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3bd69ad1 AE |
1 | /* |
2 | * Copyright 2008 by Andreas Eversberg <andreas@eversberg.eu> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, | |
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | * GNU General Public License for more details. | |
12 | * | |
13 | * Quick API description: | |
14 | * | |
15 | * A clock source registers using mISDN_register_clock: | |
475be4d8 | 16 | * name = text string to name clock source |
3bd69ad1 AE |
17 | * priority = value to priorize clock sources (0 = default) |
18 | * ctl = callback function to enable/disable clock source | |
19 | * priv = private pointer of clock source | |
475be4d8 | 20 | * return = pointer to clock source structure; |
3bd69ad1 AE |
21 | * |
22 | * Note: Callback 'ctl' can be called before mISDN_register_clock returns! | |
23 | * Also it can be called during mISDN_unregister_clock. | |
24 | * | |
25 | * A clock source calls mISDN_clock_update with given samples elapsed, if | |
26 | * enabled. If function call is delayed, tv must be set with the timestamp | |
27 | * of the actual event. | |
28 | * | |
29 | * A clock source unregisters using mISDN_unregister_clock. | |
30 | * | |
31 | * To get current clock, call mISDN_clock_get. The signed short value | |
32 | * counts the number of samples since. Time since last clock event is added. | |
33 | * | |
34 | */ | |
35 | ||
5a0e3ad6 | 36 | #include <linux/slab.h> |
3bd69ad1 AE |
37 | #include <linux/types.h> |
38 | #include <linux/stddef.h> | |
39 | #include <linux/spinlock.h> | |
ebf918cf | 40 | #include <linux/ktime.h> |
3bd69ad1 | 41 | #include <linux/mISDNif.h> |
5d76fc21 | 42 | #include <linux/export.h> |
3bd69ad1 AE |
43 | #include "core.h" |
44 | ||
45 | static u_int *debug; | |
46 | static LIST_HEAD(iclock_list); | |
f8532fde HE |
47 | static DEFINE_RWLOCK(iclock_lock); |
48 | static u16 iclock_count; /* counter of last clock */ | |
ebf918cf TR |
49 | static ktime_t iclock_timestamp; /* time stamp of last clock */ |
50 | static int iclock_timestamp_valid; /* already received one timestamp */ | |
f8532fde | 51 | static struct mISDNclock *iclock_current; |
3bd69ad1 AE |
52 | |
53 | void | |
54 | mISDN_init_clock(u_int *dp) | |
55 | { | |
56 | debug = dp; | |
ebf918cf | 57 | iclock_timestamp = ktime_get(); |
3bd69ad1 AE |
58 | } |
59 | ||
60 | static void | |
61 | select_iclock(void) | |
62 | { | |
63 | struct mISDNclock *iclock, *bestclock = NULL, *lastclock = NULL; | |
64 | int pri = -128; | |
65 | ||
66 | list_for_each_entry(iclock, &iclock_list, list) { | |
67 | if (iclock->pri > pri) { | |
68 | pri = iclock->pri; | |
69 | bestclock = iclock; | |
70 | } | |
71 | if (iclock_current == iclock) | |
72 | lastclock = iclock; | |
73 | } | |
74 | if (lastclock && bestclock != lastclock) { | |
75 | /* last used clock source still exists but changes, disable */ | |
76 | if (*debug & DEBUG_CLOCK) | |
77 | printk(KERN_DEBUG "Old clock source '%s' disable.\n", | |
475be4d8 | 78 | lastclock->name); |
3bd69ad1 AE |
79 | lastclock->ctl(lastclock->priv, 0); |
80 | } | |
81 | if (bestclock && bestclock != iclock_current) { | |
82 | /* new clock source selected, enable */ | |
83 | if (*debug & DEBUG_CLOCK) | |
84 | printk(KERN_DEBUG "New clock source '%s' enable.\n", | |
475be4d8 | 85 | bestclock->name); |
3bd69ad1 AE |
86 | bestclock->ctl(bestclock->priv, 1); |
87 | } | |
88 | if (bestclock != iclock_current) { | |
89 | /* no clock received yet */ | |
ebf918cf | 90 | iclock_timestamp_valid = 0; |
3bd69ad1 AE |
91 | } |
92 | iclock_current = bestclock; | |
93 | } | |
94 | ||
95 | struct mISDNclock | |
96 | *mISDN_register_clock(char *name, int pri, clockctl_func_t *ctl, void *priv) | |
97 | { | |
98 | u_long flags; | |
99 | struct mISDNclock *iclock; | |
100 | ||
101 | if (*debug & (DEBUG_CORE | DEBUG_CLOCK)) | |
102 | printk(KERN_DEBUG "%s: %s %d\n", __func__, name, pri); | |
103 | iclock = kzalloc(sizeof(struct mISDNclock), GFP_ATOMIC); | |
104 | if (!iclock) { | |
105 | printk(KERN_ERR "%s: No memory for clock entry.\n", __func__); | |
106 | return NULL; | |
107 | } | |
475be4d8 | 108 | strncpy(iclock->name, name, sizeof(iclock->name) - 1); |
3bd69ad1 AE |
109 | iclock->pri = pri; |
110 | iclock->priv = priv; | |
111 | iclock->ctl = ctl; | |
112 | write_lock_irqsave(&iclock_lock, flags); | |
113 | list_add_tail(&iclock->list, &iclock_list); | |
114 | select_iclock(); | |
115 | write_unlock_irqrestore(&iclock_lock, flags); | |
116 | return iclock; | |
117 | } | |
118 | EXPORT_SYMBOL(mISDN_register_clock); | |
119 | ||
120 | void | |
121 | mISDN_unregister_clock(struct mISDNclock *iclock) | |
122 | { | |
123 | u_long flags; | |
124 | ||
125 | if (*debug & (DEBUG_CORE | DEBUG_CLOCK)) | |
126 | printk(KERN_DEBUG "%s: %s %d\n", __func__, iclock->name, | |
475be4d8 | 127 | iclock->pri); |
3bd69ad1 AE |
128 | write_lock_irqsave(&iclock_lock, flags); |
129 | if (iclock_current == iclock) { | |
130 | if (*debug & DEBUG_CLOCK) | |
131 | printk(KERN_DEBUG | |
475be4d8 JP |
132 | "Current clock source '%s' unregisters.\n", |
133 | iclock->name); | |
3bd69ad1 AE |
134 | iclock->ctl(iclock->priv, 0); |
135 | } | |
136 | list_del(&iclock->list); | |
137 | select_iclock(); | |
138 | write_unlock_irqrestore(&iclock_lock, flags); | |
139 | } | |
140 | EXPORT_SYMBOL(mISDN_unregister_clock); | |
141 | ||
142 | void | |
ebf918cf | 143 | mISDN_clock_update(struct mISDNclock *iclock, int samples, ktime_t *timestamp) |
3bd69ad1 AE |
144 | { |
145 | u_long flags; | |
ebf918cf TR |
146 | ktime_t timestamp_now; |
147 | u16 delta; | |
3bd69ad1 AE |
148 | |
149 | write_lock_irqsave(&iclock_lock, flags); | |
150 | if (iclock_current != iclock) { | |
151 | printk(KERN_ERR "%s: '%s' sends us clock updates, but we do " | |
475be4d8 JP |
152 | "listen to '%s'. This is a bug!\n", __func__, |
153 | iclock->name, | |
154 | iclock_current ? iclock_current->name : "nothing"); | |
3bd69ad1 AE |
155 | iclock->ctl(iclock->priv, 0); |
156 | write_unlock_irqrestore(&iclock_lock, flags); | |
157 | return; | |
158 | } | |
ebf918cf | 159 | if (iclock_timestamp_valid) { |
3bd69ad1 AE |
160 | /* increment sample counter by given samples */ |
161 | iclock_count += samples; | |
ebf918cf TR |
162 | if (timestamp) { /* timestamp must be set, if function call is delayed */ |
163 | iclock_timestamp = *timestamp; | |
164 | } else { | |
165 | iclock_timestamp = ktime_get(); | |
166 | } | |
3bd69ad1 AE |
167 | } else { |
168 | /* calc elapsed time by system clock */ | |
ebf918cf TR |
169 | if (timestamp) { /* timestamp must be set, if function call is delayed */ |
170 | timestamp_now = *timestamp; | |
171 | } else { | |
172 | timestamp_now = ktime_get(); | |
3bd69ad1 | 173 | } |
ebf918cf TR |
174 | delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp), |
175 | (NSEC_PER_SEC / 8000)); | |
3bd69ad1 | 176 | /* add elapsed time to counter and set new timestamp */ |
ebf918cf TR |
177 | iclock_count += delta; |
178 | iclock_timestamp = timestamp_now; | |
179 | iclock_timestamp_valid = 1; | |
3bd69ad1 AE |
180 | if (*debug & DEBUG_CLOCK) |
181 | printk("Received first clock from source '%s'.\n", | |
475be4d8 | 182 | iclock_current ? iclock_current->name : "nothing"); |
3bd69ad1 AE |
183 | } |
184 | write_unlock_irqrestore(&iclock_lock, flags); | |
185 | } | |
186 | EXPORT_SYMBOL(mISDN_clock_update); | |
187 | ||
188 | unsigned short | |
189 | mISDN_clock_get(void) | |
190 | { | |
191 | u_long flags; | |
ebf918cf TR |
192 | ktime_t timestamp_now; |
193 | u16 delta; | |
3bd69ad1 AE |
194 | u16 count; |
195 | ||
196 | read_lock_irqsave(&iclock_lock, flags); | |
197 | /* calc elapsed time by system clock */ | |
ebf918cf TR |
198 | timestamp_now = ktime_get(); |
199 | delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp), | |
200 | (NSEC_PER_SEC / 8000)); | |
3bd69ad1 | 201 | /* add elapsed time to counter */ |
ebf918cf | 202 | count = iclock_count + delta; |
3bd69ad1 AE |
203 | read_unlock_irqrestore(&iclock_lock, flags); |
204 | return count; | |
205 | } | |
206 | EXPORT_SYMBOL(mISDN_clock_get); |