Merge tag 'pci-v4.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaa...

[mirror_ubuntu-bionic-kernel.git] / Documentation / PCI / endpoint / pci-endpoint-cfs.txt

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+                   CONFIGURING PCI ENDPOINT USING CONFIGFS
+                    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 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] -> Documentation/PCI/endpoint/pci-endpoint.txt