zephyrproject-rtos · jhedberg · Sep 30, 2025 · Jul 16, 2025
diff --git a/boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuapp.dts b/boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuapp.dts
@@ -330,14 +330,21 @@ zephyr_udc0: &usbhs {
 	status = "okay";
 };
 
-/* Trim this RAM block for making room on all run-time common S2RAM cpu context. */
+/* Trim this RAM block for power management related features. */
 &cpuapp_ram0 {
-	reg = <0x22000000 (DT_SIZE_K(32) - 32)>;
-	ranges = <0x0 0x22000000 (0x8000 - 0x20)>;
+	reg = <0x22000000 (DT_SIZE_K(32) - 256)>;
+	ranges = <0x0 0x22000000 (0x8000 - 0x100)>;
 };
 
 / {
 	soc {
+		/* cache control functions - must be executed from local SRAM */
+		pm_ramfunc: cpuapp_s2ram@22007f00 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x22007f00 192>;
+			zephyr,memory-region = "PMLocalRamfunc";
+		};
+
 		/* run-time common S2RAM cpu context RAM */
 		pm_s2ram: cpuapp_s2ram@22007fe0 {
 			compatible = "zephyr,memory-region", "mmio-sram";

diff --git a/boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpurad.dts b/boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpurad.dts
@@ -116,3 +116,20 @@ slot1_partition: &cpurad_slot1_partition {
 zephyr_udc0: &usbhs {
 	status = "disabled";
 };
+
+/* Trim this RAM block for power management related features. */
+&cpurad_ram0 {
+	reg = <0x23000000 (DT_SIZE_K(192) - 192)>;
+	ranges = <0x0 0x23000000 (0x30000 - 0xC0)>;
+};
+
+/ {
+	soc {
+		/* cache control functions - must be executed from RAM */
+		pm_ramfunc: cpurad_s2ram@2302ff40 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x2302ff80 192>;
+			zephyr,memory-region = "PMLocalRamfunc";
+		};
+	};
+};
diff --git a/dts/vendor/nordic/nrf54h20.dtsi b/dts/vendor/nordic/nrf54h20.dtsi
@@ -31,7 +31,7 @@
 			device_type = "cpu";
 			clocks = <&cpuapp_hsfll>;
 			clock-frequency = <DT_FREQ_M(320)>;
-			cpu-power-states = <&idle_cache_disabled &s2ram>;
+			cpu-power-states = <&idle_cache_retained &idle_cache_disabled &s2ram>;
 		};
 
 		cpurad: cpu@3 {
@@ -40,7 +40,7 @@
 			device_type = "cpu";
 			clocks = <&cpurad_hsfll>;
 			clock-frequency = <DT_FREQ_M(256)>;
-			cpu-power-states = <&idle_cache_disabled>;
+			cpu-power-states = <&idle_cache_retained &idle_cache_disabled>;
 		};
 
 		cpuppr: cpu@d {
@@ -130,7 +130,13 @@
 
 		power-states {
 			// substate-id = <0>; is reserved for "idle", cache powered on
-			// substate-id = <1>; is reserved for "idle-cache-retained"
+			idle_cache_retained: idle_cache_retained {
+				compatible = "zephyr,power-state";
+				power-state-name = "suspend-to-idle";
+				substate-id = <1>;
+				min-residency-us = <700>;
+				exit-latency-us = <5>;
+			};
 			idle_cache_disabled: idle_cache_disabled {
 				compatible = "zephyr,power-state";
 				power-state-name = "suspend-to-idle";

diff --git a/soc/nordic/nrf54h/CMakeLists.txt b/soc/nordic/nrf54h/CMakeLists.txt
@@ -5,6 +5,11 @@ if(CONFIG_ARM)
   zephyr_library_sources(soc.c)
   if(CONFIG_PM OR CONFIG_POWEROFF)
     zephyr_library_sources(power.c)
+    zephyr_code_relocate(
+      FILES       power.c
+      FILTER      ".*\\.cache_retain_and_sleep"
+      LOCATION    PMLocalRamfunc_TEXT
+    )
   endif()
 endif()
 

diff --git a/soc/nordic/nrf54h/Kconfig.defconfig.nrf54h20_cpuapp b/soc/nordic/nrf54h/Kconfig.defconfig.nrf54h20_cpuapp
@@ -14,4 +14,7 @@ config SHELL_BACKEND_SERIAL
 config POWER_DOMAIN
 	default y
 
+config CODE_DATA_RELOCATION
+	default y if PM || POWEROFF
+
 endif # SOC_NRF54H20_CPUAPP
diff --git a/soc/nordic/nrf54h/Kconfig.defconfig.nrf54h20_cpurad b/soc/nordic/nrf54h/Kconfig.defconfig.nrf54h20_cpurad
@@ -14,4 +14,7 @@ config PM
 config POWER_DOMAIN
 	default y
 
+config CODE_DATA_RELOCATION
+	default y if PM || POWEROFF
+
 endif # SOC_NRF54H20_CPURAD
diff --git a/soc/nordic/nrf54h/power.c b/soc/nordic/nrf54h/power.c
@@ -10,6 +10,7 @@
 #include <zephyr/arch/common/pm_s2ram.h>
 #include <hal/nrf_resetinfo.h>
 #include <hal/nrf_memconf.h>
+#include <hal/nrf_cache.h>
 #include <zephyr/cache.h>
 #include <power.h>
 #include <soc_lrcconf.h>
@@ -87,18 +88,43 @@ void nrf_poweroff(void)
 	CODE_UNREACHABLE;
 }
 
-static void s2idle_enter(uint8_t substate_id)
+static __attribute__((__used__, noinline)) void cache_retain_and_sleep(void)
 {
+	nrf_cache_task_trigger(NRF_DCACHE, NRF_CACHE_TASK_SAVE);
+	nrf_cache_task_trigger(NRF_ICACHE, NRF_CACHE_TASK_SAVE);
+	while (nrf_cache_busy_check(NRF_DCACHE) ||
+		  nrf_cache_busy_check(NRF_ICACHE)) {
+
+	}
+
+	__set_BASEPRI(0);
+	__ISB();
+	__DSB();
+	__WFI();
+
+	nrf_cache_task_trigger(NRF_ICACHE, NRF_CACHE_TASK_RESTORE);
+	nrf_cache_task_trigger(NRF_DCACHE, NRF_CACHE_TASK_RESTORE);
+	while (nrf_cache_busy_check(NRF_DCACHE) ||
+		  nrf_cache_busy_check(NRF_ICACHE)) {
+
+	}
+}
+
+void s2idle_enter(uint8_t substate_id)
+{
+#if !defined(CONFIG_SOC_NRF54H20_CPURAD)
+	soc_lrcconf_poweron_request(&soc_node, NRF_LRCCONF_POWER_MAIN);
+#endif
 	switch (substate_id) {
 	case 0:
 		/* Substate for idle with cache powered on - not implemented yet. */
 		break;
-	case 1: /* Substate for idle with cache retained - not implemented yet. */
-		break;
+	case 1: /* Substate for idle with cache retained. */
+		soc_lrcconf_poweron_release(&soc_node, NRF_LRCCONF_POWER_DOMAIN_0);
+		nrf_soc_memconf_retain_set(true);
+		cache_retain_and_sleep();
+		return;
 	case 2: /* Substate for idle with cache disabled. */
-#if !defined(CONFIG_SOC_NRF54H20_CPURAD)
-		soc_lrcconf_poweron_request(&soc_node, NRF_LRCCONF_POWER_MAIN);
-#endif
 		common_suspend();
 		break;
 	default: /* Unknown substate. */
@@ -117,17 +143,19 @@ static void s2idle_exit(uint8_t substate_id)
 	case 0:
 		/* Substate for idle with cache powered on - not implemented yet. */
 		break;
-	case 1: /* Substate for idle with cache retained - not implemented yet. */
+	case 1: /* Substate for idle with cache retained. */
+		nrf_soc_memconf_retain_set(false);
 		break;
 	case 2: /* Substate for idle with cache disabled. */
 		nrf_power_up_cache();
-		common_resume();
-#if !defined(CONFIG_SOC_NRF54H20_CPURAD)
-		soc_lrcconf_poweron_release(&soc_node, NRF_LRCCONF_POWER_MAIN);
-#endif
+		break;
 	default: /* Unknown substate. */
 		return;
 	}
+	common_resume();
+#if !defined(CONFIG_SOC_NRF54H20_CPURAD)
+	soc_lrcconf_poweron_release(&soc_node, NRF_LRCCONF_POWER_MAIN);
+#endif
 }
 
 #if defined(CONFIG_PM_S2RAM)

diff --git a/soc/nordic/nrf54h/soc.c b/soc/nordic/nrf54h/soc.c
@@ -60,6 +60,26 @@ sys_snode_t soc_node;
 				      ADDRESS_DOMAIN_Msk |                     \
 				      ADDRESS_BUS_Msk)))
 
+void nrf_soc_memconf_retain_set(bool enable)
+{
+	uint32_t ret_mask = BIT(RAMBLOCK_RET_BIT_ICACHE) | BIT(RAMBLOCK_RET_BIT_DCACHE);
+
+	nrf_memconf_ramblock_ret_mask_enable_set(NRF_MEMCONF, 0, ret_mask, enable);
+	nrf_memconf_ramblock_ret_mask_enable_set(NRF_MEMCONF, 1, ret_mask, enable);
+
+#if defined(RAMBLOCK_RET2_MASK)
+	ret_mask = 0;
+#if defined(RAMBLOCK_RET2_BIT_ICACHE)
+	ret_mask |= BIT(RAMBLOCK_RET2_BIT_ICACHE);
+#endif
+#if defined(RAMBLOCK_RET2_BIT_DCACHE)
+	ret_mask |= BIT(RAMBLOCK_RET2_BIT_DCACHE);
+#endif
+	nrf_memconf_ramblock_ret2_mask_enable_set(NRF_MEMCONF, 0, ret_mask, enable);
+	nrf_memconf_ramblock_ret2_mask_enable_set(NRF_MEMCONF, 1, ret_mask, enable);
+#endif /* defined(RAMBLOCK_RET2_MASK) */
+}
+
 static void power_domain_init(void)
 {
 	/*
@@ -75,28 +95,12 @@ static void power_domain_init(void)
 
 	soc_lrcconf_poweron_request(&soc_node, NRF_LRCCONF_POWER_DOMAIN_0);
 	nrf_lrcconf_poweron_force_set(NRF_LRCCONF010, NRF_LRCCONF_POWER_MAIN, false);
-
-	nrf_memconf_ramblock_ret_enable_set(NRF_MEMCONF, 0, RAMBLOCK_RET_BIT_ICACHE, false);
-	nrf_memconf_ramblock_ret_enable_set(NRF_MEMCONF, 0, RAMBLOCK_RET_BIT_DCACHE, false);
-	nrf_memconf_ramblock_ret_enable_set(NRF_MEMCONF, 1, RAMBLOCK_RET_BIT_ICACHE, false);
-	nrf_memconf_ramblock_ret_enable_set(NRF_MEMCONF, 1, RAMBLOCK_RET_BIT_DCACHE, false);
-#if defined(RAMBLOCK_RET2_BIT_ICACHE)
-	nrf_memconf_ramblock_ret2_enable_set(NRF_MEMCONF, 0, RAMBLOCK_RET2_BIT_ICACHE, false);
-	nrf_memconf_ramblock_ret2_enable_set(NRF_MEMCONF, 1, RAMBLOCK_RET2_BIT_ICACHE, false);
-#endif
-#if defined(RAMBLOCK_RET2_BIT_DCACHE)
-	nrf_memconf_ramblock_ret2_enable_set(NRF_MEMCONF, 0, RAMBLOCK_RET2_BIT_DCACHE, false);
-	nrf_memconf_ramblock_ret2_enable_set(NRF_MEMCONF, 1, RAMBLOCK_RET2_BIT_DCACHE, false);
-#endif
+	nrf_soc_memconf_retain_set(false);
 	nrf_memconf_ramblock_ret_mask_enable_set(NRF_MEMCONF, 0, RAMBLOCK_RET_MASK, true);
 	nrf_memconf_ramblock_ret_mask_enable_set(NRF_MEMCONF, 1, RAMBLOCK_RET_MASK, true);
 #if defined(RAMBLOCK_RET2_MASK)
-	/*
-	 * TODO: Use nrf_memconf_ramblock_ret2_mask_enable_set() function
-	 * when will be provided by HAL.
-	 */
-	NRF_MEMCONF->POWER[0].RET2 = RAMBLOCK_RET2_MASK;
-	NRF_MEMCONF->POWER[1].RET2 = RAMBLOCK_RET2_MASK;
+	nrf_memconf_ramblock_ret2_mask_enable_set(NRF_MEMCONF, 0, RAMBLOCK_RET2_MASK, true);
+	nrf_memconf_ramblock_ret2_mask_enable_set(NRF_MEMCONF, 1, RAMBLOCK_RET2_MASK, true);
 #endif
 }
 

diff --git a/soc/nordic/nrf54h/soc.h b/soc/nordic/nrf54h/soc.h
@@ -36,4 +36,11 @@
 #define RAMBLOCK_RET2_BIT_DCACHE MEMCONF_POWER_RET2_MEM7_Pos
 #endif
 
+/**
+ * @brief Enable or disable the retention for cache RAM blocks.
+ *
+ * @param enable True if the retention is to be enabled, false otherwise.
+ */
+void nrf_soc_memconf_retain_set(bool enable);
+
 #endif /* SOC_ARM_NORDIC_NRF_NRF54H_SOC_H_ */