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