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Diffstat (limited to 'Documentation/misc-devices/mei')
| -rw-r--r-- | Documentation/misc-devices/mei/mei-client-bus.txt | 141 | ||||
| -rw-r--r-- | Documentation/misc-devices/mei/mei.txt | 266 |
2 files changed, 407 insertions, 0 deletions
diff --git a/Documentation/misc-devices/mei/mei-client-bus.txt b/Documentation/misc-devices/mei/mei-client-bus.txt new file mode 100644 index 000000000..743be4ec8 --- /dev/null +++ b/Documentation/misc-devices/mei/mei-client-bus.txt @@ -0,0 +1,141 @@ +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 mei_cl_driver structure: + +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: + +#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: + +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 + +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/misc-devices/mei/mei.txt b/Documentation/misc-devices/mei/mei.txt new file mode 100644 index 000000000..2b80a0cd6 --- /dev/null +++ b/Documentation/misc-devices/mei/mei.txt @@ -0,0 +1,266 @@ +Intel(R) Management Engine Interface (Intel(R) MEI) +=================================================== + +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: + + 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); + + +IOCTL +===== + +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 +================== + +7 Series Chipset Family +6 Series Chipset Family +5 Series Chipset Family +4 Series Chipset Family +Mobile 4 Series Chipset Family +ICH9 +82946GZ/GL +82G35 Express +82Q963/Q965 +82P965/G965 +Mobile PM965/GM965 +Mobile GME965/GLE960 +82Q35 Express +82G33/G31/P35/P31 Express +82Q33 Express +82X38/X48 Express + +--- +linux-mei@linux.intel.com |