2 * Copyright © 2016 Intel Corporation
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:
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
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
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>
31 #include "i915_random.h"
33 u64 i915_prandom_u64_state(struct rnd_state *rnd)
37 x = prandom_u32_state(rnd);
39 x |= prandom_u32_state(rnd);
44 static inline u32 i915_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
46 return upper_32_bits((u64)prandom_u32_state(state) * ep_ro);
49 void i915_random_reorder(unsigned int *order, unsigned int count,
50 struct rnd_state *state)
54 for (i = 0; i < count; i++) {
55 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
56 j = i915_prandom_u32_max_state(count, state);
57 swap(order[i], order[j]);
61 unsigned int *i915_random_order(unsigned int count, struct rnd_state *state)
63 unsigned int *order, i;
65 order = kmalloc_array(count, sizeof(*order), GFP_TEMPORARY);
69 for (i = 0; i < count; i++)
72 i915_random_reorder(order, count, state);