[PATCH v4 10/16] IB/pvrdma: Add UAR support

[Adit Ranadive <aditr-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>]

This patch adds the UAR support for the paravirtual RDMA device. The UAR
pages are MMIO pages from the virtual PCI space. We define offsets within
this page to provide the fast data-path operations.

Reviewed-by: Yuval Shaia <yuval.shaia-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Reviewed-by: Jorgen Hansen <jhansen-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
Reviewed-by: George Zhang <georgezhang-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
Reviewed-by: Aditya Sarwade <asarwade-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
Reviewed-by: Bryan Tan <bryantan-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
Signed-off-by: Adit Ranadive <aditr-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
---
Changes v3->v4:
 - Removed an unnecessary comment.

Changes v2->v3:
 - Used is_power_of_2 function.
 - Simplify pvrdma_uar_alloc function.
---
 drivers/infiniband/hw/pvrdma/pvrdma_doorbell.c | 127 +++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 drivers/infiniband/hw/pvrdma/pvrdma_doorbell.c

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);
+}
-- 
2.7.4

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