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-----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE+QmuaPwR3wnBdVwACF8+vY7k4RUFAl+JNGYACgkQCF8+vY7k 4RV/TA//ZoRoMQE5B6zwO4kOGILMbmW2uepjoEysLgus2ctkTUoRkpNLWS3SozcU 6c/eW1rC4Fji24te6lwusciZa5zQgbGMjFYk1LhnJ65lJA+kQ+kV1DGz/ZWtklMM gLX20+tQADqGl+u2dmFCvmRhPWJ9nzt1C0auN7dGeu+9g97GnhKG6o2Kv/nVCb68 qMmAs9UrfN24DO5G1ixkdY08nSNJPrpgQnIR2ruUysUII/yTTtcnmHDbH3WWL6+9 2P87AZ6zsa3FdBhAjmG5YJklQgPkLFWEykHMTqq/Mkcpff/JB/AayrL6XNB2QoZb YXLHJp3Na6iBmdmHhecg+VQDgz28UfMk+p+HFoJh8RTtJa9/qJvYdJmIE/mUPrnY gL4jNgMVwkptGHXh7IRuSLysT5heJPMQss6TfZ6yYadeOIpx7W8MCAYnGffiElLQ hmKdmyCszS3SERJz40EOBdr2NQYcDEUt2NtEhdVfium21A4PFOdJlCejifGhJyzP n1QcyMXHnh/d4zecA6fcD0LVyxBgngeKEvdtOLZJ1ubxWwHhgWTN8R4HedoN2Nb9 cLEUK8Td+9n2RVS8UED4BBI+6vfN3Y6Syjvy8qD3pCs4SBcu3k790mf47t2QhkEq +Ho06gdrGJdEcSDO8zVY7qjZX/GX/dbRHCb5CRokL5FmNWhXd/Y= =26wi -----END PGP SIGNATURE----- Merge tag 'docs/v5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media Pull documentation updates from Mauro Carvalho Chehab: "A series of patches addressing warnings produced by make htmldocs. This includes: - kernel-doc markup fixes - ReST fixes - Updates at the build system in order to support newer versions of the docs build toolchain (Sphinx) After this series, the number of html build warnings should reduce significantly, and building with Sphinx 3.1 or later should now be supported (although it is still recommended to use Sphinx 2.4.4). As agreed with Jon, I should be sending you a late pull request by the end of the merge window addressing remaining issues with docs build, as there are a number of warning fixes that depends on pull requests that should be happening along the merge window. The end goal is to have a clean htmldocs build on Kernel 5.10. PS. It should be noticed that Sphinx 3.0 is not currently supported, as it lacks support for C domain namespaces. Such feature, needed in order to document uAPI system calls with Sphinx 3.x, was added only on Sphinx 3.1" * tag 'docs/v5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (75 commits) PM / devfreq: remove a duplicated kernel-doc markup mm/doc: fix a literal block markup workqueue: fix a kernel-doc warning docs: virt: user_mode_linux_howto_v2.rst: fix a literal block markup Input: sparse-keymap: add a description for @sw rcu/tree: docs: document bkvcache new members at struct kfree_rcu_cpu nl80211: docs: add a description for s1g_cap parameter usb: docs: document altmode register/unregister functions kunit: test.h: fix a bad kernel-doc markup drivers: core: fix kernel-doc markup for dev_err_probe() docs: bio: fix a kerneldoc markup kunit: test.h: solve kernel-doc warnings block: bio: fix a warning at the kernel-doc markups docs: powerpc: syscall64-abi.rst: fix a malformed table drivers: net: hamradio: fix document location net: appletalk: Kconfig: Fix docs location dt-bindings: fix references to files converted to yaml memblock: get rid of a :c:type leftover math64.h: kernel-docs: Convert some markups into normal comments media: uAPI: buffer.rst: remove a left-over documentation ...
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.. SPDX-License-Identifier: GPL-2.0
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Introduction
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============
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The Intel Management Engine (Intel ME) is an isolated and protected computing
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resource (Co-processor) residing inside certain Intel chipsets. The Intel ME
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provides support for computer/IT management and security features.
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The actual feature set depends on the Intel chipset SKU.
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The Intel Management Engine Interface (Intel MEI, previously known as HECI)
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is the interface between the Host and Intel ME. This interface is exposed
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to the host as a PCI device, actually multiple PCI devices might be exposed.
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The Intel MEI Driver is in charge of the communication channel between
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a host application and the Intel ME features.
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Each Intel ME feature, or Intel ME Client is addressed by a unique GUID and
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each client has its own protocol. The protocol is message-based with a
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header and payload up to maximal number of bytes advertised by the client,
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upon connection.
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Intel MEI Driver
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================
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The driver exposes a character device with device nodes /dev/meiX.
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An application maintains communication with an Intel ME feature while
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/dev/meiX is open. The binding to a specific feature is performed by calling
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:c:macro:`MEI_CONNECT_CLIENT_IOCTL`, which passes the desired GUID.
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The number of instances of an Intel ME feature that can be opened
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at the same time depends on the Intel ME feature, but most of the
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features allow only a single instance.
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The driver is transparent to data that are passed between firmware feature
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and host application.
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Because some of the Intel ME features can change the system
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configuration, the driver by default allows only a privileged
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user to access it.
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The session is terminated calling :c:expr:`close(fd)`.
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A code snippet for an application communicating with Intel AMTHI client:
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In order to support virtualization or sandboxing a trusted supervisor
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can use :c:macro:`MEI_CONNECT_CLIENT_IOCTL_VTAG` to create
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virtual channels with an Intel ME feature. Not all features support
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virtual channels such client with answer EOPNOTSUPP.
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.. code-block:: C
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struct mei_connect_client_data data;
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fd = open(MEI_DEVICE);
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data.d.in_client_uuid = AMTHI_GUID;
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ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &data);
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printf("Ver=%d, MaxLen=%ld\n",
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data.d.in_client_uuid.protocol_version,
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data.d.in_client_uuid.max_msg_length);
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[...]
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write(fd, amthi_req_data, amthi_req_data_len);
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[...]
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read(fd, &amthi_res_data, amthi_res_data_len);
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[...]
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close(fd);
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User space API
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IOCTLs:
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=======
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The Intel MEI Driver supports the following IOCTL commands:
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IOCTL_MEI_CONNECT_CLIENT
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-------------------------
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Connect to firmware Feature/Client.
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.. code-block:: none
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Usage:
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struct mei_connect_client_data client_data;
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ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &client_data);
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Inputs:
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struct mei_connect_client_data - contain the following
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Input field:
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in_client_uuid - GUID of the FW Feature that needs
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to connect to.
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Outputs:
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out_client_properties - Client Properties: MTU and Protocol Version.
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Error returns:
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ENOTTY No such client (i.e. wrong GUID) or connection is not allowed.
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EINVAL Wrong IOCTL Number
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ENODEV Device or Connection is not initialized or ready.
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ENOMEM Unable to allocate memory to client internal data.
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EFAULT Fatal Error (e.g. Unable to access user input data)
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EBUSY Connection Already Open
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:Note:
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max_msg_length (MTU) in client properties describes the maximum
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data that can be sent or received. (e.g. if MTU=2K, can send
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requests up to bytes 2k and received responses up to 2k bytes).
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IOCTL_MEI_CONNECT_CLIENT_VTAG:
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------------------------------
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.. code-block:: none
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Usage:
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struct mei_connect_client_data_vtag client_data_vtag;
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ioctl(fd, IOCTL_MEI_CONNECT_CLIENT_VTAG, &client_data_vtag);
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Inputs:
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struct mei_connect_client_data_vtag - contain the following
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Input field:
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in_client_uuid - GUID of the FW Feature that needs
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to connect to.
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vtag - virtual tag [1, 255]
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Outputs:
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out_client_properties - Client Properties: MTU and Protocol Version.
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Error returns:
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ENOTTY No such client (i.e. wrong GUID) or connection is not allowed.
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EINVAL Wrong IOCTL Number or tag == 0
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ENODEV Device or Connection is not initialized or ready.
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ENOMEM Unable to allocate memory to client internal data.
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EFAULT Fatal Error (e.g. Unable to access user input data)
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EBUSY Connection Already Open
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EOPNOTSUPP Vtag is not supported
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IOCTL_MEI_NOTIFY_SET
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---------------------
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Enable or disable event notifications.
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.. code-block:: none
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Usage:
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uint32_t enable;
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ioctl(fd, IOCTL_MEI_NOTIFY_SET, &enable);
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uint32_t enable = 1;
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or
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uint32_t enable[disable] = 0;
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Error returns:
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EINVAL Wrong IOCTL Number
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ENODEV Device is not initialized or the client not connected
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ENOMEM Unable to allocate memory to client internal data.
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EFAULT Fatal Error (e.g. Unable to access user input data)
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EOPNOTSUPP if the device doesn't support the feature
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:Note:
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The client must be connected in order to enable notification events
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IOCTL_MEI_NOTIFY_GET
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--------------------
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Retrieve event
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.. code-block:: none
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Usage:
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uint32_t event;
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ioctl(fd, IOCTL_MEI_NOTIFY_GET, &event);
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Outputs:
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1 - if an event is pending
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0 - if there is no even pending
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Error returns:
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EINVAL Wrong IOCTL Number
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ENODEV Device is not initialized or the client not connected
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ENOMEM Unable to allocate memory to client internal data.
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EFAULT Fatal Error (e.g. Unable to access user input data)
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EOPNOTSUPP if the device doesn't support the feature
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:Note:
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The client must be connected and event notification has to be enabled
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in order to receive an event
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Supported Chipsets
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==================
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82X38/X48 Express and newer
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linux-mei@linux.intel.com
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