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diff --git a/Documentation/PCI/endpoint/pci-endpoint-cfs.rst b/Documentation/PCI/endpoint/pci-endpoint-cfs.rst new file mode 100644 index 000000000..1bbd81ed0 --- /dev/null +++ b/Documentation/PCI/endpoint/pci-endpoint-cfs.rst @@ -0,0 +1,118 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================================= +Configuring PCI Endpoint Using CONFIGFS +======================================= + +:Author: Kishon Vijay Abraham I <kishon@ti.com> + +The PCI Endpoint Core exposes configfs entry (pci_ep) to configure the +PCI endpoint function and to bind the endpoint function +with the endpoint controller. (For introducing other mechanisms to +configure the PCI Endpoint Function refer to [1]). + +Mounting configfs +================= + +The PCI Endpoint Core layer creates pci_ep directory in the mounted configfs +directory. configfs can be mounted using the following command:: + + mount -t configfs none /sys/kernel/config + +Directory Structure +=================== + +The pci_ep configfs has two directories at its root: controllers and +functions. Every EPC device present in the system will have an entry in +the *controllers* directory and every EPF driver present in the system +will have an entry in the *functions* directory. +:: + + /sys/kernel/config/pci_ep/ + .. controllers/ + .. functions/ + +Creating EPF Device +=================== + +Every registered EPF driver will be listed in controllers directory. The +entries corresponding to EPF driver will be created by the EPF core. +:: + + /sys/kernel/config/pci_ep/functions/ + .. <EPF Driver1>/ + ... <EPF Device 11>/ + ... <EPF Device 21>/ + .. <EPF Driver2>/ + ... <EPF Device 12>/ + ... <EPF Device 22>/ + +In order to create a <EPF device> of the type probed by <EPF Driver>, the +user has to create a directory inside <EPF DriverN>. + +Every <EPF device> directory consists of the following entries that can be +used to configure the standard configuration header of the endpoint function. +(These entries are created by the framework when any new <EPF Device> is +created) +:: + + .. <EPF Driver1>/ + ... <EPF Device 11>/ + ... vendorid + ... deviceid + ... revid + ... progif_code + ... subclass_code + ... baseclass_code + ... cache_line_size + ... subsys_vendor_id + ... subsys_id + ... interrupt_pin + +EPC Device +========== + +Every registered EPC device will be listed in controllers directory. The +entries corresponding to EPC device will be created by the EPC core. +:: + + /sys/kernel/config/pci_ep/controllers/ + .. <EPC Device1>/ + ... <Symlink EPF Device11>/ + ... <Symlink EPF Device12>/ + ... start + .. <EPC Device2>/ + ... <Symlink EPF Device21>/ + ... <Symlink EPF Device22>/ + ... start + +The <EPC Device> directory will have a list of symbolic links to +<EPF Device>. These symbolic links should be created by the user to +represent the functions present in the endpoint device. + +The <EPC Device> directory will also have a *start* field. Once +"1" is written to this field, the endpoint device will be ready to +establish the link with the host. This is usually done after +all the EPF devices are created and linked with the EPC device. +:: + + | controllers/ + | <Directory: EPC name>/ + | <Symbolic Link: Function> + | start + | functions/ + | <Directory: EPF driver>/ + | <Directory: EPF device>/ + | vendorid + | deviceid + | revid + | progif_code + | subclass_code + | baseclass_code + | cache_line_size + | subsys_vendor_id + | subsys_id + | interrupt_pin + | function + +[1] :doc:`pci-endpoint` |