diff --git a/Documentation/ntb.txt b/Documentation/ntb.txt
index e5d1591478ca..b48249a7b607 100644
--- a/Documentation/ntb.txt
+++ b/Documentation/ntb.txt
@@ -64,6 +64,38 @@ Module Parameters:
 * dyndbg - It is suggested to specify dyndbg=+p when loading this module, and
 	then to observe debugging output on the console.
 
+### NTB Tool Test Client (ntb\_tool)
+
+The Tool test client serves for debugging, primarily, ntb hardware and drivers.
+The Tool provides access through debugfs for reading, setting, and clearing the
+NTB doorbell, and reading and writing scratchpads.
+
+The Tool does not currently have any module parameters.
+
+Debugfs Files:
+
+* *debugfs*/ntb\_tool/*hw*/ - A directory in debugfs will be created for each
+	NTB device probed by the tool.  This directory is shortened to *hw*
+	below.
+* *hw*/db - This file is used to read, set, and clear the local doorbell.  Not
+	all operations may be supported by all hardware.  To read the doorbell,
+	read the file.  To set the doorbell, write `s` followed by the bits to
+	set (eg: `echo 's 0x0101' > db`).  To clear the doorbell, write `c`
+	followed by the bits to clear.
+* *hw*/mask - This file is used to read, set, and clear the local doorbell mask.
+	See *db* for details.
+* *hw*/peer\_db - This file is used to read, set, and clear the peer doorbell.
+	See *db* for details.
+* *hw*/peer\_mask - This file is used to read, set, and clear the peer doorbell
+	mask.  See *db* for details.
+* *hw*/spad - This file is used to read and write local scratchpads.  To read
+	the values of all scratchpads, read the file.  To write values, write a
+	series of pairs of scratchpad number and value
+	(eg: `echo '4 0x123 7 0xabc' > spad`
+	# to set scratchpads `4` and `7` to `0x123` and `0xabc`, respectively).
+* *hw*/peer\_spad - This file is used to read and write peer scratchpads.  See
+	*spad* for details.
+
 ## NTB Hardware Drivers
 
 NTB hardware drivers should register devices with the NTB core driver.  After
diff --git a/MAINTAINERS b/MAINTAINERS
index 69dad8e01d80..ec19f09f6c0c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6988,6 +6988,7 @@ F:	drivers/ntb/
 F:	drivers/net/ntb_netdev.c
 F:	drivers/ntb/ntb.c
 F:	drivers/ntb/ntb_pingpong.c
+F:	drivers/ntb/ntb_tool.c
 F:	drivers/ntb/ntb_transport.c
 F:	include/linux/ntb.h
 F:	include/linux/ntb_transport.h
diff --git a/drivers/ntb/test/Kconfig b/drivers/ntb/test/Kconfig
index 72d255d220c8..01852f98a843 100644
--- a/drivers/ntb/test/Kconfig
+++ b/drivers/ntb/test/Kconfig
@@ -6,3 +6,14 @@ config NTB_PINGPONG
 	 your ntb hardware and drivers are functioning at a basic level.
 
 	 If unsure, say N.
+
+config NTB_TOOL
+	tristate "NTB Debugging Tool Test Client"
+	help
+	 This is a simple debugging driver that enables the doorbell and
+	 scratchpad registers to be read and written from the debugfs.  This
+	 enables more complicated debugging to be scripted from user space.
+	 This driver may be used to test that your ntb hardware and drivers are
+	 functioning at a basic level.
+
+	 If unsure, say N.
diff --git a/drivers/ntb/test/Makefile b/drivers/ntb/test/Makefile
index b32309307771..0ea32a324b6c 100644
--- a/drivers/ntb/test/Makefile
+++ b/drivers/ntb/test/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_NTB_PINGPONG) += ntb_pingpong.o
+obj-$(CONFIG_NTB_TOOL) += ntb_tool.o
diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
new file mode 100644
index 000000000000..c7933936b41d
--- /dev/null
+++ b/drivers/ntb/test/ntb_tool.c
@@ -0,0 +1,556 @@
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ *   redistributing this file, you may do so under either license.
+ *
+ *   GPL LICENSE SUMMARY
+ *
+ *   Copyright (C) 2015 EMC Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of version 2 of the GNU General Public License as
+ *   published by the Free Software Foundation.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *   General Public License for more details.
+ *
+ *   BSD LICENSE
+ *
+ *   Copyright (C) 2015 EMC Corporation. All Rights Reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copy
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * PCIe NTB Debugging Tool Linux driver
+ *
+ * Contact Information:
+ * Allen Hubbe <Allen.Hubbe@emc.com>
+ */
+
+/*
+ * How to use this tool, by example.
+ *
+ * Assuming $DBG_DIR is something like:
+ * '/sys/kernel/debug/ntb_tool/0000:00:03.0'
+ *
+ * Eg: check if clearing the doorbell mask generates an interrupt.
+ *
+ * # Set the doorbell mask
+ * root@self# echo 's 1' > $DBG_DIR/mask
+ *
+ * # Ring the doorbell from the peer
+ * root@peer# echo 's 1' > $DBG_DIR/peer_db
+ *
+ * # Clear the doorbell mask
+ * root@self# echo 'c 1' > $DBG_DIR/mask
+ *
+ * Observe debugging output in dmesg or your console.  You should see a
+ * doorbell event triggered by clearing the mask.  If not, this may indicate an
+ * issue with the hardware that needs to be worked around in the driver.
+ *
+ * Eg: read and write scratchpad registers
+ *
+ * root@peer# echo '0 0x01010101 1 0x7f7f7f7f' > $DBG_DIR/peer_spad
+ *
+ * root@self# cat $DBG_DIR/spad
+ *
+ * Observe that spad 0 and 1 have the values set by the peer.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include <linux/debugfs.h>
+#include <linux/dma-mapping.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+
+#include <linux/ntb.h>
+
+#define DRIVER_NAME			"ntb_tool"
+#define DRIVER_DESCRIPTION		"PCIe NTB Debugging Tool"
+
+#define DRIVER_LICENSE			"Dual BSD/GPL"
+#define DRIVER_VERSION			"1.0"
+#define DRIVER_RELDATE			"22 April 2015"
+#define DRIVER_AUTHOR			"Allen Hubbe <Allen.Hubbe@emc.com>"
+
+MODULE_LICENSE(DRIVER_LICENSE);
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESCRIPTION);
+
+static struct dentry *tool_dbgfs;
+
+struct tool_ctx {
+	struct ntb_dev *ntb;
+	struct dentry *dbgfs;
+};
+
+#define SPAD_FNAME_SIZE 0x10
+#define INT_PTR(x) ((void *)(unsigned long)x)
+#define PTR_INT(x) ((int)(unsigned long)x)
+
+#define TOOL_FOPS_RDWR(__name, __read, __write) \
+	const struct file_operations __name = {	\
+		.owner = THIS_MODULE,		\
+		.open = simple_open,		\
+		.read = __read,			\
+		.write = __write,		\
+	}
+
+static void tool_link_event(void *ctx)
+{
+	struct tool_ctx *tc = ctx;
+	enum ntb_speed speed;
+	enum ntb_width width;
+	int up;
+
+	up = ntb_link_is_up(tc->ntb, &speed, &width);
+
+	dev_dbg(&tc->ntb->dev, "link is %s speed %d width %d\n",
+		up ? "up" : "down", speed, width);
+}
+
+static void tool_db_event(void *ctx, int vec)
+{
+	struct tool_ctx *tc = ctx;
+	u64 db_bits, db_mask;
+
+	db_mask = ntb_db_vector_mask(tc->ntb, vec);
+	db_bits = ntb_db_read(tc->ntb);
+
+	dev_dbg(&tc->ntb->dev, "doorbell vec %d mask %#llx bits %#llx\n",
+		vec, db_mask, db_bits);
+}
+
+static const struct ntb_ctx_ops tool_ops = {
+	.link_event = tool_link_event,
+	.db_event = tool_db_event,
+};
+
+static ssize_t tool_dbfn_read(struct tool_ctx *tc, char __user *ubuf,
+			      size_t size, loff_t *offp,
+			      u64 (*db_read_fn)(struct ntb_dev *))
+{
+	size_t buf_size;
+	char *buf;
+	ssize_t pos, rc;
+
+	if (!db_read_fn)
+		return -EINVAL;
+
+	buf_size = min(size, 0x20ul);
+
+	buf = kmalloc(buf_size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	pos = scnprintf(buf, buf_size, "%#llx\n",
+			db_read_fn(tc->ntb));
+
+	rc = simple_read_from_buffer(ubuf, size, offp, buf, pos);
+
+	kfree(buf);
+
+	return rc;
+}
+
+static ssize_t tool_dbfn_write(struct tool_ctx *tc,
+			       const char __user *ubuf,
+			       size_t size, loff_t *offp,
+			       int (*db_set_fn)(struct ntb_dev *, u64),
+			       int (*db_clear_fn)(struct ntb_dev *, u64))
+{
+	u64 db_bits;
+	char *buf, cmd;
+	ssize_t rc;
+	int n;
+
+	buf = kmalloc(size + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	rc = simple_write_to_buffer(buf, size, offp, ubuf, size);
+	if (rc < 0) {
+		kfree(buf);
+		return rc;
+	}
+
+	buf[size] = 0;
+
+	n = sscanf(buf, "%c %lli", &cmd, &db_bits);
+
+	kfree(buf);
+
+	if (n != 2) {
+		rc = -EINVAL;
+	} else if (cmd == 's') {
+		if (!db_set_fn)
+			rc = -EINVAL;
+		else
+			rc = db_set_fn(tc->ntb, db_bits);
+	} else if (cmd == 'c') {
+		if (!db_clear_fn)
+			rc = -EINVAL;
+		else
+			rc = db_clear_fn(tc->ntb, db_bits);
+	} else {
+		rc = -EINVAL;
+	}
+
+	return rc ? : size;
+}
+
+static ssize_t tool_spadfn_read(struct tool_ctx *tc, char __user *ubuf,
+				size_t size, loff_t *offp,
+				u32 (*spad_read_fn)(struct ntb_dev *, int))
+{
+	size_t buf_size;
+	char *buf;
+	ssize_t pos, rc;
+	int i, spad_count;
+
+	if (!spad_read_fn)
+		return -EINVAL;
+
+	buf_size = min(size, 0x100ul);
+
+	buf = kmalloc(buf_size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	pos = 0;
+
+	spad_count = ntb_spad_count(tc->ntb);
+	for (i = 0; i < spad_count; ++i) {
+		pos += scnprintf(buf + pos, buf_size - pos, "%d\t%#x\n",
+				 i, spad_read_fn(tc->ntb, i));
+	}
+
+	rc = simple_read_from_buffer(ubuf, size, offp, buf, pos);
+
+	kfree(buf);
+
+	return rc;
+}
+
+static ssize_t tool_spadfn_write(struct tool_ctx *tc,
+				 const char __user *ubuf,
+				 size_t size, loff_t *offp,
+				 int (*spad_write_fn)(struct ntb_dev *,
+						      int, u32))
+{
+	int spad_idx;
+	u32 spad_val;
+	char *buf;
+	int pos, n;
+	ssize_t rc;
+
+	if (!spad_write_fn) {
+		dev_dbg(&tc->ntb->dev, "no spad write fn\n");
+		return -EINVAL;
+	}
+
+	buf = kmalloc(size + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	rc = simple_write_to_buffer(buf, size, offp, ubuf, size);
+	if (rc < 0) {
+		kfree(buf);
+		return rc;
+	}
+
+	buf[size] = 0;
+
+	n = sscanf(buf, "%d %i%n", &spad_idx, &spad_val, &pos);
+	while (n == 2) {
+		rc = spad_write_fn(tc->ntb, spad_idx, spad_val);
+		if (rc)
+			break;
+
+		n = sscanf(buf + pos, "%d %i%n", &spad_idx, &spad_val, &pos);
+	}
+
+	if (n < 0)
+		rc = n;
+
+	kfree(buf);
+
+	return rc ? : size;
+}
+
+static ssize_t tool_db_read(struct file *filep, char __user *ubuf,
+			    size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_read(tc, ubuf, size, offp,
+			      tc->ntb->ops->db_read);
+}
+
+static ssize_t tool_db_write(struct file *filep, const char __user *ubuf,
+			     size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_write(tc, ubuf, size, offp,
+			       tc->ntb->ops->db_set,
+			       tc->ntb->ops->db_clear);
+}
+
+static TOOL_FOPS_RDWR(tool_db_fops,
+		      tool_db_read,
+		      tool_db_write);
+
+static ssize_t tool_mask_read(struct file *filep, char __user *ubuf,
+			      size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_read(tc, ubuf, size, offp,
+			      tc->ntb->ops->db_read_mask);
+}
+
+static ssize_t tool_mask_write(struct file *filep, const char __user *ubuf,
+			       size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_write(tc, ubuf, size, offp,
+			       tc->ntb->ops->db_set_mask,
+			       tc->ntb->ops->db_clear_mask);
+}
+
+static TOOL_FOPS_RDWR(tool_mask_fops,
+		      tool_mask_read,
+		      tool_mask_write);
+
+static ssize_t tool_peer_db_read(struct file *filep, char __user *ubuf,
+				 size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_read(tc, ubuf, size, offp,
+			      tc->ntb->ops->peer_db_read);
+}
+
+static ssize_t tool_peer_db_write(struct file *filep, const char __user *ubuf,
+				  size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_write(tc, ubuf, size, offp,
+			       tc->ntb->ops->peer_db_set,
+			       tc->ntb->ops->peer_db_clear);
+}
+
+static TOOL_FOPS_RDWR(tool_peer_db_fops,
+		      tool_peer_db_read,
+		      tool_peer_db_write);
+
+static ssize_t tool_peer_mask_read(struct file *filep, char __user *ubuf,
+				   size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_read(tc, ubuf, size, offp,
+			      tc->ntb->ops->peer_db_read_mask);
+}
+
+static ssize_t tool_peer_mask_write(struct file *filep, const char __user *ubuf,
+				    size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_dbfn_write(tc, ubuf, size, offp,
+			       tc->ntb->ops->peer_db_set_mask,
+			       tc->ntb->ops->peer_db_clear_mask);
+}
+
+static TOOL_FOPS_RDWR(tool_peer_mask_fops,
+		      tool_peer_mask_read,
+		      tool_peer_mask_write);
+
+static ssize_t tool_spad_read(struct file *filep, char __user *ubuf,
+			      size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_spadfn_read(tc, ubuf, size, offp,
+				tc->ntb->ops->spad_read);
+}
+
+static ssize_t tool_spad_write(struct file *filep, const char __user *ubuf,
+			       size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_spadfn_write(tc, ubuf, size, offp,
+				 tc->ntb->ops->spad_write);
+}
+
+static TOOL_FOPS_RDWR(tool_spad_fops,
+		      tool_spad_read,
+		      tool_spad_write);
+
+static ssize_t tool_peer_spad_read(struct file *filep, char __user *ubuf,
+				   size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_spadfn_read(tc, ubuf, size, offp,
+				tc->ntb->ops->peer_spad_read);
+}
+
+static ssize_t tool_peer_spad_write(struct file *filep, const char __user *ubuf,
+				    size_t size, loff_t *offp)
+{
+	struct tool_ctx *tc = filep->private_data;
+
+	return tool_spadfn_write(tc, ubuf, size, offp,
+				 tc->ntb->ops->peer_spad_write);
+}
+
+static TOOL_FOPS_RDWR(tool_peer_spad_fops,
+		      tool_peer_spad_read,
+		      tool_peer_spad_write);
+
+static void tool_setup_dbgfs(struct tool_ctx *tc)
+{
+	/* This modules is useless without dbgfs... */
+	if (!tool_dbgfs) {
+		tc->dbgfs = NULL;
+		return;
+	}
+
+	tc->dbgfs = debugfs_create_dir(dev_name(&tc->ntb->dev),
+				       tool_dbgfs);
+	if (!tc->dbgfs)
+		return;
+
+	debugfs_create_file("db", S_IRUSR | S_IWUSR, tc->dbgfs,
+			    tc, &tool_db_fops);
+
+	debugfs_create_file("mask", S_IRUSR | S_IWUSR, tc->dbgfs,
+			    tc, &tool_mask_fops);
+
+	debugfs_create_file("peer_db", S_IRUSR | S_IWUSR, tc->dbgfs,
+			    tc, &tool_peer_db_fops);
+
+	debugfs_create_file("peer_mask", S_IRUSR | S_IWUSR, tc->dbgfs,
+			    tc, &tool_peer_mask_fops);
+
+	debugfs_create_file("spad", S_IRUSR | S_IWUSR, tc->dbgfs,
+			    tc, &tool_spad_fops);
+
+	debugfs_create_file("peer_spad", S_IRUSR | S_IWUSR, tc->dbgfs,
+			    tc, &tool_peer_spad_fops);
+}
+
+static int tool_probe(struct ntb_client *self, struct ntb_dev *ntb)
+{
+	struct tool_ctx *tc;
+	int rc;
+
+	if (ntb_db_is_unsafe(ntb))
+		dev_dbg(&ntb->dev, "doorbell is unsafe\n");
+
+	if (ntb_spad_is_unsafe(ntb))
+		dev_dbg(&ntb->dev, "scratchpad is unsafe\n");
+
+	tc = kmalloc(sizeof(*tc), GFP_KERNEL);
+	if (!tc) {
+		rc = -ENOMEM;
+		goto err_tc;
+	}
+
+	tc->ntb = ntb;
+
+	tool_setup_dbgfs(tc);
+
+	rc = ntb_set_ctx(ntb, tc, &tool_ops);
+	if (rc)
+		goto err_ctx;
+
+	ntb_link_enable(ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
+	ntb_link_event(ntb);
+
+	return 0;
+
+err_ctx:
+	debugfs_remove_recursive(tc->dbgfs);
+	kfree(tc);
+err_tc:
+	return rc;
+}
+
+static void tool_remove(struct ntb_client *self, struct ntb_dev *ntb)
+{
+	struct tool_ctx *tc = ntb->ctx;
+
+	ntb_clear_ctx(ntb);
+	ntb_link_disable(ntb);
+
+	debugfs_remove_recursive(tc->dbgfs);
+	kfree(tc);
+}
+
+static struct ntb_client tool_client = {
+	.ops = {
+		.probe = tool_probe,
+		.remove = tool_remove,
+	},
+};
+
+static int __init tool_init(void)
+{
+	int rc;
+
+	if (debugfs_initialized())
+		tool_dbgfs = debugfs_create_dir(KBUILD_MODNAME, NULL);
+
+	rc = ntb_register_client(&tool_client);
+	if (rc)
+		goto err_client;
+
+	return 0;
+
+err_client:
+	debugfs_remove_recursive(tool_dbgfs);
+	return rc;
+}
+module_init(tool_init);
+
+static void __exit tool_exit(void)
+{
+	ntb_unregister_client(&tool_client);
+	debugfs_remove_recursive(tool_dbgfs);
+}
+module_exit(tool_exit);
