sandbox: rng: Add a random number generator(rng) driver
Add a sandbox driver for random number generation. Mostly aimed at
providing a unit test for rng uclass.
Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/rng/sandbox_rng.c b/drivers/rng/sandbox_rng.c
new file mode 100644
index 0000000..cd0b0ac
--- /dev/null
+++ b/drivers/rng/sandbox_rng.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <rng.h>
+
+#include <linux/string.h>
+
+static int sandbox_rng_read(struct udevice *dev, void *data, size_t len)
+{
+ unsigned int i, seed, random;
+ unsigned char *buf = data;
+ size_t nrem, nloops;
+
+ if (!len)
+ return 0;
+
+ nloops = len / sizeof(random);
+ seed = get_timer(0) ^ rand();
+ srand(seed);
+
+ for (i = 0, nrem = len; i < nloops; i++) {
+ random = rand();
+ memcpy(buf, &random, sizeof(random));
+ buf += sizeof(random);
+ nrem -= sizeof(random);
+ }
+
+ if (nrem) {
+ random = rand();
+ memcpy(buf, &random, nrem);
+ }
+
+ return 0;
+}
+
+static const struct dm_rng_ops sandbox_rng_ops = {
+ .read = sandbox_rng_read,
+};
+
+static const struct udevice_id sandbox_rng_match[] = {
+ {
+ .compatible = "sandbox,sandbox-rng",
+ },
+ {},
+};
+
+U_BOOT_DRIVER(sandbox_rng) = {
+ .name = "sandbox-rng",
+ .id = UCLASS_RNG,
+ .of_match = sandbox_rng_match,
+ .ops = &sandbox_rng_ops,
+};