stm32_rng: driver for STM32 RNG

Drivers is embedded upon CFG_STM32_RNG=y.

The driver main API functions are:
- stm32_rng_read() to get a buffer of random bytes,
- stm32_rng_read_raw() to get a buffer of random bytes assuming the
  RNG hardware is ready, i.e clock enabled.

The device driver is initialized from DT resource when a secure DTB,
currently the embedded DTB, is found.

STM32 RNG driver assumes the platform supports at most RNG instance
in the secure world.

Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/core/include/drivers/stm32_rng.h b/core/include/drivers/stm32_rng.h
new file mode 100644
index 00000000..f2be3cf7
--- /dev/null
+++ b/core/include/drivers/stm32_rng.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (c) 2018-2019, STMicroelectronics
+ */
+
+#ifndef __STM32_RNG_H__
+#define __STM32_RNG_H__
+
+#include <stdint.h>
+#include <stddef.h>
+#include <tee_api_types.h>
+#include <types_ext.h>
+
+/*
+ * Fill buffer with bytes from the STM32_RNG
+ * @out: Output buffer
+ * @size: Byte size of the output buffer
+ * Return a TEE_Result compliant sttus
+ */
+TEE_Result stm32_rng_read(uint8_t *out, size_t size);
+
+/*
+ * As stm32_rng_read() but excluding clocks/reset dependencies.
+ *
+ * @rng_base: Caller provides the RNG interface base address
+ * @out: Output buffer
+ * @size: Pointer to input/output byte size of the output buffer
+ * Return a TEE_Result compliant sttus
+ *
+ * When successfully returning, @size stores the number of bytes
+ * effectively generated in the output buffer @out. The input value
+ * of @size gives the size available in buffer @out.
+ */
+TEE_Result stm32_rng_read_raw(vaddr_t rng_base, uint8_t *out, size_t *size);
+
+#endif /*__STM32_RNG_H__*/