drivers/w1/w1_family.c

   1 /*
   2  *      w1_family.c
   3  *
   4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
   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/delay.h>
  25
  26 #include "w1_family.h"
  27
  28 DEFINE_SPINLOCK(w1_flock);
  29 static LIST_HEAD(w1_families);
  30 extern void w1_reconnect_slaves(struct w1_family *f);
  31
  32 int w1_register_family(struct w1_family *newf)
  33 {
  34         struct list_head *ent, *n;
  35         struct w1_family *f;
  36         int ret = 0;
  37
  38         spin_lock(&w1_flock);
  39         list_for_each_safe(ent, n, &w1_families) {
  40                 f = list_entry(ent, struct w1_family, family_entry);
  41
  42                 if (f->fid == newf->fid) {
  43                         ret = -EEXIST;
  44                         break;
  45                 }
  46         }
  47
  48         if (!ret) {
  49                 atomic_set(&newf->refcnt, 0);
  50                 newf->need_exit = 0;
  51                 list_add_tail(&newf->family_entry, &w1_families);
  52         }
  53         spin_unlock(&w1_flock);
  54
  55         w1_reconnect_slaves(newf);
  56
  57         return ret;
  58 }
  59
  60 void w1_unregister_family(struct w1_family *fent)
  61 {
  62         struct list_head *ent, *n;
  63         struct w1_family *f;
  64
  65         spin_lock(&w1_flock);
  66         list_for_each_safe(ent, n, &w1_families) {
  67                 f = list_entry(ent, struct w1_family, family_entry);
  68
  69                 if (f->fid == fent->fid) {
  70                         list_del(&fent->family_entry);
  71                         break;
  72                 }
  73         }
  74
  75         fent->need_exit = 1;
  76
  77         spin_unlock(&w1_flock);
  78
  79         while (atomic_read(&fent->refcnt)) {
  80                 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
  81                                 fent->fid, atomic_read(&fent->refcnt));
  82
  83                 if (msleep_interruptible(1000))
  84                         flush_signals(current);
  85         }
  86 }
  87
  88 /*
  89  * Should be called under w1_flock held.
  90  */
  91 struct w1_family * w1_family_registered(u8 fid)
  92 {
  93         struct list_head *ent, *n;
  94         struct w1_family *f = NULL;
  95         int ret = 0;
  96
  97         list_for_each_safe(ent, n, &w1_families) {
  98                 f = list_entry(ent, struct w1_family, family_entry);
  99
 100                 if (f->fid == fid) {
 101                         ret = 1;
 102                         break;
 103                 }
 104         }
 105
 106         return (ret) ? f : NULL;
 107 }
 108
 109 void 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 void __w1_family_put(struct w1_family *f)
 117 {
 118         if (atomic_dec_and_test(&f->refcnt))
 119                 f->need_exit = 1;
 120 }
 121
 122 void w1_family_get(struct w1_family *f)
 123 {
 124         spin_lock(&w1_flock);
 125         __w1_family_get(f);
 126         spin_unlock(&w1_flock);
 127
 128 }
 129
 130 void __w1_family_get(struct w1_family *f)
 131 {
 132         smp_mb__before_atomic_inc();
 133         atomic_inc(&f->refcnt);
 134         smp_mb__after_atomic_inc();
 135 }
 136
 137 EXPORT_SYMBOL(w1_family_get);
 138 EXPORT_SYMBOL(w1_family_put);
 139 EXPORT_SYMBOL(w1_family_registered);
 140 EXPORT_SYMBOL(w1_unregister_family);
 141 EXPORT_SYMBOL(w1_register_family);