diff --git a/drivers/char/lrng/Kconfig b/drivers/char/lrng/Kconfig
index 12b6b3439853..e503a4bb7475 100644
--- a/drivers/char/lrng/Kconfig
+++ b/drivers/char/lrng/Kconfig
@@ -159,4 +159,20 @@ config LRNG_APT_CUTOFF
 	default 325 if !LRNG_APT_BROKEN
 	default 32 if LRNG_APT_BROKEN
 
+config LRNG_TESTING
+	bool "Enable entropy test interface to LRNG noise source"
+	depends on DEBUG_FS
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned noise that is collected by the LRNG
+	  for statistical analysis. Extracted noise data is not used
+	  to seed the LRNG.
+
+	  The raw noise data can be obtained using the lrng_raw
+	  debugfs file. Using the option lrng_testing.boot_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+	  If unsure, say N.
+
 endif # LRNG
diff --git a/drivers/char/lrng/Makefile b/drivers/char/lrng/Makefile
index c3008763dd14..b2ce1979dc4b 100644
--- a/drivers/char/lrng/Makefile
+++ b/drivers/char/lrng/Makefile
@@ -15,3 +15,4 @@ obj-$(CONFIG_LRNG_DRBG)		+= lrng_drbg.o
 obj-$(CONFIG_LRNG_KCAPI)	+= lrng_kcapi.o
 obj-$(CONFIG_LRNG_JENT)		+= lrng_jent.o
 obj-$(CONFIG_LRNG_HEALTH_TESTS)	+= lrng_health.o
+obj-$(CONFIG_LRNG_TESTING)	+= lrng_testing.o
diff --git a/drivers/char/lrng/lrng_testing.c b/drivers/char/lrng/lrng_testing.c
new file mode 100644
index 000000000000..0e287eccd622
--- /dev/null
+++ b/drivers/char/lrng/lrng_testing.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Linux Random Number Generator (LRNG) Raw entropy collection tool
+ *
+ * Copyright (C) 2019 - 2020, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/atomic.h>
+#include <linux/bug.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/workqueue.h>
+#include <asm/errno.h>
+
+#include "lrng_internal.h"
+
+#define LRNG_TESTING_RINGBUFFER_SIZE	1024
+#define LRNG_TESTING_RINGBUFFER_MASK	(LRNG_TESTING_RINGBUFFER_SIZE - 1)
+
+static u32 lrng_testing_rb[LRNG_TESTING_RINGBUFFER_SIZE];
+static u32 lrng_rb_reader = 0;
+static u32 lrng_rb_writer = 0;
+static atomic_t lrng_testing_enabled = ATOMIC_INIT(0);
+
+static DECLARE_WAIT_QUEUE_HEAD(lrng_raw_read_wait);
+static DEFINE_SPINLOCK(lrng_raw_lock);
+
+/*
+ * 0 ==> No boot test, gathering of runtime data allowed
+ * 1 ==> Boot test enabled and ready for collecting data, gathering runtime
+ *	 data is disabled
+ * 2 ==> Boot test completed and disabled, gathering of runtime data is
+ *	 disabled
+ */
+static u32 boot_test = 0;
+module_param(boot_test, uint, 0644);
+MODULE_PARM_DESC(boot_test, "Enable gathering boot time entropy of the first"
+			    " entropy events");
+
+static inline void lrng_raw_entropy_reset(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lrng_raw_lock, flags);
+	lrng_rb_reader = 0;
+	lrng_rb_writer = 0;
+	spin_unlock_irqrestore(&lrng_raw_lock, flags);
+}
+
+static void lrng_raw_entropy_init(void)
+{
+	/*
+	 * The boot time testing implies we have a running test. If the
+	 * caller wants to clear it, he has to unset the boot_test flag
+	 * at runtime via sysfs to enable regular runtime testing
+	 */
+	if (boot_test)
+		return;
+
+	lrng_raw_entropy_reset();
+	atomic_set(&lrng_testing_enabled, 1);
+	pr_warn("Enabling raw entropy collection\n");
+}
+
+static void lrng_raw_entropy_fini(void)
+{
+	if (boot_test)
+		return;
+
+	atomic_set(&lrng_testing_enabled, 0);
+	lrng_raw_entropy_reset();
+	pr_warn("Disabling raw entropy collection\n");
+}
+
+bool lrng_raw_entropy_store(u32 value)
+{
+	unsigned long flags;
+
+	if (!atomic_read(&lrng_testing_enabled) && (boot_test != 1))
+		return false;
+
+	spin_lock_irqsave(&lrng_raw_lock, flags);
+
+	/*
+	 * Disable entropy testing for boot time testing after ring buffer
+	 * is filled.
+	 */
+	if (boot_test) {
+		if (lrng_rb_writer > LRNG_TESTING_RINGBUFFER_SIZE) {
+			boot_test = 2;
+			pr_warn_once("Boot time entropy collection test "
+				     "disabled\n");
+			spin_unlock_irqrestore(&lrng_raw_lock, flags);
+			return false;
+		}
+
+		if (lrng_rb_writer == 1)
+			pr_warn("Boot time entropy collection test enabled\n");
+	}
+
+	lrng_testing_rb[lrng_rb_writer & LRNG_TESTING_RINGBUFFER_MASK] = value;
+	lrng_rb_writer++;
+
+	spin_unlock_irqrestore(&lrng_raw_lock, flags);
+
+	if (wq_has_sleeper(&lrng_raw_read_wait))
+		wake_up_interruptible(&lrng_raw_read_wait);
+
+	return true;
+}
+
+static inline bool lrng_raw_have_data(void)
+{
+	return ((lrng_rb_writer & LRNG_TESTING_RINGBUFFER_MASK) !=
+		 (lrng_rb_reader & LRNG_TESTING_RINGBUFFER_MASK));
+}
+
+static int lrng_raw_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	unsigned long flags;
+	int collected_data = 0;
+
+	lrng_raw_entropy_init();
+
+	while (outbuflen) {
+		spin_lock_irqsave(&lrng_raw_lock, flags);
+
+		/* We have no data or reached the writer. */
+		if (!lrng_rb_writer || (lrng_rb_writer == lrng_rb_reader)) {
+
+			spin_unlock_irqrestore(&lrng_raw_lock, flags);
+
+			/*
+			 * Now we gathered all boot data, enable regular data
+			 * collection.
+			 */
+			if (boot_test) {
+				boot_test = 0;
+				goto out;
+			}
+
+			wait_event_interruptible(lrng_raw_read_wait,
+						 lrng_raw_have_data());
+			if (signal_pending(current)) {
+				collected_data = -ERESTARTSYS;
+				goto out;
+			}
+
+			continue;
+		}
+
+		/* We copy out word-wise */
+		if (outbuflen < sizeof(u32)) {
+			spin_unlock_irqrestore(&lrng_raw_lock, flags);
+			goto out;
+		}
+
+		memcpy(outbuf, &lrng_testing_rb[lrng_rb_reader], sizeof(u32));
+		lrng_rb_reader++;
+
+		spin_unlock_irqrestore(&lrng_raw_lock, flags);
+
+		outbuf += sizeof(u32);
+		outbuflen -= sizeof(u32);
+		collected_data += sizeof(u32);
+	}
+
+out:
+	lrng_raw_entropy_fini();
+	return collected_data;
+}
+
+/**************************************************************************
+ * Debugfs interface
+ **************************************************************************/
+static int lrng_raw_extract_user(char __user *buf, size_t nbytes)
+{
+	u8 *tmp, *tmp_aligned;
+	int ret = 0, large_request = (nbytes > 256);
+
+	/*
+	 * The intention of this interface is for collecting at least
+	 * 1000 samples due to the SP800-90B requirements. So, we make no
+	 * effort in avoiding allocating more memory that actually needed
+	 * by the user. Hence, we allocate sufficient memory to always hold
+	 * that amount of data.
+	 */
+	tmp = kmalloc(LRNG_TESTING_RINGBUFFER_SIZE + sizeof(u32), GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	tmp_aligned = PTR_ALIGN(tmp, sizeof(u32));
+
+	while (nbytes) {
+		int i;
+
+		if (large_request && need_resched()) {
+			if (signal_pending(current)) {
+				if (ret == 0)
+					ret = -ERESTARTSYS;
+				break;
+			}
+			schedule();
+		}
+
+		i = min_t(int, nbytes, LRNG_TESTING_RINGBUFFER_SIZE);
+		i = lrng_raw_entropy_reader(tmp_aligned, i);
+		if (i <= 0) {
+			if (i < 0)
+				ret = i;
+			break;
+		}
+		if (copy_to_user(buf, tmp_aligned, i)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		nbytes -= i;
+		buf += i;
+		ret += i;
+	}
+
+	kzfree(tmp);
+	return ret;
+}
+
+/* DebugFS operations and definition of the debugfs files */
+static ssize_t lrng_raw_read(struct file *file, char __user *to,
+			     size_t count, loff_t *ppos)
+{
+	loff_t pos = *ppos;
+	int ret;
+
+	if (!count)
+		return 0;
+
+	ret = lrng_raw_extract_user(to, count);
+	if (ret < 0)
+		return ret;
+
+	count -= ret;
+	*ppos = pos + count;
+
+	return ret;
+}
+
+static const struct file_operations lrng_raw_name_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_read,
+};
+
+static int __init lrng_raw_init(void)
+{
+	struct dentry *lrng_raw_debugfs_root;
+
+	lrng_raw_debugfs_root = debugfs_create_dir(KBUILD_MODNAME, NULL);
+	debugfs_create_file_unsafe("lrng_raw", 0400, lrng_raw_debugfs_root,
+				   NULL, &lrng_raw_name_fops);
+
+	return 0;
+}
+
+module_init(lrng_raw_init);
