1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
4 */
5
6#include <linux/spinlock.h>
7#include <linux/list.h>
8#include <linux/sched/signal.h>
9#include <linux/delay.h>
10#include <linux/export.h>
11
12#include "w1_internal.h"
13
14DEFINE_SPINLOCK(w1_flock);
15static LIST_HEAD(w1_families);
16
17/**
18 * w1_register_family() - register a device family driver
19 * @newf:	family to register
20 */
21int w1_register_family(struct w1_family *newf)
22{
23	struct list_head *ent, *n;
24	struct w1_family *f;
25	int ret = 0;
26
27	spin_lock(&w1_flock);
28	list_for_each_safe(ent, n, &w1_families) {
29		f = list_entry(ent, struct w1_family, family_entry);
30
31		if (f->fid == newf->fid) {
32			ret = -EEXIST;
33			break;
34		}
35	}
36
37	if (!ret) {
38		atomic_set(&newf->refcnt, 0);
39		list_add_tail(&newf->family_entry, &w1_families);
40	}
41	spin_unlock(&w1_flock);
42
43	/* check default devices against the new set of drivers */
44	w1_reconnect_slaves(newf, 1);
45
46	return ret;
47}
48EXPORT_SYMBOL(w1_register_family);
49
50/**
51 * w1_unregister_family() - unregister a device family driver
52 * @fent:	family to unregister
53 */
54void w1_unregister_family(struct w1_family *fent)
55{
56	struct list_head *ent, *n;
57	struct w1_family *f;
58
59	spin_lock(&w1_flock);
60	list_for_each_safe(ent, n, &w1_families) {
61		f = list_entry(ent, struct w1_family, family_entry);
62
63		if (f->fid == fent->fid) {
64			list_del(&fent->family_entry);
65			break;
66		}
67	}
68	spin_unlock(&w1_flock);
69
70	/* deatch devices using this family code */
71	w1_reconnect_slaves(fent, 0);
72
73	while (atomic_read(&fent->refcnt)) {
74		pr_info("Waiting for family %u to become free: refcnt=%d.\n",
75				fent->fid, atomic_read(&fent->refcnt));
76
77		if (msleep_interruptible(1000))
78			flush_signals(current);
79	}
80}
81EXPORT_SYMBOL(w1_unregister_family);
82
83/*
84 * Should be called under w1_flock held.
85 */
86struct w1_family * w1_family_registered(u8 fid)
87{
88	struct list_head *ent, *n;
89	struct w1_family *f = NULL;
90	int ret = 0;
91
92	list_for_each_safe(ent, n, &w1_families) {
93		f = list_entry(ent, struct w1_family, family_entry);
94
95		if (f->fid == fid) {
96			ret = 1;
97			break;
98		}
99	}
100
101	return (ret) ? f : NULL;
102}
103
104static void __w1_family_put(struct w1_family *f)
105{
106	atomic_dec(&f->refcnt);
107}
108
109void 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#if 0
117void w1_family_get(struct w1_family *f)
118{
119	spin_lock(&w1_flock);
120	__w1_family_get(f);
121	spin_unlock(&w1_flock);
122}
123#endif  /*  0  */
124
125void __w1_family_get(struct w1_family *f)
126{
127	smp_mb__before_atomic();
128	atomic_inc(&f->refcnt);
129	smp_mb__after_atomic();
130}
131