Add a sandbox driver for random number generation. Mostly aimed at
providing a unit test for rng uclass.
Signed-off-by: Sughosh Ganu <sughosh.g...@linaro.org>
Reviewed-by: Patrice Chotard <patrice.chot...@st.com>
---
Changes since V4:
* Return number of bytes read on a successful read, and a -ve value on
error.
* Modify the logic of sandbox_rng_read function to use rand and srand
functions to return random data, based on feedback from Heinrich
Schuchardt.
arch/sandbox/dts/test.dts | 4 ++++
drivers/rng/Kconfig | 8 +++++++
drivers/rng/Makefile | 1 +
drivers/rng/sandbox_rng.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 69 insertions(+)
create mode 100644 drivers/rng/sandbox_rng.c
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index fdb08f2..2c85540 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -599,6 +599,10 @@
reset-names = "other", "test";
};
+ rng@0 {
+ compatible = "sandbox,sandbox-rng";
+ };
+
rproc_1: rproc@1 {
compatible = "sandbox,test-processor";
remoteproc-name = "remoteproc-test-dev1";
diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
index c9c4751..35a3bd1 100644
--- a/drivers/rng/Kconfig
+++ b/drivers/rng/Kconfig
@@ -6,6 +6,14 @@ config DM_RNG
This interface is used to initialise the rng device and to
read the random seed from the device.
+config RNG_SANDBOX
+ bool "Sandbox random number generator"
+ depends on SANDBOX && DM_RNG
+ select CONFIG_LIB_RAND
+ help
+ Enable random number generator for sandbox. This is an
+ emulation of a rng device.
+
config RNG_STM32MP1
bool "Enable random number generator for STM32MP1"
depends on ARCH_STM32MP && DM_RNG
diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
index 699beb3..3517005 100644
--- a/drivers/rng/Makefile
+++ b/drivers/rng/Makefile
@@ -4,4 +4,5 @@
#
obj-$(CONFIG_DM_RNG) += rng-uclass.o
+obj-$(CONFIG_RNG_SANDBOX) += sandbox_rng.o
obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
diff --git a/drivers/rng/sandbox_rng.c b/drivers/rng/sandbox_rng.c
new file mode 100644
index 0000000..5de1799
--- /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)
+{
+ int nbytes;
+ unsigned int i, seed;
+ unsigned int *buf = data;
+ size_t nrem, nloops;
+
+ /*
+ * Only INT_MAX number of bytes can be returned. If more
+ * bytes need to be read, the caller must do it in a loop.
+ */
+ if (len > INT_MAX)
+ len = INT_MAX;
+
+ nbytes = len;
+ nloops = len / sizeof(unsigned int);
+ seed = get_timer(0) ^ rand();
+ srand(seed);
+
+ for (i = 0, nrem = len; i < nloops; i++, nrem -= sizeof(unsigned int))
+ *buf++ = rand();
+
+ seed = rand();
+ memcpy(buf, &seed, nrem);
+
+ return nbytes;
+}
+
+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,
+};
--
2.7.4
