nrf91/common: add support for non-secure boot

boards/arm/nrf91/common/Kconfig

@@ -26,6 +26,12 @@ config NRF91_APP_FORMAT_MCUBOOT
 
 endchoice # Application Image Format
 
+config NRF91_NONSECURE_BOOT
+	bool "Non-secure image boot"
+	default n
+	---help---
+		Boot the application as non-secure code.
+
 config NRF91_PROGMEM_OTA_PARTITION
 	bool "MTD driver"
 	default n

boards/arm/nrf91/common/src/nrf91_boot_image.c

@@ -40,10 +40,25 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
+#ifndef CONFIG_NRF91_OTA_PRIMARY_SLOT_OFFSET
+#  error CONFIG_NRF91_OTA_PRIMARY_SLOT_OFFSET not defined
+#endif
+
+#ifndef CONFIG_NRF91_MCUBOOT_HEADER_SIZE
+#  error CONFIG_NRF91_MCUBOOT_HEADER_SIZE not defined
+#endif
+
+#define VECTOR_TABLE_NS ((CONFIG_NRF91_OTA_PRIMARY_SLOT_OFFSET + \
+                          CONFIG_NRF91_MCUBOOT_HEADER_SIZE))
+
 /****************************************************************************
  * Private Types
  ****************************************************************************/
 
+#ifdef CONFIG_NRF91_NONSECURE_BOOT
+typedef void cmse_nonsecure_call nsfunc(void);
+#endif
+
 /* This structure represents the first two entries on NVIC vector table */
 
 struct arm_vector_table
@@ -56,13 +71,16 @@ struct arm_vector_table
  * Private Function Prototypes
  ****************************************************************************/
 
+#ifndef CONFIG_NRF91_NONSECURE_BOOT
 static void cleanup_arm_nvic(void);
 static void systick_disable(void);
+#endif
 
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
 
+#ifndef CONFIG_NRF91_NONSECURE_BOOT
 /****************************************************************************
  * Name:  cleanup_arm_nvic
  *
@@ -100,6 +118,7 @@ static void cleanup_arm_nvic(void)
       putreg32(0xffffffff, NVIC_IRQ_CLRPEND(i));
     }
 }
+#endif
 
 /****************************************************************************
  * Name:  systick_disable
@@ -155,6 +174,9 @@ int board_boot_image(const char *path, uint32_t hdr_size)
       return bytes < 0 ? bytes : -1;
     }
 
+#ifndef CONFIG_NRF91_NONSECURE_BOOT
+  /* Secure entry point */
+
   systick_disable();
 
   cleanup_arm_nvic();
@@ -166,5 +188,26 @@ int board_boot_image(const char *path, uint32_t hdr_size)
   ARM_ISB();
   ((void (*)(void))vt.reset)();
 
+#else
+  /* Non-secure entry point */
+
+  systick_disable();
+
+  /* Set non-secure vector table */
+
+  putreg32(VECTOR_TABLE_NS, (NVIC_VECTAB + ARMV8M_NS_OFFSET));
+
+  /* Set non-secure stack pointers */
+
+  __asm__ __volatile__("\tmsr msp_ns, %0\n" : : "r" (vt.spr));
+
+  ARM_ISB();
+
+  /* Jump to non-secure entry point */
+
+  nsfunc *ns_reset = (nsfunc *)(vt.reset);
+  ns_reset();
+#endif
+
   return 0;
 }