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