xtensa: add MPU support for kernel mode

This enables support for MPU on Xtensa. Currently this is
for kernel mode only.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

arch/xtensa/Kconfig

@@ -177,4 +177,154 @@ config XTENSA_INSECURE_USERSPACE
 
 endif # CPU_HAS_MMU
 
+if CPU_HAS_MPU
+
+menuconfig XTENSA_MPU
+	bool "Xtensa MPU Support"
+	select MPU
+	select SRAM_REGION_PERMISSIONS
+	select XTENSA_SMALL_VECTOR_TABLE_ENTRY
+	select EXPERIMENTAL
+	# FIXME: the target the MPU code developed on does not have
+	#        cache or SMP capability. Need to verify functionalities
+	#        with targets supporting these.
+	depends on !CACHE && !SMP
+	help
+	  Enable support for Xtensa Memory Protection Unit.
+
+if XTENSA_MPU
+
+menuconfig XTENSA_MPU_CUSTOM_MEMFLAGS
+	bool "Override Default Memory Flags for MPU Regions"
+	help
+	  Default memory flags for MPU regions is of type non-cacheable memory,
+	  interruptible, non-bufferable, non-shareable, and no cache allocations.
+	  These flags are used for memory of Zephyr image.
+
+	  Enable this to override the default flags. Says N if unsure.
+
+if XTENSA_MPU_CUSTOM_MEMFLAGS
+
+choice XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE
+	prompt "System Type"
+	default XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_NCM
+	help
+	  Default MPU memory system type.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_DEVICE
+	bool "Device"
+	help
+	  Default system type is Device.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_NCM
+	bool "Non-Cacheable Memory"
+	help
+	  Default system type is Non-Cacheable Memory.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_CM
+	bool "Cacheable Memory"
+	help
+	  Default system type is Cacheable Memory.
+
+endchoice
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_BUFFERABLE
+	bool "Bufferable"
+	depends on !XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_CM
+	help
+	  Memory is bufferable. Only valid for device and non-cacheable memory.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_INTERRUPTIBLE
+	bool "Interruptible"
+	depends on XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_DEVICE
+	help
+	  Memory is interruptible. Only valid for device memory.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_SHAREABLE
+	bool "Shareable"
+	depends on XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_NCM
+	help
+	  Memory is shareable. Only valid for non-cacheable memory.
+
+choice
+	prompt "Shareable"
+	default XTENSA_MPU_CUSTOM_MEMFLAGS_INNER_SHAREABLE
+	depends on XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_CM
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_INNER_SHAREABLE
+	bool "Inner Shareable"
+	help
+	  Memory is inner shareable. Only valid for cacheable memory.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_OUTER_SHAREABLE
+	bool "Outer Shareable"
+	help
+	  Memory is outer shareable. Only valid for cacheable memory.
+
+endchoice
+
+choice
+	prompt "Cache type (bus)"
+	depends on XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_CM
+	default XTENSA_MPU_CUSTOM_MEMFLAGS_BUS_WRITETHRU
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_BUS_WRITEBACK
+	bool "Write-back"
+	help
+	  Memory is write-back on bus transactions.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_BUS_WRITETHRU
+	bool "Write-through"
+	help
+	  Memory is write-through on bus transactions.
+
+endchoice
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_BUS_READ_ALLOC
+	bool "Cache Allocate on Read (bus)"
+	depends on XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_CM
+	help
+	  Cache is to allocate on read during bus transactions.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_BUS_WRITE_ALLOC
+	bool "Cache Allocate on Write (bus)"
+	depends on XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_CM
+	help
+	  Cache is to allocate on write during bus transactions.
+
+choice
+	prompt "Cache type (processor local)"
+	depends on !XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_DEVICE
+	default XTENSA_MPU_CUSTOM_MEMFLAGS_LOCAL_WRITETHRU
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_LOCAL_WRITEBACK
+	bool "Write-back"
+	help
+	  Processor local cache is write-back.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_LOCAL_WRITETHRU
+	bool "Write-through"
+	help
+	  Processor local cacheeis write-through.
+
+endchoice
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_LOCAL_READ_ALLOC
+	bool "Cache Allocate on Read (processor local)"
+	depends on !XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_DEVICE
+	help
+	  Processor local cache is to allocate on read.
+
+config XTENSA_MPU_CUSTOM_MEMFLAGS_LOCAL_WRITE_ALLOC
+	bool "Cache Allocate on Write (processor local)"
+	depends on !XTENSA_MPU_CUSTOM_MEMFLAGS_TYPE_DEVICE
+	help
+	  Processor local Cache is to allocate on write.
+
+endif # XTENSA_MPU_CUSTOM_MEMFLAGS
+
+endif # XTENSA_MPU
+
+endif # CPU_HAS_MPU
+
 endmenu

arch/xtensa/core/CMakeLists.txt

@@ -27,6 +27,7 @@ zephyr_library_sources_ifdef(CONFIG_USERSPACE userspace.S)
 zephyr_library_sources_ifdef(CONFIG_XTENSA_SYSCALL_USE_HELPER syscall_helper.c)
 zephyr_library_sources_ifdef(CONFIG_LLEXT elf.c)
 zephyr_library_sources_ifdef(CONFIG_SMP smp.c)
+zephyr_library_sources_ifdef(CONFIG_XTENSA_MPU mpu.c)
 
 zephyr_library_sources_ifdef(
   CONFIG_KERNEL_VM_USE_CUSTOM_MEM_RANGE_CHECK