diff --git a/drivers/infiniband/hw/pvrdma/pvrdma_doorbell.c b/drivers/infiniband/hw/pvrdma/pvrdma_doorbell.c
new file mode 100644
index 0000000..bf51357
--- /dev/null
+++ b/drivers/infiniband/hw/pvrdma/pvrdma_doorbell.c
@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2012-2016 VMware, Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of EITHER the GNU General Public License
+ * version 2 as published by the Free Software Foundation or the BSD
+ * 2-Clause License. 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 version 2 for more details at
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program available in the file COPYING in the main
+ * directory of this source tree.
+ *
+ * The BSD 2-Clause License
+ *
+ *     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
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * 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 HOLDER 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.
+ */
+
+#include <linux/bitmap.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+#include "pvrdma.h"
+
+int pvrdma_uar_table_init(struct pvrdma_dev *dev)
+{
+	u32 num = dev->dsr->caps.max_uar;
+	u32 mask = num - 1;
+	struct pvrdma_id_table *tbl = &dev->uar_table.tbl;
+
+	if (!is_power_of_2(num))
+		return -EINVAL;
+
+	tbl->last = 0;
+	tbl->top = 0;
+	tbl->max = num;
+	tbl->mask = mask;
+	spin_lock_init(&tbl->lock);
+	tbl->table = kcalloc(BITS_TO_LONGS(num), sizeof(long), GFP_KERNEL);
+	if (!tbl->table)
+		return -ENOMEM;
+
+	/* 0th UAR is taken by the device. */
+	set_bit(0, tbl->table);
+
+	return 0;
+}
+
+void pvrdma_uar_table_cleanup(struct pvrdma_dev *dev)
+{
+	struct pvrdma_id_table *tbl = &dev->uar_table.tbl;
+
+	kfree(tbl->table);
+}
+
+int pvrdma_uar_alloc(struct pvrdma_dev *dev, struct pvrdma_uar_map *uar)
+{
+	struct pvrdma_id_table *tbl;
+	unsigned long flags;
+	u32 obj;
+
+	tbl = &dev->uar_table.tbl;
+
+	spin_lock_irqsave(&tbl->lock, flags);
+	obj = find_next_zero_bit(tbl->table, tbl->max, tbl->last);
+	if (obj >= tbl->max) {
+		tbl->top = (tbl->top + tbl->max) & tbl->mask;
+		obj = find_first_zero_bit(tbl->table, tbl->max);
+	}
+
+	if (obj >= tbl->max) {
+		spin_unlock_irqrestore(&tbl->lock, flags);
+		return -ENOMEM;
+	}
+
+	set_bit(obj, tbl->table);
+	obj |= tbl->top;
+
+	spin_unlock_irqrestore(&tbl->lock, flags);
+
+	uar->index = obj;
+	uar->pfn = (pci_resource_start(dev->pdev, PVRDMA_PCI_RESOURCE_UAR) >>
+		    PAGE_SHIFT) + uar->index;
+
+	return 0;
+}
+
+void pvrdma_uar_free(struct pvrdma_dev *dev, struct pvrdma_uar_map *uar)
+{
+	struct pvrdma_id_table *tbl = &dev->uar_table.tbl;
+	unsigned long flags;
+	u32 obj;
+
+	obj = uar->index & (tbl->max - 1);
+	spin_lock_irqsave(&tbl->lock, flags);
+	clear_bit(obj, tbl->table);
+	tbl->last = min(tbl->last, obj);
+	tbl->top = (tbl->top + tbl->max) & tbl->mask;
+	spin_unlock_irqrestore(&tbl->lock, flags);
+}
