1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net> 4 */ 5 6 #include <linux/spinlock.h> 7 #include <linux/list.h> 8 #include <linux/sched/signal.h> 9 #include <linux/delay.h> 10 #include <linux/export.h> 11 12 #include "w1_internal.h" 13 14 DEFINE_SPINLOCK(w1_flock); 15 static LIST_HEAD(w1_families); 16 17 /** 18 * w1_register_family() - register a device family driver 19 * @newf: family to register 20 */ 21 int w1_register_family(struct w1_family *newf) 22 { 23 struct list_head *ent, *n; 24 struct w1_family *f; 25 int ret = 0; 26 27 spin_lock(&w1_flock); 28 list_for_each_safe(ent, n, &w1_families) { 29 f = list_entry(ent, struct w1_family, family_entry); 30 31 if (f->fid == newf->fid) { 32 ret = -EEXIST; 33 break; 34 } 35 } 36 37 if (!ret) { 38 atomic_set(&newf->refcnt, 0); 39 list_add_tail(&newf->family_entry, &w1_families); 40 } 41 spin_unlock(&w1_flock); 42 43 /* check default devices against the new set of drivers */ 44 w1_reconnect_slaves(newf, 1); 45 46 return ret; 47 } 48 EXPORT_SYMBOL(w1_register_family); 49 50 /** 51 * w1_unregister_family() - unregister a device family driver 52 * @fent: family to unregister 53 */ 54 void w1_unregister_family(struct w1_family *fent) 55 { 56 struct list_head *ent, *n; 57 struct w1_family *f; 58 59 spin_lock(&w1_flock); 60 list_for_each_safe(ent, n, &w1_families) { 61 f = list_entry(ent, struct w1_family, family_entry); 62 63 if (f->fid == fent->fid) { 64 list_del(&fent->family_entry); 65 break; 66 } 67 } 68 spin_unlock(&w1_flock); 69 70 /* deatch devices using this family code */ 71 w1_reconnect_slaves(fent, 0); 72 73 while (atomic_read(&fent->refcnt)) { 74 pr_info("Waiting for family %u to become free: refcnt=%d.\n", 75 fent->fid, atomic_read(&fent->refcnt)); 76 77 if (msleep_interruptible(1000)) 78 flush_signals(current); 79 } 80 } 81 EXPORT_SYMBOL(w1_unregister_family); 82 83 /* 84 * Should be called under w1_flock held. 85 */ 86 struct w1_family * w1_family_registered(u8 fid) 87 { 88 struct list_head *ent, *n; 89 struct w1_family *f = NULL; 90 int ret = 0; 91 92 list_for_each_safe(ent, n, &w1_families) { 93 f = list_entry(ent, struct w1_family, family_entry); 94 95 if (f->fid == fid) { 96 ret = 1; 97 break; 98 } 99 } 100 101 return (ret) ? f : NULL; 102 } 103 104 static void __w1_family_put(struct w1_family *f) 105 { 106 atomic_dec(&f->refcnt); 107 } 108 109 void w1_family_put(struct w1_family *f) 110 { 111 spin_lock(&w1_flock); 112 __w1_family_put(f); 113 spin_unlock(&w1_flock); 114 } 115 116 #if 0 117 void w1_family_get(struct w1_family *f) 118 { 119 spin_lock(&w1_flock); 120 __w1_family_get(f); 121 spin_unlock(&w1_flock); 122 } 123 #endif /* 0 */ 124 125 void __w1_family_get(struct w1_family *f) 126 { 127 smp_mb__before_atomic(); 128 atomic_inc(&f->refcnt); 129 smp_mb__after_atomic(); 130 } 131