arm: core: mpu: Add core support to ARM MPU

This patch add arm core MPU support to ARM MPU driver.

Change-Id: I5a61da4615ae687bf42f1c9947e291ebfd2d2c1d
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@linaro.org>

arch/arm/core/cortex_m/mpu/arm_mpu.c

@@ -10,9 +10,45 @@
 #include <soc.h>
 #include <arch/arm/cortex_m/cmsis.h>
 #include <arch/arm/cortex_m/mpu/arm_mpu.h>
+#include <arch/arm/cortex_m/mpu/arm_core_mpu.h>
+#include <logging/sys_log.h>
 
 #define ARM_MPU_DEV ((volatile struct arm_mpu *) ARM_MPU_BASE)
 
+/* ARM MPU Enabled state */
+static u8_t arm_mpu_enabled;
+
+/**
+ * The attributes referenced in this function are described at:
+ * https://goo.gl/hMry3r
+ * This function is private to the driver.
+ */
+static inline u32_t _get_region_attr(u32_t xn, u32_t ap, u32_t tex,
+				     u32_t c, u32_t b, u32_t s,
+				     u32_t srd, u32_t size)
+{
+	return ((xn << 28) | (ap) | (tex << 19) | (s << 18)
+		| (c << 17) | (b << 16) | (srd << 5) | (size));
+}
+
+/**
+ * This internal function is utilized by the MPU driver to parse the intent
+ * type (i.e. THREAD_STACK_REGION) and return the correct parameter set.
+ */
+static inline u32_t _get_region_attr_by_type(u32_t type, u32_t size)
+{
+	switch (type) {
+	case THREAD_STACK_REGION:
+		return 0;
+	case THREAD_STACK_GUARD_REGION:
+		return _get_region_attr(1, P_RO_U_RO, 0, 1, 0,
+					1, 0, REGION_32B);
+	default:
+		/* Size 0 region */
+		return 0;
+	}
+}
+
 static inline u8_t _get_num_regions(void)
 {
 	u32_t type = ARM_MPU_DEV->type;
@@ -32,6 +68,61 @@ static void _region_init(u32_t index, u32_t region_addr,
 	ARM_MPU_DEV->rasr = region_attr | REGION_ENABLE;
 }
 
+/* ARM Core MPU Driver API Implementation for ARM MPU */
+
+/**
+ * @brief enable the MPU
+ */
+void arm_core_mpu_enable(void)
+{
+	if (arm_mpu_enabled == 0) {
+		/* Enable MPU */
+		ARM_MPU_DEV->ctrl = ARM_MPU_ENABLE | ARM_MPU_PRIVDEFENA;
+
+		arm_mpu_enabled = 1;
+	}
+}
+
+/**
+ * @brief disable the MPU
+ */
+void arm_core_mpu_disable(void)
+{
+	if (arm_mpu_enabled == 1) {
+		/* Disable MPU */
+		ARM_MPU_DEV->ctrl = 0;
+
+		arm_mpu_enabled = 0;
+	}
+}
+
+/**
+ * @brief configure the base address and size for an MPU region
+ *
+ * @param   type    MPU region type
+ * @param   base    base address in RAM
+ * @param   size    size of the region
+ */
+void arm_core_mpu_configure(u8_t type, u32_t base, u32_t size)
+{
+	SYS_LOG_DBG("Region info: 0x%x 0x%x", base, size);
+	/*
+	 * The new MPU regions are are allocated per type after the statically
+	 * configured regions.
+	 */
+	u32_t region_index = mpu_config.num_regions + type;
+	u32_t region_attr = _get_region_attr_by_type(type, size);
+
+	/* ARM MPU supports up to 16 Regions */
+	if (region_index > _get_num_regions()) {
+		return;
+	}
+
+	_region_init(region_index, base, region_attr);
+}
+
+/* ARM MPU Driver Initial Setup */
+
 /*
  * @brief MPU default configuration
  *
@@ -58,7 +149,9 @@ static void _arm_mpu_config(void)
 	}
 
 	/* Enable MPU */
-	ARM_MPU_DEV->ctrl = 1;
+	ARM_MPU_DEV->ctrl = ARM_MPU_ENABLE | ARM_MPU_PRIVDEFENA;
+
+	arm_mpu_enabled = 1;
 
 	/* Make sure that all the registers are set before proceeding */
 	__DSB();

include/arch/arm/cortex_m/mpu/arm_mpu.h

@@ -35,6 +35,14 @@ struct arm_mpu {
 
 #define ARM_MPU_BASE	0xE000ED90
 
+/* ARM MPU CTRL Register */
+/* Enable MPU */
+#define ARM_MPU_ENABLE		(1 << 0)
+/* Enable MPU during hard fault, NMI, and FAULTMASK handlers */
+#define ARM_MPU_HFNMIENA	(1 << 1)
+/* Enable privileged software access to the default memory map */
+#define ARM_MPU_PRIVDEFENA	(1 << 2)
+
 #define REGION_VALID	(1 << 4)
 
 /* eXecute Never */