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130 lines · 2.5 KiB

1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (c) 2004 Evgeniy Polyakov <[email protected]>
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}