modules: power: disable/enable UART on VBUS events

Disable/enable UART on VBUS events

Signed-off-by: Simen S. Røstad <simen.rostad@nordicsemi.no>

Author: simensrostad

app/prj.conf

@@ -210,3 +210,4 @@ CONFIG_TASK_WDT_MIN_TIMEOUT=10000
 
 # Device power management
 CONFIG_PM_DEVICE=y
+CONFIG_PM_DEVICE_SHELL=y

app/src/modules/power/Kconfig.power

@@ -8,9 +8,15 @@ menu "Power"
 
 config APP_POWER
 	bool "Power module"
+	depends on NRF_FUEL_GAUGE
+	depends on NPM1300_CHARGER
 
 if APP_POWER
 
+config APP_POWER_DISABLE_UART_ON_VBUS_REMOVED
+	bool "Disable UART when VBUS is removed"
+	default y
+
 config APP_POWER_THREAD_STACK_SIZE
 	int "Thread stack size"
 	default 1536

app/src/modules/power/power.c

@@ -6,6 +6,9 @@
 
 #include <zephyr/kernel.h>
 #include <zephyr/logging/log.h>
+#include <zephyr/device.h>
+#include <zephyr/devicetree.h>
+#include <zephyr/pm/device.h>
 #include <zephyr/zbus/zbus.h>
 #include <zephyr/drivers/sensor/npm1300_charger.h>
 #include <zephyr/drivers/mfd/npm1300.h>
@@ -57,6 +60,9 @@ BUILD_ASSERT(CONFIG_APP_POWER_WATCHDOG_TIMEOUT_SECONDS >
 static const struct device *charger = DEVICE_DT_GET(DT_NODELABEL(npm1300_charger));
 static const struct device *pmic = DEVICE_DT_GET(DT_NODELABEL(pmic_main));
 
+static const struct device *const uart0_dev = DEVICE_DT_GET(DT_NODELABEL(uart0));
+static const struct device *const uart1_dev = DEVICE_DT_GET(DT_NODELABEL(uart1));
+
 /* Forward declarations */
 static int subscribe_to_vsbus_events(const struct device *pmic, struct gpio_callback *event_cb);
 static int charger_read_sensors(float *voltage, float *current, float *temp, int32_t *chg_status);
@@ -118,11 +124,13 @@ static void state_running_entry(void *o)
 		return;
 	}
 
-	err = subscribe_to_vsbus_events(pmic, &event_cb);
-	if (err) {
-		LOG_ERR("subscribe_to_vsbus_events, error: %d", err);
-		SEND_FATAL_ERROR();
-		return;
+	if (IS_ENABLED(CONFIG_APP_POWER_DISABLE_UART_ON_VBUS_REMOVED)) {
+		err = subscribe_to_vsbus_events(pmic, &event_cb);
+		if (err) {
+			LOG_ERR("subscribe_to_vsbus_events, error: %d", err);
+			SEND_FATAL_ERROR();
+			return;
+		}
 	}
 
 	err = charger_read_sensors(&parameters.v0, &parameters.i0, &parameters.t0, &chg_status);
@@ -165,17 +173,97 @@ static void state_running_run(void *o)
 
 /* End of state handling */
 
+static int uart_disable(void)
+{
+	int err;
+
+	if (!device_is_ready(uart0_dev) || !device_is_ready(uart1_dev)) {
+		LOG_ERR("UART devices are not ready");
+		return -ENODEV;
+	}
+
+#ifdef CONFIG_NRF_MODEM_LIB_TRACE_BACKEND_UART
+	err = nrf_modem_lib_trace_level_set(NRF_MODEM_LIB_TRACE_LEVEL_OFF);
+	if (err) {
+		LOG_ERR("nrf_modem_lib_trace_level_set, error: %d", err);
+		return err;
+	}
+#endif
+
+	/* Wait for UART buffers to be emptied before suspending.
+	 * If a transfer is ongoing, the driver will cause an assertion to fail.
+	 * 100 ms is an arbitrary value that should be enough for the buffers to empty.
+	 */
+	k_busy_wait(100 * USEC_PER_MSEC);
+
+	err = pm_device_action_run(uart1_dev, PM_DEVICE_ACTION_SUSPEND);
+	if (err) {
+		LOG_ERR("pm_device_action_run, error: %d", err);
+		return err;
+	}
+
+	err = pm_device_action_run(uart0_dev, PM_DEVICE_ACTION_SUSPEND);
+	if (err) {
+		LOG_ERR("pm_device_actiöon_run, error: %d", err);
+		return err;
+	}
+
+	LOG_DBG("UART devices disabled");
+	return 0;
+}
+
+static int uart_enable(void)
+{
+	int err;
+
+	if (!device_is_ready(uart0_dev) || !device_is_ready(uart1_dev)) {
+		LOG_ERR("UART devices are not ready");
+		return -ENODEV;
+	}
+
+	err = pm_device_action_run(uart0_dev, PM_DEVICE_ACTION_RESUME);
+	if (err) {
+		LOG_ERR("pm_device_action_run, error: %d", err);
+		return err;
+	}
+
+	err = pm_device_action_run(uart1_dev, PM_DEVICE_ACTION_RESUME);
+	if (err) {
+		LOG_ERR("pm_device_action_run, error: %d", err);
+		return err;
+	}
+
+	LOG_DBG("UART devices enabled");
+	return 0;
+}
+
 static void event_callback(const struct device *dev, struct gpio_callback *cb, uint32_t pins)
 {
 	ARG_UNUSED(dev);
 	ARG_UNUSED(cb);
 
+	int err;
+
 	if (pins & BIT(NPM1300_EVENT_VBUS_DETECTED)) {
-		LOG_WRN("Vbus detected");
+		LOG_DBG("VBUS detected");
+
+		err = uart_enable();
+		if (err) {
+			LOG_ERR("uart_enable, error: %d", err);
+			SEND_FATAL_ERROR();
+			return;
+		}
 	}
 
 	if (pins & BIT(NPM1300_EVENT_VBUS_REMOVED)) {
-		LOG_WRN("Vbus removed");
+		LOG_DBG("VBUS removed");
+
+		err = uart_disable();
+		if (err) {
+			LOG_ERR("uart_disable, error: %d", err);
+			SEND_FATAL_ERROR();
+			return;
+		}
 	}
 }