| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net> |
| */ |
| |
| #include <linux/spinlock.h> |
| #include <linux/list.h> |
| #include <linux/sched/signal.h> |
| #include <linux/delay.h> |
| #include <linux/export.h> |
| |
| #include "w1_internal.h" |
| |
| DEFINE_SPINLOCK(w1_flock); |
| static LIST_HEAD(w1_families); |
| |
| /** |
| * w1_register_family() - register a device family driver |
| * @newf: family to register |
| */ |
| int w1_register_family(struct w1_family *newf) |
| { |
| struct list_head *ent, *n; |
| struct w1_family *f; |
| int ret = 0; |
| |
| spin_lock(&w1_flock); |
| list_for_each_safe(ent, n, &w1_families) { |
| f = list_entry(ent, struct w1_family, family_entry); |
| |
| if (f->fid == newf->fid) { |
| ret = -EEXIST; |
| break; |
| } |
| } |
| |
| if (!ret) { |
| atomic_set(&newf->refcnt, 0); |
| list_add_tail(&newf->family_entry, &w1_families); |
| } |
| spin_unlock(&w1_flock); |
| |
| /* check default devices against the new set of drivers */ |
| w1_reconnect_slaves(newf, 1); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(w1_register_family); |
| |
| /** |
| * w1_unregister_family() - unregister a device family driver |
| * @fent: family to unregister |
| */ |
| void w1_unregister_family(struct w1_family *fent) |
| { |
| struct list_head *ent, *n; |
| struct w1_family *f; |
| |
| spin_lock(&w1_flock); |
| list_for_each_safe(ent, n, &w1_families) { |
| f = list_entry(ent, struct w1_family, family_entry); |
| |
| if (f->fid == fent->fid) { |
| list_del(&fent->family_entry); |
| break; |
| } |
| } |
| spin_unlock(&w1_flock); |
| |
| /* deatch devices using this family code */ |
| w1_reconnect_slaves(fent, 0); |
| |
| while (atomic_read(&fent->refcnt)) { |
| pr_info("Waiting for family %u to become free: refcnt=%d.\n", |
| fent->fid, atomic_read(&fent->refcnt)); |
| |
| if (msleep_interruptible(1000)) |
| flush_signals(current); |
| } |
| } |
| EXPORT_SYMBOL(w1_unregister_family); |
| |
| /* |
| * Should be called under w1_flock held. |
| */ |
| struct w1_family * w1_family_registered(u8 fid) |
| { |
| struct list_head *ent, *n; |
| struct w1_family *f = NULL; |
| int ret = 0; |
| |
| list_for_each_safe(ent, n, &w1_families) { |
| f = list_entry(ent, struct w1_family, family_entry); |
| |
| if (f->fid == fid) { |
| ret = 1; |
| break; |
| } |
| } |
| |
| return (ret) ? f : NULL; |
| } |
| |
| static void __w1_family_put(struct w1_family *f) |
| { |
| atomic_dec(&f->refcnt); |
| } |
| |
| void w1_family_put(struct w1_family *f) |
| { |
| spin_lock(&w1_flock); |
| __w1_family_put(f); |
| spin_unlock(&w1_flock); |
| } |
| |
| #if 0 |
| void w1_family_get(struct w1_family *f) |
| { |
| spin_lock(&w1_flock); |
| __w1_family_get(f); |
| spin_unlock(&w1_flock); |
| } |
| #endif /* 0 */ |
| |
| void __w1_family_get(struct w1_family *f) |
| { |
| smp_mb__before_atomic(); |
| atomic_inc(&f->refcnt); |
| smp_mb__after_atomic(); |
| } |