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1.. include:: <isonum.txt>
2
3DPAA2 DPIO (Data Path I/O) Overview
4===================================
5
6:Copyright: |copy| 2016-2018 NXP
7
8This document provides an overview of the Freescale DPAA2 DPIO
9drivers
10
11Introduction
12============
13
14A DPAA2 DPIO (Data Path I/O) is a hardware object that provides
15interfaces to enqueue and dequeue frames to/from network interfaces
16and other accelerators. A DPIO also provides hardware buffer
17pool management for network interfaces.
18
19This document provides an overview the Linux DPIO driver, its
20subcomponents, and its APIs.
21
22See Documentation/networking/dpaa2/overview.rst for a general overview of DPAA2
23and the general DPAA2 driver architecture in Linux.
24
25Driver Overview
26---------------
27
28The DPIO driver is bound to DPIO objects discovered on the fsl-mc bus and
29provides services that:
30 A) allow other drivers, such as the Ethernet driver, to enqueue and dequeue
31 frames for their respective objects
32 B) allow drivers to register callbacks for data availability notifications
33 when data becomes available on a queue or channel
34 C) allow drivers to manage hardware buffer pools
35
36The Linux DPIO driver consists of 3 primary components--
37 DPIO object driver-- fsl-mc driver that manages the DPIO object
38
39 DPIO service-- provides APIs to other Linux drivers for services
40
41 QBman portal interface-- sends portal commands, gets responses
42::
43
44 fsl-mc other
45 bus drivers
46 | |
47 +---+----+ +------+-----+
48 |DPIO obj| |DPIO service|
49 | driver |---| (DPIO) |
50 +--------+ +------+-----+
51 |
52 +------+-----+
53 | QBman |
54 | portal i/f |
55 +------------+
56 |
57 hardware
58
59
60The diagram below shows how the DPIO driver components fit with the other
61DPAA2 Linux driver components::
62 +------------+
63 | OS Network |
64 | Stack |
65 +------------+ +------------+
66 | Allocator |. . . . . . . | Ethernet |
67 |(DPMCP,DPBP)| | (DPNI) |
68 +-.----------+ +---+---+----+
69 . . ^ |
70 . . <data avail, | |<enqueue,
71 . . tx confirm> | | dequeue>
72 +-------------+ . | |
73 | DPRC driver | . +--------+ +------------+
74 | (DPRC) | . . |DPIO obj| |DPIO service|
75 +----------+--+ | driver |-| (DPIO) |
76 | +--------+ +------+-----+
77 |<dev add/remove> +------|-----+
78 | | QBman |
79 +----+--------------+ | portal i/f |
80 | MC-bus driver | +------------+
81 | | |
82 | /soc/fsl-mc | |
83 +-------------------+ |
84 |
85 =========================================|=========|========================
86 +-+--DPIO---|-----------+
87 | | |
88 | QBman Portal |
89 +-----------------------+
90
91 ============================================================================
92
93
94DPIO Object Driver (dpio-driver.c)
95----------------------------------
96
97 The dpio-driver component registers with the fsl-mc bus to handle objects of
98 type "dpio". The implementation of probe() handles basic initialization
99 of the DPIO including mapping of the DPIO regions (the QBman SW portal)
100 and initializing interrupts and registering irq handlers. The dpio-driver
101 registers the probed DPIO with dpio-service.
102
103DPIO service (dpio-service.c, dpaa2-io.h)
104------------------------------------------
105
106 The dpio service component provides queuing, notification, and buffers
107 management services to DPAA2 drivers, such as the Ethernet driver. A system
108 will typically allocate 1 DPIO object per CPU to allow queuing operations
109 to happen simultaneously across all CPUs.
110
111 Notification handling
112 dpaa2_io_service_register()
113
114 dpaa2_io_service_deregister()
115
116 dpaa2_io_service_rearm()
117
118 Queuing
119 dpaa2_io_service_pull_fq()
120
121 dpaa2_io_service_pull_channel()
122
123 dpaa2_io_service_enqueue_fq()
124
125 dpaa2_io_service_enqueue_qd()
126
127 dpaa2_io_store_create()
128
129 dpaa2_io_store_destroy()
130
131 dpaa2_io_store_next()
132
133 Buffer pool management
134 dpaa2_io_service_release()
135
136 dpaa2_io_service_acquire()
137
138QBman portal interface (qbman-portal.c)
139---------------------------------------
140
141 The qbman-portal component provides APIs to do the low level hardware
142 bit twiddling for operations such as:
143 -initializing Qman software portals
144
145 -building and sending portal commands
146
147 -portal interrupt configuration and processing
148
149 The qbman-portal APIs are not public to other drivers, and are
150 only used by dpio-service.
151
152Other (dpaa2-fd.h, dpaa2-global.h)
153----------------------------------
154
155 Frame descriptor and scatter-gather definitions and the APIs used to
156 manipulate them are defined in dpaa2-fd.h.
157
158 Dequeue result struct and parsing APIs are defined in dpaa2-global.h.