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/sched.h>        /* schedule_timeout() */
  25 #include <linux/delay.h>
  26
  27 #include "w1_family.h"
  28 #include "w1.h"
  29
  30 DEFINE_SPINLOCK(w1_flock);
  31 static LIST_HEAD(w1_families);
  32
  33 int w1_register_family(struct w1_family *newf)
  34 {
  35         struct list_head *ent, *n;
  36         struct w1_family *f;
  37         int ret = 0;
  38
  39         spin_lock(&w1_flock);
  40         list_for_each_safe(ent, n, &w1_families) {
  41                 f = list_entry(ent, struct w1_family, family_entry);
  42
  43                 if (f->fid == newf->fid) {
  44                         ret = -EEXIST;
  45                         break;
  46                 }
  47         }
  48
  49         if (!ret) {
  50                 atomic_set(&newf->refcnt, 0);
  51                 newf->need_exit = 0;
  52                 list_add_tail(&newf->family_entry, &w1_families);
  53         }
  54         spin_unlock(&w1_flock);
  55
  56         /* check default devices against the new set of drivers */
  57         w1_reconnect_slaves(newf, 1);
  58
  59         return ret;
  60 }
  61
  62 void w1_unregister_family(struct w1_family *fent)
  63 {
  64         struct list_head *ent, *n;
  65         struct w1_family *f;
  66
  67         spin_lock(&w1_flock);
  68         list_for_each_safe(ent, n, &w1_families) {
  69                 f = list_entry(ent, struct w1_family, family_entry);
  70
  71                 if (f->fid == fent->fid) {
  72                         list_del(&fent->family_entry);
  73                         break;
  74                 }
  75         }
  76
  77         fent->need_exit = 1;
  78
  79         spin_unlock(&w1_flock);
  80
  81         /* deatch devices using this family code */
  82         w1_reconnect_slaves(fent, 0);
  83
  84         while (atomic_read(&fent->refcnt)) {
  85                 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
  86                                 fent->fid, atomic_read(&fent->refcnt));
  87
  88                 if (msleep_interruptible(1000))
  89                         flush_signals(current);
  90         }
  91 }
  92
  93 /*
  94  * Should be called under w1_flock held.
  95  */
  96 struct w1_family * w1_family_registered(u8 fid)
  97 {
  98         struct list_head *ent, *n;
  99         struct w1_family *f = NULL;
 100         int ret = 0;
 101
 102         list_for_each_safe(ent, n, &w1_families) {
 103                 f = list_entry(ent, struct w1_family, family_entry);
 104
 105                 if (f->fid == fid) {
 106                         ret = 1;
 107                         break;
 108                 }
 109         }
 110
 111         return (ret) ? f : NULL;
 112 }
 113
 114 static void __w1_family_put(struct w1_family *f)
 115 {
 116         if (atomic_dec_and_test(&f->refcnt))
 117                 f->need_exit = 1;
 118 }
 119
 120 void w1_family_put(struct w1_family *f)
 121 {
 122         spin_lock(&w1_flock);
 123         __w1_family_put(f);
 124         spin_unlock(&w1_flock);
 125 }
 126
 127 #if 0
 128 void w1_family_get(struct w1_family *f)
 129 {
 130         spin_lock(&w1_flock);
 131         __w1_family_get(f);
 132         spin_unlock(&w1_flock);
 133 }
 134 #endif  /*  0  */
 135
 136 void __w1_family_get(struct w1_family *f)
 137 {
 138         smp_mb__before_atomic_inc();
 139         atomic_inc(&f->refcnt);
 140         smp_mb__after_atomic_inc();
 141 }
 142
 143 EXPORT_SYMBOL(w1_unregister_family);
 144 EXPORT_SYMBOL(w1_register_family);