LXR linux/drivers/gpu/drm/lib/drm

   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);
  43