From ef322d9e16a3af68666a81a70934f9a5774be88c Mon Sep 17 00:00:00 2001
From: Ryan Erickson <ryan.erickson@lairdconnect.com>
Date: Wed, 1 Sep 2021 08:24:31 -0500
Subject: [PATCH] drivers: modem: hl7800 Add Site Survey

Add API to determine nearby cell towers and their signal
strength.

Signed-off-by: Ryan Erickson <ryan.erickson@lairdconnect.com>
---
 drivers/modem/hl7800.c         | 85 ++++++++++++++++++++++++++++++++++
 include/drivers/modem/hl7800.h | 21 ++++++++-
 2 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/drivers/modem/hl7800.c b/drivers/modem/hl7800.c
index 9f8d2704008..30122c6c9af 100644
--- a/drivers/modem/hl7800.c
+++ b/drivers/modem/hl7800.c
@@ -1220,6 +1220,22 @@ error:
 
 #endif /* CONFIG_MODEM_HL7800_POLTE */
 
+/**
+ * @brief Perform a site survey.
+ *
+ */
+int32_t mdm_hl7800_perform_site_survey(void)
+{
+	int ret;
+
+	hl7800_lock();
+	wakeup_hl7800();
+	ret = send_at_cmd(NULL, "at%meas=\"97\"", MDM_CMD_SEND_TIMEOUT, 0, false);
+	allow_sleep(true);
+	hl7800_unlock();
+	return ret;
+}
+
 void mdm_hl7800_generate_status_events(void)
 {
 	hl7800_lock();
@@ -3045,6 +3061,74 @@ done:
 	return true;
 }
 
+/* There can be multiple responses from a single command.
+ * %MEAS: EARFCN=5826, CellID=420, RSRP=-99, RSRQ=-15
+ * %MEAS: EARFCN=6400, CellID=201, RSRP=-93, RSRQ=-21
+ */
+static bool on_cmd_survey_status(struct net_buf **buf, uint16_t len)
+{
+	struct net_buf *frag = NULL;
+	char response[sizeof("EARFCN=XXXXXXXXXXX, CellID=XXXXXXXXXXX, RSRP=-XXX, RSRQ=-XXX")];
+	char *key;
+	size_t out_len;
+	char *value;
+	struct mdm_hl7800_site_survey site_survey;
+
+	wait_for_modem_data_and_newline(buf, net_buf_frags_len(*buf),
+					sizeof(response));
+
+	frag = NULL;
+	len = net_buf_findcrlf(*buf, &frag);
+	if (!frag) {
+		LOG_ERR("Unable to find end");
+		goto done;
+	}
+
+	out_len = net_buf_linearize(response, sizeof(response), *buf, 0, len);
+	LOG_HEXDUMP_DBG(response, out_len, "Site Survey");
+
+	key = "EARFCN=";
+	value = strstr(response, key);
+	if (value == NULL) {
+		goto done;
+	} else {
+		value += strlen(key);
+		site_survey.earfcn = strtoul(value, NULL, 10);
+	}
+
+	key = "CellID=";
+	value = strstr(response, key);
+	if (value == NULL) {
+		goto done;
+	} else {
+		value += strlen(key);
+		site_survey.cell_id = strtoul(value, NULL, 10);
+	}
+
+	key = "RSRP=";
+	value = strstr(response, key);
+	if (value == NULL) {
+		goto done;
+	} else {
+		value += strlen(key);
+		site_survey.rsrp = strtol(value, NULL, 10);
+	}
+
+	key = "RSRQ=";
+	value = strstr(response, key);
+	if (value == NULL) {
+		goto done;
+	} else {
+		value += strlen(key);
+		site_survey.rsrq = strtol(value, NULL, 10);
+	}
+
+	event_handler(HL7800_EVENT_SITE_SURVEY, &site_survey);
+
+done:
+	return true;
+}
+
 #ifdef CONFIG_NEWLIB_LIBC
 /* Handler: +CCLK: "yy/MM/dd,hh:mm:ss±zz" */
 static bool on_cmd_rtc_query(struct net_buf **buf, uint16_t len)
@@ -4012,6 +4096,7 @@ static void hl7800_rx(void)
 		CMD_HANDLER("+KCARRIERCFG: ", operator_index_query),
 		CMD_HANDLER("AT+CIMI", atcmdinfo_imsi),
 		CMD_HANDLER("+CFUN: ", modem_functionality),
+		CMD_HANDLER("%MEAS: ", survey_status),
 #ifdef CONFIG_NEWLIB_LIBC
 		CMD_HANDLER("+CCLK: ", rtc_query),
 #endif
diff --git a/include/drivers/modem/hl7800.h b/include/drivers/modem/hl7800.h
index 0b42d898b99..759b21a2958 100644
--- a/include/drivers/modem/hl7800.h
+++ b/include/drivers/modem/hl7800.h
@@ -84,6 +84,13 @@ struct mdm_hl7800_apn {
 
 #define MDM_HL7800_SET_POLTE_USER_AND_PASSWORD_FMT_STR "AT%%POLTECMD=\"SERVERAUTH\",\"%s\",\"%s\""
 
+struct mdm_hl7800_site_survey {
+	uint32_t earfcn; /* EUTRA Absolute Radio Frequency Channel Number */
+	uint32_t cell_id;
+	int rsrp;
+	int rsrq;
+};
+
 enum mdm_hl7800_radio_mode { MDM_RAT_CAT_M1 = 0, MDM_RAT_CAT_NB1 };
 
 enum mdm_hl7800_event {
@@ -104,7 +111,8 @@ enum mdm_hl7800_event {
 	HL7800_EVENT_GPS_POSITION_STATUS,
 	HL7800_EVENT_POLTE_REGISTRATION,
 	HL7800_EVENT_POLTE_LOCATE_STATUS,
-	HL7800_EVENT_POLTE
+	HL7800_EVENT_POLTE,
+	HL7800_EVENT_SITE_SURVEY,
 };
 
 enum mdm_hl7800_startup_state {
@@ -237,6 +245,7 @@ struct mdm_hl7800_polte_location_data {
  * HL7800_EVENT_POLTE_REGISTRATION mdm_hl7800_polte_registration_event_data
  * HL7800_EVENT_POLTE mdm_hl7800_polte_location_data
  * HL7800_EVENT_POLTE_LOCATE_STATUS int
+ * HL7800_EVENT_SITE_SURVEY mdm_hl7800_site_survey
  */
 typedef void (*mdm_hl7800_event_callback_t)(enum mdm_hl7800_event event,
 					    void *event_data);
@@ -441,6 +450,16 @@ int32_t mdm_hl7800_polte_enable(char *user, char *password);
  */
 int32_t mdm_hl7800_polte_locate(void);
 
+/**
+ * @brief Perform a site survey.  This command may return different values
+ * each time it is run (depending on what is in range).
+ *
+ * HL7800_EVENT_SITE_SURVEY is generated for each response received from modem.
+ *
+ * @retval negative error code, 0 on success
+ */
+int32_t mdm_hl7800_perform_site_survey(void);
+
 #ifdef __cplusplus
 }
 #endif