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mei: docs: update mei documentation 

The mei driver went via multiple changes, update
the documentation and fix formatting.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Tomas Winkler 2019-06-06 16:31:08 +03:00 committed by Greg Kroah-Hartman
parent 0e3743d870
commit d0a178095c
1 changed files with 61 additions and 35 deletions
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96
Documentation/driver-api/mei/mei.rst
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@ -5,34 +5,32 @@ Introduction
The Intel Management Engine (Intel ME) is an isolated and protected computing The Intel Management Engine (Intel ME) is an isolated and protected computing
resource (Co-processor) residing inside certain Intel chipsets. The Intel ME resource (Co-processor) residing inside certain Intel chipsets. The Intel ME
provides support for computer/IT management features. The feature set provides support for computer/IT management and security features.
depends on the Intel chipset SKU. The actual feature set depends on the Intel chipset SKU.
The Intel Management Engine Interface (Intel MEI, previously known as HECI) The Intel Management Engine Interface (Intel MEI, previously known as HECI)
is the interface between the Host and Intel ME. This interface is exposed is the interface between the Host and Intel ME. This interface is exposed
to the host as a PCI device. The Intel MEI Driver is in charge of the to the host as a PCI device, actually multiple PCI devices might be exposed.
communication channel between a host application and the Intel ME feature. The Intel MEI Driver is in charge of the communication channel between
a host application and the Intel ME features.
Each Intel ME feature (Intel ME Client) is addressed by a GUID/UUID and Each Intel ME feature, or Intel ME Client is addressed by a unique GUID and
each client has its own protocol. The protocol is message-based with a each client has its own protocol. The protocol is message-based with a
header and payload up to 512 bytes. header and payload up to maximal number of bytes advertised by the client,
upon connection.
Intel MEI Driver Intel MEI Driver
================ ================
The driver exposes a misc device called /dev/mei. The driver exposes a character device with device nodes /dev/meiX.
An application maintains communication with an Intel ME feature while An application maintains communication with an Intel ME feature while
/dev/mei is open. The binding to a specific feature is performed by calling /dev/meiX is open. The binding to a specific feature is performed by calling
MEI_CONNECT_CLIENT_IOCTL, which passes the desired UUID. :c:macro:`MEI_CONNECT_CLIENT_IOCTL`, which passes the desired GUID.
The number of instances of an Intel ME feature that can be opened The number of instances of an Intel ME feature that can be opened
at the same time depends on the Intel ME feature, but most of the at the same time depends on the Intel ME feature, but most of the
features allow only a single instance. features allow only a single instance.
The Intel AMT Host Interface (Intel AMTHI) feature supports multiple
simultaneous user connected applications. The Intel MEI driver
handles this internally by maintaining request queues for the applications.
The driver is transparent to data that are passed between firmware feature The driver is transparent to data that are passed between firmware feature
and host application. and host application.
@ -40,6 +38,8 @@ Because some of the Intel ME features can change the system
configuration, the driver by default allows only a privileged configuration, the driver by default allows only a privileged
user to access it. user to access it.
The session is terminated calling :c:func:`close(int fd)`.
A code snippet for an application communicating with Intel AMTHI client: A code snippet for an application communicating with Intel AMTHI client:
.. code-block:: C .. code-block:: C
@ -47,13 +47,13 @@ A code snippet for an application communicating with Intel AMTHI client:
struct mei_connect_client_data data; struct mei_connect_client_data data;
fd = open(MEI_DEVICE); fd = open(MEI_DEVICE);
data.d.in_client_uuid = AMTHI_UUID; data.d.in_client_uuid = AMTHI_GUID;
ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &data); ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &data);
printf("Ver=%d, MaxLen=%ld\n", printf("Ver=%d, MaxLen=%ld\n",
data.d.in_client_uuid.protocol_version, data.d.in_client_uuid.protocol_version,
data.d.in_client_uuid.max_msg_length); data.d.in_client_uuid.max_msg_length);
[...] [...]
@ -67,60 +67,86 @@ A code snippet for an application communicating with Intel AMTHI client:
close(fd); close(fd);
IOCTLs User space API
======
IOCTLs:
=======
The Intel MEI Driver supports the following IOCTL commands: The Intel MEI Driver supports the following IOCTL commands:
IOCTL_MEI_CONNECT_CLIENT Connect to firmware Feature (client).
usage: IOCTL_MEI_CONNECT_CLIENT
struct mei_connect_client_data clientData; -------------------------
ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &clientData); Connect to firmware Feature/Client.
inputs: .. code-block:: none
mei_connect_client_data struct contain the following
input field:
in_client_uuid - UUID of the FW Feature that needs Usage:
struct mei_connect_client_data client_data;
ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &client_data);
Inputs:
struct mei_connect_client_data - contain the following
Input field:
in_client_uuid - GUID of the FW Feature that needs
to connect to. to connect to.
outputs: Outputs:
out_client_properties - Client Properties: MTU and Protocol Version. out_client_properties - Client Properties: MTU and Protocol Version.
error returns: Error returns:
ENOTTY No such client (i.e. wrong GUID) or connection is not allowed.
EINVAL Wrong IOCTL Number EINVAL Wrong IOCTL Number
ENODEV Device or Connection is not initialized or ready. (e.g. Wrong UUID) ENODEV Device or Connection is not initialized or ready.
ENOMEM Unable to allocate memory to client internal data. ENOMEM Unable to allocate memory to client internal data.
EFAULT Fatal Error (e.g. Unable to access user input data) EFAULT Fatal Error (e.g. Unable to access user input data)
EBUSY Connection Already Open EBUSY Connection Already Open
Notes: :Note:
max_msg_length (MTU) in client properties describes the maximum max_msg_length (MTU) in client properties describes the maximum
data that can be sent or received. (e.g. if MTU=2K, can send data that can be sent or received. (e.g. if MTU=2K, can send
requests up to bytes 2k and received responses up to 2k bytes). requests up to bytes 2k and received responses up to 2k bytes).
IOCTL_MEI_NOTIFY_SET: enable or disable event notifications
IOCTL_MEI_NOTIFY_SET
---------------------
Enable or disable event notifications.
.. code-block:: none
Usage: Usage:
uint32_t enable; uint32_t enable;
ioctl(fd, IOCTL_MEI_NOTIFY_SET, &enable); ioctl(fd, IOCTL_MEI_NOTIFY_SET, &enable);
Inputs:
uint32_t enable = 1; uint32_t enable = 1;
or or
uint32_t enable[disable] = 0; uint32_t enable[disable] = 0;
Error returns: Error returns:
EINVAL Wrong IOCTL Number EINVAL Wrong IOCTL Number
ENODEV Device is not initialized or the client not connected ENODEV Device is not initialized or the client not connected
ENOMEM Unable to allocate memory to client internal data. ENOMEM Unable to allocate memory to client internal data.
EFAULT Fatal Error (e.g. Unable to access user input data) EFAULT Fatal Error (e.g. Unable to access user input data)
EOPNOTSUPP if the device doesn't support the feature EOPNOTSUPP if the device doesn't support the feature
Notes: :Note:
The client must be connected in order to enable notification events The client must be connected in order to enable notification events
IOCTL_MEI_NOTIFY_GET : retrieve event IOCTL_MEI_NOTIFY_GET
--------------------
Retrieve event
.. code-block:: none
Usage: Usage:
uint32_t event; uint32_t event;
@ -137,7 +163,7 @@ The Intel MEI Driver supports the following IOCTL commands:
EFAULT Fatal Error (e.g. Unable to access user input data) EFAULT Fatal Error (e.g. Unable to access user input data)
EOPNOTSUPP if the device doesn't support the feature EOPNOTSUPP if the device doesn't support the feature
Notes: :Note:
The client must be connected and event notification has to be enabled The client must be connected and event notification has to be enabled
in order to receive an event in order to receive an event