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diff --git a/Documentation/networking/device_drivers/freescale/dpaa2/dpio-driver.rst b/Documentation/networking/device_drivers/freescale/dpaa2/dpio-driver.rst new file mode 100644 index 000000000000..a188466b6698 --- /dev/null +++ b/Documentation/networking/device_drivers/freescale/dpaa2/dpio-driver.rst @@ -0,0 +1,158 @@ +.. 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/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. |