arch: arm: Add vectored interrupt support for Cortex-R.

This commit defines a new Cortex-R configuration 'VIC_IRQ_VECTOR' and
implements IRQ initialisation routine to configure SCTLR.VE.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

arch/arm/core/cortex_r/CMakeLists.txt

@@ -6,6 +6,7 @@ zephyr_library_sources(
   vector_table.S
   reset.S
   fault.c
+  irq_init.c
   irq_manage.c
   reboot.c
   stacks.c

arch/arm/core/cortex_r/Kconfig

@@ -79,8 +79,6 @@ config ARMV7_SYS_STACK_SIZE
 	help
 	  This option specifies the size of the stack used by the system mode.
 
-if CPU_CORTEX_R
-
 config RUNTIME_NMI
 	default y
 
@@ -90,6 +88,13 @@ config GEN_ISR_TABLES
 config GEN_IRQ_VECTOR_TABLE
 	default n
 
-endif # CPU_CORTEX_R
+config VIC_IRQ_VECTOR
+	bool "Enable VIC port hardware IRQ vector"
+	depends on (CPU_CORTEX_R4 || CPU_CORTEX_R5)
+	help
+	  Enable hardware IRQ vector using the handler address provided by the
+	  the system interrupt controller through VIC port. When this option is
+	  selected, the IRQ vector (offset 0x18) in the CPU exception vector table
+	  is not used.
 
 endif # CPU_CORTEX_R

arch/arm/core/cortex_r/irq_init.c

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2019 Stephanos Ioannidis <root@stephanos.io>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @file
+ * @brief ARM Cortex-R interrupt initialization
+ */
+
+#include <arch/cpu.h>
+
+/**
+ * @brief Initialize interrupts
+ *
+ * @return N/A
+ */
+
+void z_arm_int_lib_init(void)
+{
+    /* Configure hardware vectored interrupt mode.*/
+#if defined(CONFIG_VIC_IRQ_VECTOR)
+    __asm__ volatile(
+        "mrc p15, #0, r0, c1, c0, #0;"
+        "orr r0,  r0, #0x01000000;"     /* [24] VE bit */
+        "mcr p15, #0, r0, c1, c0, #0;"
+        : : : "memory");
+#endif
+}

include/arch/arm/irq.h

@@ -38,13 +38,7 @@ extern int z_arch_irq_is_enabled(unsigned int irq);
 
 extern void z_arm_int_exit(void);
 
-#if defined(CONFIG_CPU_CORTEX_R)
-static ALWAYS_INLINE void z_arm_int_lib_init(void)
-{
-}
-#else
 extern void z_arm_int_lib_init(void);
-#endif
 
 /* macros convert value of it's argument to a string */
 #define DO_TOSTR(s) #s