drivers/gpu/drm/i915/selftests/i915_random.c

   1 /*
   2  * Copyright © 2016 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  */
  24
  25 #include <linux/bitops.h>
  26 #include <linux/kernel.h>
  27 #include <linux/random.h>
  28 #include <linux/slab.h>
  29 #include <linux/types.h>
  30
  31 #include "i915_random.h"
  32
  33 u64 i915_prandom_u64_state(struct rnd_state *rnd)
  34 {
  35         u64 x;
  36
  37         x = prandom_u32_state(rnd);
  38         x <<= 32;
  39         x |= prandom_u32_state(rnd);
  40
  41         return x;
  42 }
  43
  44 void i915_random_reorder(unsigned int *order, unsigned int count,
  45                          struct rnd_state *state)
  46 {
  47         unsigned int i, j;
  48
  49         for (i = 0; i < count; i++) {
  50                 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
  51                 j = i915_prandom_u32_max_state(count, state);
  52                 swap(order[i], order[j]);
  53         }
  54 }
  55
  56 unsigned int *i915_random_order(unsigned int count, struct rnd_state *state)
  57 {
  58         unsigned int *order, i;
  59
  60         order = kmalloc_array(count, sizeof(*order), GFP_KERNEL | __GFP_NOWARN);
  61         if (!order)
  62                 return order;
  63
  64         for (i = 0; i < count; i++)
  65                 order[i] = i;
  66
  67         i915_random_reorder(order, count, state);
  68         return order;
  69 }