LXR uboot/cmd/rng.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * The 'rng' command prints bytes from the hardware random number generator.
   4 *
   5 * Copyright (c) 2019, Heinrich Schuchardt <xypron.glpk@gmx.de>
   6 */
   7#include <common.h>
   8#include <command.h>
   9#include <dm.h>
  10#include <hexdump.h>
  11#include <malloc.h>
  12#include <rng.h>
  13
  14static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
  15{
  16        size_t n = 0x40;
  17        struct udevice *dev;
  18        void *buf;
  19        int ret = CMD_RET_SUCCESS;
  20
  21        if (uclass_get_device(UCLASS_RNG, 0, &dev) || !dev) {
  22                printf("No RNG device\n");
  23                return CMD_RET_FAILURE;
  24        }
  25
  26        if (argc >= 2)
  27                n = hextoul(argv[1], NULL);
  28
  29        buf = malloc(n);
  30        if (!buf) {
  31                printf("Out of memory\n");
  32                return CMD_RET_FAILURE;
  33        }
  34
  35        if (dm_rng_read(dev, buf, n)) {
  36                printf("Reading RNG failed\n");
  37                ret = CMD_RET_FAILURE;
  38        } else {
  39                print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, buf, n);
  40        }
  41
  42        free(buf);
  43
  44        return ret;
  45}
  46
  47#ifdef CONFIG_SYS_LONGHELP
  48static char rng_help_text[] =
  49        "[n]\n"
  50        "  - print n random bytes\n";
  51#endif
  52
  53U_BOOT_CMD(
  54        rng, 2, 0, do_rng,
  55        "print bytes from the hardware random number generator",
  56        rng_help_text
  57);
  58