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_internal.h" 22 23 DEFINE_SPINLOCK(w1_flock); 24 static LIST_HEAD(w1_families); 25 26 /** 27 * w1_register_family() - register a device family driver 28 * @newf: family to register 29 */ 30 int w1_register_family(struct w1_family *newf) 31 { 32 struct list_head *ent, *n; 33 struct w1_family *f; 34 int ret = 0; 35 36 spin_lock(&w1_flock); 37 list_for_each_safe(ent, n, &w1_families) { 38 f = list_entry(ent, struct w1_family, family_entry); 39 40 if (f->fid == newf->fid) { 41 ret = -EEXIST; 42 break; 43 } 44 } 45 46 if (!ret) { 47 atomic_set(&newf->refcnt, 0); 48 list_add_tail(&newf->family_entry, &w1_families); 49 } 50 spin_unlock(&w1_flock); 51 52 /* check default devices against the new set of drivers */ 53 w1_reconnect_slaves(newf, 1); 54 55 return ret; 56 } 57 EXPORT_SYMBOL(w1_register_family); 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 EXPORT_SYMBOL(w1_unregister_family); 91 92 /* 93 * Should be called under w1_flock held. 94 */ 95 struct w1_family * w1_family_registered(u8 fid) 96 { 97 struct list_head *ent, *n; 98 struct w1_family *f = NULL; 99 int ret = 0; 100 101 list_for_each_safe(ent, n, &w1_families) { 102 f = list_entry(ent, struct w1_family, family_entry); 103 104 if (f->fid == fid) { 105 ret = 1; 106 break; 107 } 108 } 109 110 return (ret) ? f : NULL; 111 } 112 113 static void __w1_family_put(struct w1_family *f) 114 { 115 atomic_dec(&f->refcnt); 116 } 117 118 void w1_family_put(struct w1_family *f) 119 { 120 spin_lock(&w1_flock); 121 __w1_family_put(f); 122 spin_unlock(&w1_flock); 123 } 124 125 #if 0 126 void w1_family_get(struct w1_family *f) 127 { 128 spin_lock(&w1_flock); 129 __w1_family_get(f); 130 spin_unlock(&w1_flock); 131 } 132 #endif /* 0 */ 133 134 void __w1_family_get(struct w1_family *f) 135 { 136 smp_mb__before_atomic(); 137 atomic_inc(&f->refcnt); 138 smp_mb__after_atomic(); 139 } 140