| canfd Vitis Drivers API Documentation

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canfd Documentation

The Xilinx CANFD driver. This driver supports the Xilinx CANFD Controller.

The CANFD Controller supports the following features:

- Confirms to the ISO 11898-1, CAN 2.0A and CAN 2.0B standards.
- Supports both Standard (11 bit Identifier) and Extended (29 bit Identifier) frames.
- Supports Bit Rates up to 8 Mbps.
- Transmit message object FIFO with a user configurable depth of up to 64 message objects.
- Receive message object FIFO with a user configurable depth of up to 64 message objects.
- Acceptance filtering through a user configurable number of up to 32 acceptance filters.
- Loop Back mode for diagnostic applications.
- Maskable Error and Status Interrupts.
- Readable Error Counters.
- External PHY chip required.
- Backward compatible for Legacy CAN.
- Supports reception in Mailbox and Sequential Mode

The device driver supports all the features listed above, if applicable.

Driver Description

The device driver enables higher layer software (e.g., an application) to communicate to the CANFD. The driver handles transmission and reception of CAN frames, as well as configuration of the controller. The driver is simply a pass-through mechanism between a protocol stack and the CANFD. A single device driver can support multiple CANFDs.

Since the driver is a simple pass-through mechanism between a protocol stack and the CANFD, no assembly or disassembly of CANFD frames is done at the driver-level. This assumes that the protocol stack passes a correctly formatted CANFD frame to the driver for transmission, and that the driver does not validate the contents of an incoming frame

Operation Modes

The CANFD controller supports the following modes of operation:

- Configuration Mode: In this mode the CAN timing parameters and Baud Rate Pre-scalar parameters can be changed. In this mode the CAN controller loses synchronization with the CAN bus and drives a constant recessive bit on the bus line. The Error Counter Register are reset. The CAN controller does not receive or transmit any messages even if there are pending transmit requests from the TX FIFO or the TX High Priority Buffer. the Storage FIFOs and the CAN configuration registers are still accessible.
- Normal Mode:In Normal Mode the CAN controller participates in bus communication, by transmitting and receiving messages.
- Sleep Mode: In Sleep Mode the CAN Controller does not transmit any messages. However, if any other node transmits a message, then the CAN Controller receives the transmitted message and exits from Sleep Mode. If there are new transmission requests from either the TX FIFO or the TX High Priority Buffer when the CAN Controller is in Sleep Mode, these requests are not serviced, and the CAN Controller continues to remain in Sleep Mode. Interrupts are generated when the CAN controller enters Sleep mode or Wakes up from Sleep mode.
- Loop Back Mode: In Loop Back mode, the CAN controller transmits a recessive bit stream on to the CAN Bus. Any message that is transmitted is loop backed to the rx line and acknowledged. The CAN controller thus receives any message that it transmits. It does not participate in normal bus communication and does not receive any messages that are transmitted by other CAN nodes. This mode is used for diagnostic purposes.
- Snoop mode:in Snoop Mode,The CAN controller transmits recessive bit stream on to CAN bus and does not participate in normal bus communication but receives messages that are transmitted by other CAN nodes.Received messages are stored based on receive ID match result. Error counters are disabled and cleared to 0. Reads to error counter register will return zero.

Buffer Alignment

It is important to note that frame buffers passed to the driver must be 32-bit aligned.

Receive Address Filtering

The device can be set to accept frames whose Identifiers match any of up to 32 filters set in the Acceptance Filter Mask/ID registers.

The incoming Identifier is masked with the bits in the Acceptance Filter Mask Register. This value is compared with the result of masking the bits in the Acceptance Filter ID Register with the Acceptance Filter Mask Register. If both these values are equal, the message will be stored in the RX FIFO.

Acceptance Filtering is performed by each of the defined acceptance filters. If the incoming identifier passes through any acceptance filter then the frame is stored in the RX FIFO.

PHY Communication

This driver does not provide any mechanism for directly programming PHY.

Interrupts

The driver has no dependencies on the interrupt controller. The driver provides an interrupt handler. User of this driver needs to provide callback functions. An interrupt handler example is available with the driver.

Virtual Memory

This driver supports Virtual Memory. The RTOS is responsible for calculating the correct device base address in Virtual Memory space and invoking function XCanFd_VmInitialize(), instead of XCanFd_Initialize(), to initialize the device at first.

Threads

This driver is not thread safe. Any needs for threads or thread mutual exclusion must be satisfied by the layer above this driver.

Device Reset

Bus Off interrupt that can occur in the device requires a device reset. The user is responsible for resetting the device and re-configuring it based on its needs (the driver does not save the current configuration). When integrating into an RTOS, these reset and re-configure obligations are taken care of by the OS adapter software if it exists for that RTOS.

Device Configuration

The device can be configured in various ways during the FPGA implementation process. Configuration parameters are stored in the xcan_g.c files. A table is defined where each entry contains configuration information for a CAN device. This information includes such things as the base address of the memory-mapped device, and the number of acceptance filters.

Asserts

Asserts are used within all Xilinx drivers to enforce constraints on argument values. Asserts can be turned off on a system-wide basis by defining, at compile time, the NDEBUG identifier. By default, asserts are turned on and it is recommended that users leave asserts on during development.

Building the driver

The XCanFd driver is composed of several source files.This allows the user to build and link only those parts of the driver that are necessary.

      Temp Change
      MODIFICATION HISTORY:

      Ver   Who  Date     Changes

      1.0   nsk  06/04/15 First release
      1.0   nsk  15/05/15 Updated xcanfd.c for correct AFRID and AFRMSK Registers
                          Updated xcanfd.c and xcanfd.h to get configurable
                          TxBuffers in XCanFd_Config Struct and
                          XCanFd_GetFreeBuffer().
                          Modified XCANFD_BTR_TS1_MASK in xcanfd_hw.h.
                          Updated xcanfd.c while sending data when EDL is Zero.
                          Updated driver tcl file to get configurable TxBuffers.
                          (CR 861772).
      1.0   nsk  16/06/15 Updated XCanFd_Recv_Mailbox(), XCanFd_EnterMode()
                          XCanFd_GetMode() in xcanfd.c and Added new definition
                          for Register bits in xcanfd_hw.h and updated
                          XCanFd_IntrHandler() in xcanfd_intr.c as per new RTL.
                          Changes in RTL, Added new bits to MSR,SR,ISR,IER,ICR
                          Registers and modified TS2 bits in BTR and F_SJW bits
                          in F_BTR Registers.
      1.1   sk   11/10/15 Used UINTPTR instead of u32 for Baseaddress CR# 867425.
                          Changed the prototype of XCanFd_CfgInitialize API.
      1.2   mi   09/22/16 Fixed compilation warnings.
            ms   01/23/17 Modified xil_printf statement in main function for all
                          examples to ensure that "Successfully ran" and "Failed"
                          strings are available in all examples. This is a fix
                          for CR-965028.
            ms   03/17/17 Added readme.txt file in examples folder for doxygen
                          generation.
            ms   04/05/17 Added tabspace for return statements in functions
                          of canfd examples for proper documentation while
                          generating doxygen.
      2.0   mj   1/3/18   updated supported_peripherals and version number CR# 991037.
                          CANFD Driver not pulled by drivers.
      2.1   ask  09/12/18 Added support for canfd 2.0 spec sequential mode.
                                             API's added : XCanFd_Recv_Sequential
                                                                           XCanFd_SeqRecv_logic
                                                                           XCanFd_Recv_TXEvents_Sequential
                                                                           XCanFd_GetNofMessages_Stored_TXE_FIFO
                                                                           XCanFd_GetNofMessages_Stored_Rx_Fifo
                                                                           above apis added in xcanfd.c .

                                                                           XCanFd_SetRxIntrWatermarkFifo1
                                                                           XCanFd_SetTxEventIntrWatermark
                                                                           XCanFd_SetRxFilterPartition
                                        above apis added in xcanfd_config.c

                                   XCANFD_TXEID_OFFSET
                                   XCANFD_TXEDLC_OFFSET
                                   XCANFD_FIFO_1_RXID_OFFSET
                                   XCANFD_FIFO_1_RXDLC_OFFSET
                                   XCANFD_FIFO_1_RXDW_OFFSET
                                   above apis added in xcanfd.h

                            Fixed Message Queuing logic by modifying in functions
                                                    XCanFd_Send_Queue, XCanFd_Addto_Queue, XCanFd_Send,
                                                    and XCanFd_GetFreeBuffer.
                             Added an static function
                                                    XCanfd_TrrVal_Get_SetBit_Position, added in xcanfd.c
                                                    XCanFD_Check_TrrVal_Set_Bit, added in xcanfd.h
                             Modified apis
                                                    XCanFd_SetBitTiming
                                                    XCanFd_SetFBitTiming in xcanfd.h
            ask  07/03/18 Fix for Sequential recv CR# 992606,CR# 1004222.
            nsk  07/11/18 Updated tcl to generate CANFD Frequency macro in
                          xparameters.h (CR 1005641).
            ask  08/27/18 Modified RecvSeq function to return XST_NO_DATA when the
                          fifo fill levels are zero.
            ask  08/08/18 Fixed Gcc, Cppcheck and doxygen warnings in api's :
                                             XCanFd_PollQueue_Buffer, XCanFd_AcceptFilterSet,
                                             XCanFd_Recv_Sequential, XCanFd_SetBitTiming,
                                             XCanFd_SetBitRateSwitch_EnableNominal.
                                             Changed value of Canfd Id to 11 bit value to comply
                                             with standard Can ID.
            ask  09/21/18 Fixed CanFD hang issue in selftest by correcting the
                         Configuration regarding the Baud Rate and bit timing
                         for both Arbitration and Data Phase.
      2.1   nsk  01/22/19 Pass correct fifo number to XCanFd_SeqRecv_logic() in
                          xcanfd.c CR# 1018379
      2.1   nsk  01/22/19 Fixed XCanFd_SetFBaudPrescalar(), which is not setting
                          prescalar value properly in xcanfd_config.c CR# 1016013
      2.1   nsk  03/09/19 Updated XCanFd_GetDlc2len(), for CAN frames, to handle
                          number of data bytes greater than 8. CR# 1022045
      2.1   nsk  03/09/19 Fix for TrrMask to not to get written when using
                          XCanFd_Addto_Queue(). CR# 1022093
      2.1   nsk  03/09/19 Added support for PS CANFD, PL CANFD 1.0 and PL CANFD 2.0
                          CR# 1021963
      2.2   sn   06/11/19 Corrected below incorrect Mask values for CANFD2.0 in xcanfd_hw.h
                          XCANFD_MAILBOX_RB_MASK_BASE_OFFSET,XCANFD_WMR_RXFP_MASK
                          and CONTROL_STATUS_3.
      2.3   sne  21/11/19 Used correct macro to access RX FIFO1 buffer.
      2.3   sne  11/18/19 Fix for missing RX can packets on CANFD2.0.
      2.3   sne  11/29/19 Fix for missing TX canfd packet while sending multiple packets
                          by using multi buffer in loopback mode, CR# 1048366.
      2.3   sne  12/18/19 Added Protocol Exception Event and BusOff event support
                          CR#1048363 & CR#1046723.
      2.3   sne  03/06/20 Fixed sending extra frames in XCanFd_Send_Queue API.
      2.3   sne  03/09/20 Initialize IsPl of config structure.
      2.4   sne  08/28/20 Modify Makefile to support parallel make execution.
      2.5   sne  11/23/20 Fixed MISRAC violations.
      2.7   sne  04/26/22 Corrected Return value of XCanFd_GetFreeBuffer().
      2.8   ht   06/19/23 Added support for system device-tree flow.
      2.8   gm   06/22/23 Add XCanFd_stop to support release node.
      2.8   ht   07/18/23 Fixed GCC warnings.