1 /* 2 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 */ 14 15 #include <linux/spinlock.h> 16 #include <linux/list.h> 17 #include <linux/sched/signal.h> 18 #include <linux/delay.h> 19 #include <linux/export.h> 20 21 #include "w1_family.h" 22 #include "w1.h" 23 24 DEFINE_SPINLOCK(w1_flock); 25 static LIST_HEAD(w1_families); 26 27 /** 28 * w1_register_family() - register a device family driver 29 * @newf: family to register 30 */ 31 int w1_register_family(struct w1_family *newf) 32 { 33 struct list_head *ent, *n; 34 struct w1_family *f; 35 int ret = 0; 36 37 spin_lock(&w1_flock); 38 list_for_each_safe(ent, n, &w1_families) { 39 f = list_entry(ent, struct w1_family, family_entry); 40 41 if (f->fid == newf->fid) { 42 ret = -EEXIST; 43 break; 44 } 45 } 46 47 if (!ret) { 48 atomic_set(&newf->refcnt, 0); 49 list_add_tail(&newf->family_entry, &w1_families); 50 } 51 spin_unlock(&w1_flock); 52 53 /* check default devices against the new set of drivers */ 54 w1_reconnect_slaves(newf, 1); 55 56 return ret; 57 } 58 59 /** 60 * w1_unregister_family() - unregister a device family driver 61 * @fent: family to unregister 62 */ 63 void w1_unregister_family(struct w1_family *fent) 64 { 65 struct list_head *ent, *n; 66 struct w1_family *f; 67 68 spin_lock(&w1_flock); 69 list_for_each_safe(ent, n, &w1_families) { 70 f = list_entry(ent, struct w1_family, family_entry); 71 72 if (f->fid == fent->fid) { 73 list_del(&fent->family_entry); 74 break; 75 } 76 } 77 spin_unlock(&w1_flock); 78 79 /* deatch devices using this family code */ 80 w1_reconnect_slaves(fent, 0); 81 82 while (atomic_read(&fent->refcnt)) { 83 pr_info("Waiting for family %u to become free: refcnt=%d.\n", 84 fent->fid, atomic_read(&fent->refcnt)); 85 86 if (msleep_interruptible(1000)) 87 flush_signals(current); 88 } 89 } 90 91 /* 92 * Should be called under w1_flock held. 93 */ 94 struct w1_family * w1_family_registered(u8 fid) 95 { 96 struct list_head *ent, *n; 97 struct w1_family *f = NULL; 98 int ret = 0; 99 100 list_for_each_safe(ent, n, &w1_families) { 101 f = list_entry(ent, struct w1_family, family_entry); 102 103 if (f->fid == fid) { 104 ret = 1; 105 break; 106 } 107 } 108 109 return (ret) ? f : NULL; 110 } 111 112 static void __w1_family_put(struct w1_family *f) 113 { 114 atomic_dec(&f->refcnt); 115 } 116 117 void w1_family_put(struct w1_family *f) 118 { 119 spin_lock(&w1_flock); 120 __w1_family_put(f); 121 spin_unlock(&w1_flock); 122 } 123 124 #if 0 125 void w1_family_get(struct w1_family *f) 126 { 127 spin_lock(&w1_flock); 128 __w1_family_get(f); 129 spin_unlock(&w1_flock); 130 } 131 #endif /* 0 */ 132 133 void __w1_family_get(struct w1_family *f) 134 { 135 smp_mb__before_atomic(); 136 atomic_inc(&f->refcnt); 137 smp_mb__after_atomic(); 138 } 139 140 EXPORT_SYMBOL(w1_unregister_family); 141 EXPORT_SYMBOL(w1_register_family); 142