232 lines
7.3 KiB
ReStructuredText
232 lines
7.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
:Author: Kishon Vijay Abraham I <kishon@ti.com>
|
|
|
|
This document is a guide to use the PCI Endpoint Framework in order to create
|
|
endpoint controller driver, endpoint function driver, and using configfs
|
|
interface to bind the function driver to the controller driver.
|
|
|
|
Introduction
|
|
============
|
|
|
|
Linux has a comprehensive PCI subsystem to support PCI controllers that
|
|
operates in Root Complex mode. The subsystem has capability to scan PCI bus,
|
|
assign memory resources and IRQ resources, load PCI driver (based on
|
|
vendor ID, device ID), support other services like hot-plug, power management,
|
|
advanced error reporting and virtual channels.
|
|
|
|
However the PCI controller IP integrated in some SoCs is capable of operating
|
|
either in Root Complex mode or Endpoint mode. PCI Endpoint Framework will
|
|
add endpoint mode support in Linux. This will help to run Linux in an
|
|
EP system which can have a wide variety of use cases from testing or
|
|
validation, co-processor accelerator, etc.
|
|
|
|
PCI Endpoint Core
|
|
=================
|
|
|
|
The PCI Endpoint Core layer comprises 3 components: the Endpoint Controller
|
|
library, the Endpoint Function library, and the configfs layer to bind the
|
|
endpoint function with the endpoint controller.
|
|
|
|
PCI Endpoint Controller(EPC) Library
|
|
------------------------------------
|
|
|
|
The EPC library provides APIs to be used by the controller that can operate
|
|
in endpoint mode. It also provides APIs to be used by function driver/library
|
|
in order to implement a particular endpoint function.
|
|
|
|
APIs for the PCI controller Driver
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
This section lists the APIs that the PCI Endpoint core provides to be used
|
|
by the PCI controller driver.
|
|
|
|
* devm_pci_epc_create()/pci_epc_create()
|
|
|
|
The PCI controller driver should implement the following ops:
|
|
|
|
* write_header: ops to populate configuration space header
|
|
* set_bar: ops to configure the BAR
|
|
* clear_bar: ops to reset the BAR
|
|
* alloc_addr_space: ops to allocate in PCI controller address space
|
|
* free_addr_space: ops to free the allocated address space
|
|
* raise_irq: ops to raise a legacy, MSI or MSI-X interrupt
|
|
* start: ops to start the PCI link
|
|
* stop: ops to stop the PCI link
|
|
|
|
The PCI controller driver can then create a new EPC device by invoking
|
|
devm_pci_epc_create()/pci_epc_create().
|
|
|
|
* devm_pci_epc_destroy()/pci_epc_destroy()
|
|
|
|
The PCI controller driver can destroy the EPC device created by either
|
|
devm_pci_epc_create() or pci_epc_create() using devm_pci_epc_destroy() or
|
|
pci_epc_destroy().
|
|
|
|
* pci_epc_linkup()
|
|
|
|
In order to notify all the function devices that the EPC device to which
|
|
they are linked has established a link with the host, the PCI controller
|
|
driver should invoke pci_epc_linkup().
|
|
|
|
* pci_epc_mem_init()
|
|
|
|
Initialize the pci_epc_mem structure used for allocating EPC addr space.
|
|
|
|
* pci_epc_mem_exit()
|
|
|
|
Cleanup the pci_epc_mem structure allocated during pci_epc_mem_init().
|
|
|
|
|
|
EPC APIs for the PCI Endpoint Function Driver
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
This section lists the APIs that the PCI Endpoint core provides to be used
|
|
by the PCI endpoint function driver.
|
|
|
|
* pci_epc_write_header()
|
|
|
|
The PCI endpoint function driver should use pci_epc_write_header() to
|
|
write the standard configuration header to the endpoint controller.
|
|
|
|
* pci_epc_set_bar()
|
|
|
|
The PCI endpoint function driver should use pci_epc_set_bar() to configure
|
|
the Base Address Register in order for the host to assign PCI addr space.
|
|
Register space of the function driver is usually configured
|
|
using this API.
|
|
|
|
* pci_epc_clear_bar()
|
|
|
|
The PCI endpoint function driver should use pci_epc_clear_bar() to reset
|
|
the BAR.
|
|
|
|
* pci_epc_raise_irq()
|
|
|
|
The PCI endpoint function driver should use pci_epc_raise_irq() to raise
|
|
Legacy Interrupt, MSI or MSI-X Interrupt.
|
|
|
|
* pci_epc_mem_alloc_addr()
|
|
|
|
The PCI endpoint function driver should use pci_epc_mem_alloc_addr(), to
|
|
allocate memory address from EPC addr space which is required to access
|
|
RC's buffer
|
|
|
|
* pci_epc_mem_free_addr()
|
|
|
|
The PCI endpoint function driver should use pci_epc_mem_free_addr() to
|
|
free the memory space allocated using pci_epc_mem_alloc_addr().
|
|
|
|
Other EPC APIs
|
|
~~~~~~~~~~~~~~
|
|
|
|
There are other APIs provided by the EPC library. These are used for binding
|
|
the EPF device with EPC device. pci-ep-cfs.c can be used as reference for
|
|
using these APIs.
|
|
|
|
* pci_epc_get()
|
|
|
|
Get a reference to the PCI endpoint controller based on the device name of
|
|
the controller.
|
|
|
|
* pci_epc_put()
|
|
|
|
Release the reference to the PCI endpoint controller obtained using
|
|
pci_epc_get()
|
|
|
|
* pci_epc_add_epf()
|
|
|
|
Add a PCI endpoint function to a PCI endpoint controller. A PCIe device
|
|
can have up to 8 functions according to the specification.
|
|
|
|
* pci_epc_remove_epf()
|
|
|
|
Remove the PCI endpoint function from PCI endpoint controller.
|
|
|
|
* pci_epc_start()
|
|
|
|
The PCI endpoint function driver should invoke pci_epc_start() once it
|
|
has configured the endpoint function and wants to start the PCI link.
|
|
|
|
* pci_epc_stop()
|
|
|
|
The PCI endpoint function driver should invoke pci_epc_stop() to stop
|
|
the PCI LINK.
|
|
|
|
|
|
PCI Endpoint Function(EPF) Library
|
|
----------------------------------
|
|
|
|
The EPF library provides APIs to be used by the function driver and the EPC
|
|
library to provide endpoint mode functionality.
|
|
|
|
EPF APIs for the PCI Endpoint Function Driver
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
This section lists the APIs that the PCI Endpoint core provides to be used
|
|
by the PCI endpoint function driver.
|
|
|
|
* pci_epf_register_driver()
|
|
|
|
The PCI Endpoint Function driver should implement the following ops:
|
|
* bind: ops to perform when a EPC device has been bound to EPF device
|
|
* unbind: ops to perform when a binding has been lost between a EPC
|
|
device and EPF device
|
|
* add_cfs: optional ops to create function specific configfs
|
|
attributes
|
|
|
|
The PCI Function driver can then register the PCI EPF driver by using
|
|
pci_epf_register_driver().
|
|
|
|
* pci_epf_unregister_driver()
|
|
|
|
The PCI Function driver can unregister the PCI EPF driver by using
|
|
pci_epf_unregister_driver().
|
|
|
|
* pci_epf_alloc_space()
|
|
|
|
The PCI Function driver can allocate space for a particular BAR using
|
|
pci_epf_alloc_space().
|
|
|
|
* pci_epf_free_space()
|
|
|
|
The PCI Function driver can free the allocated space
|
|
(using pci_epf_alloc_space) by invoking pci_epf_free_space().
|
|
|
|
APIs for the PCI Endpoint Controller Library
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
This section lists the APIs that the PCI Endpoint core provides to be used
|
|
by the PCI endpoint controller library.
|
|
|
|
* pci_epf_linkup()
|
|
|
|
The PCI endpoint controller library invokes pci_epf_linkup() when the
|
|
EPC device has established the connection to the host.
|
|
|
|
Other EPF APIs
|
|
~~~~~~~~~~~~~~
|
|
|
|
There are other APIs provided by the EPF library. These are used to notify
|
|
the function driver when the EPF device is bound to the EPC device.
|
|
pci-ep-cfs.c can be used as reference for using these APIs.
|
|
|
|
* pci_epf_create()
|
|
|
|
Create a new PCI EPF device by passing the name of the PCI EPF device.
|
|
This name will be used to bind the EPF device to a EPF driver.
|
|
|
|
* pci_epf_destroy()
|
|
|
|
Destroy the created PCI EPF device.
|
|
|
|
* pci_epf_bind()
|
|
|
|
pci_epf_bind() should be invoked when the EPF device has been bound to
|
|
a EPC device.
|
|
|
|
* pci_epf_unbind()
|
|
|
|
pci_epf_unbind() should be invoked when the binding between EPC device
|
|
and EPF device is lost.
|