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); 149