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#include <linux/export.h>
27
28#include "w1_family.h"
29#include "w1.h"
30
31DEFINE_SPINLOCK(w1_flock);
32static LIST_HEAD(w1_families);
33
34/**
35 * w1_register_family() - register a device family driver
36 * @newf:	family to register
37 */
38int w1_register_family(struct w1_family *newf)
39{
40	struct list_head *ent, *n;
41	struct w1_family *f;
42	int ret = 0;
43
44	spin_lock(&w1_flock);
45	list_for_each_safe(ent, n, &w1_families) {
46		f = list_entry(ent, struct w1_family, family_entry);
47
48		if (f->fid == newf->fid) {
49			ret = -EEXIST;
50			break;
51		}
52	}
53
54	if (!ret) {
55		atomic_set(&newf->refcnt, 0);
56		list_add_tail(&newf->family_entry, &w1_families);
57	}
58	spin_unlock(&w1_flock);
59
60	/* check default devices against the new set of drivers */
61	w1_reconnect_slaves(newf, 1);
62
63	return ret;
64}
65
66/**
67 * w1_unregister_family() - unregister a device family driver
68 * @fent:	family to unregister
69 */
70void w1_unregister_family(struct w1_family *fent)
71{
72	struct list_head *ent, *n;
73	struct w1_family *f;
74
75	spin_lock(&w1_flock);
76	list_for_each_safe(ent, n, &w1_families) {
77		f = list_entry(ent, struct w1_family, family_entry);
78
79		if (f->fid == fent->fid) {
80			list_del(&fent->family_entry);
81			break;
82		}
83	}
84	spin_unlock(&w1_flock);
85
86	/* deatch devices using this family code */
87	w1_reconnect_slaves(fent, 0);
88
89	while (atomic_read(&fent->refcnt)) {
90		pr_info("Waiting for family %u to become free: refcnt=%d.\n",
91				fent->fid, atomic_read(&fent->refcnt));
92
93		if (msleep_interruptible(1000))
94			flush_signals(current);
95	}
96}
97
98/*
99 * Should be called under w1_flock held.
100 */
101struct w1_family * w1_family_registered(u8 fid)
102{
103	struct list_head *ent, *n;
104	struct w1_family *f = NULL;
105	int ret = 0;
106
107	list_for_each_safe(ent, n, &w1_families) {
108		f = list_entry(ent, struct w1_family, family_entry);
109
110		if (f->fid == fid) {
111			ret = 1;
112			break;
113		}
114	}
115
116	return (ret) ? f : NULL;
117}
118
119static void __w1_family_put(struct w1_family *f)
120{
121	atomic_dec(&f->refcnt);
122}
123
124void w1_family_put(struct w1_family *f)
125{
126	spin_lock(&w1_flock);
127	__w1_family_put(f);
128	spin_unlock(&w1_flock);
129}
130
131#if 0
132void w1_family_get(struct w1_family *f)
133{
134	spin_lock(&w1_flock);
135	__w1_family_get(f);
136	spin_unlock(&w1_flock);
137}
138#endif  /*  0  */
139
140void __w1_family_get(struct w1_family *f)
141{
142	smp_mb__before_atomic();
143	atomic_inc(&f->refcnt);
144	smp_mb__after_atomic();
145}
146
147EXPORT_SYMBOL(w1_unregister_family);
148EXPORT_SYMBOL(w1_register_family);
149