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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Evgeniy Polyakova8018762011-08-25 15:59:06 -07002 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
Evgeniy Polyakov77859252005-05-20 22:33:25 +04003 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 */
14
15#include <linux/spinlock.h>
16#include <linux/list.h>
Ingo Molnar3f07c012017-02-08 18:51:30 +010017#include <linux/sched/signal.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/delay.h>
Paul Gortmaker96239322011-07-10 13:21:52 -040019#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
21#include "w1_family.h"
Adrian Bunka9fb1c72005-12-13 14:04:33 -080022#include "w1.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
24DEFINE_SPINLOCK(w1_flock);
25static LIST_HEAD(w1_families);
26
David Friesb3be1772014-01-15 22:29:25 -060027/**
28 * w1_register_family() - register a device family driver
29 * @newf: family to register
30 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070031int w1_register_family(struct w1_family *newf)
32{
33 struct list_head *ent, *n;
34 struct w1_family *f;
35 int ret = 0;
36
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 spin_lock(&w1_flock);
38 list_for_each_safe(ent, n, &w1_families) {
39 f = list_entry(ent, struct w1_family, family_entry);
40
41 if (f->fid == newf->fid) {
42 ret = -EEXIST;
43 break;
44 }
45 }
46
47 if (!ret) {
48 atomic_set(&newf->refcnt, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 list_add_tail(&newf->family_entry, &w1_families);
50 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 spin_unlock(&w1_flock);
52
David Friesc30c9b12008-10-15 22:04:38 -070053 /* check default devices against the new set of drivers */
54 w1_reconnect_slaves(newf, 1);
Evgeniy Polyakov6adf87b2005-06-04 01:29:25 +040055
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 return ret;
57}
58
David Friesb3be1772014-01-15 22:29:25 -060059/**
60 * w1_unregister_family() - unregister a device family driver
61 * @fent: family to unregister
62 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070063void 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 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 spin_unlock(&w1_flock);
78
David Friesc30c9b12008-10-15 22:04:38 -070079 /* deatch devices using this family code */
80 w1_reconnect_slaves(fent, 0);
81
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 while (atomic_read(&fent->refcnt)) {
Fjodor Schelichowfdc91672014-06-19 02:52:00 +020083 pr_info("Waiting for family %u to become free: refcnt=%d.\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 fent->fid, atomic_read(&fent->refcnt));
85
86 if (msleep_interruptible(1000))
87 flush_signals(current);
88 }
89}
90
91/*
92 * Should be called under w1_flock held.
93 */
94struct w1_family * w1_family_registered(u8 fid)
95{
96 struct list_head *ent, *n;
97 struct w1_family *f = NULL;
98 int ret = 0;
99
100 list_for_each_safe(ent, n, &w1_families) {
101 f = list_entry(ent, struct w1_family, family_entry);
102
103 if (f->fid == fid) {
104 ret = 1;
105 break;
106 }
107 }
108
109 return (ret) ? f : NULL;
110}
111
Evgeniy Polyakov70d484b2006-04-24 10:46:14 +0400112static void __w1_family_put(struct w1_family *f)
113{
David Friesfe3cb822008-10-15 22:04:52 -0700114 atomic_dec(&f->refcnt);
Evgeniy Polyakov70d484b2006-04-24 10:46:14 +0400115}
116
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117void w1_family_put(struct w1_family *f)
118{
119 spin_lock(&w1_flock);
120 __w1_family_put(f);
121 spin_unlock(&w1_flock);
122}
123
Evgeniy Polyakov70d484b2006-04-24 10:46:14 +0400124#if 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125void w1_family_get(struct w1_family *f)
126{
127 spin_lock(&w1_flock);
128 __w1_family_get(f);
129 spin_unlock(&w1_flock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130}
Evgeniy Polyakov70d484b2006-04-24 10:46:14 +0400131#endif /* 0 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
133void __w1_family_get(struct w1_family *f)
134{
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100135 smp_mb__before_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 atomic_inc(&f->refcnt);
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100137 smp_mb__after_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138}
139
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140EXPORT_SYMBOL(w1_unregister_family);
141EXPORT_SYMBOL(w1_register_family);