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Documentation: hid: intel-ish-hid: remove section numbering
Remove section numbering from the Intel Integrated Sensor Hub (ISH) documentation to simplify the structure, making it easier to maintain and update in the future. Suggested-by: Andy Shevchenko <andriy.shevchenko@intel.com> Signed-off-by: Qianru Huang <qianru.huang@intel.com> Signed-off-by: Zhang Lixu <lixu.zhang@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Jiri Kosina <jkosina@suse.com>
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Qianru Huang
Jiri Kosina
parent
b06271e897
commit
806a4c35d7
@ -18,8 +18,8 @@ These ISH also comply to HID sensor specification, but the difference is the
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transport protocol used for communication. The current external sensor hubs
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mainly use HID over I2C or USB. But ISH doesn't use either I2C or USB.
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1. Overview
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===========
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Overview
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========
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Using a analogy with a usbhid implementation, the ISH follows a similar model
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for a very high speed communication::
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@ -58,8 +58,8 @@ implemented as a bus. Each client application executing in the ISH processor
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is registered as a device on this bus. The driver, which binds each device
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(ISH HID driver) identifies the device type and registers with the HID core.
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2. ISH Implementation: Block Diagram
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====================================
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ISH Implementation: Block Diagram
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=================================
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::
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@ -96,27 +96,27 @@ is registered as a device on this bus. The driver, which binds each device
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| ISH Hardware/Firmware(FW) |
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----------------------------
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3. High level processing in above blocks
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========================================
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High level processing in above blocks
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=====================================
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3.1 Hardware Interface
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----------------------
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Hardware Interface
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------------------
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The ISH is exposed as "Non-VGA unclassified PCI device" to the host. The PCI
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product and vendor IDs are changed from different generations of processors. So
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the source code which enumerates drivers needs to update from generation to
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generation.
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3.2 Inter Processor Communication (IPC) driver
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----------------------------------------------
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Inter Processor Communication (IPC) driver
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------------------------------------------
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Location: drivers/hid/intel-ish-hid/ipc
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The IPC message uses memory mapped I/O. The registers are defined in
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hw-ish-regs.h.
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3.2.1 IPC/FW message types
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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IPC/FW message types
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^^^^^^^^^^^^^^^^^^^^
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There are two types of messages, one for management of link and another for
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messages to and from transport layers.
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@ -142,20 +142,20 @@ register has the following format::
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Bit 31: doorbell trigger (signal H/W interrupt to the other side)
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Other bits are reserved, should be 0.
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3.2.2 Transport layer interface
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Transport layer interface
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^^^^^^^^^^^^^^^^^^^^^^^^^
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To abstract HW level IPC communication, a set of callbacks is registered.
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The transport layer uses them to send and receive messages.
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Refer to struct ishtp_hw_ops for callbacks.
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3.3 ISH Transport layer
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-----------------------
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ISH Transport layer
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-------------------
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Location: drivers/hid/intel-ish-hid/ishtp/
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3.3.1 A Generic Transport Layer
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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A Generic Transport Layer
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^^^^^^^^^^^^^^^^^^^^^^^^^
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The transport layer is a bi-directional protocol, which defines:
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- Set of commands to start, stop, connect, disconnect and flow control
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@ -166,8 +166,8 @@ This protocol resembles bus messages described in the following document:
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http://www.intel.com/content/dam/www/public/us/en/documents/technical-\
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specifications/dcmi-hi-1-0-spec.pdf "Chapter 7: Bus Message Layer"
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3.3.2 Connection and Flow Control Mechanism
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Connection and Flow Control Mechanism
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Each FW client and a protocol is identified by a UUID. In order to communicate
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to a FW client, a connection must be established using connect request and
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@ -181,8 +181,8 @@ before receiving the next flow control credit.
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Either side can send disconnect request bus message to end communication. Also
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the link will be dropped if major FW reset occurs.
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3.3.3 Peer to Peer data transfer
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Peer to Peer data transfer
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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Peer to Peer data transfer can happen with or without using DMA. Depending on
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the sensor bandwidth requirement DMA can be enabled by using module parameter
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@ -217,8 +217,8 @@ In principle, multiple DMA_XFER and DMA_XFER_ACK messages may be sent at once
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Currently, ISH FW decides to send over DMA if ISHTP message is more than 3 IPC
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fragments and via IPC otherwise.
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3.3.4 Ring Buffers
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^^^^^^^^^^^^^^^^^^
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Ring Buffers
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^^^^^^^^^^^^
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When a client initiates a connection, a ring of RX and TX buffers is allocated.
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The size of ring can be specified by the client. HID client sets 16 and 32 for
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@ -228,8 +228,8 @@ bus message protocol. These buffers are required because the FW may have not
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have processed the last message and may not have enough flow control credits
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to send. Same thing holds true on receive side and flow control is required.
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3.3.5 Host Enumeration
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^^^^^^^^^^^^^^^^^^^^^^
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Host Enumeration
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^^^^^^^^^^^^^^^^
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The host enumeration bus command allows discovery of clients present in the FW.
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There can be multiple sensor clients and clients for calibration function.
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@ -252,8 +252,8 @@ Enumeration sequence of messages:
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- Once host received properties for that last discovered client, it considers
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ISHTP device fully functional (and allocates DMA buffers)
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3.4 HID over ISH Client
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-----------------------
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HID over ISH Client
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-------------------
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Location: drivers/hid/intel-ish-hid
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@ -265,16 +265,16 @@ The ISHTP client driver is responsible for:
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- Process Get/Set feature request
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- Get input reports
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3.5 HID Sensor Hub MFD and IIO sensor drivers
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---------------------------------------------
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HID Sensor Hub MFD and IIO sensor drivers
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-----------------------------------------
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The functionality in these drivers is the same as an external sensor hub.
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Refer to
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Documentation/hid/hid-sensor.rst for HID sensor
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Documentation/ABI/testing/sysfs-bus-iio for IIO ABIs to user space.
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3.6 End to End HID transport Sequence Diagram
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---------------------------------------------
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End to End HID transport Sequence Diagram
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-----------------------------------------
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::
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@ -339,16 +339,16 @@ Documentation/ABI/testing/sysfs-bus-iio for IIO ABIs to user space.
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| | | |
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3.7 ISH Debugging
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-----------------
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ISH Debugging
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-------------
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To debug ISH, event tracing mechanism is used. To enable debug logs::
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echo 1 > /sys/kernel/tracing/events/intel_ish/enable
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cat /sys/kernel/tracing/trace
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3.8 ISH IIO sysfs Example on Lenovo thinkpad Yoga 260
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-----------------------------------------------------
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ISH IIO sysfs Example on Lenovo thinkpad Yoga 260
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-------------------------------------------------
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::
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