NAME

iflibtxrx — Device Dependent Transmit and Receive Functions

SYNOPSIS

#include <ifdi_if.h>

Interface Manipulation Functions

int
isc_txd_encap(void *sc, if_pkt_info_t pi);

void
isc_txd_flush(void *sc, uint16_t qid, uint32_t _pidx_or_credits_);

int
isc_txd_credits_update(void *sc, uint16_t qid, bool clear);

int
isc_rxd_available(void *sc, uint16_t qsid, uint32_t cidx);

void
isc_rxd_refill(void *sc, uint16_t qsid, uint8_t flid, uint32_t pidx, uint64_t *paddrs, caddr_t *vaddrs, uint16_t count);

void
isc_rxd_flush(void *sc, uint16_t qsid, uint8_t flid, uint32_t pidx);

int
isc_rxd_pkt_get(void *sc, if_rxd_info_t ri);

Global Variables

extern struct if_txrx

DATA STRUCTURES

The device dependent mechanisms for handling packet transmit and receive are primarily defined by the functions named above. The if_pkt_info data structure contains statistics and identifying info necessary for packet transmission. While the data structure for packet receipt is the if_rxd_info structure.

The if_pkt_info Structure

The fields of struct if_pkt_info are as follows:

ipi_len: (uint32_t) Denotes the size of packet to be sent on the transmit queue.
ipi_segs: (bus_dma_segment_t *) A pointer to the bus_dma_segment of the device independent transfer queue defined in iflib.
ipi_qsidx: Unique index value assigned sequentially to each transmit queue. Used to reference the currently transmitting queue.
ipi_nsegs: (uint16_t) Number of descriptors to be read into the device dependent transfer descriptors.
ipi_ndescs: (uint16_t) Number of descriptors in use. Calculated by subtracting the old pidx value from the new pidx value.
ipi_flags: (uint16_t) Flags defined on a per packet basis.
ipi_pidx: (uint32_t) Value of first pidx sent to the isc_encap function for encapsulation and subsequent transmission.
ipi_new_pidx: (uint32_t) Value set after the termination of the isc_encap function. This value will become the first pidx sent to the isc-encap the next time that the function is called.
The Following Fields Are Used For Offload Handling
ipi_csum_flags: (uint64_t) Flags describing the checksum values, used on a per packet basis.
ipi_tso_segsz: (uint16_t) Size of the TSO Segment Size.
ipi_mflags: (uint16_t) Flags describing the operational parameters of the mbuf.
ipi_vtag: (uint16_t) Contains the VLAN information in the Ethernet Frame.
ipi_etype: (uint16_t) Type of ethernet header protocol as contained by the struct ether_vlan_header.
ipi_ehrdlen: (uint8_t) Length of the Ethernet Header.
ipi_ip_hlen: (uint8_t) Length of the TCP Header
ipi_tcp_hlen: (uint8_t) Length of the TCP Header.
ipi_tcp_hflags: (uint8_t) Flags describing the operational parameters of the TCP Header.
ipi_ipproto: (uint8_t) Specifies the type of IP Protocol in use. Example TCP, UDP, or SCTP.

The if_rxd_info Structure

The fields of struct if_rxd_info are as follows:

iri_qsidx: (uint16_t) Unique index value assigned sequentially to each receive queue. Used to reference the currently receiving queue.
iri_vtag: (uint16_t) Contains the VLAN information in the Ethernet Frame.
iri_len: (uint16_t) Denotes the size of a received packet.
iri_next_offset: (uint16_t) Denotes the offset value for the next packet to be receive. A Null value signifies the end of packet.
iri_cidx: (uint32_t) Denotes the index value of the packet currently being processed in the consumer queue.
iri_flowid: (uint32_t) Value of the RSS hash for the packet.
iri_flags: (uint)
Flags describing the operational parameters of the mbuf contained in the
receive packet.
iri_csum_flags: (uint32_t) Flags describing the checksum value contained in the receive packet.
iri_csum_data: (uint32_t) Checksum data contained in the mbuf(9) packet header.
iri_m: (struct mbuf *) A mbuf for drivers that manage their own receive queues.
iri_ifp: (struct ifnet *) A link back to the interface structure. Utilized by drivers that have multiple interface per softc.
iri_rsstype: (uint8_t) The value of the RSS hash type.
iri_pad: (uint8_t) The length of any padding contained by the received data.
iri_qidx: (uint8_t) Represents the type of queue event. If value >= 0 then it is the freelist id otherwise it is a completion queue event.

FUNCTIONS

All function calls are associated exclusively with either packet transmission or receipt. The void *sc passed as the first argument to all of the following functions represents the driver's softc.

Transmit Packet Functions

isc_txd_encap(): Transmit function that sends a packet on an interface. The if_pkt_info data structure contains data information fields describing the packet. This function returns 0 if successful, otherwise an error value is returned.
isc_txd_flush(): Flush function is called immediately after the isc_txd_encap function transmits a packet. It updates the hardware producer index or increments the descriptors used to pidx_or_credits in the queue designated by the qid number. This is often referred to as poking the doorbell register.
isc_txd_credits_update(): Credit function advances the buffer ring and calculates the credits (descriptors) processed. Until the I/O is complete it cleans the range in case of multisegments and updates the count of processed packets. The function returns the number of processed credits.

Receive Packet Functions

isc_rxd_available(): Function calculates the remaining number of descriptors from a position given by idx. The function returns this value.
isc_rxd_refill(): Starting with the physical address paddrs, the function reads a packet into the rx_ring until a value designated by count is reached. vaddrs is typically not needed and is provided for devices that place their own metadata in the packet header.
isc_rxd_flush(): Flush function updates the producer pointer on the free list flid in queue set number qid to pidx to reflect the presence of new buffers.
isc_rxd_pkt_get(): Process a single software descriptor. rxr->rx_base[i] contains a descriptor that describes a received packet. Hardware specific information about the buffer referred to by ri is returned in the data structure if_rxd_info

AUTHORS

This manual page was written by Nicole Graziano