[nrf fromlist] drivers: modem: Implement support for RING indicator

Use ring indicator to wake up the CMUX device
from sleep.
Only used for runtime power management, but same event
could be used for initiating idle -> connected as well.

Upstream PR #: 97362

Signed-off-by: Seppo Takalo <[email protected]>

Author: SeppoTakalo

drivers/modem/modem_cellular.c

@@ -96,6 +96,7 @@ enum modem_cellular_event {
 	MODEM_CELLULAR_EVENT_PPP_DEAD,
 	MODEM_CELLULAR_EVENT_MODEM_READY,
 	MODEM_CELLULAR_EVENT_APN_SET,
+	MODEM_CELLULAR_EVENT_RING,
 };
 
 struct modem_cellular_event_cb {
@@ -170,6 +171,9 @@ struct modem_cellular_data {
 
 	struct k_mutex api_lock;
 	struct modem_cellular_event_cb cb;
+
+	/* Ring interrupt */
+	struct gpio_callback ring_gpio_cb;
 };
 
 struct modem_cellular_user_pipe {
@@ -186,6 +190,7 @@ struct modem_cellular_config {
 	struct gpio_dt_spec power_gpio;
 	struct gpio_dt_spec reset_gpio;
 	struct gpio_dt_spec wake_gpio;
+	struct gpio_dt_spec ring_gpio;
 	struct gpio_dt_spec dtr_gpio;
 	uint16_t power_pulse_duration_ms;
 	uint16_t reset_pulse_duration_ms;
@@ -285,6 +290,8 @@ static const char *modem_cellular_event_str(enum modem_cellular_event event)
 		return "modem ready";
 	case MODEM_CELLULAR_EVENT_APN_SET:
 		return "apn set";
+	case MODEM_CELLULAR_EVENT_RING:
+		return "RING";
 	}
 
 	return "";
@@ -1242,7 +1249,10 @@ static void modem_cellular_run_dial_script_event_handler(struct modem_cellular_d
 	case MODEM_CELLULAR_EVENT_SUSPEND:
 		modem_cellular_enter_state(data, MODEM_CELLULAR_STATE_INIT_POWER_OFF);
 		break;
-
+	case MODEM_CELLULAR_EVENT_RING:
+		LOG_INF("RING received!");
+		modem_pipe_open_async(data->uart_pipe);
+		break;
 	default:
 		break;
 	}
@@ -1287,7 +1297,10 @@ static void modem_cellular_await_registered_event_handler(struct modem_cellular_
 	case MODEM_CELLULAR_EVENT_SUSPEND:
 		modem_cellular_enter_state(data, MODEM_CELLULAR_STATE_INIT_POWER_OFF);
 		break;
-
+	case MODEM_CELLULAR_EVENT_RING:
+		LOG_INF("RING received!");
+		modem_pipe_open_async(data->uart_pipe);
+		break;
 	default:
 		break;
 	}
@@ -1332,7 +1345,10 @@ static void modem_cellular_carrier_on_event_handler(struct modem_cellular_data *
 		modem_ppp_release(data->ppp);
 		modem_cellular_enter_state(data, MODEM_CELLULAR_STATE_INIT_POWER_OFF);
 		break;
-
+	case MODEM_CELLULAR_EVENT_RING:
+		LOG_INF("RING received!");
+		modem_pipe_open_async(data->uart_pipe);
+		break;
 	default:
 		break;
 	}
@@ -2069,6 +2085,15 @@ static void net_mgmt_event_handler(struct net_mgmt_event_callback *cb, uint64_t
 	}
 }
 
+static void modem_cellular_ring_gpio_callback(const struct device *dev, struct gpio_callback *cb,
+					      uint32_t pins)
+{
+	struct modem_cellular_data *data =
+		CONTAINER_OF(cb, struct modem_cellular_data, ring_gpio_cb);
+
+	modem_cellular_delegate_event(data, MODEM_CELLULAR_EVENT_RING);
+}
+
 static void modem_cellular_init_apn(struct modem_cellular_data *data)
 {
 #ifdef CONFIG_MODEM_CELLULAR_APN
@@ -2115,6 +2140,33 @@ static int modem_cellular_init(const struct device *dev)
 		gpio_pin_configure_dt(&config->reset_gpio, GPIO_OUTPUT_ACTIVE);
 	}
 
+	if (modem_cellular_gpio_is_enabled(&config->ring_gpio)) {
+		int ret;
+
+		ret = gpio_pin_configure_dt(&config->ring_gpio, GPIO_INPUT);
+		if (ret < 0) {
+			LOG_ERR("Failed to configure ring GPIO (%d)", ret);
+			return ret;
+		}
+
+		gpio_init_callback(&data->ring_gpio_cb, modem_cellular_ring_gpio_callback,
+				   BIT(config->ring_gpio.pin));
+
+		ret = gpio_add_callback(config->ring_gpio.port, &data->ring_gpio_cb);
+		if (ret < 0) {
+			LOG_ERR("Failed to add ring GPIO callback (%d)", ret);
+			return ret;
+		}
+
+		ret = gpio_pin_interrupt_configure_dt(&config->ring_gpio, GPIO_INT_EDGE_TO_ACTIVE);
+		if (ret < 0) {
+			LOG_ERR("Failed to configure ring GPIO interrupt (%d)", ret);
+			return ret;
+		}
+
+		LOG_DBG("Ring GPIO interrupt configured");
+	}
+
 	if (modem_cellular_gpio_is_enabled(&config->dtr_gpio)) {
 		gpio_pin_configure_dt(&config->dtr_gpio, GPIO_OUTPUT_INACTIVE);
 		dtr_gpio = &config->dtr_gpio;
@@ -2891,6 +2943,7 @@ MODEM_CHAT_SCRIPT_DEFINE(sqn_gm02s_periodic_chat_script,
 		.power_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, mdm_power_gpios, {}),                 \
 		.reset_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, mdm_reset_gpios, {}),                 \
 		.wake_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, mdm_wake_gpios, {}),                   \
+		.ring_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, mdm_ring_gpios, {}),                   \
 		.dtr_gpio = GPIO_DT_SPEC_INST_GET_OR(inst, mdm_dtr_gpios, {}),                     \
 		.power_pulse_duration_ms = (power_ms),                                             \
 		.reset_pulse_duration_ms = (reset_ms),                                             \

dts/bindings/modem/zephyr,cellular-modem-device.yaml

@@ -18,6 +18,10 @@ properties:
     type: phandle-array
     description: GPIO for modem wake
 
+  mdm-ring-gpios:
+    type: phandle-array
+    description: GPIO for modem ring indicator
+
   mdm-dtr-gpios:
     type: phandle-array
     description: |