From 25b9cadb1ee3434b92de9096d4a2ae91820146bf Mon Sep 17 00:00:00 2001
From: Elizabeth Figura <zfigura@codeweavers.com>
Date: Thu, 28 Mar 2024 19:05:52 -0500
Subject: ntsync: Introduce the ntsync driver and character device.

ntsync uses a misc device as the simplest and least intrusive uAPI interface.

Each file description on the device represents an isolated NT instance, intended
to correspond to a single NT virtual machine.

Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/misc/Kconfig  | 11 +++++++++++
 drivers/misc/Makefile |  1 +
 drivers/misc/ntsync.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 drivers/misc/ntsync.c

(limited to 'drivers')

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 4fb291f0bf7c..801ed229ed7d 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -506,6 +506,17 @@ config OPEN_DICE
 
 	  If unsure, say N.
 
+config NTSYNC
+	tristate "NT synchronization primitive emulation"
+	help
+	  This module provides kernel support for emulation of Windows NT
+	  synchronization primitives. It is not a hardware driver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ntsync.
+
+	  If unsure, say N.
+
 config VCPU_STALL_DETECTOR
 	tristate "Guest vCPU stall detector"
 	depends on OF && HAS_IOMEM
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index ea6ea5bbbc9c..153a3f4837e8 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_PVPANIC)   	+= pvpanic/
 obj-$(CONFIG_UACCE)		+= uacce/
 obj-$(CONFIG_XILINX_SDFEC)	+= xilinx_sdfec.o
 obj-$(CONFIG_HISI_HIKEY_USB)	+= hisi_hikey_usb.o
+obj-$(CONFIG_NTSYNC)		+= ntsync.o
 obj-$(CONFIG_HI6421V600_IRQ)	+= hi6421v600-irq.o
 obj-$(CONFIG_OPEN_DICE)		+= open-dice.o
 obj-$(CONFIG_GP_PCI1XXXX)	+= mchp_pci1xxxx/
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
new file mode 100644
index 000000000000..bd76e653d83e
--- /dev/null
+++ b/drivers/misc/ntsync.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ntsync.c - Kernel driver for NT synchronization primitives
+ *
+ * Copyright (C) 2024 Elizabeth Figura <zfigura@codeweavers.com>
+ */
+
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+
+#define NTSYNC_NAME	"ntsync"
+
+static int ntsync_char_open(struct inode *inode, struct file *file)
+{
+	return nonseekable_open(inode, file);
+}
+
+static int ntsync_char_release(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+static long ntsync_char_ioctl(struct file *file, unsigned int cmd,
+			      unsigned long parm)
+{
+	switch (cmd) {
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+static const struct file_operations ntsync_fops = {
+	.owner		= THIS_MODULE,
+	.open		= ntsync_char_open,
+	.release	= ntsync_char_release,
+	.unlocked_ioctl	= ntsync_char_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.llseek		= no_llseek,
+};
+
+static struct miscdevice ntsync_misc = {
+	.minor		= MISC_DYNAMIC_MINOR,
+	.name		= NTSYNC_NAME,
+	.fops		= &ntsync_fops,
+};
+
+module_misc_device(ntsync_misc);
+
+MODULE_AUTHOR("Elizabeth Figura <zfigura@codeweavers.com>");
+MODULE_DESCRIPTION("Kernel driver for NT synchronization primitives");
+MODULE_LICENSE("GPL");
-- 
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