1 .. SPDX-License-Identifier: GPL-2.0
2
3 ==============================================
4 Intel(R) Management Engine (ME) Client bus API
5 ==============================================
6
7
8 Rationale
9 =========
10
11 The MEI character device is useful for dedicat
12 data to the many FW appliance found in Intel's
13 However, for some of the ME functionalities it
14 stack and expose them through existing kernel
15
16 In order to plug seamlessly into the kernel de
17 bus abstraction on top of the MEI driver. This
18 for the various MEI features as a stand alone
19 Existing device drivers can even potentially b
20 the existing code.
21
22
23 MEI CL bus API
24 ==============
25
26 A driver implementation for an MEI Client is v
27 based device drivers. The driver registers its
28 the ``struct mei_cl_driver`` structure defined
29
30 .. code-block:: C
31
32 struct mei_cl_driver {
33 struct device_driver driver;
34 const char *name;
35
36 const struct mei_cl_device_id
37
38 int (*probe)(struct mei_cl_dev
39 int (*remove)(struct mei_cl_de
40 };
41
42
43
44 The mei_cl_device_id structure defined in :fil
45 driver to bind itself against a device name.
46
47 .. code-block:: C
48
49 struct mei_cl_device_id {
50 char name[MEI_CL_NAME_SIZE];
51 uuid_le uuid;
52 __u8 version;
53 kernel_ulong_t driver_info;
54 };
55
56 To actually register a driver on the ME Client
57 API. This is typically called at module initia
58
59 Once the driver is registered and bound to the
60 try to do some I/O on this bus and this should
61 and :c:func:`mei_cl_recv` functions. More deta
62
63 In order for a driver to be notified about pen
64 should register a callback via :c:func:`mei_cl
65 :c:func:`mei_cldev_register_notify_cb` functio
66
67 .. _api:
68
69 API:
70 ----
71 .. kernel-doc:: drivers/misc/mei/bus.c
72 :export: drivers/misc/mei/bus.c
73
74
75
76 Example
77 =======
78
79 As a theoretical example let's pretend the ME
80 The driver init and exit routines for this dev
81
82 .. code-block:: C
83
84 #define CONTACT_DRIVER_NAME "contact"
85
86 static struct mei_cl_device_id contact
87 { CONTACT_DRIVER_NAME, },
88
89 /* required last entry */
90 { }
91 };
92 MODULE_DEVICE_TABLE(mei_cl, contact_me
93
94 static struct mei_cl_driver contact_dr
95 .id_table = contact_mei_tbl,
96 .name = CONTACT_DRIVER_NAME,
97
98 .probe = contact_probe,
99 .remove = contact_remove,
100 };
101
102 static int contact_init(void)
103 {
104 int r;
105
106 r = mei_cl_driver_register(&co
107 if (r) {
108 pr_err(CONTACT_DRIVER_
109 return r;
110 }
111
112 return 0;
113 }
114
115 static void __exit contact_exit(void)
116 {
117 mei_cl_driver_unregister(&cont
118 }
119
120 module_init(contact_init);
121 module_exit(contact_exit);
122
123 And the driver's simplified probe routine woul
124
125 .. code-block:: C
126
127 int contact_probe(struct mei_cl_device
128 {
129 [...]
130 mei_cldev_enable(dev);
131
132 mei_cldev_register_rx_cb(dev,
133
134 return 0;
135 }
136
137 In the probe routine the driver first enable t
138 an rx handler which is as close as it can get
139 The handler implementation will typically call
140 process received data.
141
142 .. code-block:: C
143
144 #define MAX_PAYLOAD 128
145 #define HDR_SIZE 4
146 static void conntact_rx_cb(struct mei_
147 {
148 struct contact *c = mei_cldev_
149 unsigned char payload[MAX_PAYL
150 ssize_t payload_sz;
151
152 payload_sz = mei_cldev_recv(cl
153 if (reply_size < HDR_SIZE) {
154 return;
155 }
156
157 c->process_rx(payload);
158
159 }
160
161 MEI Client Bus Drivers
162 ======================
163
164 .. toctree::
165 :maxdepth: 2
166
167 hdcp
168 nfc
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