drivers/gpu/drm/lib/drm_random.c

   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
  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
  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
  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);