QEP Linux Driver APIs

QEP Network Device Operations

This section documents the callbacks/functions exported by QEP for supporting network device operations of Linux kernel stack.

int qep_module_init(void)

This is the entry point of the NIC driver.

Parameters

void

no arguments

Description

• Called when the qep kernel module is inserted into the Linux kernel
• Creates the debugfs directory for QEP (/sys/kernel/debug/qep_dev/) in the host file system
• Initializes QDMA
• Registers the qep kernel module as a PCIe driver

Return

Returns 0 on Success or -EINVAL on Failure

void __exit qep_module_exit(void)

This is the exit point of the NIC driver. This function is called when driver is removed from the kernel. The driver is unregistered, libqdma and debugfs are cleaned up.

Parameters

void

no arguments

int qep_pci_probe(struct pci_dev * pdev, const struct pci_device_id * pci_dev_id)

This is probe function which is called when Linux kernel detects a PCIe device with vendor ID and device ID registered for this driver with the Linux kernel.

Parameters

struct pci_dev * pdev

Pointer to PCIe device struct

const struct pci_device_id * pci_dev_id

Pointer to pci_device_id structure containing the PCIe Vendor ID and Device ID

Description

• Called when the device ID and vendor ID of a PCIe device on the PCIe bus matches with the IDs registered with the Linux kernel during module init
• Creates a debugfs directory for the probed device and creates debugfs files for qep, stmn and cmac
• Maps user bar (BAR2) for accessing STM-N functionality implemented in the HW
• Reads MAC address from HW
• Initializes STM-N, QDMA and CMAC components. The default number of queues supported is minimum of number of CPU cores and number of MSI-X vectors supported (32). The number of queues for Tx/Rx can be changed using ethtool
• Thread to monitor CMAC Rx sync is launched to check for Rx sync every 5 seconds. The link monitoring starts after the device state is up
• Registers as Netdevice with Linux kernel.

Return

Returns 0 on Success or error code on Failure

void qep_pci_remove(struct pci_dev * pdev)

This function is called when PCIe device is removed from the PCIe bus.

Parameters

struct pci_dev * pdev

Pointer to PCIe Device struct

Description

This function cleans up all the initialized components of the driver

int qep_open(struct net_device * netdev)

This function is called for interface ‘UP’ request.

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

Description

• Called when an interface “up” request is triggered via net-tools such as ifconfig or ip-link
• QDMA Rx and Tx queues are setup in streaming mode with bypass.
• Per Queue NAPI for Rx and tasklet for Tx are enabled.
• The QDMA queues are configured and activated.
• CMAC is enabled
• Link monitoring for CMAC Rx sync is activated
• Rx and Tx queues operations start after CMAC Link is established

Return

Returns 0 on Success or error code on Failure

int qep_stop(struct net_device * netdev)

This function is called when there is a interface ‘down’ request.

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

Description

• Called when an interface “down” request is triggered via net-tools such as ifconfig or ip-link
• QDMA Rx and Tx queues are stopped.
• Per Queue NAPI for Rx and tasklet for Tx are disabled.
• CMAC is disabled
• Link monitoring for CMAC Rx sync is deactivated

Return

Returns 0 on Success or error code on Failure

int qep_start_xmit(struct sk_buff * skb, struct net_device * netdev)

This function is called from networking stack to send a packet

Parameters

struct sk_buff * skb

Pointer to sk_buff conataining data and metadata for transfer

struct net_device * netdev

Pointer to net_device struct of the device

Description

• Upon receiving packets from networking stack, .ndo_start_xmit callback of net_device_ops is called with sk_buff passed as an argument.
• Queue in which packet needs to be transmitted is identified from skb.
• The physical address of sk_buff data and fragments are mapped to qdma_pkt_data structure and passed to qdma_queue_packet_write() API.
• Once the packet has been DMAed, interrupt is raised by QDMA. qep_isr_tx_tophalf which is registered as the callback during initialization is called.
• qep_isr_tx_tophalf determines the queue and schedules a tasklet and acknowledges the interrupt.
• tasklet routine frees the sk_buff.

Return

Returns 0 on Success or error code on Failure

int qep_rx_pkt_process(unsigned long qhndl, unsigned long quld, unsigned int len, unsigned int sgcnt, struct qdma_sw_sg * sgl, void * udd)

This function processes Rx DMA request

Parameters

unsigned long qhndl

Handle to the queue on which data is received

unsigned long quld

Pointer to QEP private data

unsigned int len

Length of the packet data

unsigned int sgcnt

Number of entries in scatter gatherer list

struct qdma_sw_sg * sgl

Pointer to scatter gatherer list

void * udd

User logic metadata

Description

• Upon the arrival of the data packets from CMAC, QDMA will raise interrupt based on interrupt vector configuration.
• QDMA API provides support for registering additional top half processing function in qdma_dev_conf->:c:func:fp_descq_isr_top() through callback and QEP driver-specific data via qdma_dev_conf->isr_top_param. This configuration shall be done as part of qdma_device_open() API which is called from the probe function.
• qep_isr_rx_tophalf() determines the queue, acknowledges the interrupts and schedules a NAPI for the queue
• Callback registered with NAPI, when executed, fetches the data from QDMA to SKB buffer and hands over the packet to the Linux kernel stack

Return

Returns 0 on Success or error code on Failure

u16 qep_select_queue(struct net_device * netdev, struct sk_buff * skb)

This function is used to identify the queue from which packet must be transmitted.

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct sk_buff * skb

Pointer to sk_buff conataining data and metadata for the transfer

Return

queue id on which packet should be queued

struct rtnl_link_stats64 * qep_get_stats64(struct net_device * netdev, struct rtnl_link_stats64 * stats)

This function provides packet statistics.

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct rtnl_link_stats64 * stats

Pointer to struct rtnl_link_stats64 for link statistics

Return

Returns pointer to rtnl_link_stats64 struct containing stats

int qep_change_mtu(struct net_device * netdev, int new_mtu)

This function changes MTU size of the interface

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

int new_mtu

New MTU of the device to be set

Return

Returns 0 on Success or error code on Failure

QEP Ethtool Operations

This section documents the callbacks exported by QEP for supporting ethtool operation.

void qep_get_drvinfo(struct net_device * netdev, struct ethtool_drvinfo * drvinfo)

This is an ethtool callback to print driver info

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_drvinfo * drvinfo

Pointer to struct ethtool_drvinfo

Description

This is to support ethtool option “-i|–driver” which shows driver information. Module name, version and bus info are populated into drvinfo.

int qep_get_regs_len(struct net_device * netdev)

This is an ethtool callback for getting the buffer length required for register dump

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

Return

Buffer length of registers to be dumped.

void qep_get_regs(struct net_device * netdev, struct ethtool_regs * regs, void * p)

This is an ethtool callback for device register dump

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_regs * regs

Pointer to ethtool_regs struct

void * p

Pointer to register dump data

Description

This is to support ethtool option “-d|–register-dump” which provides register dump

u32 qep_get_msglevel(struct net_device * netdev)

This is an ethtool callback to get the debug message level

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

Return

current dmesg verbosity/level

void qep_set_msglevel(struct net_device * netdev, u32 data)

This is an ethtool callback to set the debug message level

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

u32 data

Message level

Description

This is to support ethtool option “-s|–change msglvl | msglvl type on|off … ]”

void qep_get_ringparam(struct net_device * netdev, struct ethtool_ringparam * ring)

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_ringparam * ring

Pointer to ethtool_ringparam struct

Description

This is to support ethtool option “-g|–show-ring” which Query Rx/Tx ring parameters

int qep_set_ringparam(struct net_device * netdev, struct ethtool_ringparam * ring)

This is an ethtool callback to set ring size of Tx and Rx queues

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_ringparam * ring

Pointer to ethtool_ringparam struct

Description

This is to support ethtool option “-G|–set-ring” which sets Rx/Tx ring parameters

void qep_get_channels(struct net_device * netdev, struct ethtool_channels * ch)

This is an ethtool callback to get number of Rx/Tx queues

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_channels * ch

Pointer to ethtool_channels struct

Description

This is to support ethtool option “-l|–show-channels” which Query number of Channels.

int qep_get_sset_count(struct net_device * netdev, int sset)

This is an ethtool callback to get count of Tx/Rx stats

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

int sset

string set ID

Return

number of strings that qep_get_strings will write

void qep_get_strings(struct net_device * netdev, u32 stringset, u8 * data)

This is an ethtool callback to populate set of strings

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

u32 stringset

string set ID

u8 * data

Pointer to memory where strings are to be populated, provided by ethtool

Description

This callback only supports ETH_SS_STATS string ID needed to get strings describing the statistics.

void qep_get_ethtool_stats(struct net_device * netdev, struct ethtool_stats * stats, u64 * data)

This is an ethtool callback to get stats

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_stats * stats

Pointer to ethtool_stats struct

u64 * data

Pointer to memory where stats are to be populated, provided by ethtool

Description

This is to support ethtool option “-S|–statistics” which shows adapter statistics. Detailed MAC level stats which include good, bad, size based stats, error packets count, etc. is provided.

int qep_get_coalesce(struct net_device * netdev, struct ethtool_coalesce * ec)

This is an ethtool callback to get global coalesce options

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_coalesce * ec

Pointer to ethtool_coalesce struct

Description

This is to support ethtool option “-c|–show-coalesce” which shows coalesce options.

int qep_set_coalesce(struct net_device * netdev, struct ethtool_coalesce * ec)

This is an ethtool callback to set global coalesce options

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_coalesce * ec

Pointer to ethtool_coalesce struct

Description

This is to support ethtool option “-C|–coalesce” which sets coalesce options

Return

Returns 0 on Success or error code on Failure

int qep_get_per_queue_coalesce(struct net_device * netdev, u32 queue, struct ethtool_coalesce * ec)

This is an ethtool callback to get per queue coalesce options

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

u32 queue

queue ID for which configuration is provided

struct ethtool_coalesce * ec

Pointer to ethtool_coalesce struct

Description

• This is to support ethtool option “-c|–show-coalesce” which shows coalesce options.
• Only rx-usecs(Timer Mode) and rx-frames(counter mode) are valid.

Return

Returns 0 on Success or error code on Failure

int qep_set_per_queue_coalesce(struct net_device * netdev, u32 queue, struct ethtool_coalesce * ec)

This is an ethtool callback to set per queue coalesce options

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

u32 queue

queue ID for which configuration is provided

struct ethtool_coalesce * ec

Pointer to ethtool_coalesce struct

Description

• This is to support ethtool option “-C|–coalesce” which sets coalesce options.
• Only rx-usecs(Timer Mode) and rx-frames(counter mode) are configured in this callback.

Return

Returns 0 on Success or error code on Failure

int qep_get_fecparam(struct net_device * netdev, struct ethtool_fecparam * fec)

This is an ethtool callback to get FEC params

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_fecparam * fec

Pointer to ethtool_fecparam struct

Description

• This is to support ethtool option “–show-fec” which shows FEC settings.

Return

Returns 0 on Success or error code on Failure

int qep_set_fecparam(struct net_device * netdev, struct ethtool_fecparam * fec)

This is an ethtool callback to set FEC params as AUTO, RS or OFF

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_fecparam * fec

Pointer to ethtool_fecparam struct

Description

• This is to support ethtool option “–set-fec” which sets FEC settings.
• This is to enable or disable RS-FEC encoding in HW.

Return

Returns 0 on Success or error code on Failure

int qep_get_rxfh_key_size(struct net_device * netdev)

This is an ethtool callback to get the size of the Rx Flow Hash key

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

Description

• This is to support ethtool option “–show-rxfh-indir” which sets FEC settings.

Return

Returns 0 on Success or error code on Failure

u32 qep_rss_indir_size(struct net_device * netdev)

This is an ethtool callback to get the size of the Rx Flow Hash Indirection table

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

Description

• This is to support ethtool option “–show-rxfh-indir” which sets FEC settings.

Return

Returns 0 on Success or error code on Failure

int qep_get_rxfh(struct net_device * netdev, u32 * indir, u8 * key, u8 * hfunc)

This is an ethtool callback to get the contents of the Rx Flow Hash key and Rx Flow Hash Indirection table

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

u32 * indir

Pointer to the RSS indirection table

u8 * key

Pointer to the Rx Flow hash key

u8 * hfunc

Pointer to the Rx Flow hash function

Description

• This is to support ethtool option “–show-rxfh-indir” which sets FEC settings.

Return

Returns 0 on Success or error code on Failure

int qep_set_rxfh(struct net_device * netdev, const u32 * indir, const u8 * key, const u8 hfunc)

This is an ethtool callback to set the contents of the Rx Flow Hash Indirection table

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

const u32 * indir

Pointer to the RSS indirection table

const u8 * key

Pointer to the Rx Flow hash key

const u8 hfunc

Pointer to the Rx Flow hash function

Description

• This is to support ethtool option “–set-rxfh-indir” which sets FEC settings.
• Setting of the Rx Flow hash key is not supported

Return

Returns 0 on Success or error code on Failure

int qep_get_rxnfc(struct net_device * netdev, struct ethtool_rxnfc * cmd, u32 * rule_locs)

This is an ethtool callback to get Rx flow classification rules

Parameters

struct net_device * netdev

Pointer to net_device struct of the device

struct ethtool_rxnfc * cmd

Command to get RX flow classification rules

u32 * rule_locs

Array of used rule locations

Description

• This is to support ethtool option “–show-nfc” which sets FEC settings.

Return

Returns 0 on Success or error code on Failure