ksdk: Add KSDK RNGA driver.

Provide a random driver wrapped around the KSDK RNGA driver.

Origin: Original

Change-Id: I43feeb37d8d5173c7b95af8e80434fb7dc77a83e
Signed-off-by: Marcus Shawcroft <marcus.shawcroft@arm.com>
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>

arch/arm/soc/nxp_kinetis/Kconfig

@@ -48,6 +48,12 @@ config HAS_MCG
 	help
 	Set if the multipurpose clock generator (MCG) module is present in the SoC.
 
+config HAS_RNGA
+	bool
+	default n
+	help
+	Set if the random number generator accelerator (RNGA) module is present in the SoC.
+
 if HAS_OSC
 
 choice

arch/arm/soc/nxp_kinetis/k6x/Kconfig.soc

@@ -24,6 +24,7 @@ config SOC_MK64F12
 	select HAS_KSDK
 	select HAS_OSC
 	select HAS_MCG
+	select HAS_RNGA
 	select CPU_HAS_FPU
 
 endchoice

drivers/random/Kconfig

@@ -55,4 +55,14 @@ config TIMER_RANDOM_GENERATOR
 	  This options enables number generator based on system timer
 	  clock. This number generator is not random and used for
 	  testing only.
+
+config KSDK_RNGA
+	bool
+	prompt "KSDK RNGA driver"
+	depends on RANDOM_GENERATOR && HAS_RNGA
+	default n
+	help
+	This option enables the random number generator accelerator (RNGA) driver based on the
+	KSDK RNGA driver.
+
 endmenu

drivers/random/Makefile

@@ -1,2 +1,3 @@
+obj-$(CONFIG_KSDK_RNGA) += rand32_ksdk_rnga.o
 obj-$(CONFIG_TIMER_RANDOM_GENERATOR) = rand32_timer.o
 obj-$(CONFIG_X86_TSC_RANDOM_GENERATOR) += rand32_timestamp.o

drivers/random/rand32_ksdk_rnga.c

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2016 ARM Limited.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * Licensed under the Apache License, Version 2.0 (the License);
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <drivers/rand32.h>
+#include <drivers/system_timer.h>
+#include <misc/sys_log.h>
+
+#include "fsl_rnga.h"
+
+
+void sys_rand32_init(void)
+{
+	uint32_t seed = sys_cycle_get_32();
+
+	RNGA_Init(RNG);
+
+	/* The range of seed values acquired by this method is likely
+	 * to be relatively small.  The RNGA hardware uses two free
+	 * running oscillators to add entropy to the seed value, we
+	 * take care below to ensure the read rate is lower than the
+	 * rate at which the hardware can add entropy.
+	 */
+	RNGA_Seed(RNG, seed);
+	RNGA_SetMode(RNG, kRNGA_ModeSleep);
+}
+
+uint32_t sys_rand32_get(void)
+{
+	uint32_t random;
+	uint32_t output = 0;
+	int i;
+
+	RNGA_SetMode(RNG, kRNGA_ModeNormal);
+	/* The Reference manual states that back to back reads from
+	 * the RNGA deliver one or two bits of entropy per 32-bit
+	 * word, therefore we deliberately only use 1 bit per 32 bit
+	 * word read.
+	 */
+	for (i = 0; i < 32; i++) {
+		status_t status;
+
+		status = RNGA_GetRandomData(RNG, &random, sizeof(random));
+		__ASSERT(!status, "RNGA_GetRandomData failed");
+		if (status) {
+			SYS_LOG_ERR("RNGA_GetRandomData failed with %d",
+				    status);
+		}
+		output <<= 1;
+		output |= random & 1;
+	}
+	RNGA_SetMode(RNG, kRNGA_ModeSleep);
+
+	return output;
+}

ext/hal/ksdk/drivers/Makefile

@@ -15,3 +15,4 @@
 # limitations under the License.
 
 obj-$(CONFIG_I2C_KSDK) += fsl_i2c.o
+obj-$(CONFIG_KSDK_RNGA) += fsl_rnga.o