kernel/drivers/w1/w1_family.c

   1 /*
   2  *      w1_family.c
   3  *
   4  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
   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 /**
  35  * w1_register_family() - register a device family driver
  36  * @newf:       family to register
  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         spin_lock(&w1_flock);
  45         list_for_each_safe(ent, n, &w1_families) {
  46                 f = list_entry(ent, struct w1_family, family_entry);
  47
  48                 if (f->fid == newf->fid) {
  49                         ret = -EEXIST;
  50                         break;
  51                 }
  52         }
  53
  54         if (!ret) {
  55                 atomic_set(&newf->refcnt, 0);
  56                 list_add_tail(&newf->family_entry, &w1_families);
  57         }
  58         spin_unlock(&w1_flock);
  59
  60         /* check default devices against the new set of drivers */
  61         w1_reconnect_slaves(newf, 1);
  62
  63         return ret;
  64 }
  65
  66 /**
  67  * w1_unregister_family() - unregister a device family driver
  68  * @fent:       family to unregister
  69  */
  70 void w1_unregister_family(struct w1_family *fent)
  71 {
  72         struct list_head *ent, *n;
  73         struct w1_family *f;
  74
  75         spin_lock(&w1_flock);
  76         list_for_each_safe(ent, n, &w1_families) {
  77                 f = list_entry(ent, struct w1_family, family_entry);
  78
  79                 if (f->fid == fent->fid) {
  80                         list_del(&fent->family_entry);
  81                         break;
  82                 }
  83         }
  84         spin_unlock(&w1_flock);
  85
  86         /* deatch devices using this family code */
  87         w1_reconnect_slaves(fent, 0);
  88
  89         while (atomic_read(&fent->refcnt)) {
  90                 pr_info("Waiting for family %u to become free: refcnt=%d.\n",
  91                                 fent->fid, atomic_read(&fent->refcnt));
  92
  93                 if (msleep_interruptible(1000))
  94                         flush_signals(current);
  95         }
  96 }
  97
  98 /*
  99  * Should be called under w1_flock held.
 100  */
 101 struct w1_family * w1_family_registered(u8 fid)
 102 {
 103         struct list_head *ent, *n;
 104         struct w1_family *f = NULL;
 105         int ret = 0;
 106
 107         list_for_each_safe(ent, n, &w1_families) {
 108                 f = list_entry(ent, struct w1_family, family_entry);
 109
 110                 if (f->fid == fid) {
 111                         ret = 1;
 112                         break;
 113                 }
 114         }
 115
 116         return (ret) ? f : NULL;
 117 }
 118
 119 static void __w1_family_put(struct w1_family *f)
 120 {
 121         atomic_dec(&f->refcnt);
 122 }
 123
 124 void w1_family_put(struct w1_family *f)
 125 {
 126         spin_lock(&w1_flock);
 127         __w1_family_put(f);
 128         spin_unlock(&w1_flock);
 129 }
 130
 131 #if 0
 132 void w1_family_get(struct w1_family *f)
 133 {
 134         spin_lock(&w1_flock);
 135         __w1_family_get(f);
 136         spin_unlock(&w1_flock);
 137 }
 138 #endif  /*  0  */
 139
 140 void __w1_family_get(struct w1_family *f)
 141 {
 142         smp_mb__before_atomic();
 143         atomic_inc(&f->refcnt);
 144         smp_mb__after_atomic();
 145 }
 146
 147 EXPORT_SYMBOL(w1_unregister_family);
 148 EXPORT_SYMBOL(w1_register_family);