1 files changed, 80 insertions, 0 deletions
diff --git a/cmd/rng.c b/cmd/rng.c
new file mode 100644
index 00000000000..b073a6c8492
--- /dev/null
+++ b/cmd/rng.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * The 'rng' command prints bytes from the hardware random number generator.
+ *
+ * Copyright (c) 2019, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+#include <common.h>
+#include <command.h>
+#include <dm.h>
+#include <hexdump.h>
+#include <malloc.h>
+#include <rng.h>
+
+static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+{
+	size_t n;
+	u8 buf[64];
+	int devnum;
+	struct udevice *dev;
+	int ret = CMD_RET_SUCCESS;
+
+	if (argc == 2 && !strcmp(argv[1], "list")) {
+		int idx = 0;
+
+		uclass_foreach_dev_probe(UCLASS_RNG, dev) {
+			idx++;
+			printf("RNG #%d - %s\n", dev->seq_, dev->name);
+		}
+
+		if (!idx) {
+			log_err("No RNG device\n");
+			return CMD_RET_FAILURE;
+		}
+
+		return CMD_RET_SUCCESS;
+	}
+
+	switch (argc) {
+	case 1:
+		devnum = 0;
+		n = 0x40;
+		break;
+	case 2:
+		devnum = hextoul(argv[1], NULL);
+		n = 0x40;
+		break;
+	case 3:
+		devnum = hextoul(argv[1], NULL);
+		n = hextoul(argv[2], NULL);
+		break;
+	default:
+		return CMD_RET_USAGE;
+	}
+
+	if (uclass_get_device_by_seq(UCLASS_RNG, devnum, &dev) || !dev) {
+		printf("No RNG device\n");
+		return CMD_RET_FAILURE;
+	}
+
+	if (!n)
+		return 0;
+
+	n = min(n, sizeof(buf));
+
+	if (dm_rng_read(dev, buf, n)) {
+		printf("Reading RNG failed\n");
+		ret = CMD_RET_FAILURE;
+	} else {
+		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, buf, n);
+	}
+
+	return ret;
+}
+
+U_BOOT_CMD(
+	rng, 3, 0, do_rng,
+	"print bytes from the hardware random number generator",
+	"list         - list all the probed rng devices\n"
+	"rng [dev] [n]    - print n random bytes(max 64) read from dev\n"
+);