aboutsummaryrefslogtreecommitdiffstats
path: root/lib/genalloc.c
blob: 9ce0a6a3b85ac49d2f160dda9c732ec65698f078 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
/*
 * Basic general purpose allocator for managing special purpose memory
 * not managed by the regular kmalloc/kfree interface.
 * Uses for this includes on-device special memory, uncached memory
 * etc.
 *
 * This code is based on the buddy allocator found in the sym53c8xx_2
 * driver Copyright (C) 1999-2001  Gerard Roudier <groudier@free.fr>,
 * and adapted for general purpose use.
 *
 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#include <linux/module.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/genalloc.h>

#include <asm/page.h>


struct gen_pool *gen_pool_create(int nr_chunks, int max_chunk_shift,
				 unsigned long (*fp)(struct gen_pool *),
				 unsigned long data)
{
	struct gen_pool *poolp;
	unsigned long tmp;
	int i;

	/*
	 * This is really an arbitrary limit, +10 is enough for
	 * IA64_GRANULE_SHIFT, aka 16MB. If anyone needs a large limit
	 * this can be increased without problems.
	 */
	if ((max_chunk_shift > (PAGE_SHIFT + 10)) ||
	    ((max_chunk_shift < ALLOC_MIN_SHIFT) && max_chunk_shift))
		return NULL;

	if (!max_chunk_shift)
		max_chunk_shift = PAGE_SHIFT;

	poolp = kmalloc(sizeof(struct gen_pool), GFP_KERNEL);
	if (!poolp)
		return NULL;
	memset(poolp, 0, sizeof(struct gen_pool));
	poolp->h = kmalloc(sizeof(struct gen_pool_link) *
			   (max_chunk_shift - ALLOC_MIN_SHIFT + 1),
			   GFP_KERNEL);
	if (!poolp->h) {
		printk(KERN_WARNING "gen_pool_alloc() failed to allocate\n");
		kfree(poolp);
		return NULL;
	}
	memset(poolp->h, 0, sizeof(struct gen_pool_link) *
	       (max_chunk_shift - ALLOC_MIN_SHIFT + 1));

	spin_lock_init(&poolp->lock);
	poolp->get_new_chunk = fp;
	poolp->max_chunk_shift = max_chunk_shift;
	poolp->private = data;

	for (i = 0; i < nr_chunks; i++) {
		tmp = poolp->get_new_chunk(poolp);
		printk(KERN_INFO "allocated %lx\n", tmp);
		if (!tmp)
			break;
		gen_pool_free(poolp, tmp, (1 << poolp->max_chunk_shift));
	}

	return poolp;
}
EXPORT_SYMBOL(gen_pool_create);


/*
 *  Simple power of two buddy-like generic allocator.
 *  Provides naturally aligned memory chunks.
 */
unsigned long gen_pool_alloc(struct gen_pool *poolp, int size)
{
	int j, i, s, max_chunk_size;
	unsigned long a, flags;
	struct gen_pool_link *h = poolp->h;

	max_chunk_size = 1 << poolp->max_chunk_shift;

	if (size > max_chunk_size)
		return 0;

	size = max(size, 1 << ALLOC_MIN_SHIFT);
	i = fls(size - 1);
	s = 1 << i;
	j = i -= ALLOC_MIN_SHIFT;

	spin_lock_irqsave(&poolp->lock, flags);
	while (!h[j].next) {
		if (s == max_chunk_size) {
			struct gen_pool_link *ptr;
			spin_unlock_irqrestore(&poolp->lock, flags);
			ptr = (struct gen_pool_link *)poolp->get_new_chunk(poolp);
			spin_lock_irqsave(&poolp->lock, flags);
			h[j].next = ptr;
			if (h[j].next)
				h[j].next->next = NULL;
			break;
		}
		j++;
		s <<= 1;
	}
	a = (unsigned long) h[j].next;
	if (a) {
		h[j].next = h[j].next->next;
		/*
		 * This should be split into a seperate function doing
		 * the chunk split in order to support custom
		 * handling memory not physically accessible by host
		 */
		while (j > i) {
			j -= 1;
			s >>= 1;
			h[j].next = (struct gen_pool_link *) (a + s);
			h[j].next->next = NULL;
		}
	}
	spin_unlock_irqrestore(&poolp->lock, flags);
	return a;
}
EXPORT_SYMBOL(gen_pool_alloc);


/*
 *  Counter-part of the generic allocator.
 */
void gen_pool_free(struct gen_pool *poolp, unsigned long ptr, int size)
{
	struct gen_pool_link *q;
	struct gen_pool_link *h = poolp->h;
	unsigned long a, b, flags;
	int i, s, max_chunk_size;

	max_chunk_size = 1 << poolp->max_chunk_shift;

	if (size > max_chunk_size)
		return;

	size = max(size, 1 << ALLOC_MIN_SHIFT);
	i = fls(size - 1);
	s = 1 << i;
	i -= ALLOC_MIN_SHIFT;

	a = ptr;

	spin_lock_irqsave(&poolp->lock, flags);
	while (1) {
		if (s == max_chunk_size) {
			((struct gen_pool_link *)a)->next = h[i].next;
			h[i].next = (struct gen_pool_link *)a;
			break;
		}
		b = a ^ s;
		q = &h[i];

		while (q->next && q->next != (struct gen_pool_link *)b)
			q = q->next;

		if (!q->next) {
			((struct gen_pool_link *)a)->next = h[i].next;
			h[i].next = (struct gen_pool_link *)a;
			break;
		}
		q->next = q->next->next;
		a = a & b;
		s <<= 1;
		i++;
	}
	spin_unlock_irqrestore(&poolp->lock, flags);
}
EXPORT_SYMBOL(gen_pool_free);