bluetooth: services: hrs: added control point write callback

- HRS control point was added to server but no write callback is
defined, this causes issues if control point characterstic is
written by the client

Signed-off-by: Anuj Pathak <anuj@croxel.com>

include/zephyr/bluetooth/services/hrs.h

@@ -25,6 +25,11 @@
 extern "C" {
 #endif
 
+/**
+ * @brief Server shall restart the accumulation of energy expended from zero
+ */
+#define BT_HRS_CONTROL_POINT_RESET_ENERGY_EXPANDED_REQ 0x01
+
 /** @brief Heart rate service callback structure */
 struct bt_hrs_cb {
 	/** @brief Heart rate notifications changed
@@ -34,6 +39,22 @@ struct bt_hrs_cb {
 	 */
 	void (*ntf_changed)(bool enabled);
 
+	/**
+	 * @brief Heart rate control point write callback
+	 *
+	 * @note if Server supports the Energy Expended feature then application
+	 * shall implement and support @ref BT_HRS_CONTROL_POINT_RESET_ENERGY_EXPANDED_REQ
+	 * request code
+	 *
+	 * @param request control point request code
+	 *
+	 * @return 0 on successful handling of control point request
+	 * @return -ENOTSUP if not supported. It can be used to pass handling to other
+	 *         listeners in case of multiple listeners
+	 * @return other negative error codes will result in immediate error response
+	 */
+	int (*ctrl_point_write)(uint8_t request);
+
 	/** Internal member to form a list of callbacks */
 	sys_snode_t _node;
 };

subsys/bluetooth/services/hrs.c

@@ -45,6 +45,12 @@ LOG_MODULE_REGISTER(hrs);
 #define CONFIG_BT_HRS_DEFAULT_PERM_RW 0
 #endif
 
+/**
+ * @brief GATT ATTR Error that should be returned in case
+ * HRS Control point request is not supported.
+ */
+#define BT_HRS_ATT_ERR_CONTROL_POINT_NOT_SUPPORTED 0x80
+
 #define HRS_GATT_PERM_DEFAULT (						\
 	CONFIG_BT_HRS_DEFAULT_PERM_RW_AUTHEN ?				\
 	(BT_GATT_PERM_READ_AUTHEN | BT_GATT_PERM_WRITE_AUTHEN) :	\
@@ -79,6 +85,33 @@ static ssize_t read_blsc(struct bt_conn *conn, const struct bt_gatt_attr *attr,
 				 sizeof(hrs_blsc));
 }
 
+static ssize_t ctrl_point_write(struct bt_conn *conn, const struct bt_gatt_attr *attr,
+				const void *buf, uint16_t len, uint16_t offset, uint8_t flags)
+{
+	int err = -ENOTSUP;
+	struct bt_hrs_cb *listener;
+
+	LOG_INF("HRS CTRL Point Written %d", len);
+
+	SYS_SLIST_FOR_EACH_CONTAINER(&hrs_cbs, listener, _node) {
+		if (listener->ctrl_point_write) {
+			err = listener->ctrl_point_write(*((uint8_t *)buf));
+			/* If we get an error other than ENOTSUP then immediately
+			 * break the loop and return a generic gatt error, assuming this
+			 * listener supports this request code, but failed to serve it
+			 */
+			if ((err != 0) && (err != -ENOTSUP)) {
+				return BT_GATT_ERR(BT_ATT_ERR_UNLIKELY);
+			}
+		}
+	}
+	if (err) {
+		return BT_GATT_ERR(BT_HRS_ATT_ERR_CONTROL_POINT_NOT_SUPPORTED);
+	} else {
+		return len;
+	}
+}
+
 /* Heart Rate Service Declaration */
 BT_GATT_SERVICE_DEFINE(hrs_svc,
 	BT_GATT_PRIMARY_SERVICE(BT_UUID_HRS),
@@ -91,7 +124,7 @@ BT_GATT_SERVICE_DEFINE(hrs_svc,
 			       read_blsc, NULL, NULL),
 	BT_GATT_CHARACTERISTIC(BT_UUID_HRS_CONTROL_POINT, BT_GATT_CHRC_WRITE,
 			       HRS_GATT_PERM_DEFAULT & GATT_PERM_WRITE_MASK,
-			       NULL, NULL, NULL),
+			       NULL, ctrl_point_write, NULL),
 );
 
 static int hrs_init(void)