path: root/drivers/infiniband/hw/ipath/ipath_qp.c

/*
 * Copyright (c) 2006 QLogic, Inc. All rights reserved.
 * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/err.h>
#include <linux/vmalloc.h>

#include "ipath_verbs.h"
#include "ipath_kernel.h"

#define BITS_PER_PAGE		(PAGE_SIZE*BITS_PER_BYTE)
#define BITS_PER_PAGE_MASK	(BITS_PER_PAGE-1)
#define mk_qpn(qpt, map, off)	(((map) - (qpt)->map) * BITS_PER_PAGE + \
				 (off))
#define find_next_offset(map, off) find_next_zero_bit((map)->page, \
						      BITS_PER_PAGE, off)

/*
 * Convert the AETH credit code into the number of credits.
 */
static u32 credit_table[31] = {
	0,			/* 0 */
	1,			/* 1 */
	2,			/* 2 */
	3,			/* 3 */
	4,			/* 4 */
	6,			/* 5 */
	8,			/* 6 */
	12,			/* 7 */
	16,			/* 8 */
	24,			/* 9 */
	32,			/* A */
	48,			/* B */
	64,			/* C */
	96,			/* D */
	128,			/* E */
	192,			/* F */
	256,			/* 10 */
	384,			/* 11 */
	512,			/* 12 */
	768,			/* 13 */
	1024,			/* 14 */
	1536,			/* 15 */
	2048,			/* 16 */
	3072,			/* 17 */
	4096,			/* 18 */
	6144,			/* 19 */
	8192,			/* 1A */
	12288,			/* 1B */
	16384,			/* 1C */
	24576,			/* 1D */
	32768			/* 1E */
};

static u32 alloc_qpn(struct ipath_qp_table *qpt)
{
	u32 i, offset, max_scan, qpn;
	struct qpn_map *map;
	u32 ret;

	qpn = qpt->last + 1;
	if (qpn >= QPN_MAX)
		qpn = 2;
	offset = qpn & BITS_PER_PAGE_MASK;
	map = &qpt->map[qpn / BITS_PER_PAGE];
	max_scan = qpt->nmaps - !offset;
	for (i = 0;;) {
		if (unlikely(!map->page)) {
			unsigned long page = get_zeroed_page(GFP_KERNEL);
			unsigned long flags;

			/*
			 * Free the page if someone raced with us
			 * installing it:
			 */
			spin_lock_irqsave(&qpt->lock, flags);
			if (map->page)
				free_page(page);
			else
				map->page = (void *)page;
			spin_unlock_irqrestore(&qpt->lock, flags);
			if (unlikely(!map->page))
				break;
		}
		if (likely(atomic_read(&map->n_free))) {
			do {
				if (!test_and_set_bit(offset, map->page)) {
					atomic_dec(&map->n_free);
					qpt->last = qpn;
					ret = qpn;
					goto bail;
				}
				offset = find_next_offset(map, offset);
				qpn = mk_qpn(qpt, map, offset);
				/*
				 * This test differs from alloc_pidmap().
				 * If find_next_offset() does find a zero
				 * bit, we don't need to check for QPN
				 * wrapping around past our starting QPN.
				 * We just need to be sure we don't loop
				 * forever.
				 */
			} while (offset < BITS_PER_PAGE && qpn < QPN_MAX);
		}
		/*
		 * In order to keep the number of pages allocated to a
		 * minimum, we scan the all existing pages before increasing
		 * the size of the bitmap table.
		 */
		if (++i > max_scan) {
			if (qpt->nmaps == QPNMAP_ENTRIES)
				break;
			map = &qpt->map[qpt->nmaps++];
			offset = 0;
		} else if (map < &qpt->map[qpt->nmaps]) {
			++map;
			offset = 0;
		} else {
			map = &qpt->map[0];
			offset = 2;
		}
		qpn = mk_qpn(qpt, map, offset);
	}

	ret = 0;

bail:
	return ret;
}

static void free_qpn(struct ipath_qp_table *qpt, u32 qpn)
{
	struct