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 
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 
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 
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), GFP_KERNEL);
61 	if (!order)
62 		return order;
63 
64 	for (i = 0; i < count; i++)
65 		order[i] = i;
66 
67 	i915_random_reorder(order, count, state);
68 	return order;
69 }
70