boot: zephyr: Add support for Cortex-R cleanup before final jump

Add code to cleanup the Cortex-R processor state to the reset
configuration and disable + acknowledge all interrupts before entering
the booted application.

Signed-off-by: Mika Braunschweig <[email protected]>

Author: m-braunschweig

boot/zephyr/CMakeLists.txt

@@ -439,9 +439,17 @@ if(CONFIG_BOOT_ENCRYPTION_KEY_FILE AND NOT CONFIG_BOOT_ENCRYPTION_KEY_FILE STREQ
 endif()
 
 if(CONFIG_MCUBOOT_CLEANUP_ARM_CORE)
-zephyr_library_sources(
-  ${BOOT_DIR}/zephyr/arm_cleanup.c
-)
+  # ARM Cortex-M
+  zephyr_library_sources_ifdef(
+    CONFIG_CPU_CORTEX_M
+    ${BOOT_DIR}/zephyr/cleanup/arm_cortex_m.c
+  )
+
+  # ARM Cortex-R
+  zephyr_library_sources_ifdef(
+    CONFIG_ARMV7_R
+    ${BOOT_DIR}/zephyr/cleanup/arm_cortex_r.c
+  )
 endif()
 
 if(CONFIG_MCUBOOT_BOOT_BANNER)

boot/zephyr/Kconfig

@@ -344,7 +344,7 @@ config BOOT_SIGNATURE_KEY_FILE
 
 config MCUBOOT_CLEANUP_ARM_CORE
 	bool "Perform core cleanup before chain-load the application"
-	depends on CPU_CORTEX_M
+	depends on CPU_CORTEX_M || ARMV7_R
 	default y
 	help
 	  This option instructs MCUboot to perform a clean-up of a set of

boot/zephyr/arm_cleanup.c renamed to boot/zephyr/cleanup/arm_cortex_m.c

@@ -11,7 +11,9 @@
 #include <fsl_sysmpu.h>
 #endif
 
-void cleanup_arm_nvic(void) {
+
+void cleanup_arm_interrupts(void)
+{
 	/* Allow any pending interrupts to be recognized */
 	__ISB();
 	__disable_irq();

boot/zephyr/cleanup/arm_cortex_r.c

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2020 Nordic Semiconductor ASA
+ * Copyright (c) 2025 Siemens Mobility GmbH
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdint.h>
+#include <zephyr/irq.h>
+#include <zephyr/sys/util_macro.h>
+#include <zephyr/toolchain.h>
+
+#ifdef CONFIG_ARM_CUSTOM_INTERRUPT_CONTROLLER
+extern void z_soc_irq_eoi(unsigned int irq);
+#else
+#include <zephyr/drivers/interrupt_controller/gic.h>
+#endif
+
+#define READ_COPROCESSOR_REGISTER(out, coproc, opc1, crn, crm, opc2) \
+	__asm__ volatile("mrc " #coproc ", " #opc1 ", %0, " #crn ", " #crm ", " #opc2 "\n" : "=r" (out) ::);
+
+#define WRITE_COPROCESSOR_REGISTER(in, coproc, opc1, crn, crm, opc2) \
+	__asm__ volatile("mcr " #coproc ", " #opc1 ", %0, " #crn ", " #crm ", " #opc2 "\n" :: "r" (in) :)
+
+void cleanup_arm_interrupts(void)
+{
+	/* Allow any pending interrupts to be recognized */
+	__ISB();
+	__disable_irq();
+
+	for (unsigned int i = 0; i < CONFIG_NUM_IRQS; ++i) {
+		irq_disable(i);
+	}
+
+	for (unsigned int i = 0; i < CONFIG_NUM_IRQS; ++i) {
+#ifdef CONFIG_ARM_CUSTOM_INTERRUPT_CONTROLLER
+		z_soc_irq_eoi(i);
+#else
+		arm_gic_eoi(i);
+#endif /* CONFIG_ARM_CUSTOM_INTERRUPT_CONTROLLER */
+	}
+}
+
+#if CONFIG_CPU_HAS_ARM_MPU
+__weak void z_arm_clear_arm_mpu_config(void)
+{
+	uint8_t i;
+	uint8_t num_regions;
+	uint32_t mpu_type_register;
+
+	/* Disable MPU */
+	uint32_t val;
+	READ_COPROCESSOR_REGISTER(val, p15, 0, c1, c0, 0);
+	val &= ~BIT(0);
+	__DSB();
+
+	WRITE_COPROCESSOR_REGISTER(val, p15, 0, c1, c0, 0);
+	__ISB();
+
+	/* The number of MPU regions is stored in bits 15:8 of the MPU type register */
+	READ_COPROCESSOR_REGISTER(mpu_type_register, p15, 0, c0, c0, 4);
+	num_regions = (uint8_t) ((mpu_type_register >> 8) & BIT_MASK(8));
+
+	for (i = 0; i < num_regions; ++i) {
+		/* Select region in the MPU and clear the region size field */
+		WRITE_COPROCESSOR_REGISTER(i, p15, 0, c6, c2, 0);
+		WRITE_COPROCESSOR_REGISTER(0, p15, 0, c6, c1, 2);
+	}
+}
+#endif

boot/zephyr/include/arm_cleanup.h

@@ -11,7 +11,7 @@
 /**
  * Cleanup interrupt priority and interupt enable registers.
  */
-void cleanup_arm_nvic(void);
+void cleanup_arm_interrupts(void);
 
 #if defined(CONFIG_CPU_HAS_ARM_MPU) || defined(CONFIG_CPU_HAS_NXP_SYSMPU)
 /**

boot/zephyr/main.c

@@ -195,7 +195,7 @@ static void do_boot(struct boot_rsp *rsp)
     usb_disable();
 #endif
 #if CONFIG_MCUBOOT_CLEANUP_ARM_CORE
-    cleanup_arm_nvic(); /* cleanup NVIC registers */
+    cleanup_arm_interrupts(); /* Disable and acknowledge all interrupts */
 
 #if defined(CONFIG_BOOT_DISABLE_CACHES)
     /* Flush and disable instruction/data caches before chain-loading the application */
@@ -243,8 +243,26 @@ static void do_boot(struct boot_rsp *rsp)
 #endif
 
 #if CONFIG_MCUBOOT_CLEANUP_ARM_CORE
+#ifdef CONFIG_CPU_CORTEX_M
     __set_CONTROL(0x00); /* application will configures core on its own */
     __ISB();
+#else
+    /* Set mode to supervisor and A, I and F bit as described in the
+     * Cortex R5 TRM */
+    __asm__ volatile(
+        "   mrs r0, CPSR\n"
+        /* change mode bits to supervisor */
+        "   bic r0, #0x1f\n"
+        "   orr r0, #0x13\n"
+        /* set the A, I and F bit */
+        "   mov r1, #0b111\n"
+        "   lsl r1, #0x6\n"
+        "   orr r0, r1\n"
+
+        "   msr CPSR, r0\n"
+        ::: "r0", "r1");
+#endif /* CONFIG_CPU_CORTEX_M */
+
 #endif
 #if CONFIG_MCUBOOT_CLEANUP_RAM
     __asm__ volatile (