598e3eedb4
by the below command:
find . -type f -name '*.rst' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
67 lines
2.6 KiB
ReStructuredText
67 lines
2.6 KiB
ReStructuredText
========================
|
||
SocketCAN Device Drivers
|
||
========================
|
||
|
||
- ``include/nuttx/net/netdev.h``. All structures and APIs
|
||
needed to work with drivers are provided in this header file.
|
||
The structure struct net_driver_s defines the interface and is
|
||
passed to the network via netdev_register().
|
||
|
||
- ``include/nuttx/can.h``. CAN & CAN FD frame data
|
||
structures.
|
||
|
||
- ``int netdev_register(FAR struct net_driver_s *dev, enum net_lltype_e lltype)'``.
|
||
Each driver registers itself by calling netdev_register().
|
||
|
||
- ``Include/nuttx/net/can.h``. contains lookup tables for CAN
|
||
dlc to CAN FD len sizes named
|
||
|
||
.. code-block:: c
|
||
|
||
extern const uint8_t can_dlc_to_len[16];
|
||
extern const uint8_t len_to_can_dlc[65];
|
||
|
||
- **Initialization sequence is as follows**.
|
||
|
||
#. up_netinitialize(void) is called on startup of NuttX in this
|
||
function you call your own init function to initialize your
|
||
CAN driver
|
||
#. In your own init function you create the net_driver_s
|
||
structure set required init values and register the required
|
||
callbacks for SocketCAN
|
||
#. Then you ensure that the CAN interface is in down mode
|
||
(usually done by calling the d_ifdown function)
|
||
#. Register the net_driver_s using netdev_register
|
||
|
||
- **Receive sequence is as follows**.
|
||
|
||
#. Device generates interrupt
|
||
#. Process this interrupt in your interrupt handler
|
||
#. When a new CAN frame has been received you process this
|
||
frame
|
||
#. When the CAN frame is a normal CAN frame you allocate the
|
||
can_frame struct, when it's a CAN FD frame you allocate a
|
||
canfd_frame struct (note you can of course preallocate and
|
||
just use the pointer).
|
||
#. Copy the frame from the driver to the struct you've
|
||
allocated in the previous step.
|
||
#. Point the net_driver_s d_buf pointer to the allocated
|
||
can_frame
|
||
#. Call the ``can_input(FAR struct net_driver_s *dev)``
|
||
function ``include/nuttx/net/can.h``
|
||
|
||
- **Transmit sequence is as follows**.
|
||
|
||
#. Socket layer executes d_txavail callback
|
||
#. An example of the txavail function can be found in
|
||
``arch/arm/src/s32k1xx/s32k1xx_flexcan.c``
|
||
#. An example of the txpoll function can be found in
|
||
``arch/arm/src/s32k1xx/s32k1xx_flexcan.c``
|
||
#. In your ``transmit(struct driver_s *priv)`` function you
|
||
check the length of ``net_driver_s.d_len`` whether it
|
||
matches the size of a ``struct can_frame`` or
|
||
``struct canfd_frame`` then you cast the content of the
|
||
``net_driver_s.d_buf`` pointer to the correct CAN frame
|
||
struct
|
||
|