1 files changed, 130 insertions, 0 deletions
diff --git a/drivers/w1/w1_family.c b/drivers/w1/w1_family.c
new file mode 100644
index 0000000000..97da4f156e
--- /dev/null
+++ b/drivers/w1/w1_family.c
@@ -0,0 +1,130 @@
+// 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();
+}