From 7697fe0de6bdc7a8e0a4c722dbf6dec24ffe53d5 Mon Sep 17 00:00:00 2001
From: Stephan Mueller <smueller@chronox.de>
Date: Sun, 15 May 2022 18:39:30 +0200
Subject: [PATCH 24/25] LRNG - add /dev/lrng device file support

The LRNG can create a character device file that operates identically
to /dev/random including IOCTL, read and write operations.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 drivers/char/lrng/Kconfig              | 18 ++++++-------
 drivers/char/lrng/Makefile             |  1 +
 drivers/char/lrng/lrng_interface_dev.c | 35 ++++++++++++++++++++++++++
 3 files changed, 45 insertions(+), 9 deletions(-)
 create mode 100644 drivers/char/lrng/lrng_interface_dev.c

--- a/drivers/char/lrng/Kconfig
+++ b/drivers/char/lrng/Kconfig
@@ -111,15 +111,15 @@ config LRNG_KCAPI_IF
 # 	  with the name "lrng" that is accessible via the framework.
 # 	  For example it allows pulling data from the LRNG via the
 # 	  /dev/hwrng file.
-#
-# config LRNG_DEV_IF
-# 	bool "Character device file interface"
-# 	select LRNG_COMMON_DEV_IF
-# 	help
-# 	  The LRNG can create a character device file that operates
-# 	  identically to /dev/random including IOCTL, read and write
-# 	  operations.
-#
+
+config LRNG_DEV_IF
+	bool "Character device file interface"
+	select LRNG_COMMON_DEV_IF
+	help
+	  The LRNG can create a character device file that operates
+	  identically to /dev/random including IOCTL, read and write
+	  operations.
+
 endmenu # "LRNG Interfaces"
 
 menu "Entropy Source Configuration"
--- a/drivers/char/lrng/Makefile
+++ b/drivers/char/lrng/Makefile
@@ -35,3 +35,4 @@ obj-$(CONFIG_LRNG_RANDOM_IF)		+= lrng_in
 					   lrng_interface_random_kernel.o \
 					   lrng_interface_aux.o
 obj-$(CONFIG_LRNG_KCAPI_IF)		+= lrng_interface_kcapi.o
+obj-$(CONFIG_LRNG_DEV_IF)		+= lrng_interface_dev.o
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_dev.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG user space device file interface
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+
+#include "lrng_interface_dev_common.h"
+
+static const struct file_operations lrng_fops = {
+	.read  = lrng_drng_read_block,
+	.write = lrng_drng_write,
+	.poll  = lrng_random_poll,
+	.unlocked_ioctl = lrng_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
+	.fasync = lrng_fasync,
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice lrng_miscdev = {
+	.minor          = MISC_DYNAMIC_MINOR,
+	.name           = "lrng",
+	.nodename       = "lrng",
+	.fops           = &lrng_fops,
+	.mode		= 0666
+};
+
+static int __init lrng_dev_if_mod_init(void)
+{
+	return misc_register(&lrng_miscdev);
+}
+device_initcall(lrng_dev_if_mod_init);