Contribution description

This PR is a refactoring of the ESP32 CAN controller driver implementation. Refactoring became necessary to follow the approach as introduced with PR #6178, which defines CAN interfaces as peripherals with automatic configuration.

Accordingly, the ESP32 CAN controller driver is no longer a separate module (esp_can), but rather part of the peripheral drivers which is enabled when module periph_can is used.

Testing procedure

For testing, an ESP32 board with a connected CAN transceiver module is required. The only supported board is which already has such a CAN transceiver module on board, is the Olimex ESP32-EVB. Therefore, it is suggested to use this board.

After flashing the board with application tests/conn_can

make BOARD=esp32-olimex-evb -C tests/conn_can flash term

the CAN-L and CAN-H have to be connected to a can bus. As counterpart a Linux box should be used with the can-utils.

linux> sudo ip link set can0 type can bitrate 500000
linux> sudo ip link set can0 up

After connecting to the ESP32 board in a terminal, the following tests can be executed.

1. List CAN interfaces:

   esp32> can list
   CAN #0: esp-can
   

2. Send a CAN frame from ESP32 to the Linux box (start candump first):

   linux$ candump can0
    
   can0  123   [4]  11 22 33 44
   

   esp32> can send 0 123 11 22 33 44
   

3. Send a CAN frame from Linux box to ESP32 (start can dump first and send within 10 seconds):

   esp32> can dump 0 0 10000
   esp-can (0)      5A1  [8]  11 22 33 44 55 66 77 88
   

   linux$ cansend can0 5A1#11.2233.44556677.88
   

Issues/PRs references

Implements #6178 for ESP32.