[FL-2053] BLE MTU processing #830

Co-authored-by: あく <alleteam@gmail.com>

firmware/targets/f6/ble-glue/gap.c

@@ -155,6 +155,16 @@ SVCCTL_UserEvtFlowStatus_t SVCCTL_App_Notification( void *pckt )
             }
                 break;
 
+            case EVT_BLUE_ATT_EXCHANGE_MTU_RESP:
+            {
+                aci_att_exchange_mtu_resp_event_rp0 *pr = (void*)blue_evt->data;
+                FURI_LOG_I(TAG, "Rx MTU size: %d", pr->Server_RX_MTU);
+                // Set maximum packet size given header size is 3 bytes
+                BleEvent event = {.type = BleEventTypeUpdateMTU, .data.max_packet_size = pr->Server_RX_MTU - 3};
+                gap->on_event_cb(event, gap->context);
+            }
+                break;
+
             case EVT_BLUE_GAP_AUTHORIZATION_REQUEST:
                 FURI_LOG_I(TAG, "Authorization request event");
                 break;

firmware/targets/f6/ble-glue/gap.h

@@ -13,10 +13,12 @@ typedef enum {
     BleEventTypeStartAdvertising,
     BleEventTypeStopAdvertising,
     BleEventTypePinCodeShow,
+    BleEventTypeUpdateMTU,
 } BleEventType;
 
 typedef union {
     uint32_t pin_code;
+    uint16_t max_packet_size;
 } BleEventData;
 
 typedef struct {

firmware/targets/f6/ble-glue/serial_service.h

@@ -3,7 +3,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-#define SERIAL_SVC_DATA_LEN_MAX (245)
+#define SERIAL_SVC_DATA_LEN_MAX (248)
 
 #ifdef __cplusplus
 extern "C" {