53 lines
1.8 KiB
ReStructuredText
53 lines
1.8 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0
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===============================================
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Marvell CN10K DMA packet interface (DPI) driver
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===============================================
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Overview
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========
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DPI is a DMA packet interface hardware block in Marvell's CN10K silicon.
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DPI hardware comprises a physical function (PF), its virtual functions,
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mailbox logic, and a set of DMA engines & DMA command queues.
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DPI PF function is an administrative function which services the mailbox
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requests from its VF functions and provisions DMA engine resources to
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it's VF functions.
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mrvl_cn10k_dpi.ko misc driver loads on DPI PF device and services the
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mailbox commands submitted by the VF devices and accordingly initializes
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the DMA engines and VF device's DMA command queues. Also, driver creates
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/dev/mrvl-cn10k-dpi node to set DMA engine and PEM (PCIe interface) port
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attributes like fifo length, molr, mps & mrrs.
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DPI PF driver is just an administrative driver to setup its VF device's
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queues and provisions the hardware resources, it cannot initiate any
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DMA operations. Only VF devices are provisioned with DMA capabilities.
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Driver location
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===============
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drivers/misc/mrvl_cn10k_dpi.c
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Driver IOCTLs
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=============
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:c:macro::`DPI_MPS_MRRS_CFG`
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ioctl that sets max payload size & max read request size parameters of
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a pem port to which DMA engines are wired.
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:c:macro::`DPI_ENGINE_CFG`
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ioctl that sets DMA engine's fifo sizes & max outstanding load request
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thresholds.
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User space code example
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=======================
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DPI VF devices are probed and accessed from user space applications using
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vfio-pci driver. Below is a sample dpi dma application to demonstrate on
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how applications use mailbox and ioctl services from DPI PF kernel driver.
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https://github.com/MarvellEmbeddedProcessors/dpi-sample-app
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