-Overview of DPAA2 objects
-DPAA2 Linux driver architecture overview
-bus driver
- -dprc driver
+ -DPRC driver
-allocator
- -dpio driver
+ -DPIO driver
-Ethernet
- -mac
+ -MAC
DPAA2 Overview
--------------
The MC provides memory-mapped I/O command interfaces (MC portals)
which DPAA2 software drivers use to operate on DPAA2 objects:
+The diagram below shows an overview of the DPAA2 resource management
+architecture:
+
+--------------------------------------+
| OS |
| DPAA2 drivers |
Overview of DPAA2 Objects
-------------------------
-The section provides a brief overview of some key objects
-in the DPAA2 hardware. A simple scenario is described illustrating
-the objects involved in creating a network interfaces.
+The section provides a brief overview of some key DPAA2 objects.
+A simple scenario is described illustrating the objects involved
+in creating a network interfaces.
-DPRC (Datapath Resource Container)
- A DPRC is an container object that holds all the other
+ A DPRC is a container object that holds all the other
types of DPAA2 objects. In the example diagram below there
are 8 objects of 5 types (DPMCP, DPIO, DPBP, DPNI, and DPMAC)
in the container.
| |
+---------------------------------------------------------+
- From the point of view of an OS, a DPRC is bus-like. Like
- a plug-and-play bus, such as PCI, DPRC commands can be used to
- enumerate the contents of the DPRC, discover the hardware
- objects present (including mappable regions and interrupts).
+ From the point of view of an OS, a DPRC behaves similar to a plug and
+ play bus, like PCI. DPRC commands can be used to enumerate the contents
+ of the DPRC, discover the hardware objects present (including mappable
+ regions and interrupts).
- dprc.1 (bus)
+ DPRC.1 (bus)
|
+--+--------+-------+-------+-------+
| | | | |
- dpmcp.1 dpio.1 dpbp.1 dpni.1 dpmac.1
- dpmcp.2 dpio.2
- dpmcp.3
+ DPMCP.1 DPIO.1 DPBP.1 DPNI.1 DPMAC.1
+ DPMCP.2 DPIO.2
+ DPMCP.3
Hardware objects can be created and destroyed dynamically, providing
the ability to hot plug/unplug objects in and out of the DPRC.
- A DPRC has a mappable mmio region (an MC portal) that can be used
+ A DPRC has a mappable MMIO region (an MC portal) that can be used
to send MC commands. It has an interrupt for status events (like
hotplug).
A typical Ethernet NIC is monolithic-- the NIC device contains TX/RX
queuing mechanisms, configuration mechanisms, buffer management,
physical ports, and interrupts. DPAA2 uses a more granular approach
- utilizing multiple hardware objects. Each object has specialized
- functions, and are used together by software to provide Ethernet network
- interface functionality. This approach provides efficient use of finite
- hardware resources, flexibility, and performance advantages.
+ utilizing multiple hardware objects. Each object provides specialized
+ functions. Groups of these objects are used by software to provide
+ Ethernet network interface functionality. This approach provides
+ efficient use of finite hardware resources, flexibility, and
+ performance advantages.
The diagram below shows the objects needed for a simple
network interface configuration on a system with 2 CPUs.
Below the objects are described. For each object a brief description
is provided along with a summary of the kinds of operations the object
- supports and a summary of key resources of the object (mmio regions
- and irqs).
+ supports and a summary of key resources of the object (MMIO regions
+ and IRQs).
-DPMAC (Datapath Ethernet MAC): represents an Ethernet MAC, a
hardware device that connects to an Ethernet PHY and allows
physical transmission and reception of Ethernet frames.
- -mmio regions: none
- -irqs: dpni link change
+ -MMIO regions: none
+ -IRQs: DPNI link change
-commands: set link up/down, link config, get stats,
- irq config, enable, reset
+ IRQ config, enable, reset
-DPNI (Datapath Network Interface): contains TX/RX queues,
- network interface configuration, and rx buffer pool configuration
- mechanisms.
- -mmio regions: none
- -irqs: link state
+ network interface configuration, and RX buffer pool configuration
+ mechanisms. The TX/RX queues are in memory and are identified by
+ queue number.
+ -MMIO regions: none
+ -IRQs: link state
-commands: port config, offload config, queue config,
- parse/classify config, irq config, enable, reset
+ parse/classify config, IRQ config, enable, reset
-DPIO (Datapath I/O): provides interfaces to enqueue and dequeue
- packets and do hardware buffer pool management operations. For
- optimum performance there is typically DPIO per CPU. This allows
- each CPU to perform simultaneous enqueue/dequeue operations.
- -mmio regions: queue operations, buffer mgmt
- -irqs: data availability, congestion notification, buffer
+ packets and do hardware buffer pool management operations. The DPAA2
+ architecture separates the mechanism to access queues (the DPIO object)
+ from the queues themselves. The DPIO provides an MMIO interface to
+ enqueue/dequeue packets. To enqueue something a descriptor is written
+ to the DPIO MMIO region, which includes the target queue number.
+ There will typically be one DPIO assigned to each CPU. This allows all
+ CPUs to simultaneously perform enqueue/dequeued operations. DPIOs are
+ expected to be shared by different DPAA2 drivers.
+ -MMIO regions: queue operations, buffer management
+ -IRQs: data availability, congestion notification, buffer
pool depletion
- -commands: irq config, enable, reset
+ -commands: IRQ config, enable, reset
-DPBP (Datapath Buffer Pool): represents a hardware buffer
pool.
- -mmio regions: none
- -irqs: none
+ -MMIO regions: none
+ -IRQs: none
-commands: enable, reset
-DPMCP (Datapath MC Portal): provides an MC command portal.
Used by drivers to send commands to the MC to manage
objects.
- -mmio regions: MC command portal
- -irqs: command completion
- -commands: irq config, enable, reset
+ -MMIO regions: MC command portal
+ -IRQs: command completion
+ -commands: IRQ config, enable, reset
Object Connections
------------------
| Stack |
+------------+ +------------+
| Allocator |. . . . . . . | Ethernet |
- |(dpmcp,dpbp)| | (dpni) |
+ |(DPMCP,DPBP)| | (DPNI) |
+-.----------+ +---+---+----+
. . ^ |
. . <data avail, | |<enqueue,
. . tx confirm> | | dequeue>
+-------------+ . | |
| DPRC driver | . +---+---V----+ +---------+
- | (dprc) | . . . . . .| DPIO driver| | MAC |
- +----------+--+ | (dpio) | | (dpmac) |
+ | (DPRC) | . . . . . .| DPIO driver| | MAC |
+ +----------+--+ | (DPIO) | | (DPMAC) |
| +------+-----+ +-----+---+
|<dev add/remove> | |
| | |
+----+--------------+ | +--+---+
- | mc-bus driver | | | PHY |
+ | MC-bus driver | | | PHY |
| | | |driver|
- | /fsl-mc@80c000000 | | +--+---+
+ | /soc/fsl-mc | | +--+---+
+-------------------+ | |
| |
================================ HARDWARE =========|=================|======
A brief description of each driver is provided below.
- mc-bus driver
+ MC-bus driver
-------------
- The mc-bus driver is a platform driver and is probed from an
- "/fsl-mc@xxxx" node in the device tree passed in by boot firmware.
- It is responsible for bootstrapping the DPAA2 kernel infrastructure.
+ The MC-bus driver is a platform driver and is probed from a
+ node in the device tree (compatible "fsl,qoriq-mc") passed in by boot
+ firmware. It is responsible for bootstrapping the DPAA2 kernel
+ infrastructure.
Key functions include:
-registering a new bus type named "fsl-mc" with the kernel,
and implementing bus call-backs (e.g. match/uevent/dev_groups)
- -implemeting APIs for DPAA2 driver registration and for device
+ -implementing APIs for DPAA2 driver registration and for device
add/remove
- -creates an MSI irq domain
- -do a device add of the 'root' DPRC device, which is needed
- to bootstrap things
+ -creates an MSI IRQ domain
+ -doing a 'device add' to expose the 'root' DPRC, in turn triggering
+ a bind of the root DPRC to the DPRC driver
DPRC driver
-----------
- The dprc-driver is bound DPRC objects and does runtime management
+ The DPRC driver is bound to DPRC objects and does runtime management
of a bus instance. It performs the initial bus scan of the DPRC
- and handles interrupts for container events such as hot plug.
+ and handles interrupts for container events such as hot plug by
+ re-scanning the DPRC.
Allocator
----------
DPIO driver
-----------
The DPIO driver is bound to DPIO objects and provides services that allow
- other drivers such as the Ethernet driver to receive and transmit data.
+ other drivers such as the Ethernet driver to enqueue and dequeue data for
+ their respective objects.
Key services include:
-data availability notifications
-hardware queuing operations (enqueue and dequeue of data)
-hardware buffer pool management
+ To transmit a packet the Ethernet driver puts data on a queue and
+ invokes a DPIO API. For receive, the Ethernet driver registers
+ a data availability notification callback. To dequeue a packet
+ a DPIO API is used.
+
There is typically one DPIO object per physical CPU for optimum
- performance, allowing each CPU to simultaneously enqueue
+ performance, allowing different CPUs to simultaneously enqueue
and dequeue data.
The DPIO driver operates on behalf of all DPAA2 drivers
by the appropriate PHY driver via an mdio bus. The MAC driver
plays a role of being a proxy between the PHY driver and the
MC. It does this proxy via the MC commands to a DPMAC object.
+ If the PHY driver signals a link change, the MAC driver notifies
+ the MC via a DPMAC command. If a network interface is brought
+ up or down, the MC notifies the DPMAC driver via an interrupt and
+ the driver can take appropriate action.