Texas Instruments TMS320DM36X manual Receive Buffer Descriptor Format

Page 26

Architecture

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2.6.5Receive Buffer Descriptor Format

A receive (RX) buffer descriptor (Figure 7) is a contiguous block of four 32-bit data words aligned on a 32-bit boundary that describes a packet or a packet fragment. Example 2 shows the receive buffer descriptor described by a C structure.

2.6.5.1Next Descriptor Pointer

This pointer points to the 32–bit word aligned memory address of the next buffer descriptor in the receive queue. This pointer is used to create a linked list of buffer descriptors. If the value of this pointer is zero, then the current buffer is the last buffer in the queue. The software application must set this value prior to adding the descriptor to the active receive list. This pointer is not altered by the EMAC.

The value of pNext should never be altered once the descriptor is in an active receive queue, unless its current value is NULL. If the pNext pointer is initially NULL, and more empty buffers can be added to the pool, the software application may alter this pointer to point to a newly appended descriptor. The EMAC will use the new pointer value and proceed to the next descriptor unless the pNext value has already been read. In this latter case, the receiver will halt the receive channel in question, and the software application may restart it at that time. The software can detect this case by checking for an end of queue (EOQ) condition flag on the updated packet descriptor when it is returned by the EMAC.

2.6.5.2Buffer Pointer

The buffer pointer is the byte-aligned memory address of the memory buffer associated with the buffer descriptor. The software application must set this value prior to adding the descriptor to the active receive list. This pointer is not altered by the EMAC.

		Figure 7. Receive Buffer Descriptor Format
Word 0
31								0

			Next Descriptor Pointer

Word 1
31								0

			Buffer Pointer
Word 2
31			16		15			0

	Buffer Offset					Buffer Length
Word 3
31	30	29	28		27	26	25	24

SOP	EOP	OWNER	EOQ		TDOWNCMPLT	PASSCRC	JABBER	OVERSIZE
23	22	21	20		19	18	17	16

FRAGMENT	UNDERSIZED	CONTROL	OVERRUN		CODEERROR	ALIGNERROR	CRCERROR	NOMATCH
15								0

			Packet Length

26 Ethernet Media Access Controller (EMAC)/Management Data Input/Output SPRUFI5B –March 2009 –Revised December 2010

(MDIO)	Submit Documentation Feedback

© 2009–2010, Texas Instruments Incorporated

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Contents Users Guide Submit Documentation Feedback Mdio Registers Mdio Version Register Version Mdio Control Register Control Appendix a Appendix BList of Figures Transmit Interrupt Mask Set Register Txintmaskset List of Tables MAC Control Register Maccontrol Field Descriptions Read This First Related Documentation From Texas Instruments Related Documentation From Texas Instruments Features Purpose of the PeripheralFunctional Block Diagram Emac and Mdio Block DiagramMII Clocking Industry Standards Compliance StatementClock Control Media Independent Interface MII Connections Signal DescriptionsMemory Map Pin Multiplexing Emac and Mdio Signals for MII InterfaceSignal Type Description Ethernet Frame Description Ethernet Protocol OverviewEthernet Frame Format Field Bytes DescriptionPacket Buffer Descriptors Ethernet’s Multiple Access ProtocolProgramming Interface WordBasic Descriptor Description Field Field DescriptionTransmit and Receive Descriptor Queues Transmit and Receive Emac Interrupts Transmit Buffer Descriptor Format Example 1. Transmit Buffer Descriptor in C Structure FormatBuffer Offset Next Descriptor PointerBuffer Pointer Buffer LengthEnd of Queue EOQ Flag End of Packet EOP FlagOwnership Owner Flag Teardown Complete Tdowncmplt FlagReceive Buffer Descriptor Format Receive Buffer Descriptor FormatExample 2. Receive Buffer Descriptor in C Structure Format Buffer Length CRC Error Crcerror Flag Code Error Codeerror FlagAlignment Error Alignerror Flag Jabber FlagBus Arbiter Emac Control ModuleInternal Memory CPUReceive Pulse Interrupt Interrupt ControlTransmit Pulse Interrupt Interrupt Pacing Receive Threshold Pulse InterruptMiscellaneous Pulse Interrupt Mdio Clock Generator Mdio ModuleMdio Module Components Global PHY Detection and Link State MonitoringMdio Module Operational Overview PHY Register User AccessActive PHY Monitoring Reading Data From a PHY Register Initializing the Mdio ModuleWriting Data To a PHY Register Example of Mdio Register Access Code Example 3. Mdio Register Access MacrosReceive DMA Engine Emac ModuleEmac Module Components Receive FifoReceive Address Clock and Reset LogicMAC Receiver Transmit DMA EngineEmac Module Operational Overview Receive Control Media Independent Interface MIIData Reception Receive Inter-Frame IntervalCollision-Based Receive Buffer Flow Control Ieee 802.3x-Based Receive Buffer Flow ControlAdaptive Performance Optimization APO Transmit ControlCRC Insertion Interpacket-Gap IPG EnforcementTransmit Flow Control Speed, Duplex, and Pause Frame SupportReceive Channel Enabling Receive DMA Host ConfigurationPacket Receive Operation Receive Address Matching Hardware Receive QOS SupportReceive Frame Classification Host Free Buffer TrackingReceive Channel Teardown Receive Frame Treatment Promiscuous Receive ModeReceive Frame Treatment Summary Middle of Frame Overrun Treatment Receive OverrunMiddle of Frame Overrun Treatment Receive and Transmit Latency Transmit DMA Host ConfigurationPacket Transmit Operation Transmit Channel TeardownTransfer Node Priority Reset ConsiderationsSoftware Reset Considerations Enabling the EMAC/MDIO Peripheral Hardware Reset ConsiderationsInitialization Emac Control Module InitializationExample 4. Emac Control Module Initialization Code Mdio Module Initialization Example 5. Mdio Module Initialization CodeEmac Module Initialization Receive Threshold Interrupts Interrupt SupportEmac Module Interrupt Events and Requests Transmit Packet Completion InterruptsReceive Packet Completion Interrupts Host Error Interrupt Statistics InterruptLink Change Interrupt User Access Completion InterruptMdio Module Interrupt Events and Requests Proper Interrupt ProcessingEmulation Control Power ManagementEmulation Considerations Soft Free DescriptionAcronym Register Description Emac Control Module RegistersSlave Vbus Bit Field Value DescriptionEmac Control Module Emulation Control Register Cmemcontrol Emac Control Module Software Reset Register CmsoftresetSoftreset Soft FreeIntprescale Emac Control Module Interrupt Control Register CmintctrlIntpaceen Rxthreshen RxpulseenTxpulseen Statpendinten Statpendinten Hostpendinten Linkinten UserintenBit Field Rxthreshinttstat RxpulseinttstatTxpulseinttstat 31-8 Reserved TXPULSEINTTSTATnStatpendintstat Hostpendintstat Linkintstat Userintstat StatpendintstatRximax TximaxMdio Version Register Version Field Descriptions Mdio Version Register VersionManagement Data Input/Output Mdio Registers Mdio Control Register Control Mdio Control Register Control Field DescriptionsPHY Acknowledge Status Register Alive Field Descriptions PHY Acknowledge Status Register AlivePHY Link Status Register Link PHY Link Status Register Link Field Descriptions31-2 Reserved Will clear the event and writing a 0 has no effect No Mdio user command complete event USERINTMASKED0 and USERINTMASKED1 correspond to USERACCESS0 W1S-0 Mdio User Command Complete Interrupt Mask Clear Register Mdio User Command Complete Interrupt Mask Clear RegisterMdio User Access Register 0 USERACCESS0 Mdio User Access Register 0 USERACCESS0 Field DescriptionsPhyadrmon Mdio User PHY Select Register 0 USERPHYSEL0Linksel Linkintenb LinkselMdio User Access Register 1 USERACCESS1 Mdio User Access Register 1 USERACCESS1 Field DescriptionsMdio User PHY Select Register 1 USERPHYSEL1 Mdio User PHY Select Register 1 USERPHYSEL1Ethernet Media Access Controller Emac Registers Offset Acronym Register Description Network Statistics Registers Transmit Control Register Txcontrol Field Descriptions Transmit Identification and Version Register TxidverTransmit Control Register Txcontrol Txtdnch Transmit Teardown Register TxteardownTransmit Teardown Register Txteardown Field Descriptions Rxmajorver Rxminorver Receive Identification and Version Register RxidverRxident RxmajorverReceive Control Register Rxcontrol Field Descriptions Receive Control Register RxcontrolReceive Teardown Register Rxteardown Receive Teardown Register Rxteardown Field DescriptionsTransmit Interrupt Status Unmasked Register Txintstatraw TX7PENDTransmit Interrupt Status Masked Register Txintstatmasked Transmit Interrupt Status Masked Register TxintstatmaskedTransmit Interrupt Mask Set Register Txintmaskset TX7MASKTransmit Interrupt Mask Clear Register Txintmaskclear Transmit Interrupt Mask Clear Register TxintmaskclearMAC Input Vector Register Macinvector Field Descriptions MAC Input Vector Register MacinvectorMAC End Of Interrupt Vector Register Maceoivector StatpendReceive Interrupt Status Unmasked Register Rxintstatraw RX7PENDReceive Interrupt Status Masked Register Rxintstatmasked Receive Interrupt Status Masked Register RxintstatmaskedReceive Interrupt Mask Set Register Rxintmaskset RX7MASKReceive Interrupt Mask Clear Register Rxintmaskclear Receive Interrupt Mask Clear Register RxintmaskclearHostpend Statpend MAC Interrupt Status Unmasked Register MacintstatrawMAC Interrupt Status Masked Register Macintstatmasked Hostmask Statmask MAC Interrupt Mask Set Register MacintmasksetMAC Interrupt Mask Clear Register Macintmaskclear HostmaskRxcsfen Rxcefen Rxcafen Rxpasscrc Rxqosen RxnochainRxcmfen RxpromchFrames containing errors are filtered Receive multicast channel select Receive Unicast Enable Set Register Rxunicastset RXCH7ENReceive Unicast Clear Register Rxunicastclear Receive Unicast Clear Register RxunicastclearReceive Maximum Length Register Rxmaxlen Field Descriptions Receive Maximum Length Register RxmaxlenReceive Buffer Offset Register Rxbufferoffset Rxfilterthresh Receive Channel 0-7 Free Buffer Count Register RXnFREEBUFFER MAC Control Register Maccontrol MAC Control Register Maccontrol Field DescriptionsLoopback TxflowenRxbufferflowen FullduplexMAC Status Register Macstatus MAC Status Register Macstatus Field DescriptionsRxqosact Emulation Control Register Emcontrol Field Descriptions Emulation Control Register EmcontrolFifo Control Register Fifocontrol Fifo Control Register Fifocontrol Field DescriptionsMAC Configuration Register Macconfig Field Descriptions MAC Configuration Register MacconfigSoft Reset Register Softreset Soft Reset Register Softreset Field DescriptionsMAC Source Address Low Bytes Register Macsrcaddrlo MAC Source Address High Bytes Register MacsrcaddrhiMAC Hash Address Register 1 MACHASH1 Field Descriptions MAC Hash Address Register 1 MACHASH1MAC Hash Address Register 2 MACHASH2 MAC Hash Address Register 2 MACHASH2 Field DescriptionsBack Off Test Register Bofftest Field Descriptions Back Off Test Register BofftestTransmit Pacing Algorithm Test Register Tpacetest Receive Pause Timer Register Rxpause Field Descriptions Receive Pause Timer Register RxpauseTransmit Pause Timer Register Txpause Transmit Pause Timer Register Txpause Field DescriptionsValid Matchfilt Channel MACADDR0 MACADDR1 MAC Address Low Bytes Register MacaddrloMAC Address Low Bytes Register Macaddrlo Field Descriptions ValidMAC Index Register Macindex Field Descriptions MAC Address High Bytes Register MacaddrhiMAC Index Register Macindex MACADDR2 MACADDR3 MACADDR4 MACADDR5TXnHDP Transmit Channel 0-7 Completion Pointer Register TXnCP Receive Channel 0-7 Completion Pointer Register RXnCPBroadcast Receive Frames Register Rxbcastframes Network Statistics RegistersGood Receive Frames Register Rxgoodframes Multicast Receive Frames Register RxmcastframesPause Receive Frames Register Rxpauseframes Receive CRC Errors Register RxcrcerrorsReceive Alignment/Code Errors Register Rxaligncodeerrors Receive Oversized Frames Register RxoversizedReceive Frame Fragments Register Rxfragments Receive Jabber Frames Register RxjabberReceive Undersized Frames Register Rxundersized Filtered Receive Frames Register RxfilteredGood Transmit Frames Register Txgoodframes Receive QOS Filtered Frames Register RxqosfilteredReceive Octet Frames Register Rxoctets Broadcast Transmit Frames Register TxbcastframesTransmit Collision Frames Register Txcollision Pause Transmit Frames Register TxpauseframesDeferred Transmit Frames Register Txdeferred Transmit Single Collision Frames Register TxsinglecollTransmit Late Collision Frames Register Txlatecoll Transmit Underrun Error Register TxunderrunTransmit Carrier Sense Errors Register Txcarriersense Transmit Octet Frames Register TxoctetsSubmit Documentation Feedback Network Octet Frames Register Netoctets Receive DMA Overruns Register RxdmaoverrunsAppendix a Glossary Physical Layer Definitions Term DefinitionDocument Revision History Reference Additions/Modifications/DeletionsRfid Products ApplicationsDSP

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