arch: arm: Setup Static MPU regions earlier in boot flow

Setup the static MPU regions before PRE_KERNEL_1 and
PRE_KERNEL_2 functions are invoked. This will setup
the MPU for SRAM regions in case code relocated to SRAM
is invoked from any of these functions.

Signed-off-by: Mahesh Mahadevan <[email protected]>

Author: mmahadevan108

arch/arm/core/aarch32/cortex_m/mpu/arm_mpu.c

@@ -302,7 +302,7 @@ void arm_core_mpu_configure_dynamic_mpu_regions(const struct z_arm_mpu_partition
  * This function provides the default configuration mechanism for the Memory
  * Protection Unit (MPU).
  */
-static int arm_mpu_init(const struct device *arg)
+int z_arm_mpu_init(void)
 {
 	uint32_t r_index;
 
@@ -416,8 +416,6 @@ static int arm_mpu_init(const struct device *arg)
 		NUM_MPU_REGIONS,
 		"Invalid number of MPU regions\n");
 #endif /* CORTEX_M0PLUS || CPU_CORTEX_M3 || CPU_CORTEX_M4 */
+
 	return 0;
 }
-
-SYS_INIT(arm_mpu_init, PRE_KERNEL_1,
-	 CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);

arch/arm/core/aarch32/cortex_m/mpu/nxp_mpu.c

@@ -601,10 +601,8 @@ void arm_core_mpu_configure_dynamic_mpu_regions(
  * This function provides the default configuration mechanism for the Memory
  * Protection Unit (MPU).
  */
-static int nxp_mpu_init(const struct device *arg)
+int z_arm_mpu_init(void)
 {
-	ARG_UNUSED(arg);
-
 	uint32_t r_index;
 
 	if (mpu_config.num_regions > get_num_regions()) {
@@ -640,15 +638,5 @@ static int nxp_mpu_init(const struct device *arg)
 
 	arm_core_mpu_enable();
 
-
 	return 0;
 }
-
-#if defined(CONFIG_LOG)
-/* To have logging the driver needs to be initialized later */
-SYS_INIT(nxp_mpu_init, PRE_KERNEL_2,
-	 CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
-#else
-SYS_INIT(nxp_mpu_init, PRE_KERNEL_1,
-	 CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
-#endif

arch/arm/core/aarch32/thread.c

@@ -484,16 +484,6 @@ static void z_arm_prepare_switch_to_main(void)
 	__ISB();
 #endif /* CONFIG_FPU_SHARING */
 #endif /* CONFIG_FPU */
-
-#ifdef CONFIG_ARM_MPU
-	/* Configure static memory map. This will program MPU regions,
-	 * to set up access permissions for fixed memory sections, such
-	 * as Application Memory or No-Cacheable SRAM area.
-	 *
-	 * This function is invoked once, upon system initialization.
-	 */
-	z_arm_configure_static_mpu_regions();
-#endif
 }
 
 void arch_switch_to_main_thread(struct k_thread *main_thread, char *stack_ptr,

arch/arm/include/aarch32/kernel_arch_func.h

@@ -33,6 +33,7 @@ extern void z_arm_cpu_idle_init(void);
 #ifdef CONFIG_ARM_MPU
 extern void z_arm_configure_static_mpu_regions(void);
 extern void z_arm_configure_dynamic_mpu_regions(struct k_thread *thread);
+extern int z_arm_mpu_init(void);
 #endif /* CONFIG_ARM_MPU */
 
 static ALWAYS_INLINE void arch_kernel_init(void)
@@ -42,6 +43,16 @@ static ALWAYS_INLINE void arch_kernel_init(void)
 	z_arm_fault_init();
 	z_arm_cpu_idle_init();
 	z_arm_clear_faults();
+#if defined(CONFIG_ARM_MPU)
+	z_arm_mpu_init();
+	/* Configure static memory map. This will program MPU regions,
+	 * to set up access permissions for fixed memory sections, such
+	 * as Application Memory or No-Cacheable SRAM area.
+	 *
+	 * This function is invoked once, upon system initialization.
+	 */
+	z_arm_configure_static_mpu_regions();
+#endif
 }
 
 static ALWAYS_INLINE void