From d4a16768bfd0ab0cf60ba7eb806ab1a8a1b18f2c Mon Sep 17 00:00:00 2001
From: Ryan Erickson <ryan.erickson@lairdconnect.com>
Date: Wed, 1 Jun 2022 09:23:25 -0500
Subject: [PATCH] modem: hl7800: Enable multi-user callbacks

Change callback registration so it can support multiple users.

Signed-off-by: Ryan Erickson <ryan.erickson@lairdconnect.com>
---
 drivers/modem/hl7800.c                | 34 +++++++++++++++++++++------
 include/zephyr/drivers/modem/hl7800.h | 17 ++++++++++++--
 2 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/drivers/modem/hl7800.c b/drivers/modem/hl7800.c
index 350717cb4fc..3061939ed27 100644
--- a/drivers/modem/hl7800.c
+++ b/drivers/modem/hl7800.c
@@ -406,6 +406,7 @@ static uint8_t mdm_recv_buf[MDM_MAX_DATA_LENGTH];
 
 static K_SEM_DEFINE(hl7800_RX_lock_sem, 1, 1);
 static K_SEM_DEFINE(hl7800_TX_lock_sem, 1, 1);
+static K_MUTEX_DEFINE(cb_lock);
 
 /* RX thread structures */
 K_THREAD_STACK_DEFINE(hl7800_rx_stack, CONFIG_MODEM_HL7800_RX_STACK_SIZE);
@@ -557,7 +558,6 @@ struct hl7800_iface_ctx {
 	enum hl7800_lpm low_power_mode;
 	enum mdm_hl7800_network_state network_state;
 	enum net_operator_status operator_status;
-	void (*event_callback)(enum mdm_hl7800_event event, void *event_data);
 	struct tm local_time;
 	int32_t local_time_offset;
 	bool local_time_valid;
@@ -578,6 +578,9 @@ struct cmd_handler {
 	bool (*func)(struct net_buf **buf, uint16_t len);
 };
 
+static sys_slist_t hl7800_event_callback_list =
+	SYS_SLIST_STATIC_INIT(&hl7800_event_callback_list);
+
 static struct hl7800_iface_ctx ictx;
 
 static size_t hl7800_read_rx(struct net_buf **buf);
@@ -962,9 +965,17 @@ static void allow_sleep(bool allow)
 
 static void event_handler(enum mdm_hl7800_event event, void *event_data)
 {
-	if (ictx.event_callback != NULL) {
-		ictx.event_callback(event, event_data);
+	sys_snode_t *node;
+	struct mdm_hl7800_callback_agent *agent;
+
+	k_mutex_lock(&cb_lock, K_FOREVER);
+	SYS_SLIST_FOR_EACH_NODE(&hl7800_event_callback_list, node) {
+		agent = CONTAINER_OF(node, struct mdm_hl7800_callback_agent, node);
+		if (agent->event_callback != NULL) {
+			agent->event_callback(event, event_data);
+		}
 	}
+	k_mutex_unlock(&cb_lock);
 }
 
 void mdm_hl7800_get_signal_quality(int *rsrp, int *sinr)
@@ -5476,12 +5487,21 @@ int32_t mdm_hl7800_power_off(void)
 	return rc;
 }
 
-void mdm_hl7800_register_event_callback(mdm_hl7800_event_callback_t cb)
+void mdm_hl7800_register_event_callback(struct mdm_hl7800_callback_agent *agent)
 {
-	int key = irq_lock();
+	k_mutex_lock(&cb_lock, K_FOREVER);
+	if (!agent->event_callback) {
+		LOG_WRN("event_callback is NULL");
+	}
+	sys_slist_append(&hl7800_event_callback_list, &agent->node);
+	k_mutex_unlock(&cb_lock);
+}
 
-	ictx.event_callback = cb;
-	irq_unlock(key);
+void mdm_hl7800_unregister_event_callback(struct mdm_hl7800_callback_agent *agent)
+{
+	k_mutex_lock(&cb_lock, K_FOREVER);
+	(void)sys_slist_find_and_remove(&hl7800_event_callback_list, &agent->node);
+	k_mutex_unlock(&cb_lock);
 }
 
 /*** OFFLOAD FUNCTIONS ***/
diff --git a/include/zephyr/drivers/modem/hl7800.h b/include/zephyr/drivers/modem/hl7800.h
index e4a26cc11d7..98a7caaeba8 100644
--- a/include/zephyr/drivers/modem/hl7800.h
+++ b/include/zephyr/drivers/modem/hl7800.h
@@ -250,6 +250,11 @@ struct mdm_hl7800_polte_location_data {
 typedef void (*mdm_hl7800_event_callback_t)(enum mdm_hl7800_event event,
 					    void *event_data);
 
+struct mdm_hl7800_callback_agent {
+	sys_snode_t node;
+	mdm_hl7800_event_callback_t event_callback;
+};
+
 /**
  * @brief Power off the HL7800
  *
@@ -346,10 +351,18 @@ bool mdm_hl7800_valid_rat(uint8_t value);
 
 /**
  * @brief Register a function that is called when a modem event occurs.
+ * Multiple users registering for callbacks is supported.
  *
- * @param cb event callback
+ * @param agent event callback agent
  */
-void mdm_hl7800_register_event_callback(mdm_hl7800_event_callback_t cb);
+void mdm_hl7800_register_event_callback(struct mdm_hl7800_callback_agent *agent);
+
+/**
+ * @brief Unregister a callback event function
+ *
+ * @param agent event callback agent
+ */
+void mdm_hl7800_unregister_event_callback(struct mdm_hl7800_callback_agent *agent);
 
 /**
  * @brief Force modem module to generate status events.