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 #include <linux/export.h>
  27
  28 #include "w1_family.h"
  29 #include "w1.h"
  30
  31 DEFINE_SPINLOCK(w1_flock);
  32 static LIST_HEAD(w1_families);
  33
  34 int w1_register_family(struct w1_family *newf)
  35 {
  36         struct list_head *ent, *n;
  37         struct w1_family *f;
  38         int ret = 0;
  39
  40         spin_lock(&w1_flock);
  41         list_for_each_safe(ent, n, &w1_families) {
  42                 f = list_entry(ent, struct w1_family, family_entry);
  43
  44                 if (f->fid == newf->fid) {
  45                         ret = -EEXIST;
  46                         break;
  47                 }
  48         }
  49
  50         if (!ret) {
  51                 atomic_set(&newf->refcnt, 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         spin_unlock(&w1_flock);
  77
  78         /* deatch devices using this family code */
  79         w1_reconnect_slaves(fent, 0);
  80
  81         while (atomic_read(&fent->refcnt)) {
  82                 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
  83                                 fent->fid, atomic_read(&fent->refcnt));
  84
  85                 if (msleep_interruptible(1000))
  86                         flush_signals(current);
  87         }
  88 }
  89
  90 /*
  91  * Should be called under w1_flock held.
  92  */
  93 struct w1_family * w1_family_registered(u8 fid)
  94 {
  95         struct list_head *ent, *n;
  96         struct w1_family *f = NULL;
  97         int ret = 0;
  98
  99         list_for_each_safe(ent, n, &w1_families) {
 100                 f = list_entry(ent, struct w1_family, family_entry);
 101
 102                 if (f->fid == fid) {
 103                         ret = 1;
 104                         break;
 105                 }
 106         }
 107
 108         return (ret) ? f : NULL;
 109 }
 110
 111 static void __w1_family_put(struct w1_family *f)
 112 {
 113         atomic_dec(&f->refcnt);
 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);