xtensa: mpu: introduce CONFIG_XTENSA_MPU_ONLY_SOC_RANGES

This allows the SoC to have total control on what MPU ranges
to be programmed at boot. This overrides the generic ranges
in the architecture core code.

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

arch/xtensa/Kconfig

@@ -243,6 +243,14 @@ config XTENSA_MPU_DEFAULT_MEM_TYPE
 	  If userspace is enabled, it will be used to restore the memory type of
 	  the region being removed from a memory domain.
 
+config XTENSA_MPU_ONLY_SOC_RANGES
+	bool
+	help
+	  Enable this by the SoC to indicate to the architecture code to use
+	  the MPU ranges specified by SoC only, and skip the common ranges
+	  defined in the core architecture code. This gives total control to
+	  the SoC on the MPU ranges.
+
 endif # XTENSA_MPU
 
 endif # CPU_HAS_MPU

arch/xtensa/core/mpu.c

@@ -72,6 +72,7 @@ static struct xtensa_mpu_map xtensa_mpu_map_fg_kernel;
  *   definied in the processor configuration.
  */
 
+#ifndef CONFIG_XTENSA_MPU_ONLY_SOC_RANGES
 /**
  * Static definition of all code and data memory regions of the
  * current Zephyr image. This information must be available and
@@ -129,6 +130,7 @@ static const struct xtensa_mpu_range mpu_zephyr_ranges[] = {
 		.memory_type = CONFIG_XTENSA_MPU_DEFAULT_MEM_TYPE,
 	},
 };
+#endif /* !CONFIG_XTENSA_MPU_ONLY_SOC_RANGES */
 
 /**
  * Return the pointer to the entry encompassing @a addr out of an array of MPU entries.
@@ -679,6 +681,7 @@ void xtensa_mpu_init(void)
 		xtensa_mpu_map_fg_kernel.entries[entry] = ent;
 	}
 
+#ifndef CONFIG_XTENSA_MPU_ONLY_SOC_RANGES
 	/*
 	 * Add necessary MPU entries for the memory regions of base Zephyr image.
 	 */
@@ -696,6 +699,7 @@ void xtensa_mpu_init(void)
 				   (unsigned int)range->end,
 				   ret);
 	}
+#endif /* !CONFIG_XTENSA_MPU_ONLY_SOC_RANGES */
 
 	/*
 	 * Now for the entries for memory regions needed by SoC.