3. Marvell CNXK RVU LF Driver

CNXK product families can have a use case to allow RVU PF and RVU VF driver to communicate using mailboxes and also get notified of any interrupt that may occur on the device. Hence, a new raw device driver is added for such RVU LF devices. These devices can map to a RVU PF or a RVU VF which can send mailboxes to each other.

3.1. Features

The RVU LF device implements following features in the rawdev API:

  • Get PF FUNC of associated NPA and SSO devices.

  • Get PF FUNC for RVU LF device.

  • Register/unregister interrupt handlers.

  • Register/unregister mailbox callbacks for the other side to process mailboxes.

  • Set mailbox message ID range to be used by the driver.

  • Process mailbox messages.

  • Get BAR Addresses for the out-of-tree drivers to configure registers.

3.2. Limitations

In multi-process mode user-space application must ensure no resources sharing takes place. Otherwise, user-space application should ensure synchronization.

3.3. Device Setup

The RVU LF devices will need to be bound to a user-space IO driver for use. The script dpdk-devbind.py included with DPDK can be used to view the state of the devices and to bind them to a suitable DPDK-supported kernel driver. When querying the status of the devices, they will appear under the category of “Misc (rawdev) devices”, i.e. the command dpdk-devbind.py --status-dev misc can be used to see the state of those devices alone.

3.4. Get NPA and SSO PF FUNC

API functions rte_pmd_rvu_lf_npa_pf_func_get() and rte_pmd_rvu_lf_sso_pf_func_get() can be used to get the cnxk NPA PF func and SSO PF func which application can use for NPA/SSO specific configuration.

3.5. Get RVU LF PF FUNC

API function rte_pmd_rvu_lf_pf_func_get() gets the RVU LF device PF FUNC.

3.6. Register or remove interrupt handler

Out-of-tree drivers can register interrupt handlers using rte_pmd_rvu_lf_irq_register() or remove interrupt handler using rte_pmd_rvu_lf_irq_unregister(). The IRQ numbers for which the interrupts are registered is negotiated separately and is not in scope of the driver.

3.7. RVU LF raw message processing

For processing of mailboxes received on RVU PF/VF application, out-of-tree drivers can register/unregister callbacks using rte_pmd_rvu_lf_msg_handler_register() and rte_pmd_rvu_lf_msg_handler_unregister(). Required responses as per the request and message id received can be filled in the callbacks.

Once a RVU LF raw device is probed, a range of message ids can be configured for which mailboxes will be sent using the API rte_pmd_rvu_lf_msg_id_range_set().

The out-of-tree driver can call rte_pmd_rvu_lf_msg_process() to send a request and receive corresponding response from the other side (PF/VF). It accepts an opaque pointer of a request and its size which can be defined by user and provides an opaque pointer for a response and its length. PF and VF out-of-tree driver can define its own request and response based on the message id of the mailbox.

For sample usage of the API, refer rvu_lf_rawdev_selftest().

3.8. Get BAR addresses

Out-of-tree drivers can retrieve PCI BAR addresses of the device using the API function rte_pmd_rvu_lf_bar_get(). This helps PF/VF drivers to configure the registers of the hardware device.

3.9. Self test

On EAL initialization RVU LF devices will be probed and populated into the raw devices. The rawdev ID of the device can be obtained using invocation of rte_rawdev_get_dev_id("NAME:x") from the test application, where:

  • NAME is the desired subsystem: use “RVU_LF”.

  • x is the device’s bus id specified in “bus:device.func” (BDF) format. BDF follows convention used by lspci i.e. bus, device and func are specified using respectively two, two and one hex digit(s).

Use this identifier for further rawdev function calls.

Selftest rawdev API can be used to verify the mailbox communication between PF and VF devices based applications. There can be multiple VFs for a particular PF. Each VF can send mailboxes to PF and PF can broadcast message to all VFs.