Automated Generation of the Register Set of a SOC and its Verification Environment

Automated Generation of the Register Set of a SOC and its Verification

EnvironmentK. Poulos, K. Adaos, G.P. Alexiou

Dept. of Computer Engineering and Informatics Univ. of Patras, Greece

18th Panhellenic Conference on Informatics

• Introduction• System Environment• UVM Register Layer• Register Field Template• Register File Template• Register Generation Procedure• Examples• Conclusion – Current Work

Apr 19, 2023 2Dept. of Computer Engineering and Informatics, Univ. of Patras

Agenda

• Part of System-on-Chip Platform for Research and Education

• Result of a graduate thesis in the VLSI Lab of CEID.• Target: Develop an automated tool that

a) Generates the synthesizabe set of the registers of a SOC

b) Generates its verification environmentc) Be compliant with design and verification

standards

Introduction


System Environment


Cortex-M0

SPI

APB Bus

AHB Bridge

Regular AHB Bus

Serial Debug

AHB to APB

Timer(s)

UART(s)

AHB Register FileInternal AHB Memory

Clock Control

Power Control

BootROM

GPIO

• The register file enables the parts of the system to communicate and control each other.

System Environment


Cortex-M0

SPI

APB Bus

AHB Bridge

Regular AHB Bus

Serial Debug

AHB to APB

Timer(s)

UART(s)


Clock Control

Power Control

BootROM

GPIO

• The register file enables the parts of the system to communicate and control each other.– A processor or a HOST system can change the

behavior of the SOC

System Environment


Cortex-M0

SPI

APB Bus

AHB Bridge

Regular AHB Bus

Serial Debug

AHB to APB

Timer(s)

UART(s)


Clock Control

Power Control

BootROM

GPIO

• The register file enables the parts of the system to communicate and control each other.– A processor or a HOST system can change the

behavior of the SOC– Peripherals return data and status

• UVM is the industry standard for verification• Object Oriented , Based on SystemVerilog• Provides a set of predefined agents to control and monitor the

bahavior of the DUV• Constraint Randomization Techniques

UVM Register Layer


• UVM Register Layer is a part of the UVM spec– Models the behavior of the registers of a SOC/HW design based on their

properties– Enables frontdoor/backdoor access to the registers during verification– With predefined operations, the user can bypass/omit HW components and

focus on the peripheral operation• Our tool supports registers named after the UVM register layer => Consistent

view of design and verification process.

UVM Register Layer


• A generic register template is utilized with an interface that is common in all fields

• Two access ports:– Bus Port (activated during bus operations)– HW Port (driven by a HW module/state machine).

• Differentiation is done internally based on the register’s properties

Register Field Template


register_field

clkreset_n

sreset

bus_dinbus_we

hw_dinhw_we q

bus_rebus_dout{Bus access

signals

HW access signals {

Signal Direction Descriptionreset_n input Asynchronous reset input

(active low)clk input Clock input

sreset input Synchronous reset signal (active high)

bus_re input Read enable for the busbus_we input Write enable for the busbus_din input Data input for the bushw_we input Write enable input for HW blockshw_din input Data input for the HW blocks

q output Register Outputbus_dout output Data output for the bus.

• Differentiation is done internally based on the properties of the processor port



Field Type buswe

busdin

hwwe

hwdin

busre

busdout

RO RW RC RS

WRC WRS WC WS

WSRC WCRS W1C W1S W1T W0C W0S

W1SRC W1CRS W0SRC W1CRS

WO WOC WOS

• RO : A read only register can be written by HW blocks (via signals hw_we and hw_din) and can only be read by the Bus of the System (via ports bus_re and bus_dout)



Field Type buswe

busdin

hwwe

hwdin

busre

busdout

RO RW RC RS

WRC WRS WC WS



WO WOC WOS



Field Type buswe

busdin

hwwe

hwdin

busre

busdout

RO RW RC RS

WRC WRS WC WS



WO WOC WOS

• Other register field types model other common HW operations:– W1C: To clear the register, the processor has to write logic-1

(for example for clearing an interrupt flag).



Field Type buswe

busdin

hwwe

hwdin

busre

busdout

RO RW RC RS

WRC WRS WC WS



WO WOC WOS

• RW : A Read/Write field uses all ports

Register Field Code example


Field Type buswe

busdin

hwwe

hwdin

busre

busdout

RO RW RC RS

WRC WRS WC WS



WO WOC WOS

RW : begin always_ff @(posedge clk or negedge reset_n) begin if (~reset_n) begin q <= RESET_VAL; end else begin if (sreset) begin q <= RESET_VAL; end else begin if (bus_we) begin q <= bus_din; end else begin if (hw_we) begin q <= hw_din; end end end end endend

AHB Register File Architecture


registerfield

registerfield

registerfield

registerfield

registerfield

registerfield

Register#1

Register#2

Register#3

AHB Bus Interface Logic

ahb_register_file

• A register consists of one or more register fields.

• The AHB bus interface logic adapts the AHB bus signals to the bus access signals (bus_we, bus_re, bus_din, bus_dout).

• By changing only the bus interface logic we can support bus standards different than the AHB.

Register File Generation


Generation is based on three input files•Register File Desciption (the only file defined by the user)•A predesigned Register Field Template•A predesigned Register File Template


AHB Register File Template

Register File Description

ahb_register_file.sv

ahb_register_file.h

ahb_register_file_uvm.sv

Register File Generator

Register File Generation



AHB Register File Template

Register File Description

ahb_register_file.sv

ahb_register_file.h

ahb_register_file_uvm.sv

Register File Generator

The generator provides three outputs•A synthesizable system verilog file with the register file description•A C header file (compatible with GNU compilers)•The description of the register file according to UVM register layer to be used for verification

Register File Description File


################################################################################################name : left : right : address : type : reset : comment################################################################################################CONTROL_REG : : : 00 : : : General Control Register 0CONTROL : 31 : 0 : 00 : RW : 32'h00 : Control 0 (rw)#-----------------------------------------------------------------------------------------------STATUS_REG : : : 04 : : : General Status Register 0STATUS : 31 : 0 : 04 : RO : 32'h00 : Status 0 (ro)#-----------------------------------------------------------------------------------------------HEX_REG : : : 08 : : : HEX Display Register (HEX0 to HEX3)HEX0 : 6 : 0 : 08 : RW : 4'h0 : HEX Digit 0 ( for 7-segment display)HEX0_DP : 7 : 7 : 08 : RW : 1'h1 : HEX Digit 0 Decimal PointHEX1 : 14 : 8 : 08 : RW : 4'h0 : HEX Digit 1 ( for 7-segment display)HEX1_DP : 15 : 15 : 08 : RW : 1'h1 : HEX Digit 1 Decimal PointHEX2 : 22 : 16 : 08 : RW : 4'h0 : HEX Digit 2 ( for 7-segment display)HEX2_DP : 23 : 23 : 08 : RW : 1'h1 : HEX Digit 2 Decimal PointHEX3 : 30 : 24 : 08 : RW : 4'h0 : HEX Digit 3 ( for 7-segment display)HEX3_DP : 31 : 31 : 08 : RW : 1'h1 : HEX Digit 3 Decimal Point################################################################################################

• Name• Position - Width• Address

• Type• Reset Value• Comment (optional)

Register File Description File



• Text Based: Easily Integrates in a Version Control System (we use git)

• Available parsers can also support spreadsheet files (Microsoft xls or OpenOffice)

Example


Cortex-M0

SPI

APB Bus

AHB Bridge

Regular AHB Bus

Serial Debug

AHB to APB

Timer(s)

UART(s)


Clock Control

Power Control

BootROM

GPIO

Simple microcontroller (175 total register bits)

Example




Example



Area Speed

Technology Xilinx Spartan3A

UMC 180n Xilinx Spartan3A

UMC 180n

Total DesignArea

5,049 LUTs 42 K gates 50 MHz 142 MHz

Register FileArea

281 LUTs 2.72 K gates 122 MHz 398 MHz

• Support of extra register fields and types• Support of additional bus standards

(Wishbone, APB, AXI)• GUI support• Extend automation in other SOC components

Current Work



Automated Generation of the Register Set of a SOC and its Verification Environment

[email protected]

www.ceid.upatras.gr/webpages/faculty/alexiou/vlsilab

Documents

Automated Generation of the Register Set of a SOC and its Verification Environment