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 static inline u32 i915_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) 45 { 46 return upper_32_bits((u64)prandom_u32_state(state) * ep_ro); 47 } 48 49 void i915_random_reorder(unsigned int *order, unsigned int count, 50 struct rnd_state *state) 51 { 52 unsigned int i, j; 53 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]); 58 } 59 } 60 61 unsigned int *i915_random_order(unsigned int count, struct rnd_state *state) 62 { 63 unsigned int *order, i; 64 65 order = kmalloc_array(count, sizeof(*order), GFP_TEMPORARY); 66 if (!order) 67 return order; 68 69 for (i = 0; i < count; i++) 70 order[i] = i; 71 72 i915_random_reorder(order, count, state); 73 return order; 74 } 75