159 lines
5.7 KiB
ReStructuredText
159 lines
5.7 KiB
ReStructuredText
.. include:: <isonum.txt>
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DPAA2 DPIO (Data Path I/O) Overview
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===================================
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:Copyright: |copy| 2016-2018 NXP
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This document provides an overview of the Freescale DPAA2 DPIO
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drivers
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Introduction
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============
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A DPAA2 DPIO (Data Path I/O) is a hardware object that provides
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interfaces to enqueue and dequeue frames to/from network interfaces
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and other accelerators. A DPIO also provides hardware buffer
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pool management for network interfaces.
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This document provides an overview the Linux DPIO driver, its
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subcomponents, and its APIs.
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See Documentation/networking/dpaa2/overview.rst for a general overview of DPAA2
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and the general DPAA2 driver architecture in Linux.
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Driver Overview
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---------------
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The DPIO driver is bound to DPIO objects discovered on the fsl-mc bus and
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provides services that:
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A) allow other drivers, such as the Ethernet driver, to enqueue and dequeue
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frames for their respective objects
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B) allow drivers to register callbacks for data availability notifications
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when data becomes available on a queue or channel
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C) allow drivers to manage hardware buffer pools
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The Linux DPIO driver consists of 3 primary components--
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DPIO object driver-- fsl-mc driver that manages the DPIO object
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DPIO service-- provides APIs to other Linux drivers for services
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QBman portal interface-- sends portal commands, gets responses
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::
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fsl-mc other
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bus drivers
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+---+----+ +------+-----+
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|DPIO obj| |DPIO service|
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| driver |---| (DPIO) |
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+--------+ +------+-----+
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+------+-----+
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| QBman |
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| portal i/f |
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+------------+
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hardware
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The diagram below shows how the DPIO driver components fit with the other
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DPAA2 Linux driver components::
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+------------+
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| OS Network |
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| Stack |
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+------------+ +------------+
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| Allocator |. . . . . . . | Ethernet |
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|(DPMCP,DPBP)| | (DPNI) |
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+-.----------+ +---+---+----+
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. . ^ |
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. . <data avail, | |<enqueue,
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. . tx confirm> | | dequeue>
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+-------------+ . | |
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| DPRC driver | . +--------+ +------------+
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| (DPRC) | . . |DPIO obj| |DPIO service|
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+----------+--+ | driver |-| (DPIO) |
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| +--------+ +------+-----+
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|<dev add/remove> +------|-----+
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| | QBman |
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+----+--------------+ | portal i/f |
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| MC-bus driver | +------------+
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| /soc/fsl-mc | |
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+-------------------+ |
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=========================================|=========|========================
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+-+--DPIO---|-----------+
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| QBman Portal |
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+-----------------------+
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============================================================================
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DPIO Object Driver (dpio-driver.c)
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----------------------------------
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The dpio-driver component registers with the fsl-mc bus to handle objects of
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type "dpio". The implementation of probe() handles basic initialization
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of the DPIO including mapping of the DPIO regions (the QBman SW portal)
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and initializing interrupts and registering irq handlers. The dpio-driver
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registers the probed DPIO with dpio-service.
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DPIO service (dpio-service.c, dpaa2-io.h)
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------------------------------------------
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The dpio service component provides queuing, notification, and buffers
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management services to DPAA2 drivers, such as the Ethernet driver. A system
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will typically allocate 1 DPIO object per CPU to allow queuing operations
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to happen simultaneously across all CPUs.
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Notification handling
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dpaa2_io_service_register()
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dpaa2_io_service_deregister()
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dpaa2_io_service_rearm()
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Queuing
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dpaa2_io_service_pull_fq()
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dpaa2_io_service_pull_channel()
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dpaa2_io_service_enqueue_fq()
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dpaa2_io_service_enqueue_qd()
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dpaa2_io_store_create()
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dpaa2_io_store_destroy()
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dpaa2_io_store_next()
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Buffer pool management
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dpaa2_io_service_release()
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dpaa2_io_service_acquire()
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QBman portal interface (qbman-portal.c)
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---------------------------------------
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The qbman-portal component provides APIs to do the low level hardware
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bit twiddling for operations such as:
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-initializing Qman software portals
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-building and sending portal commands
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-portal interrupt configuration and processing
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The qbman-portal APIs are not public to other drivers, and are
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only used by dpio-service.
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Other (dpaa2-fd.h, dpaa2-global.h)
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----------------------------------
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Frame descriptor and scatter-gather definitions and the APIs used to
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manipulate them are defined in dpaa2-fd.h.
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Dequeue result struct and parsing APIs are defined in dpaa2-global.h.
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