Documentation/PCI/endpoint/pci-endpoint-cfs.rst

   1 .. SPDX-License-Identifier: GPL-2.0
   2
   3 =======================================
   4 Configuring PCI Endpoint Using CONFIGFS
   5 =======================================
   6
   7 :Author: Kishon Vijay Abraham I <kishon@ti.com>
   8
   9 The PCI Endpoint Core exposes configfs entry (pci_ep) to configure the
  10 PCI endpoint function and to bind the endpoint function
  11 with the endpoint controller. (For introducing other mechanisms to
  12 configure the PCI Endpoint Function refer to [1]).
  13
  14 Mounting configfs
  15 =================
  16
  17 The PCI Endpoint Core layer creates pci_ep directory in the mounted configfs
  18 directory. configfs can be mounted using the following command::
  19
  20         mount -t configfs none /sys/kernel/config
  21
  22 Directory Structure
  23 ===================
  24
  25 The pci_ep configfs has two directories at its root: controllers and
  26 functions. Every EPC device present in the system will have an entry in
  27 the *controllers* directory and every EPF driver present in the system
  28 will have an entry in the *functions* directory.
  29 ::
  30
  31         /sys/kernel/config/pci_ep/
  32                 .. controllers/
  33                 .. functions/
  34
  35 Creating EPF Device
  36 ===================
  37
  38 Every registered EPF driver will be listed in controllers directory. The
  39 entries corresponding to EPF driver will be created by the EPF core.
  40 ::
  41
  42         /sys/kernel/config/pci_ep/functions/
  43                 .. <EPF Driver1>/
  44                         ... <EPF Device 11>/
  45                         ... <EPF Device 21>/
  46                 .. <EPF Driver2>/
  47                         ... <EPF Device 12>/
  48                         ... <EPF Device 22>/
  49
  50 In order to create a <EPF device> of the type probed by <EPF Driver>, the
  51 user has to create a directory inside <EPF DriverN>.
  52
  53 Every <EPF device> directory consists of the following entries that can be
  54 used to configure the standard configuration header of the endpoint function.
  55 (These entries are created by the framework when any new <EPF Device> is
  56 created)
  57 ::
  58
  59                 .. <EPF Driver1>/
  60                         ... <EPF Device 11>/
  61                                 ... vendorid
  62                                 ... deviceid
  63                                 ... revid
  64                                 ... progif_code
  65                                 ... subclass_code
  66                                 ... baseclass_code
  67                                 ... cache_line_size
  68                                 ... subsys_vendor_id
  69                                 ... subsys_id
  70                                 ... interrupt_pin
  71
  72 EPC Device
  73 ==========
  74
  75 Every registered EPC device will be listed in controllers directory. The
  76 entries corresponding to EPC device will be created by the EPC core.
  77 ::
  78
  79         /sys/kernel/config/pci_ep/controllers/
  80                 .. <EPC Device1>/
  81                         ... <Symlink EPF Device11>/
  82                         ... <Symlink EPF Device12>/
  83                         ... start
  84                 .. <EPC Device2>/
  85                         ... <Symlink EPF Device21>/
  86                         ... <Symlink EPF Device22>/
  87                         ... start
  88
  89 The <EPC Device> directory will have a list of symbolic links to
  90 <EPF Device>. These symbolic links should be created by the user to
  91 represent the functions present in the endpoint device.
  92
  93 The <EPC Device> directory will also have a *start* field. Once
  94 "1" is written to this field, the endpoint device will be ready to
  95 establish the link with the host. This is usually done after
  96 all the EPF devices are created and linked with the EPC device.
  97 ::
  98
  99                          | controllers/
 100                                 | <Directory: EPC name>/
 101                                         | <Symbolic Link: Function>
 102                                         | start
 103                          | functions/
 104                                 | <Directory: EPF driver>/
 105                                         | <Directory: EPF device>/
 106                                                 | vendorid
 107                                                 | deviceid
 108                                                 | revid
 109                                                 | progif_code
 110                                                 | subclass_code
 111                                                 | baseclass_code
 112                                                 | cache_line_size
 113                                                 | subsys_vendor_id
 114                                                 | subsys_id
 115                                                 | interrupt_pin
 116                                                 | function
 117
 118 [1] :doc:`pci-endpoint`