1 files changed, 80 insertions, 0 deletions
diff --git a/bsps/arm/stm32h7/start/getentropy-rng.c b/bsps/arm/stm32h7/start/getentropy-rng.c
new file mode 100644
index 0000000000..7f75c2e915
--- /dev/null
+++ b/bsps/arm/stm32h7/start/getentropy-rng.c
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/*
+ * Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stm32h7/hal.h>
+
+#include <rtems.h>
+#include <rtems/sysinit.h>
+
+#include <sys/param.h>
+#include <unistd.h>
+#include <string.h>
+
+static RNG_HandleTypeDef stm32h7_rng_instance = {
+  .Instance = RNG,
+  .Init.ClockErrorDetection = RNG_CED_DISABLE
+};
+
+static void stm32h7_rng_enable(void)
+{
+  stm32h7_clk_enable(STM32H7_MODULE_RNG);
+  HAL_RNG_Init(&stm32h7_rng_instance);
+}
+
+int getentropy(void *ptr, size_t n)
+{
+  while (n > 0) {
+    rtems_interrupt_level level;
+    uint32_t random;
+    bool ok;
+    size_t copy;
+
+    do {
+      rtems_interrupt_disable(level);
+
+      ok = (RNG->SR & RNG_FLAG_DRDY) != 0;
+      if (ok) {
+        random = RNG->DR;
+      }
+
+      rtems_interrupt_enable(level);
+    } while (!ok);
+
+    copy = MIN(sizeof(random), n);
+    ptr = memcpy(ptr, &random, copy);
+    n -= copy;
+    ptr += copy;
+  }
+
+  return 0;
+}
+
+RTEMS_SYSINIT_ITEM(
+  stm32h7_rng_enable,
+  RTEMS_SYSINIT_DEVICE_DRIVERS,
+  RTEMS_SYSINIT_ORDER_LAST_BUT_5
+);