/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
 30DEFINE_SPINLOCK(w1_flock);
 31static LIST_HEAD(w1_families);
 32
 33int 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		list_add_tail(&newf->family_entry, &w1_families);
 52	}
 53	spin_unlock(&w1_flock);
 54
 55	/* check default devices against the new set of drivers */
 56	w1_reconnect_slaves(newf, 1);
 57
 58	return ret;
 59}
 60
 61void 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	spin_unlock(&w1_flock);
 76
 77	/* deatch devices using this family code */
 78	w1_reconnect_slaves(fent, 0);
 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 */
 92struct 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
110static void __w1_family_put(struct w1_family *f)
111{
112	atomic_dec(&f->refcnt);
113}
114
115void w1_family_put(struct w1_family *f)
116{
117	spin_lock(&w1_flock);
118	__w1_family_put(f);
119	spin_unlock(&w1_flock);
120}
121
122#if 0
123void w1_family_get(struct w1_family *f)
124{
125	spin_lock(&w1_flock);
126	__w1_family_get(f);
127	spin_unlock(&w1_flock);
128}
129#endif  /*  0  */
130
131void __w1_family_get(struct w1_family *f)
132{
133	smp_mb__before_atomic_inc();
134	atomic_inc(&f->refcnt);
135	smp_mb__after_atomic_inc();
136}
137
138EXPORT_SYMBOL(w1_unregister_family);
139EXPORT_SYMBOL(w1_register_family);