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sys/dev/isci/scil/scif_sas_design.h

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    #ifndef _SCIF_SAS_DESIGN_H_
    #define _SCIF_SAS_DESIGN_H_
    
    /**
    @page scif_sas_design_page SCIF SAS High Level Design
    
    <b>Authors:</b>
    - Nathan Marushak
    
    <b>Key Contributors:</b>
    - Richard Boyd
    
    @section scif_sas_scope_and_audience Scope and Audience
    
    This document provides design information relating to the SAS specific
    implementation of the SCI Framework.  Driver developers are the primary
    audience for this document.  The reader is expected to have an understanding
    of the SCU Software Architecture Specification, the Storage Controller
    Interface Specification, and the SCI Base Design.
    
    @section scif_sas_overview Overview
    
    To begin, it's important to discuss the utilization of state machines in
    the design.  State machines are pervasive in this design, because of the
    abilities they provide.  A properly implemented state machine allows the
    developer to code for a specific task.  The developer is not encumbered
    with needed to handle other situations all in a single function.  For
    example, if a specific event can only occur when the object is in a specific
    state, then the event handler is added to handle such an event.  Thus, a
    single function is not spliced to handle multiple events under various
    potentially disparate conditions.
    
    Additionally, the SCI Base Design document specifies a number of state
    machines, objects, and methods that are heavily utilized by this design.
    Please refer to Base Design specification for further information.
    
    Many of the framework objects have state machines associated with them.
    As a result, there are a number of state entrance and exit methods as well
    as event handlers for each individual state.  This design places all of
    the state entrance and exit methods for a given state machine into a single
    file (e.g. scif_sas_controller_states.c).  Furthermore, all of the state
    event handler methods are also placed into a single file (e.g.
    scif_sas_controller_state_handlers.c).  This format is reused for each
    object that contains state machine(s).
   
   Some of the SAS framework objects contain sub-state machines.  These
   sub-state machines are started upon entrance to the super-state and stopped
   upon exit of the super-state.
   
   All other method, data, constant description information will be found in
   the remaining source file (e.g. scif_sas_controller.c).  As a result, please
   be sure to follow the link to that specific object/file definition for
   further information.
   
   @note Currently a large number of function pointers are utilized during the
   course of a normal IO request.  Once stability of the driver is achieved,
   performance improvements will be made as needed.  This likely will include
   removal of the function pointers from the IO path.
   
   @section scif_sas_use_cases Use Cases
   
   The following use case diagram depicts the high-level user interactions with
   the SAS framework.  This diagram does not encompass all use cases implemented
   in the system.  The low-level design section will contain detailed use cases
   for each significant object and their associated detailed sequences and/or
   activities.  For the purposes of readability, the use cases are not directly
   connected to the associated actor utilizing the use case.  Instead naming
   is utilized to different which actor is involved with the use case.
   
   Actors:
   - The Framework user also called the OS Specific Driver initiates activities in
   the Framework.
   - The SCI Core calls back into the Framework as a result of an operation either
   started by the OS Specific Driver or by the Framework itself.
   
   @image latex Use_Case_Diagram__SCIF_SAS__Use_Cases.eps "SCIF SAS OS Use Cases" width=11cm
   @image html Use_Case_Diagram__SCIF_SAS__Use_Cases.jpg "SCIF SAS OS Use Cases"
   
   @section scif_sas_class_hierarchy Class Hierarchy
   
   This section delineates the high-level class organization for the SCIF_SAS
   component.  Details concerning each class will be found in the corresponding
   low-level design sections.  Furthermore, additional classes not germane to
   the overall architecture of the component will also be defined in these
   low-level design sections.
   
   @image latex Class_Diagram__scif_sas__Class_Diagram.eps "SCIF SAS Class Diagram" width=16cm
   @image html Class_Diagram__scif_sas__Class_Diagram.jpg "SCIF SAS Class Diagram"
   
   For more information on each object appearing in the diagram, please
   reference the subsequent sections.
   
   @section scif_sas_library SCIF SAS Library
   
   First, the SCIF_SAS_LIBRARY object provides an implementation
   for the roles and responsibilities defined in the Storage Controller
   Interface (SCI) specification.  It is suggested that the user read the
   storage controller interface specification for background information on
   the library object.
   
   The SCIF_SAS_LIBRARY object is broken down into 2 individual source files
   and one direct header file.  These files delineate the methods, members, etc.
   associated with this object.  Please reference these files directly for
   further design information:
   - scif_sas_library.h
   - scif_sas_library.c
   
   @section scif_sas_controller SCIF SAS Controller
   
   First, the SCIF_SAS_CONTROLLER object provides an implementation
   for the roles and responsibilities defined in the Storage Controller
   Interface (SCI) specification.  It is suggested that the user read the
   storage controller interface specification for background information on
   the controller object.
   
   The SCIF_SAS_CONTROLLER object is broken down into 3 individual source files
   and one direct header file.  These files delineate the methods, members, etc.
   associated with this object.  Please reference these files directly for
   further design information:
   - scif_sas_controller.h
   - scif_sas_controller.c
   - scif_sas_controller_state_handlers.c
   - scif_sas_controller_states.c
   
   @section scif_sas_domain SCIF SAS Domain
   
   First, the SCIF_SAS_DOMAIN object provides an implementation
   for the roles and responsibilities defined in the Storage Controller
   Interface (SCI) specification.  It is suggested that the user read the
   storage controller interface specification for background information on
   the SCIF_SAS_DOMAIN object.
   
   The SCIF_SAS_DOMAIN object is broken down into 3 individual
   source files and one direct header file.  These files delineate the
   methods, members, etc. associated with this object.  Please reference
   these files directly for
   further design information:
   - scif_sas_domain.h
   - scif_sas_domain.c
   - scif_sas_domain_state_handlers.c
   - scif_sas_domain_states.c
   
   @section scif_sas_remote_device SCIF SAS Remote Device
   
   First, the SCIF_SAS_REMOTE_DEVICE object provides an implementation
   for the roles and responsibilities defined in the Storage Controller
   Interface (SCI) specification.  It is suggested that the user read the
   storage controller interface specification for background information on
   the SCIF_SAS_REMOTE_DEVICE object.
   
   The SCIF_SAS_REMOTE_DEVICE object is broken down into 7 individual source files
   and one direct header file.  These files delineate the methods, members, etc.
   associated with this object.  Methods, data, and functionality specific to a
   particular protocol type (e.g. SMP, STP, etc.) are broken out into their own
   object/file.  SSP specific remote device functionality is covered by the base
   classes (common files).  Please reference these files directly for further
   design information:
   - scif_sas_remote_device.h
   - scif_sas_smp_remote_device.h
   - scif_sas_stp_remote_device.h
   - scif_sas_remote_device.c
   - scif_sas_remote_device_state_handlers.c
   - scif_sas_remote_device_states.c
   - scif_sas_remote_device_starting_substate_handlers.c
   - scif_sas_remote_device_starting_substates.c
   - scif_sas_remote_device_ready_substate_handlers.c
   - scif_sas_remote_device_ready_substates.c
   - scif_sas_smp_remote_device.c
   - scif_sas_stp_remote_device.c
   
   The SCIF_SAS_REMOTE_DEVICE object has sub-state machines defined for
   the READY and STARTING super-states.  For more information on the
   super-state machine please refer to SCI_BASE_REMOTE_DEVICE_STATES
   in the SCI Base design document.
   
   In the SCIF_SAS_REMOTE_DEVICE_STARTING_SUBSTATES sub-state machine,
   the remote device currently has to wait for the core to
   return an indication that the remote device has successfully started
   and become ready.  If all goes well, then the remote device will
   transition into the READY state.
   
   For more information on the starting sub-state machine states please refer
   to the scif_sas_remote_device.h::_SCIF_SAS_REMOTE_DEVICE_STARTING_SUBSTATES
   enumeration.
   
   @image latex State_Machine_Diagram__STARTING_SUB-STATE__STARTING_SUB-STATE.eps "SCIF SAS Remote Device Starting Sub-state Machine Diagram" width=16cm
   @image html State_Machine_Diagram__STARTING_SUB-STATE__STARTING_SUB-STATE.jpg "SCIF SAS Remote Device Starting Sub-state Machine Diagram"
   
   In the SCIF_SAS_REMOTE_DEVICE_READY_SUBSTATES sub-state machine,
   the remote device currently only allows new host IO requests during the
   OPERATIONAL state.  In the TASK MANAGEMENT state only new task management
   requests are allowed.
   
   For more information on the ready sub-state machine states please refer
   to the scif_sas_remote_device.h::_SCIF_SAS_REMOTE_DEVICE_READY_SUBSTATES
   enumeration.
   
   @image latex State_Machine_Diagram__READY_SUB-STATE__READY_SUB-STATE.eps "SCIF SAS Remote Device Ready Sub-state Machine Diagram" width=16cm
   @image html State_Machine_Diagram__READY_SUB-STATE__READY_SUB-STATE.jpg "SCIF SAS Remote Device Ready Sub-state Machine Diagram"
   
   @section scif_sas_request SCIF SAS Request
   
   The SCIF_SAS_REQUEST object provide common functionality for the
   SCIF_SAS_IO_REQUEST and the SCIF_SAS_TASK_REQUEST objects.  This object
   does not directly map to an SCI defined object, but its children do.  For
   additional information, you may reference the SCIF_SAS_IO_REQUEST or
   SCIF_SAS_TASK_REQUEST objects.
   
   The SCIF_SAS_REQUEST object is broken down into 1 individual source file
   and one direct header file.  These files delineate the methods, members, etc.
   associated with this object.  Please reference these files directly for
   further design information:
   - scif_sas_request.h
   - scif_sas_request.c
   
   @section scif_sas_io_request SCIF SAS IO Request
   
   First, the SCIF_SAS_IO_REQUEST object provides an implementation
   for the roles and responsibilities defined in the Storage Controller
   Interface (SCI) specification.  It is suggested that the user read the
   storage controller interface specification for background information on
   the SCIF_SAS_IO_REQUEST object.
   
   The SCIF_SAS_IO_REQUEST object is broken down into 3 individual
   source files and one direct header file.  These files delineate the
   methods, members, etc. associated with this object.  Please reference
   these files directly for further design information:
   - scif_sas_io_request.h
   - scif_sas_smp_io_request.h
   - scif_sas_stp_io_request.h
   - scif_sas_sati_binding.h
   - scif_sas_io_request.c
   - scif_sas_io_request_state_handlers.c
   - scif_sas_io_request_states.c
   - scif_sas_smp_io_request.c
   - scif_sas_stp_io_request.c
   
   @section scif_sas_task_request SCIF SAS Task Request
   
   First, the SCIF_SAS_TASK_REQUEST object provides an implementation
   for the roles and responsibilities defined in the Storage Controller
   Interface (SCI) specification.  It is suggested that the user read the
   storage controller interface specification for background information on
   the SCIF_SAS_TASK_REQUEST object.
   
   The SCIF_SAS_TASK_REQUEST object is broken down into 3 individual
   source files and one direct header file.  These files delineate the
   methods, members, etc. associated with this object.  Please reference
   these files directly for further design information:
   - scif_sas_task_request.h
   - scif_sas_stp_task_request.h
   - scif_sas_task_request.c
   - scif_sas_task_request_state_handlers.c
   - scif_sas_task_request_states.c
   - scif_sas_stp_task_request.c
   
   @section scif_sas_internal_io_request SCIF SAS INTERNAL IO Request
   
   The SCIF_SAS_INTERNAL_IO_REQUEST object fulfills the SCI's need to create
   and send out the internal io request. These internal io requests could be
   smp request for expander device discover process, or stp request for NCQ
   error handling. Internal IOs consume the reserved internal io space in
   scif_sas_controller. When an internal IO is constructed, it is put into an
   internal high priority queue. A defferred task (start_internal_io_task) will be
   scheduled at the end of every completion process. The task looks up the high
   priority queue and starts each internal io in the queue. There is one exception
   that start_internal_io_task is scheduled immediately when the first internal io
   is constructed. A retry mechanism is also provided for internal io. When an
   internal io response is decoded, if the decoding indicates a retry is needed,
   the internal io will be retried.
   
   Please refer to these files directly for further design information:
   - scif_sas_internal_io_request.h
   - scif_sas_internal_io_request.c
   - scif_sas_controller.h
   
   @section scif_sas_smp_remote_device SCIF SAS SMP REMOTE DEVICE
   
   The SCIF SAS SMP REMOTE DEVICE object represents the expander device and fulfills
   its SMP discover activities. The discover procedure includes a initial discover
   phase and a following SATA spinup_hold release phase, if there are expander attached
   SATA device is discovered and in spinup_hold condition. The SCIF SAS SMP REMOTE DEVICE
   object also fulfills expander attached device Target Reset (Phy Control) activity.
   
   @image latex Discover Process.eps "SMP Discover Activity Diagram" width=10cm
   @image html Discover Process.jpg "SMP Discover Activity Diagram"
   
   Please refer to these files directly for further design information:
   - scif_sas_smp_remote_device.h
   - scif_sas_smp_remote_device.c
   - scif_sas_smp_request.h
   - scif_sas_smp_request.c
   */
   
   #endif // _SCIF_SAS_DESIGN_H_

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