Synopsys验证VIP学习笔记（2）Port Monitor用法

1年前更新

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Synopsys AXI VIP为master和slave agent中的monitor提供了名为item_started_port和item_observed_port的analysis port，前者仅在总线事务传输开始时发送，后者则在总线事务传输完成后发送完整svt_axi_master_transaction和svt_axi_slave_transaction对象到item_observed_port端口，并且在vip agent为passive和active模式下都有效。可以将该端口连接至现有scoreboard用以分析总线事务信号，方法如下：

首先需要在scoreboard中声明export(或import)端口

/** Macro that define two analysis ports with unique suffixes */
`uvm_analysis_imp_decl(_initiated)
`uvm_analysis_imp_decl(_response)


/** Analysis port conneted to the AXI Slave Agent */
uvm_analysis_imp_response#(svt_axi_transaction, axi_uvm_scoreboard) item_observed_response_export;

在scoreboard::build_phase()中创建export对象

function void build_phase(uvm_phase phase);
  super.build_phase();
  /** Construct the analysis ports */
  item_observed_initiated_export = new("item_observed_initiated_export", this);
  item_observed_response_export = new("item_observed_response_export", this);
endfunction

添加write_xxx函数以从analysis port中获取transaction

/* This method is called by item_observed_response_export */
virtual function void write_response(input svt_axi_transaction xact);
  svt_axi_transaction  resp_xact;
  if (!$cast(resp_xact, xact.clone())) begin
    `uvm_fatal("write_response", "Unable to $cast the received transaction to svt_axi_transaction");
  end
  `uvm_info("write_response", $sformatf("xact:n%s", resp_xact.sprint()), UVM_FULL)
endfunction

在base_test的connect_phase()中连接slave agent的analysis port和scoreboard
```
function void connect_phase(uvm_phase phase);
  /* Connect the master and slave agent's analysis ports with
   * item_observed_port and import of the scoreboard. */
  axi_system_env.slave[0].monitor.item_observed_port.connect(axi_scoreboard.item_observed_response_export);
endfunction
```
注意，vip monitor中某些信号的监测需要在port_configuration中配置使能开启，如arqos和awqos信号：
```
this.slave_cfg[0].arqos_enable = 1;
this.slave_cfg[0].awqos_enable = 1;
```
如果要在VIP环境中添加自定义TLM analysis port，需采用callback方法。SVT AXI VIP提供了很多callback方法，以下举例说明如何在AXI port monitor中添加自定义端口svt_axi_port_monitor_callback::read_address_phase_ended。

首先创建自定义callback类，并在read_address_phase_ended方法中添加自定义端口item_observed_port_addr

class axiMasterMonitorCallbacks extends svt_axi_port_monitor_callback;


  int                       master_num=0;
  svt_axi_system_configuration     vip_cfg;
  //user-defined analysis ports
  uvm_analysis_port #(svt_axi_transaction) item_observed_port_addr;


  function new(int master_num=0,svt_axi_system_configuration vip_cfg,uvm_component parent=null);
    this.master_num=master_num;
    this.vip_cfg=vip_cfg;
    item_observed_port_addr=new("",parent);
  endfunction  


  //for initiating masters
  extern virtual function void read_address_phase_ended( 
                  svt_axi_port_monitor axi_monitor, 
                  svt_axi_transaction  item);
endclass


function void axiMasterMonitorCallbacks::read_address_phase_ended( 
                  svt_axi_port_monitor axi_monitor, 
                  svt_axi_transaction  item);
    svt_axi_transaction item_copy;


    //user-defined analysis port
    $cast(item_copy,item.clone());  
    item_copy.port_id=master_num; 
    item_observed_port_addr.write(item_copy);
endfunction

2. 在scoreboard中创建export端口和write()方法，这一步同上步骤1、2、3，代码略去

3. 在env中连接TLM端口，需要在uvm_env::build_phase()中创建callback，在connect_phase()中连接端口，并在start_of_simulation_phase() 中注册callback

virtual function void build_phase(uvm_phase phase);
    super.build_phase(phase);
    axi_system_env = svt_axi_system_env::type_id::create("axi_system_env", this);
    uvm_config_db#(svt_axi_system_configuration)::set(this, "axi_system_env", "cfg", cfg);
    axi_sb = axiSB::type_id::create("axi_sb", this);
    master_monitor_cb=new[cfg.num_masters];
    foreach(cfg.master_cfg[i]) begin
      master_monitor_cb[i]=new(i,cfg,this);
    end
  endfunction


  function void connect_phase(uvm_phase phase); 
    master_monitor_cb[0].item_observed_port_addr.connect(axi_sb.master_cb_addr_export[0]);    
    master_monitor_cb[1].item_observed_port_addr.connect(axi_sb.master_cb_addr_export[1]);    
    master_monitor_cb[2].item_observed_port_addr.connect(axi_sb.master_cb_addr_export[2]);    
    master_monitor_cb[3].item_observed_port_addr.connect(axi_sb.master_cb_addr_export[3]);
  endfunction


  virtual function void start_of_simulation_phase(uvm_phase phase);
    super.start_of_simulation_phase(phase);
    //Master Monitor callbacks
    foreach(cfg.master_cfg[i]) begin          
     uvm_callbacks#(svt_axi_port_monitor)::add(axi_system_env.master[i].monitor,master_monitor_cb[i]); 
    end
  endfunction

参考资料：VC Verification IP AMBA AXI UVM User Guide R-2020.09

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