wiki:Component/VciAvalonBus

SocLib Components General Index

VciAvalonBus

1) Functional Description

This hardware component is a generic Avalon switch fabric allowing the interconnection of Nb_Master Avalon masters and Nb_Slave Avalon slaves. The master-to-slave relationship can be one-to-one, one-to-many, many-to-one, or many-to-many. Masters and slaves have the same data and address widths and operate in the same clock domain. It can be used in conjunction with the Vci Avalon Initiator Wrapper and the Vci Avalon Target Wrapper wrappers to build a system using an Avalon interconnect.

VCI-Avalon wrappers do not require to support full Avalon features, so not all Avalon slave and master ports are supported (trunk/soclib/soclib/communication/avalonbus/caba/source/include/avalon_switch_slave.h, trunk/soclib/soclib/communication/avalonbus/caba/source/include/avalon_switch_master.h).

Implemented functionnalities :

  • fundamental read, fundamental write with variable wait-state
  • burst transfer
  • flow control (dataavailable)
  • round robin arbitration

Unimplemented functionnalities :

  • wait state insertion
  • pipelined read transfers
  • tristate transfert
  • setup and hold time
  • dynamic bus sizing
  • interrupt requests

Address decoding logic (ADL) (trunk/soclib/soclib/module/network_component/avalon_switch_fabric/caba/source/include/avalon_address_decoding_logic.h) in the system interconnect fabric distributes an appropriate address and produces a chipselect signal for each slave.

Datapath multiplexing (MUX) (trunk/soclib/soclib/module/network_component/avalon_switch_fabric/caba/source/include/avalon_mux.h) in the system interconnect fabric drives the writedata signal from the granted master to the selected slave, and the readdata signal from the selected slave back to the requesting master.

Multiple Avalon masters can simultaneously perform transfers with independent slaves. The system interconnect fabric provides shared access to slaves using a technique called slave-side arbitration. Slave-side arbitration moves the arbitration logic (ARBITER) (trunk/soclib/soclib/module/network_component/avalon_arbiter/caba/source/include/avalon_arbiter.h) close to the slave. The arbiter grants shares in a round-robin order.

The switch fabric implementation is described through the following example: trunk/soclib/soclib/communication/avalonbus/caba/source/include/avalon_switch_config.h_multimer_nios2.

2) Component definition & usage

3) CABA Implementation

CABA sources

CABA Constructor parameters

AvalonSwitchFabric(sc_module_name insname, 
                   AvalonSwitchConfig<NB_MASTER, NB_SLAVE> config) ;

CABA Ports

  • sc_in<bool> p_resetn : Global system reset
  • sc_in<bool> p_clk : Global system clock
  • !AvalonSwitch_Master *p_avalon_master: Nb_Master ports from Avalon masters
  • !AvalonSwitch_Slave *p_avalon_slave: Nb_Slave ports to Avalon slaves

CABA Implementation Notes

The configuration of the switch fabric is platform dependant. The AvalonSwitchConfig component ([source:trunk/soclib/soclib/communication/avalonbus/caba/source/include/avalon_switch_config.h_multimer_nios2) is used to configure the switch for a specific platform.

AvalonSwitchConfig<nb_master, nb_slave> config_switch;

where Nb_Master, Nb_slave are parameters defined in the platform description (top.cpp file).

For each master the routing table !SwitchFabricParam_Master[0]->route[] describes the connection between this given master and the slaves.

!SwitchFabricParam_Master[]->mux_n_slave is the number of slaves connected to this master (number of MUX inputs).

For each slave the routing table !SwitchFabricParam_Slave[0]->route[] describes the connection between this slave and the masters.

  • !SwitchFabricParam_Slave[]->arbiter_n_master is the number of masters connected to this slave (number of ARBITER inputs).
  • !SwitchFabricParam_Slave[]->Base_Address,
  • !SwitchFabricParam_Slave[]->Address_Span is the addressing space of this slave (decoded in the ADL module)

4) TLM-T implementation

There is no TLM-T implementation for this component.

Last modified 14 years ago Last modified on Jan 21, 2009, 11:10:59 AM

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