soc/arm/silabs: support BLE with PM in Series 2 SoCs

Using EM2 or deeper sleep states (where HF clocks are off) requires
special care if BLE radio is used, since BLE radio relies on that clock,
and its power/clock requirements need to be taken into account
On SiLabs, radio PM is implemented as part of RAIL blob, which relies
on sl_power_manager HAL service. I've implemented SoC PM
state changes using sl_power_manager instead of emlib, and added
call to RAIL PM initialization in Gecko HCI driver.

Signed-off-by: Roman Dobrodii <rdobrodii@antmicro.com>

boards/arm/efr32_thunderboard/Kconfig.defconfig

@@ -32,6 +32,7 @@ config COMMON_LIBC_MALLOC_ARENA_SIZE
 	default 8192
 
 config MAIN_STACK_SIZE
+	default 3072 if PM
 	default 2304
 
 choice BT_HCI_BUS_TYPE

drivers/bluetooth/hci/Kconfig

@@ -59,6 +59,7 @@ config BT_STM32_IPM
 config BT_SILABS_HCI
 	bool "Silicon Labs Bluetooth interface"
 	depends on SOC_SERIES_EFR32BG22 || SOC_SERIES_EFR32MG24
+	depends on !PM || SOC_GECKO_PM_BACKEND_PMGR
 	select ENTROPY_GENERATOR
 	select MBEDTLS
 	select MBEDTLS_PSA_CRYPTO_C

drivers/bluetooth/hci/slz_hci.c

@@ -10,6 +10,7 @@
 #include <sl_hci_common_transport.h>
 #include <pa_conversions_efr32.h>
 #include <sl_bt_ll_zephyr.h>
+#include <rail.h>
 
 #define LOG_LEVEL CONFIG_BT_HCI_DRIVER_LOG_LEVEL
 #include <zephyr/logging/log.h>
@@ -156,6 +157,19 @@ static int slz_bt_open(void)
 
 	sl_bthci_init_upper();
 
+#ifdef CONFIG_PM
+	{
+		RAIL_Status_t status = RAIL_InitPowerManager();
+
+		if (status != RAIL_STATUS_NO_ERROR) {
+			LOG_ERR("RAIL: failed to initialize power management, status=%d",
+					status);
+			ret = -EIO;
+			goto deinit;
+		}
+	}
+#endif
+
 	LOG_DBG("SiLabs BT HCI started");
 
 	return 0;

drivers/timer/gecko_burtc_timer.c

@@ -70,7 +70,7 @@ static atomic_t g_last_count;
 static struct k_spinlock g_lock;
 
 /* Set to true when timer is initialized */
-static atomic_t g_init = ATOMIC_INIT(0);
+static bool g_init;
 
 static void burtc_isr(const void *arg)
 {
@@ -161,12 +161,10 @@ void sys_clock_set_timeout(int32_t ticks, bool idle)
 
 uint32_t sys_clock_elapsed(void)
 {
-	if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL)) {
+	if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL) || !g_init) {
 		return 0;
-	} else if (atomic_get(&g_init)) {
-		return (BURTC_CounterGet() - g_last_count) / g_cyc_per_tick;
 	} else {
-		return 0;
+		return (BURTC_CounterGet() - g_last_count) / g_cyc_per_tick;
 	}
 }
 
@@ -176,10 +174,10 @@ uint32_t sys_clock_cycle_get_32(void)
 	 * a value of some 32-bit hw_cycles counter which counts with
 	 * z_clock_hw_cycles_per_sec frequency
 	 */
-	if (atomic_get(&g_init)) {
-		return BURTC_CounterGet();
-	} else {
+	if (!g_init) {
 		return 0;
+	} else {
+		return BURTC_CounterGet();
 	}
 }
 
@@ -222,7 +220,7 @@ static int burtc_init(void)
 	init.clkDiv = 1;
 	init.start = false;
 	BURTC_Init(&init);
-	atomic_set(&g_init, 1);
+	g_init = true;
 
 	/* Enable compare match interrupt */
 	BURTC_IntClear(BURTC_IF_COMP);

samples/bluetooth/ibeacon/boards/efr32bg22_brd4184a.conf

@@ -0,0 +1 @@
+CONFIG_PM=y

soc/arm/silabs_exx32/Kconfig

@@ -126,6 +126,22 @@ config SOC_GECKO_TRNG
 	help
 	  Set if the SoC has a True Random Number Generator (TRNG) module.
 
+if PM
+
+config SOC_GECKO_PM_BACKEND_PMGR
+	bool
+	default y if SOC_GECKO_SERIES2
+	help
+	  Implement PM using sl_power_manager service from Gecko SDK
+
+config SOC_GECKO_PM_BACKEND_EMU
+	bool
+	default y if !SOC_GECKO_PM_BACKEND_PMGR
+	help
+	  Implement PM using direct calls to EMU driver in emlib
+
+endif
+
 config SOC_GECKO_EMU_DCDC
 	bool "SoC DC/DC regulator"
 	select SOC_GECKO_EMU

soc/arm/silabs_exx32/Kconfig.defconfig

@@ -12,4 +12,10 @@ config SOC_GECKO_EMU
 config CORTEX_M_SYSTICK
 	default n if GECKO_BURTC_TIMER
 
+# With sl_power_manager, pm_state_set()'s stack footrpting is noticeably
+# large, especially with logs enabled. Since it is called from IDLE task,
+# its stack size has to be increased
+config IDLE_STACK_SIZE
+	default 512 if SOC_GECKO_PM_BACKEND_PMGR
+
 endif

soc/arm/silabs_exx32/common/CMakeLists.txt

@@ -2,5 +2,7 @@
 
 zephyr_sources(soc.c)
 
-zephyr_sources_ifdef(CONFIG_PM soc_power.c)
+zephyr_sources_ifdef(CONFIG_SOC_GECKO_PM_BACKEND_EMU    soc_power.c)
+zephyr_sources_ifdef(CONFIG_SOC_GECKO_PM_BACKEND_PMGR   soc_power_pmgr.c)
+
 zephyr_include_directories(.)

soc/arm/silabs_exx32/common/soc_power_pmgr.c

@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2018, Piotr Mienkowski
+ * Copyright (c) 2023, Antmicro <www.antmicro.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <zephyr/kernel.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/pm/pm.h>
+#include <sl_power_manager.h>
+
+LOG_MODULE_DECLARE(soc, CONFIG_SOC_LOG_LEVEL);
+
+/*
+ * Power state map:
+ * PM_STATE_RUNTIME_IDLE: EM1 Sleep
+ * PM_STATE_SUSPEND_TO_IDLE: EM2 Deep Sleep
+ * PM_STATE_STANDBY: EM3 Stop
+ * PM_STATE_SOFT_OFF: EM4
+ */
+
+
+/* Invoke Low Power/System Off specific Tasks */
+__weak void pm_state_set(enum pm_state state, uint8_t substate_id)
+{
+	ARG_UNUSED(substate_id);
+	sl_power_manager_em_t energy_mode = SL_POWER_MANAGER_EM0;
+
+	LOG_DBG("SoC entering power state %d", state);
+
+	switch (state) {
+	case PM_STATE_RUNTIME_IDLE:
+		energy_mode = SL_POWER_MANAGER_EM1;
+		break;
+	case PM_STATE_SUSPEND_TO_IDLE:
+		energy_mode = SL_POWER_MANAGER_EM2;
+		break;
+	case PM_STATE_STANDBY:
+		energy_mode = SL_POWER_MANAGER_EM3;
+		break;
+	case PM_STATE_SOFT_OFF:
+		energy_mode = SL_POWER_MANAGER_EM4;
+		break;
+	default:
+		LOG_DBG("Unsupported power state %d", state);
+		break;
+	}
+
+	/* FIXME: When this function is entered the Kernel has disabled
+	 * interrupts using BASEPRI register. This is incorrect as it prevents
+	 * waking up from any interrupt which priority is not 0. Work around the
+	 * issue and disable interrupts using PRIMASK register as recommended
+	 * by ARM.
+	 */
+
+	/* Set PRIMASK */
+	__disable_irq();
+	/* Set BASEPRI to 0 */
+	irq_unlock(0);
+
+	LOG_DBG("Entry to energy mode %d", energy_mode);
+
+	if (energy_mode != SL_POWER_MANAGER_EM0) {
+		sl_power_manager_add_em_requirement(energy_mode);
+		sl_power_manager_sleep();
+		k_cpu_idle();
+		sl_power_manager_remove_em_requirement(energy_mode);
+	}
+
+	LOG_DBG("Exit from energy mode %d", energy_mode);
+
+	/* Clear PRIMASK */
+	__enable_irq();
+}
+
+
+/**
+ * Some SiLabs blobs, such as RAIL, call directly into sl_power_manager, and
+ * for that they had to include sl_power_manager.h during build. Some of those
+ * blobs have been compiled with -DSL_POWER_MANAGER_DEBUG=1, making inlined
+ * functions from that header to rely on
+ * sli_power_manager_debug_log_em_requirement() callback.
+ *
+ * This is irrespective of whether *we* enable SL_POWER_MANAGER_DEBUG when
+ * compiling sl_power_manager code as part of Zephyr build.
+ *
+ * Therefore, we provide sli_power_manager_debug_log_em_requirement()
+ * definition here just to satisfy those blobs. It will also be used if we
+ * attempt to build sl_power_manager with SL_POWER_MANAGER_DEBUG enabled.
+ *
+ * @note Please keep this at the end of the file.
+ */
+
+#ifdef sli_power_manager_debug_log_em_requirement
+#undef sli_power_manager_debug_log_em_requirement
+#endif
+
+void sli_power_manager_debug_init(void)
+{
+}
+
+void sli_power_manager_debug_log_em_requirement(
+	sl_power_manager_em_t em, bool add, const char *name)
+{
+	LOG_DBG("Set PM requirement em=%d add=%s name=%s",
+			(int)em, add ? "true" : "false", name);
+}