1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 ======================================= 3 =======================================
4 Configuring PCI Endpoint Using CONFIGFS 4 Configuring PCI Endpoint Using CONFIGFS
5 ======================================= 5 =======================================
6 6
7 :Author: Kishon Vijay Abraham I <kishon@ti.com> 7 :Author: Kishon Vijay Abraham I <kishon@ti.com>
8 8
9 The PCI Endpoint Core exposes configfs entry ( 9 The PCI Endpoint Core exposes configfs entry (pci_ep) to configure the
10 PCI endpoint function and to bind the endpoint 10 PCI endpoint function and to bind the endpoint function
11 with the endpoint controller. (For introducing 11 with the endpoint controller. (For introducing other mechanisms to
12 configure the PCI Endpoint Function refer to [ 12 configure the PCI Endpoint Function refer to [1]).
13 13
14 Mounting configfs 14 Mounting configfs
15 ================= 15 =================
16 16
17 The PCI Endpoint Core layer creates pci_ep dir 17 The PCI Endpoint Core layer creates pci_ep directory in the mounted configfs
18 directory. configfs can be mounted using the f 18 directory. configfs can be mounted using the following command::
19 19
20 mount -t configfs none /sys/kernel/con 20 mount -t configfs none /sys/kernel/config
21 21
22 Directory Structure 22 Directory Structure
23 =================== 23 ===================
24 24
25 The pci_ep configfs has two directories at its 25 The pci_ep configfs has two directories at its root: controllers and
26 functions. Every EPC device present in the sys 26 functions. Every EPC device present in the system will have an entry in
27 the *controllers* directory and every EPF driv 27 the *controllers* directory and every EPF driver present in the system
28 will have an entry in the *functions* director 28 will have an entry in the *functions* directory.
29 :: 29 ::
30 30
31 /sys/kernel/config/pci_ep/ 31 /sys/kernel/config/pci_ep/
32 .. controllers/ 32 .. controllers/
33 .. functions/ 33 .. functions/
34 34
35 Creating EPF Device 35 Creating EPF Device
36 =================== 36 ===================
37 37
38 Every registered EPF driver will be listed in 38 Every registered EPF driver will be listed in controllers directory. The
39 entries corresponding to EPF driver will be cr 39 entries corresponding to EPF driver will be created by the EPF core.
40 :: 40 ::
41 41
42 /sys/kernel/config/pci_ep/functions/ 42 /sys/kernel/config/pci_ep/functions/
43 .. <EPF Driver1>/ 43 .. <EPF Driver1>/
44 ... <EPF Device 11>/ 44 ... <EPF Device 11>/
45 ... <EPF Device 21>/ 45 ... <EPF Device 21>/
46 ... <EPF Device 31>/ 46 ... <EPF Device 31>/
47 .. <EPF Driver2>/ 47 .. <EPF Driver2>/
48 ... <EPF Device 12>/ 48 ... <EPF Device 12>/
49 ... <EPF Device 22>/ 49 ... <EPF Device 22>/
50 50
51 In order to create a <EPF device> of the type 51 In order to create a <EPF device> of the type probed by <EPF Driver>, the
52 user has to create a directory inside <EPF Dri 52 user has to create a directory inside <EPF DriverN>.
53 53
54 Every <EPF device> directory consists of the f 54 Every <EPF device> directory consists of the following entries that can be
55 used to configure the standard configuration h 55 used to configure the standard configuration header of the endpoint function.
56 (These entries are created by the framework wh 56 (These entries are created by the framework when any new <EPF Device> is
57 created) 57 created)
58 :: 58 ::
59 59
60 .. <EPF Driver1>/ 60 .. <EPF Driver1>/
61 ... <EPF Device 11>/ 61 ... <EPF Device 11>/
62 ... vendorid 62 ... vendorid
63 ... deviceid 63 ... deviceid
64 ... revid 64 ... revid
65 ... progif_cod 65 ... progif_code
66 ... subclass_c 66 ... subclass_code
67 ... baseclass_ 67 ... baseclass_code
68 ... cache_line 68 ... cache_line_size
69 ... subsys_ven 69 ... subsys_vendor_id
70 ... subsys_id 70 ... subsys_id
71 ... interrupt_ 71 ... interrupt_pin
72 ... <Symlink E 72 ... <Symlink EPF Device 31>/
73 ... primary/ 73 ... primary/
74 ... <S 74 ... <Symlink EPC Device1>/
75 ... secondary/ 75 ... secondary/
76 ... <S 76 ... <Symlink EPC Device2>/
77 77
78 If an EPF device has to be associated with 2 E 78 If an EPF device has to be associated with 2 EPCs (like in the case of
79 Non-transparent bridge), symlink of endpoint c 79 Non-transparent bridge), symlink of endpoint controller connected to primary
80 interface should be added in 'primary' directo 80 interface should be added in 'primary' directory and symlink of endpoint
81 controller connected to secondary interface sh 81 controller connected to secondary interface should be added in 'secondary'
82 directory. 82 directory.
83 83
84 The <EPF Device> directory can have a list of 84 The <EPF Device> directory can have a list of symbolic links
85 (<Symlink EPF Device 31>) to other <EPF Device 85 (<Symlink EPF Device 31>) to other <EPF Device>. These symbolic links should
86 be created by the user to represent the virtua 86 be created by the user to represent the virtual functions that are bound to
87 the physical function. In the above directory 87 the physical function. In the above directory structure <EPF Device 11> is a
88 physical function and <EPF Device 31> is a vir 88 physical function and <EPF Device 31> is a virtual function. An EPF device once
89 it's linked to another EPF device, cannot be l 89 it's linked to another EPF device, cannot be linked to a EPC device.
90 90
91 EPC Device 91 EPC Device
92 ========== 92 ==========
93 93
94 Every registered EPC device will be listed in 94 Every registered EPC device will be listed in controllers directory. The
95 entries corresponding to EPC device will be cr 95 entries corresponding to EPC device will be created by the EPC core.
96 :: 96 ::
97 97
98 /sys/kernel/config/pci_ep/controllers/ 98 /sys/kernel/config/pci_ep/controllers/
99 .. <EPC Device1>/ 99 .. <EPC Device1>/
100 ... <Symlink EPF Devic 100 ... <Symlink EPF Device11>/
101 ... <Symlink EPF Devic 101 ... <Symlink EPF Device12>/
102 ... start 102 ... start
103 .. <EPC Device2>/ 103 .. <EPC Device2>/
104 ... <Symlink EPF Devic 104 ... <Symlink EPF Device21>/
105 ... <Symlink EPF Devic 105 ... <Symlink EPF Device22>/
106 ... start 106 ... start
107 107
108 The <EPC Device> directory will have a list of 108 The <EPC Device> directory will have a list of symbolic links to
109 <EPF Device>. These symbolic links should be c 109 <EPF Device>. These symbolic links should be created by the user to
110 represent the functions present in the endpoin 110 represent the functions present in the endpoint device. Only <EPF Device>
111 that represents a physical function can be lin 111 that represents a physical function can be linked to a EPC device.
112 112
113 The <EPC Device> directory will also have a *s 113 The <EPC Device> directory will also have a *start* field. Once
114 "1" is written to this field, the endpoint dev 114 "1" is written to this field, the endpoint device will be ready to
115 establish the link with the host. This is usua 115 establish the link with the host. This is usually done after
116 all the EPF devices are created and linked wit 116 all the EPF devices are created and linked with the EPC device.
117 :: 117 ::
118 118
119 | controllers/ 119 | controllers/
120 | <Directory: 120 | <Directory: EPC name>/
121 | <Sym 121 | <Symbolic Link: Function>
122 | star 122 | start
123 | functions/ 123 | functions/
124 | <Directory: 124 | <Directory: EPF driver>/
125 | <Dir 125 | <Directory: EPF device>/
126 126 | vendorid
127 127 | deviceid
128 128 | revid
129 129 | progif_code
130 130 | subclass_code
131 131 | baseclass_code
132 132 | cache_line_size
133 133 | subsys_vendor_id
134 134 | subsys_id
135 135 | interrupt_pin
136 136 | function
137 137
138 [1] Documentation/PCI/endpoint/pci-endpoint.rs 138 [1] Documentation/PCI/endpoint/pci-endpoint.rst
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