[nrf noup] boot/zephyr: improve S2RAM resume support using dedicated API

nrf-squash! [nrf noup] boot/zephyr: nRF54h20 resume from S2RAM (hardened)

CONFIG_ARM_SOC_START_HOOK=y allow to rework the
resume from S2RAM code to work without PM_S2RAM mocking.
It allows to implement only what really needed from
the MCUboot perspective.

Signed-off-by: Andrzej Puzdrowski <[email protected]>

Author: nvlsianpu

boot/zephyr/CMakeLists.txt

@@ -496,7 +496,8 @@ if(CONFIG_MCUBOOT_CLEANUP_ARM_CORE)
   )
 endif()
 
-if(CONFIG_SOC_NRF54H20_PM_S2RAM_OVERRIDE)
+if(CONFIG_SOC_EARLY_RESET_HOOK)
+  zephyr_library_sources(${BOOT_DIR}/zephyr/nrf54h20_custom_s2ram.S)
   zephyr_library_sources(${BOOT_DIR}/zephyr/nrf54h20_custom_s2ram.c)
 endif()
 

boot/zephyr/nrf54h20_custom_s2ram.S

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2025, Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @file
+ * @brief ARM Cortex-M suspend-to-RAM resume intermediary code (S2RAM)
+ */
+
+
+
+/*
+ *             resume or
+ *              reboot                                                  reboot==T
+ *[S2RAM sleep]---------->[ boot (reset.S) ]---->[soc_early_reset_hook]---------->[regular boot]
+ *                                                       |
+ *                                                       |   resume==T
+ *                                                       \/
+ *                                                  [jump to well-known]
+ *                                                  [ App reset vector ]
+ */
+
+
+
+#include <zephyr/toolchain.h>
+#include <zephyr/arch/cpu.h>
+
+GTEXT(pm_s2ram_mark_check_and_mediate)
+
+GTEXT(soc_early_reset_hook)
+SECTION_FUNC(TEXT, soc_early_reset_hook)
+#if DT_NODE_EXISTS(DT_NODELABEL(pm_s2ram_stack)) &&\
+	DT_NODE_HAS_COMPAT(DT_NODELABEL(pm_s2ram_stack), zephyr_memory_region)
+     ldr r0, =DT_REG_ADDR(DT_NODELABEL(pm_s2ram_stack)) + DT_REG_SIZE(DT_NODELABEL(pm_s2ram_stack))
+#else
+#error "The support of bridge for S2RAM resume requires dedicated small stack"
+#endif
+     msr msp, r0
+     push {r0, lr}
+     bl pm_s2ram_mark_check_and_mediate
+     pop {r0, pc}

boot/zephyr/nrf54h20_custom_s2ram.c

@@ -45,17 +45,6 @@ void s2ram_designate_slot(uint8_t slot)
 }
 #endif
 
-int soc_s2ram_suspend(pm_s2ram_system_off_fn_t system_off)
-{
-    (void)(system_off);
-    return -1;
-}
-
-void pm_s2ram_mark_set(void)
-{
-    /* empty */
-}
-
 struct arm_vector_table {
     uint32_t msp;
     uint32_t reset;
@@ -66,13 +55,13 @@ struct arm_vector_table {
  */
 #define APP_EXE_START_OFFSET 0x800 /* nRF54H20 */
 
-bool pm_s2ram_mark_check_and_clear(void)
+void pm_s2ram_mark_check_and_mediate(void)
 {
     uint32_t reset_reason = nrf_resetinfo_resetreas_local_get(NRF_RESETINFO);
 
     if (reset_reason != NRF_RESETINFO_RESETREAS_LOCAL_UNRETAINED_MASK) {
         /* Normal boot */
-        return false;
+        return;
     }
 
     /* S2RAM resume expected, do doublecheck */
@@ -120,6 +109,4 @@ bool pm_s2ram_mark_check_and_clear(void)
 
 resume_failed:
     FIH_PANIC;
-
-    return true;
 }