1/*
2 * Copyright (c) 2011 Chelsio Communications.  All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses.  You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 *     Redistribution and use in source and binary forms, with or
11 *     without modification, are permitted provided that the following
12 *     conditions are met:
13 *
14 *      - Redistributions of source code must retain the above
15 *        copyright notice, this list of conditions and the following
16 *        disclaimer.
17 *
18 *      - Redistributions in binary form must reproduce the above
19 *        copyright notice, this list of conditions and the following
20 *        disclaimer in the documentation and/or other materials
21 *        provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 */
32#include <linux/kernel.h>
33#include <linux/random.h>
34#include "iw_cxgb4.h"
35
36#define RANDOM_SKIP 16
37
38/*
39 * Trivial bitmap-based allocator. If the random flag is set, the
40 * allocator is designed to:
41 * - pseudo-randomize the id returned such that it is not trivially predictable.
42 * - avoid reuse of recently used id (at the expense of predictability)
43 */
44u32 c4iw_id_alloc(struct c4iw_id_table *alloc)
45{
46	unsigned long flags;
47	u32 obj;
48
49	spin_lock_irqsave(&alloc->lock, flags);
50
51	obj = find_next_zero_bit(alloc->table, alloc->max, alloc->last);
52	if (obj >= alloc->max)
53		obj = find_first_zero_bit(alloc->table, alloc->max);
54
55	if (obj < alloc->max) {
56		if (alloc->flags & C4IW_ID_TABLE_F_RANDOM)
57			alloc->last += prandom_u32() % RANDOM_SKIP;
58		else
59			alloc->last = obj + 1;
60		if (alloc->last >= alloc->max)
61			alloc->last = 0;
62		set_bit(obj, alloc->table);
63		obj += alloc->start;
64	} else
65		obj = -1;
66
67	spin_unlock_irqrestore(&alloc->lock, flags);
68	return obj;
69}
70
71void c4iw_id_free(struct c4iw_id_table *alloc, u32 obj)
72{
73	unsigned long flags;
74
75	obj -= alloc->start;
76	BUG_ON((int)obj < 0);
77
78	spin_lock_irqsave(&alloc->lock, flags);
79	clear_bit(obj, alloc->table);
80	spin_unlock_irqrestore(&alloc->lock, flags);
81}
82
83int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num,
84			u32 reserved, u32 flags)
85{
86	int i;
87
88	alloc->start = start;
89	alloc->flags = flags;
90	if (flags & C4IW_ID_TABLE_F_RANDOM)
91		alloc->last = prandom_u32() % RANDOM_SKIP;
92	else
93		alloc->last = 0;
94	alloc->max  = num;
95	spin_lock_init(&alloc->lock);
96	alloc->table = kmalloc(BITS_TO_LONGS(num) * sizeof(long),
97				GFP_KERNEL);
98	if (!alloc->table)
99		return -ENOMEM;
100
101	bitmap_zero(alloc->table, num);
102	if (!(alloc->flags & C4IW_ID_TABLE_F_EMPTY))
103		for (i = 0; i < reserved; ++i)
104			set_bit(i, alloc->table);
105
106	return 0;
107}
108
109void c4iw_id_table_free(struct c4iw_id_table *alloc)
110{
111	kfree(alloc->table);
112}
113