tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15#include <linux/spinlock.h>
16#include <linux/list.h>
17#include <linux/sched/signal.h>
18#include <linux/delay.h>
19#include <linux/export.h>
20
21#include "w1_internal.h"
22
23DEFINE_SPINLOCK(w1_flock);
24static LIST_HEAD(w1_families);
25
26/**
27 * w1_register_family() - register a device family driver
28 * @newf: family to register
29 */
30int w1_register_family(struct w1_family *newf)
31{
32 struct list_head *ent, *n;
33 struct w1_family *f;
34 int ret = 0;
35
36 spin_lock(&w1_flock);
37 list_for_each_safe(ent, n, &w1_families) {
38 f = list_entry(ent, struct w1_family, family_entry);
39
40 if (f->fid == newf->fid) {
41 ret = -EEXIST;
42 break;
43 }
44 }
45
46 if (!ret) {
47 atomic_set(&newf->refcnt, 0);
48 list_add_tail(&newf->family_entry, &w1_families);
49 }
50 spin_unlock(&w1_flock);
51
52 /* check default devices against the new set of drivers */
53 w1_reconnect_slaves(newf, 1);
54
55 return ret;
56}
57EXPORT_SYMBOL(w1_register_family);
58
59/**
60 * w1_unregister_family() - unregister a device family driver
61 * @fent: family to unregister
62 */
63void w1_unregister_family(struct w1_family *fent)
64{
65 struct list_head *ent, *n;
66 struct w1_family *f;
67
68 spin_lock(&w1_flock);
69 list_for_each_safe(ent, n, &w1_families) {
70 f = list_entry(ent, struct w1_family, family_entry);
71
72 if (f->fid == fent->fid) {
73 list_del(&fent->family_entry);
74 break;
75 }
76 }
77 spin_unlock(&w1_flock);
78
79 /* deatch devices using this family code */
80 w1_reconnect_slaves(fent, 0);
81
82 while (atomic_read(&fent->refcnt)) {
83 pr_info("Waiting for family %u to become free: refcnt=%d.\n",
84 fent->fid, atomic_read(&fent->refcnt));
85
86 if (msleep_interruptible(1000))
87 flush_signals(current);
88 }
89}
90EXPORT_SYMBOL(w1_unregister_family);
91
92/*
93 * Should be called under w1_flock held.
94 */
95struct w1_family * w1_family_registered(u8 fid)
96{
97 struct list_head *ent, *n;
98 struct w1_family *f = NULL;
99 int ret = 0;
100
101 list_for_each_safe(ent, n, &w1_families) {
102 f = list_entry(ent, struct w1_family, family_entry);
103
104 if (f->fid == fid) {
105 ret = 1;
106 break;
107 }
108 }
109
110 return (ret) ? f : NULL;
111}
112
113static void __w1_family_put(struct w1_family *f)
114{
115 atomic_dec(&f->refcnt);
116}
117
118void w1_family_put(struct w1_family *f)
119{
120 spin_lock(&w1_flock);
121 __w1_family_put(f);
122 spin_unlock(&w1_flock);
123}
124
125#if 0
126void w1_family_get(struct w1_family *f)
127{
128 spin_lock(&w1_flock);
129 __w1_family_get(f);
130 spin_unlock(&w1_flock);
131}
132#endif /* 0 */
133
134void __w1_family_get(struct w1_family *f)
135{
136 smp_mb__before_atomic();
137 atomic_inc(&f->refcnt);
138 smp_mb__after_atomic();
139}