csu3_am335x/board-support/linux-4.9.59+gitAUTOINC+a75d8e9305-ga75d8e9305/Documentation/PCI/endpoint/pci-endpoint-cfs.txt

                   CONFIGURING PCI ENDPOINT USING CONFIGFS
                    Kishon Vijay Abraham I <kishon@ti.com>

The PCI Endpoint Core exposes configfs entry (pci_ep) in order to configure the
PCI endpoint function and in order to bind the endpoint function
with the endpoint controller. (For introducing other mechanisms to
configure the PCI Endpoint Function refer [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 directory structure has been created to reflect the
natural tree like structure of PCI devices. So every directory created
inside pci_ep represents a EPC device and every directory created inside
epf directory represents EPF device.

/sys/kernel/config/pci_ep/
			 | <dir>/ --------------------------------------> [2]
				| epc
				| epf/
				     | <dir>/ --------------------------> [3]
					    | vendorid
					    | deviceid
					    | revid
					    | progif_code
					    | subclass_code
					    | baseclass_code
					    | cache_line_size
					    | subsys_vendor_id
					    | subsys_id
					    | interrupt_pin
					    | function

*) Creating configfs entry for EPC

Any directory created inside *pci_ep* represents an EPC device. In the above
directory structure [2] represents an EPC device. It consists of

	*) epc: Use it to associate the configfs entry to an actual EPC device.
		The list of valid entries for this field can be obtained from
			ls /sys/class/pci_epc/

	*) epf: Directory that contains all the endpoint functions. The name
		of the created directory determines the driver this particular
		epf device will be bound to. The name can be obtained either
		from the function binding documentation [4] or
			ls /sys/bus/pci-epf/drivers

		If more than one endpoint function device has to be bound to
		the same driver, then the directory should be created using
		the following notation
			mkdir <name>.<num>

*) Creating configfs entry for EPF

Any directory created inside *epf* directory represents an EPF device. In the
above directory structure, [3] represents an EPF device. It 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 directory is created inside epf directory.)

        | vendorid
        | deviceid
        | revid
        | progif_code
        | subclass_code
        | baseclass_code
        | cache_line_size
        | subsys_vendor_id
        | subsys_id
        | interrupt_pin

The following entry identifies the function driver that is bound to the
function device
	| function

[1] -> Documentation/PCI/endpoint/pci-endpoint.txt
[4] -> Documentation/PCI/endpoint/function/binding/