1// SPDX-License-Identifier: GPL-2.0
2#include <linux/bitops.h>
3#include <linux/export.h>
4#include <linux/kernel.h>
5#include <linux/random.h>
6#include <linux/slab.h>
7#include <linux/types.h>
8
9#include "drm_random.h"
10
11u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
12{
13 return upper_32_bits((u64)prandom_u32_state(state) * ep_ro);
14}
15EXPORT_SYMBOL(drm_prandom_u32_max_state);
16
17void drm_random_reorder(unsigned int *order, unsigned int count,
18 struct rnd_state *state)
19{
20 unsigned int i, j;
21
22 for (i = 0; i < count; ++i) {
23 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
24 j = drm_prandom_u32_max_state(count, state);
25 swap(order[i], order[j]);
26 }
27}
28EXPORT_SYMBOL(drm_random_reorder);
29
30unsigned int *drm_random_order(unsigned int count, struct rnd_state *state)
31{
32 unsigned int *order, i;
33
34 order = kmalloc_array(count, sizeof(*order), GFP_KERNEL);
35 if (!order)
36 return order;
37
38 for (i = 0; i < count; i++)
39 order[i] = i;
40
41 drm_random_reorder(order, count, state);
42 return order;
43}
44EXPORT_SYMBOL(drm_random_order);
45

source code of linux/drivers/gpu/drm/lib/drm_random.c