axiethernet
Xilinx Vitis Drivers API Documentation
axiethernet Documentation

The Xilinx AXI Ethernet MAC driver component. This driver supports hard Ethernet core for Virtex-6(TM) devices and soft Ethernet core for Spartan-6(TM) and other supported devices. The supported speed can be 10/100/1000 Mbps and can reach up to 2000/2500 Mbps (1000Base-X versions).

For a full description of AXI Ethernet features, please see the hardware spec. This driver supports the following features:

  • Memory mapped access to host interface registers
  • Virtual memory support
  • Unicast, broadcast, and multicast receive address filtering
  • Full duplex operation
  • Automatic source address insertion or overwrite (programmable)
  • Automatic PAD & FCS insertion and stripping (programmable)
  • Flow control
  • VLAN frame support
  • Pause frame support
  • Jumbo frame support
  • Partial and full checksum offload
  • Extended multicast addresses to 2**23.
  • Extended VLAN translation, tagging and stripping supports.

Driver Description

The device driver enables higher layer software (e.g., an application) to configure a Axi Ethernet device. It is intended that this driver be used in cooperation with another driver (FIFO or DMA) for data communication. This device driver can support multiple devices even when those devices have significantly different configurations.

Initialization & Configuration

The XAxiEthernet_Config structure can be used by the driver to configure itself. This configuration structure is typically created by the tool-chain based on hardware build properties, although, other methods are allowed and currently used in some systems.

To support multiple runtime loading and initialization strategies employed by various operating systems, the driver instance can be initialized using the XAxiEthernet_CfgInitialze() routine.

Interrupts and Asynchronous Callbacks

The driver has no dependencies on the interrupt controller. It provides no interrupt handlers. The application/OS software should set up its own interrupt handlers if required.

Device Reset

When a Axi Ethernet device is connected up to a FIFO or DMA core in hardware, errors may be reported on one of those cores (FIFO or DMA) such that it can be determined that the Axi Ethernet device needs to be reset. If a reset is performed, the calling code should also reconfigure and reapply the proper settings in the Axi Ethernet device.

When a Axi Ethernet device reset is required, XAxiEthernet_Reset() should be utilized.

Virtual Memory

This driver may be used in systems with virtual memory support by passing the appropriate value for the EffectiveAddress parameter to the XAxiEthernet_CfgInitialize() routine.

Transferring Data

The Axi Ethernet core by itself is not capable of transmitting or receiving data in any meaningful way. Instead the Axi Ethernet device need to be connected to a FIFO or DMA core in hardware.

This Axi Ethernet driver is modeled in a similar fashion where the application code or O/S adapter driver needs to make use of a separate FIFO or DMA driver in connection with this driver to establish meaningful communication over Ethernet.

Checksum Offloading

If configured, the device can compute a 16-bit checksum from frame data. In most circumstances this can lead to a substantial gain in throughput.

The checksum offload settings for each frame sent or received are transmitted through the AXI4-Stream interface in hardware. What this means is that the checksum offload feature is indirectly controlled in the Axi Ethernet device through the driver for DMA core connected to the Axi Ethernet device.

Refer to the documentation for DMA driver used for data communication on how to set the values for the relevant AXI4-Stream control words.

Since this hardware implementation is general purpose in nature system software must perform pre and post frame processing to obtain the desired results for the types of packets being transferred. Most of the time this will be TCP/IP traffic.

TCP/IP and UDP/IP frames contain separate checksums for the IP header and UDP/TCP header+data. For partial checksum offloading (enabled while configuring the hardware), the IP header checksum cannot be offloaded. Many stacks that support offloading will compute the IP header if required and use hardware to compute the UDP/TCP header+data checksum. There are other complications concerning the IP pseudo header that must be taken into consideration. Readers should consult a TCP/IP design reference for more details.

For full checksum offloading (enabled while configuring the hardware), the IPv4 checksum calculation and validation can also be offloaded at the harwdare. Full checksum offload is supported only under certain conditions. IP checksum offload will be supported on valid IP datagrams that meet the following conditions.

  • If present, the VLAN header is 4 bytes long
  • Encapsulation into the Ethernet frame is either Ethernet II or Ethernet SNAP format
  • Only IPv4 is supported. IPv6 is not supported.
  • IP header is a valid length TCP/UDP checksum offloading will be supported on valid TCP/UDP segments that meet the following conditions.
  • Encapsulated in IPv4 (IPv6 is not supported)
  • Good IP header checksum
  • No fragmentation
  • TCP or UDP segment When full checksum offload is enabled, the hardware does the following:
  • Calculates the IP header checksum and inserts it in the IP header.
  • Calculates the TCP/UDP Pseudo header from IP header.
  • Calculates TCP/UDP header from, TCP/UDP psedu header, TCP/UDP header and TCP/UDP payload.
  • On the receive path, it again calculates all the above and validates for IP header checksum and TCP/UDP checksum.

There are certain device options that will affect the checksum calculation performed by hardware for Tx:

  • FCS insertion disabled (XAE_FCS_INSERT_OPTION): software is required to calculate and insert the FCS value at the end of the frame, but the checksum must be known ahead of time prior to calculating the FCS. Therefore checksum offloading cannot be used in this situation.

And for Rx:

  • FCS/PAD stripping disabled (XAE_FCS_STRIP_OPTION): The 4 byte FCS at the end of frame will be included in the hardware calculated checksum. software must subtract out this data.
  • FCS/PAD stripping disabled (XAE_FCS_STRIP_OPTION): For frames smaller than 64 bytes, padding will be included in the hardware calculated checksum. software must subtract out this data. It may be better to allow the TCP/IP stack verify checksums for this type of packet.
  • VLAN enabled (XAE_VLAN_OPTION): The 4 extra bytes in the Ethernet header affect the hardware calculated checksum. software must subtract out the 1st two 16-bit words starting at the 15th byte.

Transmit Checksum Offloading

For partial checksum offloading, for the TX path, the software can specify where in the frame the checksum calculation is to start, where the result should be inserted, and a seed value. The checksum is calculated from the start point through the end of frame.

For full checksum offloading, for the TX path, the software just need to enable Full Checksum offload in the appropriate AXI4-Stream Control word on a per packet basis.

The checksum offloading settings are sent in the transmit AXI4 Stream control words. The relevant control word fields are described in brief below. Refer to the Axi Ethernet hardware specification for more details.

AXI4-Stream Control Word 0:

        Bits  1-0  : Transmit Checksum Enable:  01 - Partial checsum offload,
                                                10 - Full checksum offload
                                                00 - No checksum offloading
                                                11 - Not used, reserved
        Bits 27-2  : Reserved
        Bits 31-28 : Used for AXI4-Stream Control Mode flag
*

AXI4-Stream Control Word 1:

        Bits 31-16 (MSB): Transmit Checksum Calculation Starting Point: Offset
                          in the frame where checksum calculation should begin.
                          Relevant only for partial checksum offloading.
        Bits 15-0  (LSB): Transmit Checksum Insertion Point: Frame offset where
                          the computed checksum value is stored, which should be
                          in the TCP or UDP header.
                          Relevant only for partial checksum offloading.
    

AXI4-Stream Control Word 2:

        Bits 31-16 (MSB): Reserved
        Bits  0-15 (LSB): Transmit Checksum Calculation Initial Value: Checksum
                          seed value.
                          Relevant only for partial checksum offloading.
*

Receive Checksum Offloading

For partial checksum offload on the RX path, the 15th byte to end of frame is check summed. This range of bytes is the entire Ethernet payload (for non-VLAN frames).

For full checksum offload on the RX path, both the IP and TCP checksums are validated if the packet meets the specified conditions.

The checksum offloading information is sent in the receive AXI4-Stream status words. There are 4 relevant status words available. However only the relevant status words are described in brief below. Refer to the Axi Ethernet hardware specification for more details.

AXI4-Stream Status Word 0:

        Bits 31-28 (MSB): Always 0x5 to represent receive status frame
        Bits 27-16      : Undefined
        Bits 15-0  (LSB): MCAST_ADR_U. Upper 16 bits of the multicast
                          destination address of the frame.
*

AXI4-Stream Status Word 1:

*

Bits 31-0 : MCAST_ADR_L. The lower 32 bits of the multicast destination address.

AXI4-Stream Status Word 2:

Bits 5-3 : Specifies the receive full checksum status. This is relevant only for full checksum offloading. 000 -> Neither the IP header nor the TCP/UDP checksums were checked. 001 -> The IP header checksum was checked and was correct. The TCP/UDP checksum was not checked. 010 -> Both the IP header checksum and the TCP checksum were checked and were correct. 011 -> Both the IP header checksum and the UDP checksum were checked and were correct. 100 -> Reserved. 101 -> The IP header checksum was checked and was incorrect. The TCP/UDP checksum was not checked. 110 -> The IP header checksum was checked and is correct but the TCP checksum was checked and was incorrect. 111 -> The IP header checksum was checked and is correct but the UDP checksum was checked and was incorrect.

AXI4-Stream Status Word 3:

Bits 31-16 : T_L_TPID. This is the value of 13th and 14th byte of the frame. Bits 15-0 : Receive Raw Checksum: Computed checksum value

AXI4-Stream Status Word 3:

Bits 31-16 : VLAN_TAG. Value of 15th and 16th byte of the frame. Bits 15-0 : RX_BYTECNT. Received frame length.

Extended multicast

(XAE_EXT_MULTICAST_OPTION): Allow and perform address filtering more than 4 multicast addresses. Hardware requires to enable promiscuous mode (XAE_PROMISCUOUS_OPTION) and disable legacy multicast mode (XAE_MULTICAST_OPTION) for this feature to work.

Extended VLAN

TX/RX VLAN stripping

(XAE_EXT_[T|R]XVLAN_STRP_OPTION) handles transmit/receive one VLAN tag stripping in Ethernet frames. To enable this option, hardware requires to build with this feature and enable (XAE_FCS_INSERT_OPTION), (XAE_FCS_STRP_OPTION) and disable (XAE_VLAN_OPTION). Supports three modes, -XAE_VSTRP_NONE : no stripping -XAE_VSTRP_ALL : strip one tag from all frames -XAE_VSTRP_SELECT : strip one tag from selected frames

TX/RX VLAN translation

(XATE_EXT_[T|R]XVLAN_TRAN_OPTION) handles transmit/receive one VLAN tag translation in Ethernet frames. To enable this option, hardware requires to build with this feature and enable (XATE_FCS_INSERT_OPTION), (XAE_FCS_STRP_OPTION), and disable (XAE_VLAN_OPTION).

TX/RX VLAN tagging

(XAE_EXT_[T|R]XVLAN_TAG_OPTION) adds transmit/receive one VLAN tag in Ethernet frames. To enable this option, hardware requires to build with this feature and enable (XAE_FCS_INSERT_OPTION), (XAE_FCS_STRP_OPTION), (XAE_JUMBO_OPTION) and disable (XAE_VLAN_OPTION). Support four modes, -XAE_VTAG_NONE : no tagging -XAE_VTAG_ALL : tag all frames -XAE_VTAG_EXISTED : tag already tagged frames -XAE_VTAG_SELECT : tag selected already tagged frames

PHY Communication

Prior to PHY access, the MDIO clock must be setup. This driver will set a safe default that should work with AXI4-Lite bus speeds of up to 150 MHz and keep the MDIO clock below 2.5 MHz. If the user wishes faster access to the PHY then the clock divisor can be set to a different value (see XAxiEthernet_PhySetMdioDivisor()).

MII register access is performed through the functions XAxiEthernet_PhyRead() and XAxiEthernet_PhyWrite().

Link Sync

When the device is used in a multi speed environment, the link speed must be explicitly set using XAxiEthernet_SetOperatingSpeed() and must match the speed PHY has negotiated. If the speeds are mismatched, then the MAC will not pass traffic.

The application/OS software may use the AutoNegotiation interrupt to be notified when the PHY has completed auto-negotiation.

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. For deployment use -DNDEBUG compiler switch to remove assert code.

Driver Errata

  • A dropped receive frame indication may be reported by the driver after calling XAxiEthernet_Stop() followed by XAxiEthernet_Start(). This can occur if a frame is arriving when stop is called.
  • On Rx with checksum offloading enabled and FCS/PAD stripping disabled, FCS and PAD data will be included in the checksum result.
  • On Tx with checksum offloading enabled and auto FCS insertion disabled, the user calculated FCS will be included in the checksum result.
Note

Xilinx drivers are typically composed of two components, one is the driver and the other is the adapter. The driver is independent of OS and processor and is intended to be highly portable. The adapter is OS-specific and facilitates communication between the driver and an OS.

This driver is intended to be RTOS and processor independent. Any needs for dynamic memory management, threads or thread mutual exclusion, or cache control must be satisfied by the layer above this driver.

  MODIFICATION HISTORY:
  Ver   Who  Date     Changes


1.00a asa 6/30/10 First release based on the ll temac driver 1.01a asa 12/10/10 Added macros XAxiEthernet_IsRxFullCsum and XAxiEthernet_IsTxFullCsum for supporting full checksum offload. The full checksum offload is only supported in newer versions of the core, please refer to the core HW datasheet. 1.02a asa 2/16/11 Inserted a delay in the driver function XAxiEthernet_Reset in file xaxiethernet.c. This is done because immediately after a core reset none of the AxiEthernet registers are accessible for some duration. Changed the value of XAE_LOOPS_TO_COME_OUT_OF_RST to 10000 in file xaxiethernet_hw.h.

  2.00a asa  8/29/11  A new major version of AxiEthernet driver is being
                      released to accommodate the change in avb software. The
                      AxiEthernet hardware v3_00_a has the latest avb
                      hardware which needs a corresponding change in avb
                      software (released in examples/avb folder). This change
                      in avb software is not backwards compatible (which
                      means this avb software will not work with older
                      axiethernet hardware).
                      Hence a new major version of axiethernet is being
                      released.
                      Added defines for Ability Reg, Identification Reg, Rx max
                      Frame and Tx Max Frame registers.
                      Changed define for TEMAC RGMII/SGMII Config (PHYC) Reg.
  3.00a asa  4/10/12  A new major version of AxiEthernet is being released to
                      accommodate the change in AVB example. From AxiEthernet
                      core version 3.01a onwards the AVB implementation has
                      changed. The AVB module is now a part of AxiEthernet IP.
                      Because of this change, the AVB example works only
                      when promiscuous mode is not enabled (unlike earlier
                      implementation where promiscuous mode was required for
                      AVB example to work). Hence the file xavb_example.c is
                      changed so that the core is not put in promiscuous mode.
                      Also since AVB is a part of AxiEthernet some of the
                      register mappings in xavb_hw.h has changed.
                      These changes are not backward compatible which means
                      this changed example will not work for previous versions
                      of cores.
                      Hence a new major version of axiethernet is being
                      released.
  3.01a srt  02/03/13 - Added support for SGMII mode (CR 676793)

  • Added support for IPI designs (CR 698249) 02/14/13 - Added support for Zynq (CR 681136) 3.02a srt 04/13/13 - Removed Warnings (CR 704998). 04/24/13 - Modified parameter *_SGMII_PHYADDR to *_PHYADDR, the config parameter C_PHYADDR applies to SGMII/1000BaseX modes of operation 04/24/13 - Added support for 1000BaseX mode in examples (_util.c) (CR 704195) 04/24/13 - Added support for RGMII mode in examples (_util.c) 3.02a srt 08/06/13 - Fixed CR 727634: Modified FifoHandler() function logic of FIFO interrupt example to reflect the bit changes in the Interrupt Status Register as per the latest AXI FIFO stream IP.
  • Fixed CR 721141: Added support to handle multiple instances of AxiEthernet FIFO interface (CR 721141)
  • Fixed CR 717949: Configures external Marvel 88E1111 PHY based on the AXI Ethernet physical interface type and allows to operate in specific interface mode without changing jumpers on the Microblaze boards. This change is in example_util.c 3.02a adk 15/11/13 - Fixed CR 761035 removed dependency with fifo in MDD file 4.0 adk 19/12/13 - Updated as per the New Tcl API's asa 30/01/14 - Added defines for 1588 registers and bit masks Added config parameter for SGMII over LVDS
  4.1  adk 21/04/14 - Fixed CR:780537 Changes are Made in the file
                      axiethernet test-app tcl
  4.2  adk 08/08/14 - Fixed CR:810643 SDK generated 'xparamters.h' erroneously
                      generated with errors due to part of '#define' misplaced
                      changes are made in the driver tcl file.
  4.3 adk 29/10/14 -  Added support for generating parameters for SGMII/1000BaseX
                      modes When IP is configured with the PCS/PMA core.
                      Changes are made in the driver tcl file (CR 828796).
  4.4  adk  8/1/15 -  Fixed TCL errors when axiethernet is configured with the
                      Axi stream fifo (CR 835605). Changes are made in the
                      driver tcl file.
  5.0  adk 13/06/15 - Updated the driver tcl for Hier IP(To support User parameters).
  5.0  adk 28/07/15 - Fixed CR:870631 AXI Ethernet with FIFO will fail to
                      Create the BSP if the interrupt pin on the FIFO is unconnected
  5.1  sk  11/10/15 Used UINTPTR instead of u32 for Baseaddress CR# 867425.
                    Changed the prototype of XAxiEthernet_CfgInitialize API.
  5.1  adk 30/01/15  Fix compilation errors in case of zynqmp. CR#933825.
  5.1  adk 02/11/16  Updated example to Support ZynqMp.
  5.2  adk 13/05/16  Fixed CR#951669 Fix compilation errors when axi dma
                     interrupts are not connected.
  5.3  adk 05/10/16  Fixed CR#961152 PMU template firmware fails to compile on
                     ZynqMP AXI-Ethernet designs.
  5.4  adk 07/12/16  Added Support for TI PHY DP83867 changes are made in the
                     examples xaxiethernet_example_util.c file.
        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.
        adk 03/09/17 Fixed CR#971367 fix race condition in the tcl
                     for a multi mac design(AXI_CONNECTED_TYPE defined for
                     only one instance)
        ms 03/17/17 Modified text file in examples folder for doxygen
                    generation.
        ms 04/05/17 Added tabspace for return statements in functions
                    of axiethernet examples for proper documentation while
                    generating doxygen.
  5.5   adk 19/05/17 Increase Timeout value in the driver as per new h/w update
                     i.e. Increase of transceiver initialization times in
                     ultrascale+ devices (CR#976244).
  5.6  adk 03/07/17 Fixed issue lwip stops working as soon as something is
                    plugged to it`s AXI stream bus (CR#979634). Changes
                    are made in the driver tcl and test app tcl.
  5.6  adk 03/07/17 Fixed CR#979023 Intr fifo example failed to compile.
       ms  04/18/17 Modified tcl file to add suffix U for all macro
                    definitions of axiethernet in xparameters.h
       adk 08/08/17 Fixed CR#981893 Fix bsp compilation error for axiethernet
                    mcdma chiscope based designs.
       ms  08/16/17 Fixed compilation warnings in xaxiethernet_sinit.c
       adk 08/22/17 Fixed CR#983008 app generation errors for Specific IPI design.
       adk 08/28/17 Fixed CR#982877 couple of dsv_ced tests are failing in peripheral
                    app generation.
       adk 09/21/17 Fixed CR#985686 bsp generation error with specific design.
                    Changes are made in the driver tcl.
  5.7  rsp 01/09/18 Add NumTableEntries member in XAxiEthernet_Config.
                    Instead of #define XAE_MULTI_MAT_ENTRIES derive multicast table
                    entries max count from ethernet config structure.
           01/11/18 Fixed CR#976392 Use UINTPTR for DMA base address.