mei: docs: move documentation under driver-api

Move mei driver documentation under Documentation/driver-api/
Perform some minimal formating changes to produce correct sphinx rendering
and add index.rst

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 424 insertions, 0 deletions

diff --git a/Documentation/driver-api/mei/index.rst b/Documentation/driver-api/mei/index.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+===================================================
+Intel(R) Management Engine Interface (Intel(R) MEI)
+===================================================
+
+**Copyright** |copy| 2019 Intel Corporation
+
+
+.. only:: html
+
+   .. class:: toc-title
+
+        Table of Contents
+
+.. toctree::
+   :maxdepth: 2
+
+   mei
+   mei-client-bus
diff --git a/Documentation/driver-api/mei/mei-client-bus.rst b/Documentation/driver-api/mei/mei-client-bus.rst
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index 000000000000..a26a85453bdf
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+.. SPDX-License-Identifier: GPL-2.0
+
+==============================================
+Intel(R) Management Engine (ME) Client bus API
+==============================================
+
+
+Rationale
+=========
+
+MEI misc character device is useful for dedicated applications to send and receive
+data to the many FW appliance found in Intel's ME from the user space.
+However for some of the ME functionalities it make sense to leverage existing software
+stack and expose them through existing kernel subsystems.
+
+In order to plug seamlessly into the kernel device driver model we add kernel virtual
+bus abstraction on top of the MEI driver. This allows implementing linux kernel drivers
+for the various MEI features as a stand alone entities found in their respective subsystem.
+Existing device drivers can even potentially be re-used by adding an MEI CL bus layer to
+the existing code.
+
+
+MEI CL bus API
+==============
+
+A driver implementation for an MEI Client is very similar to existing bus
+based device drivers. The driver registers itself as an MEI CL bus driver through
+the ``struct mei_cl_driver`` structure:
+
+.. code-block:: C
+
+        struct mei_cl_driver {
+                struct device_driver driver;
+                const char *name;
+
+                const struct mei_cl_device_id *id_table;
+
+                int (*probe)(struct mei_cl_device *dev, const struct mei_cl_id *id);
+                int (*remove)(struct mei_cl_device *dev);
+        };
+
+        struct mei_cl_id {
+                char name[MEI_NAME_SIZE];
+                kernel_ulong_t driver_info;
+        };
+
+The mei_cl_id structure allows the driver to bind itself against a device name.
+
+To actually register a driver on the ME Client bus one must call the mei_cl_add_driver()
+API. This is typically called at module init time.
+
+Once registered on the ME Client bus, a driver will typically try to do some I/O on
+this bus and this should be done through the mei_cl_send() and mei_cl_recv()
+routines. The latter is synchronous (blocks and sleeps until data shows up).
+In order for drivers to be notified of pending events waiting for them (e.g.
+an Rx event) they can register an event handler through the
+mei_cl_register_event_cb() routine. Currently only the MEI_EVENT_RX event
+will trigger an event handler call and the driver implementation is supposed
+to call mei_recv() from the event handler in order to fetch the pending
+received buffers.
+
+
+Example
+=======
+
+As a theoretical example let's pretend the ME comes with a "contact" NFC IP.
+The driver init and exit routines for this device would look like:
+
+.. code-block:: C
+
+	#define CONTACT_DRIVER_NAME "contact"
+
+	static struct mei_cl_device_id contact_mei_cl_tbl[] = {
+		{ CONTACT_DRIVER_NAME, },
+
+		/* required last entry */
+		{ }
+	};
+	MODULE_DEVICE_TABLE(mei_cl, contact_mei_cl_tbl);
+
+	static struct mei_cl_driver contact_driver = {
+		.id_table = contact_mei_tbl,
+		.name = CONTACT_DRIVER_NAME,
+
+		.probe = contact_probe,
+		.remove = contact_remove,
+	};
+
+	static int contact_init(void)
+	{
+		int r;
+
+		r = mei_cl_driver_register(&contact_driver);
+		if (r) {
+			pr_err(CONTACT_DRIVER_NAME ": driver registration failed\n");
+			return r;
+		}
+
+		return 0;
+	}
+
+	static void __exit contact_exit(void)
+	{
+		mei_cl_driver_unregister(&contact_driver);
+	}
+
+	module_init(contact_init);
+	module_exit(contact_exit);
+
+And the driver's simplified probe routine would look like that:
+
+.. code-block:: C
+
+	int contact_probe(struct mei_cl_device *dev, struct mei_cl_device_id *id)
+	{
+		struct contact_driver *contact;
+
+		[...]
+		mei_cl_enable_device(dev);
+
+		mei_cl_register_event_cb(dev, contact_event_cb, contact);
+
+		return 0;
+	}
+
+In the probe routine the driver first enable the MEI device and then registers
+an ME bus event handler which is as close as it can get to registering a
+threaded IRQ handler.
+The handler implementation will typically call some I/O routine depending on
+the pending events:
+
+#define MAX_NFC_PAYLOAD 128
+
+.. code-block:: C
+
+	static void contact_event_cb(struct mei_cl_device *dev, u32 events,
+				     void *context)
+	{
+		struct contact_driver *contact = context;
+
+		if (events & BIT(MEI_EVENT_RX)) {
+			u8 payload[MAX_NFC_PAYLOAD];
+			int payload_size;
+
+			payload_size = mei_recv(dev, payload, MAX_NFC_PAYLOAD);
+			if (payload_size <= 0)
+				return;
+
+			/* Hook to the NFC subsystem */
+			nfc_hci_recv_frame(contact->hdev, payload, payload_size);
+		}
+	}
diff --git a/Documentation/driver-api/mei/mei.rst b/Documentation/driver-api/mei/mei.rst
new file mode 100644
index 000000000000..5aa3a5e6496a
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+++ b/Documentation/driver-api/mei/mei.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+Introduction
+============
+
+The Intel Management Engine (Intel ME) is an isolated and protected computing
+resource (Co-processor) residing inside certain Intel chipsets. The Intel ME
+provides support for computer/IT management features. The feature set
+depends on the Intel chipset SKU.
+
+The Intel Management Engine Interface (Intel MEI, previously known as HECI)
+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
+communication channel between a host application and the Intel ME feature.
+
+Each Intel ME feature (Intel ME Client) is addressed by a GUID/UUID and
+each client has its own protocol. The protocol is message-based with a
+header and payload up to 512 bytes.
+
+Prominent usage of the Intel ME Interface is to communicate with Intel(R)
+Active Management Technology (Intel AMT) implemented in firmware running on
+the Intel ME.
+
+Intel AMT provides the ability to manage a host remotely out-of-band (OOB)
+even when the operating system running on the host processor has crashed or
+is in a sleep state.
+
+Some examples of Intel AMT usage are:
+   - Monitoring hardware state and platform components
+   - Remote power off/on (useful for green computing or overnight IT
+     maintenance)
+   - OS updates
+   - Storage of useful platform information such as software assets
+   - Built-in hardware KVM
+   - Selective network isolation of Ethernet and IP protocol flows based
+     on policies set by a remote management console
+   - IDE device redirection from remote management console
+
+Intel AMT (OOB) communication is based on SOAP (deprecated
+starting with Release 6.0) over HTTP/S or WS-Management protocol over
+HTTP/S that are received from a remote management console application.
+
+For more information about Intel AMT:
+http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide
+
+
+Intel MEI Driver
+================
+
+The driver exposes a misc device called /dev/mei.
+
+An application maintains communication with an Intel ME feature while
+/dev/mei is open. The binding to a specific feature is performed by calling
+MEI_CONNECT_CLIENT_IOCTL, which passes the desired UUID.
+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
+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
+and host application.
+
+Because some of the Intel ME features can change the system
+configuration, the driver by default allows only a privileged
+user to access it.
+
+A code snippet for an application communicating with Intel AMTHI client:
+
+.. code-block:: C
+
+	struct mei_connect_client_data data;
+	fd = open(MEI_DEVICE);
+
+	data.d.in_client_uuid = AMTHI_UUID;
+
+	ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &data);
+
+	printf("Ver=%d, MaxLen=%ld\n",
+			data.d.in_client_uuid.protocol_version,
+			data.d.in_client_uuid.max_msg_length);
+
+	[...]
+
+	write(fd, amthi_req_data, amthi_req_data_len);
+
+	[...]
+
+	read(fd, &amthi_res_data, amthi_res_data_len);
+
+	[...]
+	close(fd);
+
+
+IOCTLs
+======
+
+The Intel MEI Driver supports the following IOCTL commands:
+	IOCTL_MEI_CONNECT_CLIENT	Connect to firmware Feature (client).
+
+	usage:
+		struct mei_connect_client_data clientData;
+		ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &clientData);
+
+	inputs:
+		mei_connect_client_data struct contain the following
+		input field:
+
+		in_client_uuid -	UUID of the FW Feature that needs
+					to connect to.
+	outputs:
+		out_client_properties - Client Properties: MTU and Protocol Version.
+
+	error returns:
+		EINVAL	Wrong IOCTL Number
+		ENODEV	Device or Connection is not initialized or ready. (e.g. Wrong UUID)
+		ENOMEM	Unable to allocate memory to client internal data.
+		EFAULT	Fatal Error (e.g. Unable to access user input data)
+		EBUSY	Connection Already Open
+
+	Notes:
+        max_msg_length (MTU) in client properties describes the maximum
+        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).
+
+	IOCTL_MEI_NOTIFY_SET: enable or disable event notifications
+
+	Usage:
+		uint32_t enable;
+		ioctl(fd, IOCTL_MEI_NOTIFY_SET, &enable);
+
+	Inputs:
+		uint32_t enable = 1;
+		or
+		uint32_t enable[disable] = 0;
+
+	Error returns:
+		EINVAL	Wrong IOCTL Number
+		ENODEV	Device  is not initialized or the client not connected
+		ENOMEM	Unable to allocate memory to client internal data.
+		EFAULT	Fatal Error (e.g. Unable to access user input data)
+		EOPNOTSUPP if the device doesn't support the feature
+
+	Notes:
+	The client must be connected in order to enable notification events
+
+
+	IOCTL_MEI_NOTIFY_GET : retrieve event
+
+	Usage:
+		uint32_t event;
+		ioctl(fd, IOCTL_MEI_NOTIFY_GET, &event);
+
+	Outputs:
+		1 - if an event is pending
+		0 - if there is no even pending
+
+	Error returns:
+		EINVAL	Wrong IOCTL Number
+		ENODEV	Device is not initialized or the client not connected
+		ENOMEM	Unable to allocate memory to client internal data.
+		EFAULT	Fatal Error (e.g. Unable to access user input data)
+		EOPNOTSUPP if the device doesn't support the feature
+
+	Notes:
+	The client must be connected and event notification has to be enabled
+	in order to receive an event
+
+
+Intel ME Applications
+=====================
+
+	1) Intel Local Management Service (Intel LMS)
+
+	   Applications running locally on the platform communicate with Intel AMT Release
+	   2.0 and later releases in the same way that network applications do via SOAP
+	   over HTTP (deprecated starting with Release 6.0) or with WS-Management over
+	   SOAP over HTTP. This means that some Intel AMT features can be accessed from a
+	   local application using the same network interface as a remote application
+	   communicating with Intel AMT over the network.
+
+	   When a local application sends a message addressed to the local Intel AMT host
+	   name, the Intel LMS, which listens for traffic directed to the host name,
+	   intercepts the message and routes it to the Intel MEI.
+	   For more information:
+	   http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide
+	   Under "About Intel AMT" => "Local Access"
+
+	   For downloading Intel LMS:
+	   http://software.intel.com/en-us/articles/download-the-latest-intel-amt-open-source-drivers/
+
+	   The Intel LMS opens a connection using the Intel MEI driver to the Intel LMS
+	   firmware feature using a defined UUID and then communicates with the feature
+	   using a protocol called Intel AMT Port Forwarding Protocol (Intel APF protocol).
+	   The protocol is used to maintain multiple sessions with Intel AMT from a
+	   single application.
+
+	   See the protocol specification in the Intel AMT Software Development Kit (SDK)
+	   http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide
+	   Under "SDK Resources" => "Intel(R) vPro(TM) Gateway (MPS)"
+	   => "Information for Intel(R) vPro(TM) Gateway Developers"
+	   => "Description of the Intel AMT Port Forwarding (APF) Protocol"
+
+	2) Intel AMT Remote configuration using a Local Agent
+
+	   A Local Agent enables IT personnel to configure Intel AMT out-of-the-box
+	   without requiring installing additional data to enable setup. The remote
+	   configuration process may involve an ISV-developed remote configuration
+	   agent that runs on the host.
+	   For more information:
+	   http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide
+	   Under "Setup and Configuration of Intel AMT" =>
+	   "SDK Tools Supporting Setup and Configuration" =>
+	   "Using the Local Agent Sample"
+
+	   An open source Intel AMT configuration utility,	implementing a local agent
+	   that accesses the Intel MEI driver, can be found here:
+	   http://software.intel.com/en-us/articles/download-the-latest-intel-amt-open-source-drivers/
+
+
+Intel AMT OS Health Watchdog
+============================
+
+The Intel AMT Watchdog is an OS Health (Hang/Crash) watchdog.
+Whenever the OS hangs or crashes, Intel AMT will send an event
+to any subscriber to this event. This mechanism means that
+IT knows when a platform crashes even when there is a hard failure on the host.
+
+The Intel AMT Watchdog is composed of two parts:
+	1) Firmware feature - receives the heartbeats
+	   and sends an event when the heartbeats stop.
+	2) Intel MEI iAMT watchdog driver - connects to the watchdog feature,
+	   configures the watchdog and sends the heartbeats.
+
+The Intel iAMT watchdog MEI driver uses the kernel watchdog API to configure
+the Intel AMT Watchdog and to send heartbeats to it. The default timeout of the
+watchdog is 120 seconds.
+
+If the Intel AMT is not enabled in the firmware then the watchdog client won't enumerate
+on the me client bus and watchdog devices won't be exposed.
+
+Supported Chipsets
+==================
+82X38/X48 Express and newer
+
+
+---
+linux-mei@linux.intel.com