1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 Introduction 3 Introduction
4 ============ 4 ============
5 5
6 The Intel Management Engine (Intel ME) is an i 6 The Intel Management Engine (Intel ME) is an isolated and protected computing
7 resource (Co-processor) residing inside certai 7 resource (Co-processor) residing inside certain Intel chipsets. The Intel ME
8 provides support for computer/IT management an 8 provides support for computer/IT management and security features.
9 The actual feature set depends on the Intel ch 9 The actual feature set depends on the Intel chipset SKU.
10 10
11 The Intel Management Engine Interface (Intel M 11 The Intel Management Engine Interface (Intel MEI, previously known as HECI)
12 is the interface between the Host and Intel ME 12 is the interface between the Host and Intel ME. This interface is exposed
13 to the host as a PCI device, actually multiple 13 to the host as a PCI device, actually multiple PCI devices might be exposed.
14 The Intel MEI Driver is in charge of the commu 14 The Intel MEI Driver is in charge of the communication channel between
15 a host application and the Intel ME features. 15 a host application and the Intel ME features.
16 16
17 Each Intel ME feature, or Intel ME Client is a 17 Each Intel ME feature, or Intel ME Client is addressed by a unique GUID and
18 each client has its own protocol. The protocol 18 each client has its own protocol. The protocol is message-based with a
19 header and payload up to maximal number of byt 19 header and payload up to maximal number of bytes advertised by the client,
20 upon connection. 20 upon connection.
21 21
22 Intel MEI Driver 22 Intel MEI Driver
23 ================ 23 ================
24 24
25 The driver exposes a character device with dev 25 The driver exposes a character device with device nodes /dev/meiX.
26 26
27 An application maintains communication with an 27 An application maintains communication with an Intel ME feature while
28 /dev/meiX is open. The binding to a specific f 28 /dev/meiX is open. The binding to a specific feature is performed by calling
29 :c:macro:`MEI_CONNECT_CLIENT_IOCTL`, which pas 29 :c:macro:`MEI_CONNECT_CLIENT_IOCTL`, which passes the desired GUID.
30 The number of instances of an Intel ME feature 30 The number of instances of an Intel ME feature that can be opened
31 at the same time depends on the Intel ME featu 31 at the same time depends on the Intel ME feature, but most of the
32 features allow only a single instance. 32 features allow only a single instance.
33 33
34 The driver is transparent to data that are pas 34 The driver is transparent to data that are passed between firmware feature
35 and host application. 35 and host application.
36 36
37 Because some of the Intel ME features can chan 37 Because some of the Intel ME features can change the system
38 configuration, the driver by default allows on 38 configuration, the driver by default allows only a privileged
39 user to access it. 39 user to access it.
40 40
41 The session is terminated calling :c:expr:`clo 41 The session is terminated calling :c:expr:`close(fd)`.
42 42
43 A code snippet for an application communicatin 43 A code snippet for an application communicating with Intel AMTHI client:
44 44
45 In order to support virtualization or sandboxi 45 In order to support virtualization or sandboxing a trusted supervisor
46 can use :c:macro:`MEI_CONNECT_CLIENT_IOCTL_VTA 46 can use :c:macro:`MEI_CONNECT_CLIENT_IOCTL_VTAG` to create
47 virtual channels with an Intel ME feature. Not 47 virtual channels with an Intel ME feature. Not all features support
48 virtual channels such client with answer EOPNO 48 virtual channels such client with answer EOPNOTSUPP.
49 49
50 .. code-block:: C 50 .. code-block:: C
51 51
52 struct mei_connect_client_data data; 52 struct mei_connect_client_data data;
53 fd = open(MEI_DEVICE); 53 fd = open(MEI_DEVICE);
54 54
55 data.d.in_client_uuid = AMTHI_GUID; 55 data.d.in_client_uuid = AMTHI_GUID;
56 56
57 ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &d 57 ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &data);
58 58
59 printf("Ver=%d, MaxLen=%ld\n", 59 printf("Ver=%d, MaxLen=%ld\n",
60 data.d.in_client_uuid.protocol_ 60 data.d.in_client_uuid.protocol_version,
61 data.d.in_client_uuid.max_msg_l 61 data.d.in_client_uuid.max_msg_length);
62 62
63 [...] 63 [...]
64 64
65 write(fd, amthi_req_data, amthi_req_da 65 write(fd, amthi_req_data, amthi_req_data_len);
66 66
67 [...] 67 [...]
68 68
69 read(fd, &amthi_res_data, amthi_res_da 69 read(fd, &amthi_res_data, amthi_res_data_len);
70 70
71 [...] 71 [...]
72 close(fd); 72 close(fd);
73 73
74 74
75 User space API 75 User space API
76 76
77 IOCTLs: 77 IOCTLs:
78 ======= 78 =======
79 79
80 The Intel MEI Driver supports the following IO 80 The Intel MEI Driver supports the following IOCTL commands:
81 81
82 IOCTL_MEI_CONNECT_CLIENT 82 IOCTL_MEI_CONNECT_CLIENT
83 ------------------------- 83 -------------------------
84 Connect to firmware Feature/Client. 84 Connect to firmware Feature/Client.
85 85
86 .. code-block:: none 86 .. code-block:: none
87 87
88 Usage: 88 Usage:
89 89
90 struct mei_connect_client_data client_ 90 struct mei_connect_client_data client_data;
91 91
92 ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &c 92 ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &client_data);
93 93
94 Inputs: 94 Inputs:
95 95
96 struct mei_connect_client_data - conta 96 struct mei_connect_client_data - contain the following
97 Input field: 97 Input field:
98 98
99 in_client_uuid - GUID o 99 in_client_uuid - GUID of the FW Feature that needs
100 to con 100 to connect to.
101 Outputs: 101 Outputs:
102 out_client_properties - Client 102 out_client_properties - Client Properties: MTU and Protocol Version.
103 103
104 Error returns: 104 Error returns:
105 105
106 ENOTTY No such client (i.e. w 106 ENOTTY No such client (i.e. wrong GUID) or connection is not allowed.
107 EINVAL Wrong IOCTL Number 107 EINVAL Wrong IOCTL Number
108 ENODEV Device or Connection i 108 ENODEV Device or Connection is not initialized or ready.
109 ENOMEM Unable to allocate mem 109 ENOMEM Unable to allocate memory to client internal data.
110 EFAULT Fatal Error (e.g. Unab 110 EFAULT Fatal Error (e.g. Unable to access user input data)
111 EBUSY Connection Already Ope 111 EBUSY Connection Already Open
112 112
113 :Note: 113 :Note:
114 max_msg_length (MTU) in client propert 114 max_msg_length (MTU) in client properties describes the maximum
115 data that can be sent or received. (e. 115 data that can be sent or received. (e.g. if MTU=2K, can send
116 requests up to bytes 2k and received r 116 requests up to bytes 2k and received responses up to 2k bytes).
117 117
118 IOCTL_MEI_CONNECT_CLIENT_VTAG: 118 IOCTL_MEI_CONNECT_CLIENT_VTAG:
119 ------------------------------ 119 ------------------------------
120 120
121 .. code-block:: none 121 .. code-block:: none
122 122
123 Usage: 123 Usage:
124 124
125 struct mei_connect_client_data_vtag cl 125 struct mei_connect_client_data_vtag client_data_vtag;
126 126
127 ioctl(fd, IOCTL_MEI_CONNECT_CLIENT_VTA 127 ioctl(fd, IOCTL_MEI_CONNECT_CLIENT_VTAG, &client_data_vtag);
128 128
129 Inputs: 129 Inputs:
130 130
131 struct mei_connect_client_data_vtag - 131 struct mei_connect_client_data_vtag - contain the following
132 Input field: 132 Input field:
133 133
134 in_client_uuid - GUID of the 134 in_client_uuid - GUID of the FW Feature that needs
135 to connect t 135 to connect to.
136 vtag - virtual tag [1, 255] 136 vtag - virtual tag [1, 255]
137 137
138 Outputs: 138 Outputs:
139 out_client_properties - Client 139 out_client_properties - Client Properties: MTU and Protocol Version.
140 140
141 Error returns: 141 Error returns:
142 142
143 ENOTTY No such client (i.e. wr 143 ENOTTY No such client (i.e. wrong GUID) or connection is not allowed.
144 EINVAL Wrong IOCTL Number or t 144 EINVAL Wrong IOCTL Number or tag == 0
145 ENODEV Device or Connection is 145 ENODEV Device or Connection is not initialized or ready.
146 ENOMEM Unable to allocate memo 146 ENOMEM Unable to allocate memory to client internal data.
147 EFAULT Fatal Error (e.g. Unabl 147 EFAULT Fatal Error (e.g. Unable to access user input data)
148 EBUSY Connection Already Open 148 EBUSY Connection Already Open
149 EOPNOTSUPP Vtag is not support 149 EOPNOTSUPP Vtag is not supported
150 150
151 IOCTL_MEI_NOTIFY_SET 151 IOCTL_MEI_NOTIFY_SET
152 --------------------- 152 ---------------------
153 Enable or disable event notifications. 153 Enable or disable event notifications.
154 154
155 155
156 .. code-block:: none 156 .. code-block:: none
157 157
158 Usage: 158 Usage:
159 159
160 uint32_t enable; 160 uint32_t enable;
161 161
162 ioctl(fd, IOCTL_MEI_NOTIFY_SET 162 ioctl(fd, IOCTL_MEI_NOTIFY_SET, &enable);
163 163
164 164
165 uint32_t enable = 1; 165 uint32_t enable = 1;
166 or 166 or
167 uint32_t enable[disable] = 0; 167 uint32_t enable[disable] = 0;
168 168
169 Error returns: 169 Error returns:
170 170
171 171
172 EINVAL Wrong IOCTL Number 172 EINVAL Wrong IOCTL Number
173 ENODEV Device is not initial 173 ENODEV Device is not initialized or the client not connected
174 ENOMEM Unable to allocate mem 174 ENOMEM Unable to allocate memory to client internal data.
175 EFAULT Fatal Error (e.g. Unab 175 EFAULT Fatal Error (e.g. Unable to access user input data)
176 EOPNOTSUPP if the device doesn 176 EOPNOTSUPP if the device doesn't support the feature
177 177
178 :Note: 178 :Note:
179 The client must be connected in order 179 The client must be connected in order to enable notification events
180 180
181 181
182 IOCTL_MEI_NOTIFY_GET 182 IOCTL_MEI_NOTIFY_GET
183 -------------------- 183 --------------------
184 Retrieve event 184 Retrieve event
185 185
186 .. code-block:: none 186 .. code-block:: none
187 187
188 Usage: 188 Usage:
189 uint32_t event; 189 uint32_t event;
190 ioctl(fd, IOCTL_MEI_NOTIFY_GET 190 ioctl(fd, IOCTL_MEI_NOTIFY_GET, &event);
191 191
192 Outputs: 192 Outputs:
193 1 - if an event is pending 193 1 - if an event is pending
194 0 - if there is no even pendin 194 0 - if there is no even pending
195 195
196 Error returns: 196 Error returns:
197 EINVAL Wrong IOCTL Number 197 EINVAL Wrong IOCTL Number
198 ENODEV Device is not initiali 198 ENODEV Device is not initialized or the client not connected
199 ENOMEM Unable to allocate mem 199 ENOMEM Unable to allocate memory to client internal data.
200 EFAULT Fatal Error (e.g. Unab 200 EFAULT Fatal Error (e.g. Unable to access user input data)
201 EOPNOTSUPP if the device doesn 201 EOPNOTSUPP if the device doesn't support the feature
202 202
203 :Note: 203 :Note:
204 The client must be connected and event 204 The client must be connected and event notification has to be enabled
205 in order to receive an event 205 in order to receive an event
206 206
207 207
208 208
209 Supported Chipsets 209 Supported Chipsets
210 ================== 210 ==================
211 82X38/X48 Express and newer 211 82X38/X48 Express and newer
212 212
213 linux-mei@linux.intel.com 213 linux-mei@linux.intel.com
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