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
  25 #include "w1_family.h"
  26
  27 spinlock_t w1_flock = SPIN_LOCK_UNLOCKED;
  28 static LIST_HEAD(w1_families);
  29
  30 static int w1_check_family(struct w1_family *f)
  31 {
  32         if (!f->fops->rname || !f->fops->rbin || !f->fops->rval || !f->fops->rvalname)
  33                 return -EINVAL;
  34
  35         return 0;
  36 }
  37
  38 int w1_register_family(struct w1_family *newf)
  39 {
  40         struct list_head *ent, *n;
  41         struct w1_family *f;
  42         int ret = 0;
  43
  44         if (w1_check_family(newf))
  45                 return -EINVAL;
  46
  47         spin_lock(&w1_flock);
  48         list_for_each_safe(ent, n, &w1_families) {
  49                 f = list_entry(ent, struct w1_family, family_entry);
  50
  51                 if (f->fid == newf->fid) {
  52                         ret = -EEXIST;
  53                         break;
  54                 }
  55         }
  56
  57         if (!ret) {
  58                 atomic_set(&newf->refcnt, 0);
  59                 newf->need_exit = 0;
  60                 list_add_tail(&newf->family_entry, &w1_families);
  61         }
  62
  63         spin_unlock(&w1_flock);
  64
  65         return ret;
  66 }
  67
  68 void w1_unregister_family(struct w1_family *fent)
  69 {
  70         struct list_head *ent, *n;
  71         struct w1_family *f;
  72
  73         spin_lock(&w1_flock);
  74         list_for_each_safe(ent, n, &w1_families) {
  75                 f = list_entry(ent, struct w1_family, family_entry);
  76
  77                 if (f->fid == fent->fid) {
  78                         list_del(&fent->family_entry);
  79                         break;
  80                 }
  81         }
  82
  83         fent->need_exit = 1;
  84
  85         spin_unlock(&w1_flock);
  86
  87         while (atomic_read(&fent->refcnt))
  88                 schedule_timeout(10);
  89 }
  90
  91 /*
  92  * Should be called under w1_flock held.
  93  */
  94 struct 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
 112 void w1_family_put(struct w1_family *f)
 113 {
 114         spin_lock(&w1_flock);
 115         __w1_family_put(f);
 116         spin_unlock(&w1_flock);
 117 }
 118
 119 void __w1_family_put(struct w1_family *f)
 120 {
 121         if (atomic_dec_and_test(&f->refcnt))
 122                 f->need_exit = 1;
 123 }
 124
 125 void w1_family_get(struct w1_family *f)
 126 {
 127         spin_lock(&w1_flock);
 128         __w1_family_get(f);
 129         spin_unlock(&w1_flock);
 130
 131 }
 132
 133 void __w1_family_get(struct w1_family *f)
 134 {
 135         atomic_inc(&f->refcnt);
 136 }
 137
 138 EXPORT_SYMBOL(w1_family_get);
 139 EXPORT_SYMBOL(w1_family_put);
 140 EXPORT_SYMBOL(__w1_family_get);
 141 EXPORT_SYMBOL(__w1_family_put);
 142 EXPORT_SYMBOL(w1_family_registered);
 143 EXPORT_SYMBOL(w1_unregister_family);
 144 EXPORT_SYMBOL(w1_register_family);