app: Switch nRF Cloud AT commands from MQTT to CoAP

Replace nRF Cloud MQTT transport with the more lightweight CoAP
protocol.

Introduced new Kconfig option CONFIG_SM_NRF_CLOUD_LOCATION to
enable location support, since CONFIG_NRF_CLOUD_LOCATION depends
on NRF_CLOUD_MQTT and cannot be enabled when using NRF_CLOUD_COAP.

Jira: SM-235

Signed-off-by: Juha Ylinen <juha.ylinen@nordicsemi.no>

Author: juhaylinen

app/Kconfig

@@ -259,6 +259,13 @@ config HEAP_MEM_POOL_ADD_SIZE_SM_NRF_CLOUD
 	  dynamic memory allocation.
 endif # SM_NRF_CLOUD
 
+config SM_NRF_CLOUD_LOCATION
+	bool "nRF Cloud Location support"
+	depends on SM_NRF_CLOUD
+	help
+	  Enable the nRF Cloud Location service for cloud-assisted geolocation.
+	  Supports cellular and Wi-Fi positioning.
+
 config SM_MQTTC
 	bool "MQTT client support"
 	default y

app/prj.conf

@@ -94,13 +94,14 @@ CONFIG_SETTINGS_NVS=y
 CONFIG_NVS=y
 
 # nRF Cloud
+CONFIG_SM_NRF_CLOUD_LOCATION=y
 CONFIG_NRF_CLOUD=y
-CONFIG_NRF_CLOUD_MQTT=y
+CONFIG_NRF_CLOUD_COAP=y
+CONFIG_NRF_CLOUD_COAP_DOWNLOADS=n
 CONFIG_NRF_CLOUD_FOTA=n
 CONFIG_NRF_CLOUD_AGNSS=y
 CONFIG_NRF_CLOUD_AGNSS_FILTERED=n
 CONFIG_NRF_CLOUD_PGPS=n
-CONFIG_NRF_CLOUD_LOCATION=y
 CONFIG_NRF_CLOUD_LOG_LEVEL_INF=y
 CONFIG_NRF_CLOUD_GPS_LOG_LEVEL_INF=y
 CONFIG_NRF_CLOUD_CLIENT_ID_SRC_INTERNAL_UUID=y
@@ -109,6 +110,12 @@ CONFIG_DATE_TIME=y
 CONFIG_MODEM_INFO=y
 CONFIG_MODEM_INFO_ADD_DATE_TIME=n
 
+# CoAP client settings
+CONFIG_COAP_CLIENT_BLOCK_SIZE=1024
+CONFIG_COAP_CLIENT_THREAD_PRIORITY=0
+CONFIG_COAP_EXTENDED_OPTIONS_LEN_VALUE=96
+CONFIG_COAP_CLIENT_STACK_SIZE=2048
+
 # UUID and JWT
 CONFIG_MODEM_JWT=y
 

app/src/sm_at_gnss.c

@@ -16,6 +16,7 @@
 #if defined(CONFIG_SM_NRF_CLOUD)
 #include <net/nrf_cloud.h>
 #include <net/nrf_cloud_codec.h>
+#include <net/nrf_cloud_coap.h>
 #include "sm_at_nrfcloud.h"
 
 #if defined(CONFIG_NRF_CLOUD_AGNSS)
@@ -60,6 +61,8 @@ static struct k_work agnss_req_work;
 #endif
 #if defined(CONFIG_NRF_CLOUD_PGPS)
 static struct k_work pgps_req_work;
+static struct k_work pgps_coap_req_work;
+static struct gps_pgps_request pgps_coap_request;
 #endif
 
 #endif /* CONFIG_SM_NRF_CLOUD */
@@ -317,24 +320,41 @@ static void agnss_requestor(struct k_work *)
 {
 	int err;
 	struct nrf_modem_gnss_agnss_data_frame req;
+	static char agnss_rest_data_buf[NRF_CLOUD_AGNSS_MAX_DATA_SIZE];
+	struct nrf_cloud_rest_agnss_request request = {
+		NRF_CLOUD_REST_AGNSS_REQ_CUSTOM,
+		&req,
+	};
 
 	err = read_agnss_req(&req);
 	if (err) {
 		LOG_ERR("Failed to read A-GNSS request (%d).", err);
 		return;
 	}
 
-	err = nrf_cloud_agnss_request(&req);
+	struct nrf_cloud_rest_agnss_result result = {agnss_rest_data_buf,
+						     sizeof(agnss_rest_data_buf), 0};
+	struct lte_lc_cells_info net_info = {0};
+
+	err = get_single_cell_info(&net_info.current_cell);
 	if (err) {
-		LOG_ERR("Failed to request A-GNSS data (%d).", err);
-	} else {
-		LOG_INF("A-GNSS data requested.");
-		/* When A-GNSS data is received it gets injected in the background by
-		 * nrf_cloud_agnss_process() without notification. In the case where
-		 * CONFIG_NRF_CLOUD_PGPS=y, nrf_cloud_pgps_inject() (called on PGPS_EVT_AVAILABLE)
-		 * plays a role as A-GNSS expects P-GPS to process some of the data.
-		 */
+		LOG_ERR("Failed to obtain single-cell cellular network information (%d).", err);
+		return;
 	}
+	request.net_info = &net_info;
+
+	err = nrf_cloud_coap_agnss_data_get(&request, &result);
+	if (err) {
+		LOG_ERR("Failed to request A-GNSS data via REST (%d).", err);
+		return;
+	}
+
+	err = nrf_cloud_agnss_process(result.buf, result.agnss_sz);
+	if (err) {
+		LOG_ERR("Failed to process A-GNSS data, error: %d", err);
+		return;
+	}
+	LOG_INF("A-GNSS data received via CoAP.");
 }
 #endif /* CONFIG_NRF_CLOUD_AGNSS */
 
@@ -352,6 +372,47 @@ static void pgps_requestor(struct k_work *)
 	}
 }
 
+static void pgps_coap_requestor(struct k_work *)
+{
+	int err;
+	struct nrf_cloud_rest_pgps_request request = {.pgps_req = &pgps_coap_request};
+	struct nrf_cloud_pgps_result file_location = {0};
+	static char host[64];
+	static char path[128];
+
+	LOG_INF("Getting P-GPS predictions from nRF Cloud...");
+
+	memset(host, 0, sizeof(host));
+	memset(path, 0, sizeof(path));
+
+	file_location.host = host;
+	file_location.host_sz = sizeof(host);
+	file_location.path = path;
+	file_location.path_sz = sizeof(path);
+
+	err = nrf_cloud_coap_pgps_url_get(&request, &file_location);
+	if (err) {
+		LOG_ERR("Failed to get P-GPS data, error: %d", err);
+		nrf_cloud_pgps_request_reset();
+		return;
+	}
+
+	err = nrf_cloud_pgps_update(&file_location);
+	if (err) {
+		LOG_ERR("Failed to process P-GPS response, error: %d", err);
+		nrf_cloud_pgps_request_reset();
+		return;
+	}
+
+	err = nrf_cloud_pgps_notify_prediction();
+	if (err) {
+		LOG_ERR("Failed to request current prediction, error: %d", err);
+		return;
+	}
+
+	LOG_INF("P-GPS predictions requested");
+}
+
 static void pgps_event_handler(struct nrf_cloud_pgps_event *event)
 {
 	int err;
@@ -403,6 +464,8 @@ static void pgps_event_handler(struct nrf_cloud_pgps_event *event)
 		break;
 	case PGPS_EVT_REQUEST:
 		LOG_INF("PGPS_EVT_REQUEST");
+		memcpy(&pgps_coap_request, event->request, sizeof(pgps_coap_request));
+		k_work_submit_to_queue(&sm_work_q, &pgps_coap_req_work);
 		break;
 	}
 }
@@ -457,13 +520,8 @@ static void on_gnss_evt_pvt(void)
 static int do_cloud_send_obj(struct nrf_cloud_obj *const obj)
 {
 	int err;
-	struct nrf_cloud_tx_data msg = {
-		.obj = obj,
-		.topic_type = NRF_CLOUD_TOPIC_MESSAGE,
-		.qos = MQTT_QOS_0_AT_MOST_ONCE
-	};
 
-	err = nrf_cloud_send(&msg);
+	err = nrf_cloud_coap_obj_send(obj, true);
 	if (err) {
 		LOG_ERR("nrf_cloud_send failed, error: %d", err);
 	}
@@ -475,15 +533,31 @@ static int do_cloud_send_obj(struct nrf_cloud_obj *const obj)
 
 static void send_location(struct nrf_modem_gnss_pvt_data_frame * const pvt_data)
 {
+#define CLOUD_GNSS_HEADING_ACC_LIMIT (float)60.0
+
 	static int64_t last_ts_ms = NRF_CLOUD_NO_TIMESTAMP;
 	int err;
+
+	/* Map modem PVT data to nRF Cloud PVT structure */
+	struct nrf_cloud_gnss_pvt pvt = {
+		.lat        = pvt_data->latitude,
+		.lon        = pvt_data->longitude,
+		.accuracy   = pvt_data->accuracy,
+		.alt        = pvt_data->altitude,
+		.has_alt    = 1,
+		.speed      = pvt_data->speed,
+		.has_speed  = pvt_data->flags & NRF_MODEM_GNSS_PVT_FLAG_VELOCITY_VALID,
+		.heading    = pvt_data->heading,
+		.has_heading = pvt_data->heading_accuracy < CLOUD_GNSS_HEADING_ACC_LIMIT ? 1 : 0,
+	};
+
 	struct nrf_cloud_gnss_data gnss = {
 		.ts_ms = NRF_CLOUD_NO_TIMESTAMP,
-		.type = NRF_CLOUD_GNSS_TYPE_MODEM_PVT,
-		.mdm_pvt = pvt_data
+		.type = NRF_CLOUD_GNSS_TYPE_PVT,
+		.pvt = pvt,
 	};
-	NRF_CLOUD_OBJ_JSON_DEFINE(msg_obj);
 
+	NRF_CLOUD_OBJ_COAP_CBOR_DEFINE(msg_obj);
 	/* On failure, NRF_CLOUD_NO_TIMESTAMP is used and the timestamp is omitted */
 	(void)date_time_now(&gnss.ts_ms);
 
@@ -816,7 +890,8 @@ static int sm_at_gnss_init(void)
 #endif
 #if defined(CONFIG_NRF_CLOUD_PGPS)
 	k_work_init(&pgps_req_work, pgps_requestor);
-#endif
+	k_work_init(&pgps_coap_req_work, pgps_coap_requestor);
+#endif /* CONFIG_NRF_CLOUD_PGPS */
 #endif /* CONFIG_SM_NRF_CLOUD */
 	k_work_init(&gnss_fix_send_work, gnss_fix_sender);