[FL-2244] Companion reboot fix (#988)

* bt: don't open rpc session if it is busy
* bq27220: fix incorrect checksum calculation

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

applications/bt/bt_service/bt.c

@@ -199,13 +199,18 @@ static bool bt_on_gap_event_callback(GapEvent event, void* context) {
         furi_check(osMessageQueuePut(bt->message_queue, &message, 0, osWaitForever) == osOK);
         if(bt->profile == BtProfileSerial) {
             // Open RPC session
-            FURI_LOG_I(TAG, "Open RPC connection");
             bt->rpc_session = rpc_session_open(bt->rpc);
-            rpc_session_set_send_bytes_callback(bt->rpc_session, bt_rpc_send_bytes_callback);
-            rpc_session_set_buffer_is_empty_callback(
-                bt->rpc_session, furi_hal_bt_serial_notify_buffer_is_empty);
-            rpc_session_set_context(bt->rpc_session, bt);
-            furi_hal_bt_serial_set_event_callback(RPC_BUFFER_SIZE, bt_serial_event_callback, bt);
+            if(bt->rpc_session) {
+                FURI_LOG_I(TAG, "Open RPC connection");
+                rpc_session_set_send_bytes_callback(bt->rpc_session, bt_rpc_send_bytes_callback);
+                rpc_session_set_buffer_is_empty_callback(
+                    bt->rpc_session, furi_hal_bt_serial_notify_buffer_is_empty);
+                rpc_session_set_context(bt->rpc_session, bt);
+                furi_hal_bt_serial_set_event_callback(
+                    RPC_BUFFER_SIZE, bt_serial_event_callback, bt);
+            } else {
+                FURI_LOG_W(TAG, "RPC is busy, failed to open new session");
+            }
         }
         // Update battery level
         PowerInfo info;

firmware/targets/f6/furi_hal/furi_hal_bt.c

@@ -47,7 +47,7 @@ FuriHalBtProfileConfig profile_config[FuriHalBtProfileNumber] = {
                             .conn_int_min = 0x08,
                             .conn_int_max = 0x18,
                             .slave_latency = 0,
-                            .supervisor_timeout = 50,
+                            .supervisor_timeout = 0,
                         },
                 },
         },

firmware/targets/f7/furi_hal/furi_hal_bt.c

@@ -47,7 +47,7 @@ FuriHalBtProfileConfig profile_config[FuriHalBtProfileNumber] = {
                             .conn_int_min = 0x08,
                             .conn_int_max = 0x18,
                             .slave_latency = 0,
-                            .supervisor_timeout = 50,
+                            .supervisor_timeout = 0,
                         },
                 },
         },

lib/drivers/bq27220.c

@@ -44,7 +44,7 @@ bool bq27220_set_parameter_u16(FuriHalI2cBusHandle* handle, uint16_t address, ui
 
     delay_us(10000);
 
-    uint8_t checksum = bq27220_get_checksum(&buffer[1], 4);
+    uint8_t checksum = bq27220_get_checksum(buffer, 4);
     buffer[0] = checksum;
     buffer[1] = 6;
     ret = furi_hal_i2c_write_mem(