The user-defined register block is derived from uvm_reg_block. It consists of all registers, maps, register files, and other register blocks if any. A block can have one or more address maps, each corresponding to a physical interface on the block. The register block at the highest hierarchical level provides the “Register Model” as an instance.

uvm_reg_block methods

Methods	Description
new	Creates a new instance.
configure	Configuration for a specific instance.
create_map	Create an address map in the block
set_default_map	Defines the default address map
lock_model	Lock the model and build the address map
get_block	Get the sub-blocks
get_map	Get the address maps
get_registers	Get the registers
get_fields	Get the fields
get_memories	Get the memories
reset	Reset the mirror for the block
update	Update the mirrored values
set_backdoor	Set the user-defined backdoor for all registers in the block
get_backdoor	Get the user-defined backdoor for all registers in the block
add_hdl_path	Add the HDL path

Note: Please refer to the UVM class reference manual to see all methods associated with the uvm_reg_block class

Example:

class RegModel_SFR extends uvm_reg_block;
  // declaration for registers/ blocks/ register files/ memories/ address map
  `uvm_object_utils(RegModel_SFR)
  
  function new(string name = "RegModel_SFR");
    super.new(name, ./*other arguments*/);
  endfunction
  
  virtual function void build();
    // create registers/ blocks/ register files/ memories/ address map
  endfunction
endclass

uvm_reg

The user-defined register class is derived from uvm_reg. It mimics the register of the design. To represent fields present in the register, RAL provides the uvm_reg_field class.

uvm_reg methods

Methods	Description
new	Creates a new instance.
configure	Configuration for a specific instance.
set_offset	Modifies the register offset
get_offset	Returns the register offset
get_address	Returns the base external physical address of the register
get_fields	Returns the register fields
set	Sets the desired value of the register
get	Gets the desired value of the register
reset	Reset the desired/mirrored value of the register
update	Update the desired value to the register present in the DUT.
read	Read the current value from the register
write	Write the specified value in the register
mirror	Update the mirrored value for the register.
set_backdoor	Set the user-defined backdoor for all registers in the block
get_backdoor	Get the user-defined backdoor for all registers in the block
add_hdl_path	Add the HDL path

Note: Please refer to the UVM class reference manual to see all methods associated with the uvm_reg class

Example:

class my_reg extends uvm_reg;
  // declaration for register fields
  
  `uvm_object_utils(my_reg)
  function new(string name = "my_reg");
    super.new(name, ./*other arguments*/);
  endfunction
  
  virtual function void build();
    // create and configure register fields
  endfunction
endclass

uvm_reg_field

It represents fields of the register. Each register can have one or more register fields that can have different access policies out of which RW, RO, W1C, W1S, etc are commonly used.

uvm_reg_field access policies

Access policies	Description
RO	Read Only. It can simply read the register field value. Writing a field value has no effect
RW	Read Write: Field value can be written/modified and read the field value.
W1C	Write 1 to clear: 1. Writing 1 clears the corresponding bit. 2. Writing 0 has no effect. 3. Reads field value
W1S	Write 1 to set: 1. Writing 1 set the corresponding bit. 2. Writing 0 has no effect. 3. Reads field value

uvm_reg_field methods

Methods	Description
new	Creates a new instance.
configure	Configuration for a specific instance.
set_access	Set the access policy of the field.
get_access	Get the access policy of the field.
set	Sets the desired value of the field
get	Gets the desired value of the field
reset	Reset the desired/mirrored value of the field
read	Read the current value from the field
write	Write the specified value in the field
mirror	Update the mirrored value for the field

Note: Please refer to the UVM class reference manual to see all methods associated with the uvm_reg_field class

uvm_reg_file

The register file is derived from uvm_reg_file. The register file is nothing but a set of registers or register files.

uvm_reg_file methods

Methods	Description
new	Creates a new instance.
configure	Configuration for a specific instance.
get_regfile	Get the parent register file
add_hdl_path	Add the HDL path

Note: Please refer to the UVM class reference manual to see all methods associated with the uvm_reg_file class

uvm_mem

UVM RAL also supports memory implementation. As uvm_reg mimics registers of DUT. Similarly, uvm_mem mimics the memory of DUT.

uvm_mem methods

Methods	Description
new	Creates a new instance.
configure	Configuration for a specific instance.
set_offset	Modifies the memory offset
get_offset	Returns the memory offset
get_address	Returns the base address of the memory location
read	Read the current value from the memory location
write	Write the specified value in the memory location
set_backdoor	Set the user-defined backdoor for the memory
get_backdoor	Get the user-defined backdoor for the memory
add_hdl_path	Add the HDL path

Note: Please refer to the UVM class reference manual to see all methods associated with the uvm_mem class

uvm_reg_map

The user-defined uvm_reg_map is a base class used to access the model via a specific interface/bus.

uvm_reg_map methods

Methods	Description
new	Creates a new instance.
configure	Configuration for a specific instance.
add_reg	Add a register
add_mem	Add a memory
add_submap	Add an address map
reset	Reset the mirror for all registers in this address map
set_sequencer	Set the sequencer and associated adapter for the map
get_sequencer	Get the sequencer and associated adapter for the map
get_registers	Get the registers
get_reg_by_offset	Get register mapped at offset
get_mem_by_offset	Get memory mapped at offset

Note: Please refer to the UVM class reference manual to see all methods associated with the uvm_reg_map class

Set the sequencer and associated adapter for a single map

Example:

reg_model.axi_map.set_sequencer(.sequencer(agt.sequencer), .adapter(adapter) );

Where,

reg_model – register block

axi_map – address map

adapter – register adapter for converting register transactions to bus transaction (It will be discussed in RAL adapter section)

For multiple maps associated with different interfaces

Example:

In the case of AXI and AHB interfaces, if the same RAL model has to be accessed, then a separate adapter class needs to be created. So, each register maps RAL model sequencer need to be set.

reg_model.axi_map.set_sequencer( .sequencer(axi_agt.sequencer), .adapter(axi_adapter) );
reg_model.ahb_map.set_sequencer( .sequencer(ahb_agt.sequencer), .adapter(ahb_adapter) );

Accessing a register of the different maps

reg_model.module_reg.control_sfr.write(.status(status), .value(wdata), .map(reg_model.axi_map)); 
reg_model.module_reg.control_sfr.write(.status(status), .value(wdata), .map(reg_model.ahb_map));

RAL Tutorials