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;
17	u8 buf[64];
18	int devnum;
19	struct udevice *dev;
20	int ret = CMD_RET_SUCCESS, err;
21
22	if (argc == 2 && !strcmp(argv[1], "list")) {
23		int idx = 0;
24
25		uclass_foreach_dev_probe(UCLASS_RNG, dev) {
26			idx++;
27			printf("RNG #%d - %s\n", dev->seq_, dev->name);
28		}
29
30		if (!idx) {
31			log_err("No RNG device\n");
32			return CMD_RET_FAILURE;
33		}
34
35		return CMD_RET_SUCCESS;
36	}
37
38	switch (argc) {
39	case 1:
40		devnum = 0;
41		n = 0x40;
42		break;
43	case 2:
44		devnum = hextoul(argv[1], NULL);
45		n = 0x40;
46		break;
47	case 3:
48		devnum = hextoul(argv[1], NULL);
49		n = hextoul(argv[2], NULL);
50		break;
51	default:
52		return CMD_RET_USAGE;
53	}
54
55	if (uclass_get_device_by_seq(UCLASS_RNG, devnum, &dev) || !dev) {
56		printf("No RNG device\n");
57		return CMD_RET_FAILURE;
58	}
59
60	if (!n)
61		return 0;
62
63	n = min(n, sizeof(buf));
64
65	err = dm_rng_read(dev, buf, n);
66	if (err) {
67		puts(err == -EINTR ? "Abort\n" : "Reading RNG failed\n");
68		ret = CMD_RET_FAILURE;
69	} else {
70		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, buf, n);
71	}
72
73	return ret;
74}
75
76U_BOOT_CMD(
77	rng, 3, 0, do_rng,
78	"print bytes from the hardware random number generator",
79	"list         - list all the probed rng devices\n"
80	"rng [dev] [n]    - print n random bytes(max 64) read from dev\n"
81);
82