drivers/rng/sandbox_rng.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) 2019, Linaro Limited
   4  */
   5
   6 #include <common.h>
   7 #include <dm.h>
   8 #include <rng.h>
   9
  10 #include <linux/string.h>
  11
  12 static int sandbox_rng_read(struct udevice *dev, void *data, size_t len)
  13 {
  14         unsigned int i, seed, random;
  15         unsigned char *buf = data;
  16         size_t nrem, nloops;
  17
  18         if (!len)
  19                 return 0;
  20
  21         nloops = len / sizeof(random);
  22         seed = get_timer(0) ^ rand();
  23         srand(seed);
  24
  25         for (i = 0, nrem = len; i < nloops; i++) {
  26                 random = rand();
  27                 memcpy(buf, &random, sizeof(random));
  28                 buf += sizeof(random);
  29                 nrem -= sizeof(random);
  30         }
  31
  32         if (nrem) {
  33                 random = rand();
  34                 memcpy(buf, &random, nrem);
  35         }
  36
  37         return 0;
  38 }
  39
  40 static const struct dm_rng_ops sandbox_rng_ops = {
  41         .read = sandbox_rng_read,
  42 };
  43
  44 static const struct udevice_id sandbox_rng_match[] = {
  45         {
  46                 .compatible = "sandbox,sandbox-rng",
  47         },
  48         {},
  49 };
  50
  51 U_BOOT_DRIVER(sandbox_rng) = {
  52         .name = "sandbox-rng",
  53         .id = UCLASS_RNG,
  54         .of_match = sandbox_rng_match,
  55         .ops = &sandbox_rng_ops,
  56 };