv.tv_sec = tv_now.tv_sec;
iclock_tv.tv_usec = tv_now.tv_usec;
iclock_tv_valid = 1;
if (*debug & DEBUG_CLOCK)
printk("Received first clock from source '%s'.\n",
iclock_current ? iclock_current->name : "nothing");
}
write_unlock_irqrestore(&iclock_lock, flags);
}
EXPORT_SYMBOL(mISDN_clock_update);
unsigned short
mISDN_clock_get(void)
{
u_long flags;
struct timeval tv_now;
time_t elapsed_sec;
int elapsed_8000th;
u16 count;
read_lock_irqsave(&iclock_lock, flags);
/* calc elapsed time by system clock */
do_gettimeofday(&tv_now);
elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
elapsed_8000th = (tv_now.tv_usec / 125) - (iclock_tv.tv_usec / 125);
if (elapsed_8000th < 0) {
elapsed_sec -= 1;
elapsed_8000th += 8000;
}
/* add elapsed time to counter */
count = iclock_count + elapsed_sec * 8000 + elapsed_8000th;
read_unlock_irqrestore(&iclock_lock, flags);
return count;
}
EXPORT_SYMBOL(mISDN_clock_get);
|
