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
do_rng(struct cmd_tbl * cmdtp,int flag,int argc,char * const argv[])14 static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
15 {
16 size_t n;
17 u8 buf[64];
18 int devnum;
19 struct udevice *dev;
20 int ret = CMD_RET_SUCCESS;
21
22 switch (argc) {
23 case 1:
24 devnum = 0;
25 n = 0x40;
26 break;
27 case 2:
28 devnum = hextoul(argv[1], NULL);
29 n = 0x40;
30 break;
31 case 3:
32 devnum = hextoul(argv[1], NULL);
33 n = hextoul(argv[2], NULL);
34 break;
35 default:
36 return CMD_RET_USAGE;
37 }
38
39 if (uclass_get_device_by_seq(UCLASS_RNG, devnum, &dev) || !dev) {
40 printf("No RNG device\n");
41 return CMD_RET_FAILURE;
42 }
43
44 if (!n)
45 return 0;
46
47 n = min(n, sizeof(buf));
48
49 if (dm_rng_read(dev, buf, n)) {
50 printf("Reading RNG failed\n");
51 ret = CMD_RET_FAILURE;
52 } else {
53 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, buf, n);
54 }
55
56 return ret;
57 }
58
59 #ifdef CONFIG_SYS_LONGHELP
60 static char rng_help_text[] =
61 "[dev [n]]\n"
62 " - print n random bytes(max 64) read from dev\n";
63 #endif
64
65 U_BOOT_CMD(
66 rng, 3, 0, do_rng,
67 "print bytes from the hardware random number generator",
68 rng_help_text
69 );
70