diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index c472423412bf..a141e8e65c5d 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -174,6 +174,8 @@ Code  Seq#    Include File                                           Comments
 'M'   00-0F  drivers/video/fsl-diu-fb.h                              conflict!
 'N'   00-1F  drivers/usb/scanner.h
 'N'   40-7F  drivers/block/nvme.c
+'N'   80-8F  uapi/linux/ntsync.h                                     NT synchronization primitives
+                                                                     <mailto:wine-devel@winehq.org>
 'O'   00-06  mtd/ubi-user.h                                          UBI
 'P'   all    linux/soundcard.h                                       conflict!
 'P'   60-6F  sound/sscape_ioctl.h                                    conflict!
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index bd76e653d83e..20158ec148bc 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -5,26 +5,157 @@
  * Copyright (C) 2024 Elizabeth Figura <zfigura@codeweavers.com>
  */
 
+#include <linux/anon_inodes.h>
+#include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
+#include <linux/slab.h>
+#include <uapi/linux/ntsync.h>
 
 #define NTSYNC_NAME	"ntsync"
 
+enum ntsync_type {
+	NTSYNC_TYPE_SEM,
+};
+
+/*
+ * Individual synchronization primitives are represented by
+ * struct ntsync_obj, and each primitive is backed by a file.
+ *
+ * The whole namespace is represented by a struct ntsync_device also
+ * backed by a file.
+ *
+ * Both rely on struct file for reference counting. Individual
+ * ntsync_obj objects take a reference to the device when created.
+ */
+
+struct ntsync_obj {
+	enum ntsync_type type;
+
+	union {
+		struct {
+			__u32 count;
+			__u32 max;
+		} sem;
+	} u;
+
+	struct file *file;
+	struct ntsync_device *dev;
+};
+
+struct ntsync_device {
+	struct file *file;
+};
+
+static int ntsync_obj_release(struct inode *inode, struct file *file)
+{
+	struct ntsync_obj *obj = file->private_data;
+
+	fput(obj->dev->file);
+	kfree(obj);
+
+	return 0;
+}
+
+static const struct file_operations ntsync_obj_fops = {
+	.owner		= THIS_MODULE,
+	.release	= ntsync_obj_release,
+	.llseek		= no_llseek,
+};
+
+static struct ntsync_obj *ntsync_alloc_obj(struct ntsync_device *dev,
+					   enum ntsync_type type)
+{
+	struct ntsync_obj *obj;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (!obj)
+		return NULL;
+	obj->type = type;
+	obj->dev = dev;
+	get_file(dev->file);
+
+	return obj;
+}
+
+static int ntsync_obj_get_fd(struct ntsync_obj *obj)
+{
+	struct file *file;
+	int fd;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+	file = anon_inode_getfile("ntsync", &ntsync_obj_fops, obj, O_RDWR);
+	if (IS_ERR(file)) {
+		put_unused_fd(fd);
+		return PTR_ERR(file);
+	}
+	obj->file = file;
+	fd_install(fd, file);
+
+	return fd;
+}
+
+static int ntsync_create_sem(struct ntsync_device *dev, void __user *argp)
+{
+	struct ntsync_sem_args __user *user_args = argp;
+	struct ntsync_sem_args args;
+	struct ntsync_obj *sem;
+	int fd;
+
+	if (copy_from_user(&args, argp, sizeof(args)))
+		return -EFAULT;
+
+	if (args.count > args.max)
+		return -EINVAL;
+
+	sem = ntsync_alloc_obj(dev, NTSYNC_TYPE_SEM);
+	if (!sem)
+		return -ENOMEM;
+	sem->u.sem.count = args.count;
+	sem->u.sem.max = args.max;
+	fd = ntsync_obj_get_fd(sem);
+	if (fd < 0) {
+		kfree(sem);
+		return fd;
+	}
+
+	return put_user(fd, &user_args->sem);
+}
+
 static int ntsync_char_open(struct inode *inode, struct file *file)
 {
+	struct ntsync_device *dev;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	file->private_data = dev;
+	dev->file = file;
 	return nonseekable_open(inode, file);
 }
 
 static int ntsync_char_release(struct inode *inode, struct file *file)
 {
+	struct ntsync_device *dev = file->private_data;
+
+	kfree(dev);
+
 	return 0;
 }
 
 static long ntsync_char_ioctl(struct file *file, unsigned int cmd,
 			      unsigned long parm)
 {
+	struct ntsync_device *dev = file->private_data;
+	void __user *argp = (void __user *)parm;
+
 	switch (cmd) {
+	case NTSYNC_IOC_CREATE_SEM:
+		return ntsync_create_sem(dev, argp);
 	default:
 		return -ENOIOCTLCMD;
 	}
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
new file mode 100644
index 000000000000..6a4867a6c97b
--- /dev/null
+++ b/include/uapi/linux/ntsync.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Kernel support for NT synchronization primitive emulation
+ *
+ * Copyright (C) 2021-2022 Elizabeth Figura <zfigura@codeweavers.com>
+ */
+
+#ifndef __LINUX_NTSYNC_H
+#define __LINUX_NTSYNC_H
+
+#include <linux/types.h>
+
+struct ntsync_sem_args {
+	__u32 sem;
+	__u32 count;
+	__u32 max;
+};
+
+#define NTSYNC_IOC_CREATE_SEM		_IOWR('N', 0x80, struct ntsync_sem_args)
+
+#endif