Soft off ironside

drivers/timer/Kconfig.nrf_grtc

@@ -56,4 +56,11 @@ config NRF_GRTC_TIMER_AUTO_KEEP_ALIVE
 	  This feature prevents the SYSCOUNTER from sleeping when any core is in
 	  active state.
 
+config NRF_GRTC_TIMER_USE_SYSTEM_CHANNEL_TO_WAKEUP_FROM_SYSTEMOFF
+	bool
+	depends on POWEROFF
+	default y if SOC_NRF54H20
+	help
+	  Use system channel to schedule wake up time.
+
 endif # NRF_GRTC_TIMER

drivers/timer/nrf_grtc_timer.c

@@ -364,17 +364,41 @@ uint64_t z_nrf_grtc_timer_startup_value_get(void)
 	return grtc_start_value;
 }
 
-#if defined(CONFIG_POWEROFF) && defined(CONFIG_NRF_GRTC_START_SYSCOUNTER)
+#if defined(CONFIG_POWEROFF)
+static int32_t wakeup_channel = -1;
+
+int32_t z_nrf_grtc_timer_wakeup_channel_get(void)
+{
+	return wakeup_channel;
+}
+
+void z_nrf_grtc_timer_disable_owned_cc_channels(int32_t reserved_channel)
+{
+	uint32_t chan;
+
+	k_spinlock_key_t key = k_spin_lock(&lock);
+
+	for (uint32_t grtc_chan_mask = NRFX_GRTC_CONFIG_ALLOWED_CC_CHANNELS_MASK;
+	     grtc_chan_mask > 0; grtc_chan_mask &= ~BIT(chan)) {
+		/* Clear all GRTC channels except the reserved_channel. */
+		chan = u32_count_trailing_zeros(grtc_chan_mask);
+		if (chan != reserved_channel) {
+			nrfx_grtc_syscounter_cc_disable(chan);
+		}
+	}
+	k_spin_unlock(&lock, key);
+}
+
 int z_nrf_grtc_wakeup_prepare(uint64_t wake_time_us)
 {
-	nrfx_err_t err_code;
 	static uint8_t systemoff_channel;
 	uint64_t now = counter();
-	nrfx_grtc_sleep_config_t sleep_cfg;
+	int ret;
 	/* Minimum time that ensures valid execution of system-off procedure. */
 	uint32_t minimum_latency_us;
-	uint32_t chan;
-	int ret;
+
+#if CONFIG_NRF_GRTC_START_SYSCOUNTER
+	nrfx_grtc_sleep_config_t sleep_cfg;
 
 	nrfx_grtc_sleep_configuration_get(&sleep_cfg);
 	minimum_latency_us = (sleep_cfg.waketime + sleep_cfg.timeout) *
@@ -383,34 +407,34 @@ int z_nrf_grtc_wakeup_prepare(uint64_t wake_time_us)
 	sleep_cfg.auto_mode = false;
 	nrfx_grtc_sleep_configure(&sleep_cfg);
 
+#else
+	minimum_latency_us = CONFIG_NRF_GRTC_SYSCOUNTER_SLEEP_MINIMUM_LATENCY;
+#endif
 	if (minimum_latency_us > wake_time_us) {
 		return -EINVAL;
 	}
 
 	k_spinlock_key_t key = k_spin_lock(&lock);
 
-	err_code = nrfx_grtc_channel_alloc(&systemoff_channel);
+#if CONFIG_NRF_GRTC_TIMER_USE_SYSTEM_CHANNEL_TO_WAKEUP_FROM_SYSTEMOFF
+	systemoff_channel = system_clock_channel_data.channel;
+#else
+	nrfx_err_t err_code = nrfx_grtc_channel_alloc(&systemoff_channel);
 	if (err_code != NRFX_SUCCESS) {
 		k_spin_unlock(&lock, key);
 		return -ENOMEM;
 	}
-	(void)nrfx_grtc_syscounter_cc_int_disable(systemoff_channel);
-	ret = compare_set(systemoff_channel,
-			  now + wake_time_us * sys_clock_hw_cycles_per_sec() / USEC_PER_SEC, NULL,
-			  NULL);
+#endif
+	(void) nrfx_grtc_syscounter_cc_int_disable(systemoff_channel);
+	int64_t delay = now + wake_time_us * sys_clock_hw_cycles_per_sec() / USEC_PER_SEC;
+
+	ret = compare_set(systemoff_channel, delay, NULL, NULL);
 	if (ret < 0) {
 		k_spin_unlock(&lock, key);
 		return ret;
 	}
 
-	for (uint32_t grtc_chan_mask = NRFX_GRTC_CONFIG_ALLOWED_CC_CHANNELS_MASK;
-	     grtc_chan_mask > 0; grtc_chan_mask &= ~BIT(chan)) {
-		/* Clear all GRTC channels except the systemoff_channel. */
-		chan = u32_count_trailing_zeros(grtc_chan_mask);
-		if (chan != systemoff_channel) {
-			nrfx_grtc_syscounter_cc_disable(chan);
-		}
-	}
+	z_nrf_grtc_timer_disable_owned_cc_channels(systemoff_channel);
 
 	/* Make sure that wake_time_us was not triggered yet. */
 	if (nrfx_grtc_syscounter_compare_event_check(systemoff_channel)) {
@@ -419,11 +443,19 @@ int z_nrf_grtc_wakeup_prepare(uint64_t wake_time_us)
 	}
 
 	/* This mechanism ensures that stored CC value is latched. */
+#if CONFIG_NRF_GRTC_START_SYSCOUNTER
 	uint32_t wait_time =
 		nrfy_grtc_timeout_get(NRF_GRTC) * CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC / 32768 +
 		MAX_CC_LATCH_WAIT_TIME_US;
+#else
+	uint32_t wait_time = MAX_CC_LATCH_WAIT_TIME_US;
+#endif
+	/* Wait until the CC value is latched. */
 	k_busy_wait(wait_time);
 	k_spin_unlock(&lock, key);
+
+	wakeup_channel = systemoff_channel;
+
 	return 0;
 }
 #endif /* CONFIG_POWEROFF */

include/zephyr/drivers/timer/nrf_grtc_timer.h

@@ -175,6 +175,24 @@ int z_nrf_grtc_timer_capture_prepare(int32_t chan);
  */
 int z_nrf_grtc_timer_capture_read(int32_t chan, uint64_t *captured_time);
 
+/** @brief Get the channel used for wakeup from system-off.
+ *
+ * @return Channel ID or -1 if no channel is reserved for that purpose.
+ */
+int32_t z_nrf_grtc_timer_wakeup_channel_get(void);
+
+/** @brief Disable all owned compare channels except the one specified.
+ *
+ * This function is used when preparing the system to enter system-off mode.
+ * It disables all compare channels owned by the driver except the one
+ * specified by @p reserved_channel. The reserved channel is typically used
+ * for wake-up from system-off.
+ * @param reserved_channel Channel ID to remain enabled.
+ *
+ * @note Set @p reserved_channel to -1 to disable all owned channels.
+ */
+void z_nrf_grtc_timer_disable_owned_cc_channels(int32_t reserved_channel);
+
 /** @brief Prepare GRTC as a source of wake up event and set the wake up time.
  *
  * @note Calling this function should be immediately followed by low-power mode enter

samples/boards/nordic/system_off/Kconfig.sysbuild

@@ -0,0 +1,9 @@
+# Copyright 2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+source "share/sysbuild/Kconfig"
+
+config REMOTE_CORE_BOARD
+string
+	default "nrf54h20dk/nrf54h20/cpurad" if $(BOARD) = "nrf54h20dk"

samples/boards/nordic/system_off/boards/nrf54h20dk_nrf54h20_cpuapp.conf

@@ -0,0 +1,7 @@
+#
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_SOC_NRF54H20_CPURAD_ENABLE=y

samples/boards/nordic/system_off/boards/nrf54h20dk_nrf54h20_cpuapp.overlay

@@ -0,0 +1,4 @@
+&uart136 {
+	zephyr,pm-device-runtime-auto;
+	disable-rx;
+};

samples/boards/nordic/system_off/prj.conf

@@ -1,4 +1,7 @@
+CONFIG_PM=y
 CONFIG_PM_DEVICE=y
+CONFIG_PM_DEVICE_RUNTIME=y
+CONFIG_UART_ASYNC_API=y
 CONFIG_GPIO=y
 CONFIG_CRC=y
 CONFIG_POWEROFF=y

samples/boards/nordic/system_off/remote/CMakeLists.txt

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(nrf_system_off_remote)
+
+target_sources(app PRIVATE src/main.c)

samples/boards/nordic/system_off/remote/boards/nrf54h20dk_nrf54h20_cpurad.overlay

@@ -0,0 +1,5 @@
+&uart135 {
+	status = "disabled";
+	zephyr,pm-device-runtime-auto;
+	disable-rx;
+};

samples/boards/nordic/system_off/remote/prj.conf

@@ -0,0 +1,8 @@
+CONFIG_PM=y
+CONFIG_PM_DEVICE=y
+CONFIG_PM_DEVICE_RUNTIME=y
+CONFIG_POWEROFF=y
+CONFIG_UART_ASYNC_API=y
+CONFIG_SERIAL=n
+CONFIG_CONSOLE=n
+CONFIG_UART_CONSOLE=n

samples/boards/nordic/system_off/remote/src/main.c

@@ -0,0 +1,24 @@
+/* Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/pm/device.h>
+#include <zephyr/pm/device_runtime.h>
+#include <zephyr/sys/poweroff.h>
+#include <hal/nrf_memconf.h>
+#include <zephyr/drivers/timer/nrf_grtc_timer.h>
+
+int main(void)
+{
+
+	if (IS_ENABLED(CONFIG_CONSOLE)) {
+		printf("%s system off demo. Ready for system off.\n", CONFIG_BOARD);
+	}
+
+	sys_poweroff();
+
+	return 0;
+}