diff options
Diffstat (limited to 'Documentation/PCI/endpoint/pci-endpoint-cfs.rst')
| -rw-r--r-- | Documentation/PCI/endpoint/pci-endpoint-cfs.rst | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/Documentation/PCI/endpoint/pci-endpoint-cfs.rst b/Documentation/PCI/endpoint/pci-endpoint-cfs.rst new file mode 100644 index 000000000..fb73345cf --- /dev/null +++ b/Documentation/PCI/endpoint/pci-endpoint-cfs.rst @@ -0,0 +1,138 @@ +.. 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 Device 31>/ + .. <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 + ... <Symlink EPF Device 31>/ + ... primary/ + ... <Symlink EPC Device1>/ + ... secondary/ + ... <Symlink EPC Device2>/ + +If an EPF device has to be associated with 2 EPCs (like in the case of +Non-transparent bridge), symlink of endpoint controller connected to primary +interface should be added in 'primary' directory and symlink of endpoint +controller connected to secondary interface should be added in 'secondary' +directory. + +The <EPF Device> directory can have a list of symbolic links +(<Symlink EPF Device 31>) to other <EPF Device>. These symbolic links should +be created by the user to represent the virtual functions that are bound to +the physical function. In the above directory structure <EPF Device 11> is a +physical function and <EPF Device 31> is a virtual function. An EPF device once +it's linked to another EPF device, cannot be linked to a EPC device. + +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. Only <EPF Device> +that represents a physical function can be linked to a EPC 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.rst |