1 /*
2 * Copyright © 2016 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 *
23 */
24
25 #include <linux/bitops.h>
26 #include <linux/kernel.h>
27 #include <linux/random.h>
28 #include <linux/slab.h>
29 #include <linux/types.h>
30
31 #include "i915_random.h"
32
i915_prandom_u64_state(struct rnd_state * rnd)33 u64 i915_prandom_u64_state(struct rnd_state *rnd)
34 {
35 u64 x;
36
37 x = prandom_u32_state(rnd);
38 x <<= 32;
39 x |= prandom_u32_state(rnd);
40
41 return x;
42 }
43
i915_random_reorder(unsigned int * order,unsigned int count,struct rnd_state * state)44 void i915_random_reorder(unsigned int *order, unsigned int count,
45 struct rnd_state *state)
46 {
47 unsigned int i, j;
48
49 for (i = 0; i < count; i++) {
50 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
51 j = i915_prandom_u32_max_state(count, state);
52 swap(order[i], order[j]);
53 }
54 }
55
i915_random_order(unsigned int count,struct rnd_state * state)56 unsigned int *i915_random_order(unsigned int count, struct rnd_state *state)
57 {
58 unsigned int *order, i;
59
60 order = kmalloc_array(count, sizeof(*order),
61 GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
62 if (!order)
63 return order;
64
65 for (i = 0; i < count; i++)
66 order[i] = i;
67
68 i915_random_reorder(order, count, state);
69 return order;
70 }
71
