soc: arm: beetle: Add Initial MPU Support

This patch adds initial MPU support to ARM Beetle.
The boot configuration prevents the following security issues:
* Prevent to read at an address that is reserved in the memory map.
* Prevent to write into the boot Flash/ROM.
* Prevent from running code located in SRAM.

Change-Id: I64f1001369896fffb0647de6be605a95161c4695
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@linaro.org>

arch/arm/core/cortex_m/mpu/Kconfig

@@ -9,6 +9,7 @@
 config ARM_MPU
 	bool "ARM MPU Support"
 	depends on CPU_HAS_MPU
+	depends on SOC_FAMILY_ARM || SOC_FAMILY_STM32
 	default n
 	help
 	  MCU has ARM MPU

arch/arm/soc/arm/beetle/Kconfig.series

@@ -13,5 +13,6 @@ config SOC_SERIES_BEETLE
 	select CPU_CORTEX_M3
 	select SOC_FAMILY_ARM
 	select CPU_HAS_SYSTICK
+	select CPU_HAS_MPU
 	help
 	 Enable support for Beetle MCU Series

arch/arm/soc/arm/beetle/Kconfig.soc

@@ -14,3 +14,11 @@ config SOC_BEETLE_R0
 	bool "ARM BEETLE R0"
 
 endchoice
+
+config ARM_MPU_ENABLE
+	bool "Enable MPU"
+	depends on CPU_HAS_MPU
+	select ARM_MPU
+	default n
+	help
+	  Enable MPU

arch/arm/soc/arm/beetle/Makefile

@@ -7,3 +7,4 @@
 #
 
 obj-y += soc.o power.o
+obj-$(CONFIG_ARM_MPU_ENABLE) += arm_mpu_regions.o

arch/arm/soc/arm/beetle/arm_mpu_regions.c

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2017 Linaro Limited.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+ #include <soc.h>
+ #include <arch/arm/cortex_m/mpu/arm_mpu.h>
+
+static struct arm_mpu_region mpu_regions[] = {
+	/* Region 0 */
+	MPU_REGION_ENTRY("FLASH_0",
+			 CONFIG_FLASH_BASE_ADDRESS,
+			 REGION_FLASH_ATTR(REGION_256K)),
+	/* Region 1 */
+	MPU_REGION_ENTRY("RAM_0",
+			 CONFIG_SRAM_BASE_ADDRESS,
+			 REGION_RAM_ATTR(REGION_128K)),
+	/* Region 2 */
+	MPU_REGION_ENTRY("APB_0",
+			 _BEETLE_APB_BASE,
+			 REGION_IO_ATTR(REGION_64K)),
+	/* Region 3 */
+	MPU_REGION_ENTRY("AHB_0",
+			 _BEETLE_AHB_BASE,
+			 REGION_IO_ATTR(REGION_64K)),
+	/* Region 4 */
+	MPU_REGION_ENTRY("BITBAND_0",
+			 _BEETLE_BITBAND_BASE,
+			 REGION_IO_ATTR(REGION_32M)),
+	/* Region 5 */
+	MPU_REGION_ENTRY("PPB_0",
+			 _BEETLE_PPB_BASE,
+			 REGION_PPB_ATTR(REGION_1M)),
+};
+
+struct arm_mpu_config mpu_config = {
+	.num_regions = ARRAY_SIZE(mpu_regions),
+	.mpu_regions = mpu_regions,
+};