[PATCH] crc16: remove w1 specific comments.
[linux-2.6.git] / drivers / w1 / w1_family.c
1 /*
2  *      w1_family.c
3  *
4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
5  *
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  */
21
22 #include <linux/spinlock.h>
23 #include <linux/list.h>
24 #include <linux/delay.h>
25
26 #include "w1_family.h"
27
28 DEFINE_SPINLOCK(w1_flock);
29 static LIST_HEAD(w1_families);
30 extern void w1_reconnect_slaves(struct w1_family *f);
31
32 int w1_register_family(struct w1_family *newf)
33 {
34         struct list_head *ent, *n;
35         struct w1_family *f;
36         int ret = 0;
37
38         spin_lock(&w1_flock);
39         list_for_each_safe(ent, n, &w1_families) {
40                 f = list_entry(ent, struct w1_family, family_entry);
41
42                 if (f->fid == newf->fid) {
43                         ret = -EEXIST;
44                         break;
45                 }
46         }
47
48         if (!ret) {
49                 atomic_set(&newf->refcnt, 0);
50                 newf->need_exit = 0;
51                 list_add_tail(&newf->family_entry, &w1_families);
52         }
53         spin_unlock(&w1_flock);
54
55         w1_reconnect_slaves(newf);
56
57         return ret;
58 }
59
60 void w1_unregister_family(struct w1_family *fent)
61 {
62         struct list_head *ent, *n;
63         struct w1_family *f;
64
65         spin_lock(&w1_flock);
66         list_for_each_safe(ent, n, &w1_families) {
67                 f = list_entry(ent, struct w1_family, family_entry);
68
69                 if (f->fid == fent->fid) {
70                         list_del(&fent->family_entry);
71                         break;
72                 }
73         }
74
75         fent->need_exit = 1;
76
77         spin_unlock(&w1_flock);
78
79         while (atomic_read(&fent->refcnt)) {
80                 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
81                                 fent->fid, atomic_read(&fent->refcnt));
82
83                 if (msleep_interruptible(1000))
84                         flush_signals(current);
85         }
86 }
87
88 /*
89  * Should be called under w1_flock held.
90  */
91 struct w1_family * w1_family_registered(u8 fid)
92 {
93         struct list_head *ent, *n;
94         struct w1_family *f = NULL;
95         int ret = 0;
96
97         list_for_each_safe(ent, n, &w1_families) {
98                 f = list_entry(ent, struct w1_family, family_entry);
99
100                 if (f->fid == fid) {
101                         ret = 1;
102                         break;
103                 }
104         }
105
106         return (ret) ? f : NULL;
107 }
108
109 void w1_family_put(struct w1_family *f)
110 {
111         spin_lock(&w1_flock);
112         __w1_family_put(f);
113         spin_unlock(&w1_flock);
114 }
115
116 void __w1_family_put(struct w1_family *f)
117 {
118         if (atomic_dec_and_test(&f->refcnt))
119                 f->need_exit = 1;
120 }
121
122 void w1_family_get(struct w1_family *f)
123 {
124         spin_lock(&w1_flock);
125         __w1_family_get(f);
126         spin_unlock(&w1_flock);
127
128 }
129
130 void __w1_family_get(struct w1_family *f)
131 {
132         smp_mb__before_atomic_inc();
133         atomic_inc(&f->refcnt);
134         smp_mb__after_atomic_inc();
135 }
136
137 EXPORT_SYMBOL(w1_family_get);
138 EXPORT_SYMBOL(w1_family_put);
139 EXPORT_SYMBOL(w1_family_registered);
140 EXPORT_SYMBOL(w1_unregister_family);
141 EXPORT_SYMBOL(w1_register_family);