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         w1_reconnect_slaves(newf);
  57
  58         return ret;
  59 }
  60
  61 void w1_unregister_family(struct w1_family *fent)
  62 {
  63         struct list_head *ent, *n;
  64         struct w1_family *f;
  65
  66         spin_lock(&w1_flock);
  67         list_for_each_safe(ent, n, &w1_families) {
  68                 f = list_entry(ent, struct w1_family, family_entry);
  69
  70                 if (f->fid == fent->fid) {
  71                         list_del(&fent->family_entry);
  72                         break;
  73                 }
  74         }
  75
  76         fent->need_exit = 1;
  77
  78         spin_unlock(&w1_flock);
  79
  80         while (atomic_read(&fent->refcnt)) {
  81                 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
  82                                 fent->fid, atomic_read(&fent->refcnt));
  83
  84                 if (msleep_interruptible(1000))
  85                         flush_signals(current);
  86         }
  87 }
  88
  89 /*
  90  * Should be called under w1_flock held.
  91  */
  92 struct w1_family * w1_family_registered(u8 fid)
  93 {
  94         struct list_head *ent, *n;
  95         struct w1_family *f = NULL;
  96         int ret = 0;
  97
  98         list_for_each_safe(ent, n, &w1_families) {
  99                 f = list_entry(ent, struct w1_family, family_entry);
 100
 101                 if (f->fid == fid) {
 102                         ret = 1;
 103                         break;
 104                 }
 105         }
 106
 107         return (ret) ? f : NULL;
 108 }
 109
 110 static void __w1_family_put(struct w1_family *f)
 111 {
 112         if (atomic_dec_and_test(&f->refcnt))
 113                 f->need_exit = 1;
 114 }
 115
 116 void w1_family_put(struct w1_family *f)
 117 {
 118         spin_lock(&w1_flock);
 119         __w1_family_put(f);
 120         spin_unlock(&w1_flock);
 121 }
 122
 123 #if 0
 124 void w1_family_get(struct w1_family *f)
 125 {
 126         spin_lock(&w1_flock);
 127         __w1_family_get(f);
 128         spin_unlock(&w1_flock);
 129 }
 130 #endif  /*  0  */
 131
 132 void __w1_family_get(struct w1_family *f)
 133 {
 134         smp_mb__before_atomic_inc();
 135         atomic_inc(&f->refcnt);
 136         smp_mb__after_atomic_inc();
 137 }
 138
 139 EXPORT_SYMBOL(w1_unregister_family);
 140 EXPORT_SYMBOL(w1_register_family);