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
drm_prandom_u32_max_state(u32 ep_ro,struct rnd_state * state)10 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 EXPORT_SYMBOL(drm_prandom_u32_max_state);
15
drm_random_reorder(unsigned int * order,unsigned int count,struct rnd_state * state)16 void drm_random_reorder(unsigned int *order, unsigned int count,
17 struct rnd_state *state)
18 {
19 unsigned int i, j;
20
21 for (i = 0; i < count; ++i) {
22 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
23 j = drm_prandom_u32_max_state(count, state);
24 swap(order[i], order[j]);
25 }
26 }
27 EXPORT_SYMBOL(drm_random_reorder);
28
drm_random_order(unsigned int count,struct rnd_state * state)29 unsigned int *drm_random_order(unsigned int count, struct rnd_state *state)
30 {
31 unsigned int *order, i;
32
33 order = kmalloc_array(count, sizeof(*order), GFP_KERNEL);
34 if (!order)
35 return order;
36
37 for (i = 0; i < count; i++)
38 order[i] = i;
39
40 drm_random_reorder(order, count, state);
41 return order;
42 }
43 EXPORT_SYMBOL(drm_random_order);
44