[rtems commit] bsp/atsam: Add getentropy().

[Sebastian Huber]

Module:    rtems
Branch:    master
Commit:    a9de9a7b95b2e775d7a693782f041abb2b9caa75
Changeset: http://git.rtems.org/rtems/commit/?id=a9de9a7b95b2e775d7a693782f041abb2b9caa75

Author:    Christian Mauderer <Christian.Mauderer at embedded-brains.de>
Date:      Mon Nov 13 09:21:31 2017 +0100

bsp/atsam: Add getentropy().

Update #3239.

---

 c/src/lib/libbsp/arm/atsam/Makefile.am             |  2 +-
 .../lib/libbsp/arm/atsam/startup/getentropy-trng.c | 61 ++++++++++++++++++++++
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/c/src/lib/libbsp/arm/atsam/Makefile.am b/c/src/lib/libbsp/arm/atsam/Makefile.am
index d29ba08..d44a722 100644
--- a/c/src/lib/libbsp/arm/atsam/Makefile.am
+++ b/c/src/lib/libbsp/arm/atsam/Makefile.am
@@ -332,7 +332,6 @@ libbsp_a_LIBADD =
 
 # Shared
 libbsp_a_SOURCES += ../../shared/bootcard.c
-libbsp_a_SOURCES += ../../shared/getentropy-cpucounter.c
 libbsp_a_SOURCES += ../../shared/bspclean.c
 libbsp_a_SOURCES += ../../shared/bspgetworkarea.c
 libbsp_a_SOURCES += ../../shared/bsppredriverhook.c
@@ -397,6 +396,7 @@ libbsp_a_SOURCES += ../shared/armv7m/startup/bspreset.c
 libbsp_a_SOURCES += ../shared/armv7m/startup/armv7m-cpucounter.c
 libbsp_a_SOURCES += startup/bspstart.c
 libbsp_a_SOURCES += startup/bspstarthooks.c
+libbsp_a_SOURCES += startup/getentropy-trng.c
 libbsp_a_SOURCES += startup/pin-config.c
 libbsp_a_SOURCES += startup/power.c
 libbsp_a_SOURCES += startup/power-rtc.c
diff --git a/c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c b/c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c
new file mode 100644
index 0000000..11e24dc
--- /dev/null
+++ b/c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2017 embedded brains GmbH.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Dornierstr. 4
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems at embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#include <libchip/chip.h>
+#include <unistd.h>
+#include <string.h>
+#include <rtems/sysinit.h>
+
+static void atsam_trng_enable(void)
+{
+	PMC_EnablePeripheral(ID_TRNG);
+	TRNG_Enable();
+}
+
+int getentropy(void *ptr, size_t n)
+{
+	while (n > 0) {
+		uint32_t random;
+		size_t copy;
+
+		while ((TRNG_GetStatus() & TRNG_ISR_DATRDY) == 0) {
+			/* wait */
+		}
+		random = TRNG_GetRandData();
+
+		/*
+		 * Read TRNG status one more time to avoid race condition.
+		 * Otherwise we can read (and clear) an old ready status but get
+		 * a new value. The ready status for this value wouldn't be
+		 * reset.
+		 */
+		TRNG_GetStatus();
+
+		copy = sizeof(random);
+		if (n < copy ) {
+			copy = n;
+		}
+		memcpy(ptr, &random, copy);
+		n -= copy;
+		ptr += copy;
+	}
+
+	return 0;
+}
+
+RTEMS_SYSINIT_ITEM(
+  atsam_trng_enable,
+  RTEMS_SYSINIT_DEVICE_DRIVERS,
+  RTEMS_SYSINIT_ORDER_LAST
+);