139 lines
4.3 KiB
ReStructuredText
139 lines
4.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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=======================================
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Configuring PCI Endpoint Using CONFIGFS
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=======================================
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:Author: Kishon Vijay Abraham I <kishon@ti.com>
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The PCI Endpoint Core exposes configfs entry (pci_ep) to configure the
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PCI endpoint function and to bind the endpoint function
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with the endpoint controller. (For introducing other mechanisms to
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configure the PCI Endpoint Function refer to [1]).
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Mounting configfs
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=================
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The PCI Endpoint Core layer creates pci_ep directory in the mounted configfs
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directory. configfs can be mounted using the following command::
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mount -t configfs none /sys/kernel/config
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Directory Structure
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===================
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The pci_ep configfs has two directories at its root: controllers and
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functions. Every EPC device present in the system will have an entry in
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the *controllers* directory and every EPF driver present in the system
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will have an entry in the *functions* directory.
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::
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/sys/kernel/config/pci_ep/
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.. controllers/
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.. functions/
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Creating EPF Device
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===================
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Every registered EPF driver will be listed in controllers directory. The
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entries corresponding to EPF driver will be created by the EPF core.
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::
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/sys/kernel/config/pci_ep/functions/
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.. <EPF Driver1>/
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... <EPF Device 11>/
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... <EPF Device 21>/
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... <EPF Device 31>/
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.. <EPF Driver2>/
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... <EPF Device 12>/
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... <EPF Device 22>/
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In order to create a <EPF device> of the type probed by <EPF Driver>, the
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user has to create a directory inside <EPF DriverN>.
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Every <EPF device> directory consists of the following entries that can be
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used to configure the standard configuration header of the endpoint function.
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(These entries are created by the framework when any new <EPF Device> is
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created)
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::
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.. <EPF Driver1>/
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... <EPF Device 11>/
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... vendorid
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... deviceid
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... revid
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... progif_code
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... subclass_code
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... baseclass_code
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... cache_line_size
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... subsys_vendor_id
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... subsys_id
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... interrupt_pin
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... <Symlink EPF Device 31>/
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... primary/
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... <Symlink EPC Device1>/
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... secondary/
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... <Symlink EPC Device2>/
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If an EPF device has to be associated with 2 EPCs (like in the case of
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Non-transparent bridge), symlink of endpoint controller connected to primary
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interface should be added in 'primary' directory and symlink of endpoint
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controller connected to secondary interface should be added in 'secondary'
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directory.
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The <EPF Device> directory can have a list of symbolic links
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(<Symlink EPF Device 31>) to other <EPF Device>. These symbolic links should
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be created by the user to represent the virtual functions that are bound to
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the physical function. In the above directory structure <EPF Device 11> is a
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physical function and <EPF Device 31> is a virtual function. An EPF device once
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it's linked to another EPF device, cannot be linked to a EPC device.
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EPC Device
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==========
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Every registered EPC device will be listed in controllers directory. The
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entries corresponding to EPC device will be created by the EPC core.
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::
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/sys/kernel/config/pci_ep/controllers/
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.. <EPC Device1>/
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... <Symlink EPF Device11>/
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... <Symlink EPF Device12>/
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... start
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.. <EPC Device2>/
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... <Symlink EPF Device21>/
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... <Symlink EPF Device22>/
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... start
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The <EPC Device> directory will have a list of symbolic links to
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<EPF Device>. These symbolic links should be created by the user to
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represent the functions present in the endpoint device. Only <EPF Device>
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that represents a physical function can be linked to a EPC device.
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The <EPC Device> directory will also have a *start* field. Once
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"1" is written to this field, the endpoint device will be ready to
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establish the link with the host. This is usually done after
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all the EPF devices are created and linked with the EPC device.
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::
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| controllers/
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| <Directory: EPC name>/
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| <Symbolic Link: Function>
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| start
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| functions/
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| <Directory: EPF driver>/
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| <Directory: EPF device>/
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| vendorid
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| deviceid
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| revid
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| progif_code
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| subclass_code
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| baseclass_code
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| cache_line_size
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| subsys_vendor_id
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| subsys_id
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| interrupt_pin
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| function
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[1] Documentation/PCI/endpoint/pci-endpoint.rst
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