63359797c8b199abcf62d09122f37981bca7cc41
[linux-2.6.git] / drivers / w1 / w1_family.c
1 /*
2  *      w1_family.c
3  *
4  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
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/sched.h>        /* schedule_timeout() */
25 #include <linux/delay.h>
26
27 #include "w1_family.h"
28 #include "w1.h"
29
30 DEFINE_SPINLOCK(w1_flock);
31 static LIST_HEAD(w1_families);
32
33 int w1_register_family(struct w1_family *newf)
34 {
35         struct list_head *ent, *n;
36         struct w1_family *f;
37         int ret = 0;
38
39         spin_lock(&w1_flock);
40         list_for_each_safe(ent, n, &w1_families) {
41                 f = list_entry(ent, struct w1_family, family_entry);
42
43                 if (f->fid == newf->fid) {
44                         ret = -EEXIST;
45                         break;
46                 }
47         }
48
49         if (!ret) {
50                 atomic_set(&newf->refcnt, 0);
51                 list_add_tail(&newf->family_entry, &w1_families);
52         }
53         spin_unlock(&w1_flock);
54
55         /* check default devices against the new set of drivers */
56         w1_reconnect_slaves(newf, 1);
57
58         return ret;
59 }
60
61 void w1_unregister_family(struct w1_family *fent)
62 {
63         struct list_head *ent, *n;
64         struct w1_family *f;
65
66         spin_lock(&w1_flock);
67         list_for_each_safe(ent, n, &w1_families) {
68                 f = list_entry(ent, struct w1_family, family_entry);
69
70                 if (f->fid == fent->fid) {
71                         list_del(&fent->family_entry);
72                         break;
73                 }
74         }
75         spin_unlock(&w1_flock);
76
77         /* deatch devices using this family code */
78         w1_reconnect_slaves(fent, 0);
79
80         while (atomic_read(&fent->refcnt)) {
81                 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
82                                 fent->fid, atomic_read(&fent->refcnt));
83
84                 if (msleep_interruptible(1000))
85                         flush_signals(current);
86         }
87 }
88
89 /*
90  * Should be called under w1_flock held.
91  */
92 struct w1_family * w1_family_registered(u8 fid)
93 {
94         struct list_head *ent, *n;
95         struct w1_family *f = NULL;
96         int ret = 0;
97
98         list_for_each_safe(ent, n, &w1_families) {
99                 f = list_entry(ent, struct w1_family, family_entry);
100
101                 if (f->fid == fid) {
102                         ret = 1;
103                         break;
104                 }
105         }
106
107         return (ret) ? f : NULL;
108 }
109
110 static void __w1_family_put(struct w1_family *f)
111 {
112         atomic_dec(&f->refcnt);
113 }
114
115 void w1_family_put(struct w1_family *f)
116 {
117         spin_lock(&w1_flock);
118         __w1_family_put(f);
119         spin_unlock(&w1_flock);
120 }
121
122 #if 0
123 void w1_family_get(struct w1_family *f)
124 {
125         spin_lock(&w1_flock);
126         __w1_family_get(f);
127         spin_unlock(&w1_flock);
128 }
129 #endif  /*  0  */
130
131 void __w1_family_get(struct w1_family *f)
132 {
133         smp_mb__before_atomic_inc();
134         atomic_inc(&f->refcnt);
135         smp_mb__after_atomic_inc();
136 }
137
138 EXPORT_SYMBOL(w1_unregister_family);
139 EXPORT_SYMBOL(w1_register_family);