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@@ -79,20 +79,63 @@ master port that is used to communicate with devices within the network.
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In order to initialize the RapidIO subsystem, a platform must initialize and
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register at least one master port within the RapidIO network. To register mport
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within the subsystem controller driver initialization code calls function
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-rio_register_mport() for each available master port. After all active master
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-ports are registered with a RapidIO subsystem, the rio_init_mports() routine
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-is called to perform enumeration and discovery.
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+rio_register_mport() for each available master port.
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-In the current PowerPC-based implementation a subsys_initcall() is specified to
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-perform controller initialization and mport registration. At the end it directly
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-calls rio_init_mports() to execute RapidIO enumeration and discovery.
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+RapidIO subsystem uses subsys_initcall() or device_initcall() to perform
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+controller initialization (depending on controller device type).
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+
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+After all active master ports are registered with a RapidIO subsystem,
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+an enumeration and/or discovery routine may be called automatically or
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+by user-space command.
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4. Enumeration and Discovery
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----------------------------
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-When rio_init_mports() is called it scans a list of registered master ports and
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-calls an enumeration or discovery routine depending on the configured role of a
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-master port: host or agent.
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+4.1 Overview
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+------------
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+
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+RapidIO subsystem configuration options allow users to specify enumeration and
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+discovery methods as statically linked components or loadable modules.
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+An enumeration/discovery method implementation and available input parameters
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+define how any given method can be attached to available RapidIO mports:
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+simply to all available mports OR individually to the specified mport device.
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+
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+Depending on selected enumeration/discovery build configuration, there are
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+several methods to initiate an enumeration and/or discovery process:
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+
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+ (a) Statically linked enumeration and discovery process can be started
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+ automatically during kernel initialization time using corresponding module
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+ parameters. This was the original method used since introduction of RapidIO
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+ subsystem. Now this method relies on enumerator module parameter which is
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+ 'rio-scan.scan' for existing basic enumeration/discovery method.
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+ When automatic start of enumeration/discovery is used a user has to ensure
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+ that all discovering endpoints are started before the enumerating endpoint
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+ and are waiting for enumeration to be completed.
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+ Configuration option CONFIG_RAPIDIO_DISC_TIMEOUT defines time that discovering
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+ endpoint waits for enumeration to be completed. If the specified timeout
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+ expires the discovery process is terminated without obtaining RapidIO network
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+ information. NOTE: a timed out discovery process may be restarted later using
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+ a user-space command as it is described later if the given endpoint was
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+ enumerated successfully.
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+
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+ (b) Statically linked enumeration and discovery process can be started by
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+ a command from user space. This initiation method provides more flexibility
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+ for a system startup compared to the option (a) above. After all participating
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+ endpoints have been successfully booted, an enumeration process shall be
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+ started first by issuing a user-space command, after an enumeration is
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+ completed a discovery process can be started on all remaining endpoints.
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+
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+ (c) Modular enumeration and discovery process can be started by a command from
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+ user space. After an enumeration/discovery module is loaded, a network scan
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+ process can be started by issuing a user-space command.
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+ Similar to the option (b) above, an enumerator has to be started first.
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+
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+ (d) Modular enumeration and discovery process can be started by a module
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+ initialization routine. In this case an enumerating module shall be loaded
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+ first.
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+
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+When a network scan process is started it calls an enumeration or discovery
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+routine depending on the configured role of a master port: host or agent.
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Enumeration is performed by a master port if it is configured as a host port by
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assigning a host device ID greater than or equal to zero. A host device ID is
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@@ -104,8 +147,58 @@ for it.
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The enumeration and discovery routines use RapidIO maintenance transactions
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to access the configuration space of devices.
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-The enumeration process is implemented according to the enumeration algorithm
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-outlined in the RapidIO Interconnect Specification: Annex I [1].
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+4.2 Automatic Start of Enumeration and Discovery
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+------------------------------------------------
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+
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+Automatic enumeration/discovery start method is applicable only to built-in
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+enumeration/discovery RapidIO configuration selection. To enable automatic
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+enumeration/discovery start by existing basic enumerator method set use boot
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+command line parameter "rio-scan.scan=1".
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+
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+This configuration requires synchronized start of all RapidIO endpoints that
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+form a network which will be enumerated/discovered. Discovering endpoints have
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+to be started before an enumeration starts to ensure that all RapidIO
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+controllers have been initialized and are ready to be discovered. Configuration
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+parameter CONFIG_RAPIDIO_DISC_TIMEOUT defines time (in seconds) which
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+a discovering endpoint will wait for enumeration to be completed.
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+
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+When automatic enumeration/discovery start is selected, basic method's
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+initialization routine calls rio_init_mports() to perform enumeration or
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+discovery for all known mport devices.
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+
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+Depending on RapidIO network size and configuration this automatic
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+enumeration/discovery start method may be difficult to use due to the
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+requirement for synchronized start of all endpoints.
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+
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+4.3 User-space Start of Enumeration and Discovery
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+-------------------------------------------------
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+
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+User-space start of enumeration and discovery can be used with built-in and
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+modular build configurations. For user-space controlled start RapidIO subsystem
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+creates the sysfs write-only attribute file '/sys/bus/rapidio/scan'. To initiate
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+an enumeration or discovery process on specific mport device, a user needs to
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+write mport_ID (not RapidIO destination ID) into that file. The mport_ID is a
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+sequential number (0 ... RIO_MAX_MPORTS) assigned during mport device
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+registration. For example for machine with single RapidIO controller, mport_ID
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+for that controller always will be 0.
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+
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+To initiate RapidIO enumeration/discovery on all available mports a user may
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+write '-1' (or RIO_MPORT_ANY) into the scan attribute file.
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+
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+4.4 Basic Enumeration Method
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+----------------------------
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+
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+This is an original enumeration/discovery method which is available since
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+first release of RapidIO subsystem code. The enumeration process is
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+implemented according to the enumeration algorithm outlined in the RapidIO
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+Interconnect Specification: Annex I [1].
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+
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+This method can be configured as statically linked or loadable module.
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+The method's single parameter "scan" allows to trigger the enumeration/discovery
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+process from module initialization routine.
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+
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+This enumeration/discovery method can be started only once and does not support
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+unloading if it is built as a module.
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The enumeration process traverses the network using a recursive depth-first
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algorithm. When a new device is found, the enumerator takes ownership of that
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@@ -160,6 +253,19 @@ time period. If this wait time period expires before enumeration is completed,
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an agent skips RapidIO discovery and continues with remaining kernel
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initialization.
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+4.5 Adding New Enumeration/Discovery Method
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+-------------------------------------------
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+
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+RapidIO subsystem code organization allows addition of new enumeration/discovery
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+methods as new configuration options without significant impact to to the core
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+RapidIO code.
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+
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+A new enumeration/discovery method has to be attached to one or more mport
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+devices before an enumeration/discovery process can be started. Normally,
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+method's module initialization routine calls rio_register_scan() to attach
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+an enumerator to a specified mport device (or devices). The basic enumerator
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+implementation demonstrates this process.
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+
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5. References
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-------------
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