This material exempt per Department of Commerce license exception TSU Software Development

This material exempt per Department of Commerce license exception TSU

Software Development

Software Design 2

Objectives

After completing this module, you will be able to:• Identify the functionality included in the GNU tools: GCC, AS, LD,

GDB• Examine the IP driver’s functionality and design• Examine the Xilinx Libraries• Determine what is a BSP and what is included

Software Design 3

Outline

• Introduction• Software Settings

– Software Platform Settings– Compiler Settings

• GNU Tools: GCC, AS, LD, Binutils• Device Drivers

– Level 0, Level 1– PowerPC Processor: Exceptions, Sleep, Time– Integration in EDK

• Libraries• BSP

– Boot Files and Sequence

Software Design 4

Desktop versus Embedded

• Desktop development: written, debugged, and run on the same machine

• OS loads the program into the memory when the program has been requested to run

• Address resolution takes place at the time of loading by a program called the loader – The loader is included

in the OS

• The programmer glues into one executable file called ELF – Boot code, application code,

RTOS, and ISRs – address resolution takes place

during the “gluing” stage

• The executable file is downloaded into the target system through different methods– Ethernet, serial, JTAG, BDM,

ROM programmer

Software Design 5

Embedded Development• Development takes place on one

machine (host) and is downloaded to the embedded system (target)

On-Chip Memory Std JTAG

PortGB I/O

PortUserPorts

CS ICONCores

OCM IF

I/O Selection

Firmware#Include stdio.hMain()

ControlSystemICE

Core

Off & On-Chip Memory

PPC405 Dbg Facilities

CPU JTAGPort

CPU TracePort

Core ConnectTM

Other PPC405Cores

Post FirstRelease

Host Computer

Target Computer

A cross-compiler is run on the host

Software Design 6

Embedded Development

• Different set of problems – Unique hardware for every design– Reliability– Real-time response requirement (sometimes)

• RTOS versus OS

– Code compactness– High-level languages and assembly

Software Design 7

Outline• Introduction• Software Settings






Software Design 8

Simulation Generator

Hardware Platform Generation

Library Generation

Embedded SoftwareDevelopment

ISE Tools

IP Library or User Repository

MSS

LibGen

.a

Compiler (GCC)

.o

Linker (GCC)

ELF

MHS

PlatGenDrivers,

MDDMPD, PAO

PCoreHDL System and

Wrapper VHDsystem.BMM

Synthesis (XST)

NGC

NGDBuildUCF

NGD

MAP

NCD, PCF

PAR

NCD

BitGensystem.BIT

BitInit

download.BIT

iMPACT

system_BD.BMM

SimGen

BehavioralVHD Model

SimGen

StructuralVHD Model

SimGen

TimingVHD Model

Simulation

IP Models ISE ModelsTestbenchStimulus

CompEDKLib CompXLib

ApplicationSource.c, .h, .s

EDK Tool Flow

download.CMD

EDK SWLibraries

Software Design Environment

• The Library Generator (LibGen) utility generates the necessary libraries and drivers for the embedded processors

• LibGen takes an MSS (Microprocessor Software Specification) file created by the user as input. The MSS file defines the drivers associated with peripherals, standard input/output devices, interrupt handler routines, and other related software features

• The MSS file is generated by XPS by using the software settings specified

LibGen

• code directory– A repository for EDK executables

• include directory– C header files that are required by

drivers– xparameters.h

• Defines base and high addresses of the peripherals in the system

• Defines the peripheral IDs required by the drivers and user programs

• Defines the function prototypes

LibGen Generated Directories

project_directory

Processor instance directory

code directory

include directory

lib directory

libsrc directory

Note: The number of processor instance directoriesgenerated is related to the number of processor instances present in the system

LibGen

• lib directory– libc.a, libm.a and libxil.a libraries

• The libxil library contains driver functions that the particular processor can access

• libsrc directory– Intermediate files and makefiles that

compile the libraries and drivers– Peripheral-specific driver files that

are copied from the EDK and user driver directories

LibGen Generated Directories

project_directory

processor instance directory

code directory

include directory

lib directory

libsrc directory

Note: The processor instance directoriescontent is overwritten every time LibGen is run

Software Design 12

Outline







Software Design 13

Software Platform Settings

• Software settings can be assigned to individual processor instance by selecting Software Software Platform Settings or clicking button on the toolbar

• In case of multiple processors in the design software platform settings allow you to select each processor instance and set parameters

Software Design 14

Software Platform

12

3 4

1

2

3

4

Select Software Platform panel

Select processor instance

Select OS

Check desired libraries and their version

Software Design 15

OS and Libraries

3

4

1

2

Select OS and Libraries panel

Select processor instance

Set stdin and stdout devices as well as assign fpu, malloc, and profiling related parameters

Configure selected libraries parameters

1 2

3

4

Software Design 16

Drivers

21 Select Drivers panel

Select drivers and version for each device in the design

21

Software Design 17

Interrupt Handlers

2

1 Select Interrupt Handler panel

If an interrupt signal is used from any peripheral then a corresponding entry will be listed

Enter interrupt handler function name

2

1

3

3

Software Design 18

Outline• Introduction• Software Settings






Compiler Settings• Compiler settings can be assigned by

double-clicking Compiler Options entry under an application in the Application tab

• Environment tab– Application Mode

• Executable• XmdStub (MicroBlaze™ processor only)

– Use Custom Linker Script• If checked then provide the path to the linker

script– Use default Linker Script

• Program Start Address• Stack Size• Heap Size

Compiler Settings

• Debug and Optimization tab– Optimization Parameters

• Optimization Level: 0 to 3• Use Global Pointer Optimization

– Generate Debug Symbols• Checking this option allows the

generation of debugging information based on the option selected

• Create symbol for debugging (-g option)

• Create symbols for assembly (-gstabs option)

Compiler Settings

• Paths tab– Search Paths

• Compiler (-B)• Library (-L)• Include (-I)

– Libraries to Link against

• List user libraries to be used

Compiler Settings

• Advanced tab– Other Compiler Options

• Add additional options– For example: -g

– Symbol Definitions field• Pass Space Separated

Options to– Preprocessor (-Wp)– Assembler (-Wa)– Linker (-Wl)

Software Design 23

Outline







Software Design 24

Simulation Generator

Hardware Platform Generation

Library Generation

Embedded SoftwareDevelopment

ISETools

IP Library or User Repository

MSS

LibGen

.a

Compiler (GCC)

.o

Linker (GCC)

ELF

MHS

PlatGenDrivers,

MDDMPD, PAO

PCoreHDL System and

Wrapper VHDsystem.BMM

Synthesis (XST)

NGC

NGDBuildUCF

NGD

MAP

NCD, PCF

PAR

NCD

BitGensystem.BIT

BitInit

download.BIT

iMPACT

system_BD.BMM

SimGen

BehavioralVHD Model

SimGen

StructuralVHD Model

SimGen

TimingVHD Model

Simulation

IP Models ISE ModelsTestbenchStimulus

CompEDKLib CompXLib

ApplicationSource.c, .h, .s

EDK Tool Flow

download.CMD

EDK SWLibraries

GNU Tools: GCC

• GCC translates C source code into assembly language

• GCC also functions as the user interface to the GNU assembler and to the GNU linker, calling the assembler and the linker with the appropriate parameters

• Supported cross-compilers:– PowerPC processor compiler

• GNU GCC (powerpc-eabi-gcc)• Wind River Diab compiler (dcc)

– MicroBlaze processor compiler• GNU GCC (mb-gcc)

• Command line only; uses the settings set through the GUI

C files

Cross-compiler

Assembly files

Software Design 26

GNU Tools• Calls four different executables

– Preprocessor (cpp0)– Language specific c-compiler

• cc1 C-programming language• cc1plus C++ language

– Assembler• mb-as (MicroBlaze processor)• powerpc-eabi-as (PowerPC

processor)– Linker and loader

• mb-ld (MicroBlaze processor)• powerpc-eabi-ld (PowerPC

processor)

GNU Tools: AS

• Input: Assembly language files– File extension: .s

• Output: Object code – File extension: .o– Contains

• Assembled piece of code• Constant data• External references• Debugging information

• Typically, the compiler automatically calls the assembler

• Use –Wa switch if the source files are assembly only and use gcc

Assembly files

Cross-assembler

Object files

Software Design 28

GNU Tools: LD

• Linker• Inputs:

– Several object files – Archived object files (library)– Linker script (mapfile)

• Outputs: – Executable image (.ELF) – Mapfile (different from linker script)

Object files

Linker script

Linker/Locator

Executable Map

Software Design 29

Binutils: Binary Utilities

• AR Archiver– Create, modify, and extract from libraries– Used in EDK to combine the object files of the Board Support Package

(BSP) in a library– Used in EDK to extract object files from different libraries

• OBJDUMP– Display information from object files and executables

• Header information, memory map• Data• Disassemble code

– GNU executables• powerpc-eabi-objdump• mb-objdump

Software Design 30

Powerpc-eabi-objdump

Memorylocation

Text section

Machinecode

Assemblyinstructions

Software Design 31

Outline







Device Drivers• The Xilinx device drivers are designed to meet the following

objectives:– Provide maximum portability

• The device drivers are provided as ANSI C source code– Support FPGA configurability

• Supports multiple instances of the device without code duplication for each instance, while at the same time managing unique characteristics on a per-instance basis

– Support simple and complex use cases• A layered device driver architecture provides both

– Simple device drivers with minimal memory footprints– Full-featured device drivers with larger memory footprints

– Ease of use and maintenance• Xilinx uses coding standards and provides well-documented source code for

developers

Software Design 33

Outline







Drivers: Level 0 / Level 1

• The layered architecture provides seamless integration with… – (Layer 2) RTOS application layer– (Layer 1) High-level device drivers that are full-featured and portable

across operating systems and processors – (Layer 0) Low-level drivers for simple use cases

Layer 2, RTOS Adaptation

Layer 1, High-level Drivers

Layer 0, Low-level Drivers

Drivers: Level 0

• Consists of low-level device drivers• Implemented as macros and functions that are designed to allow a

developer to create a small system• Characteristics:

– Small memory footprint– Little to no error checking is performed– Supports primary device features only– No support of device configuration parameters– Supports multiple instances of a device with base address input to the API– Polled I/O only– Blocking function calls– Header files have “_l” in their names (e.g. xuartlite_l.h)

Drivers: Level 1

• Consists of high-level device drivers• Implemented as macros and functions and designed to allow a

developer to utilize all of the features of a device• Characteristics:

– Abstract API that isolates the API from hardware device changes– Supports device configuration parameters– Supports multiple instances of a device– Polled and interrupt driven I/O– Non-blocking function calls to aid complex applications– May have a large memory footprint– Typically, provides buffer interfaces for data transfers as opposed to byte

interfaces– Header files do not have “_l” in their names (e.g. xuartlite.h)

Comparison Example• Uartlite Level 1

– XStatus XUartLite_Initialize (XUartLite *InstancePtr, Xuint16 DeviceId)– void XUartLite_ResetFifos (XUartLite *InstancePtr)– unsigned int XUartLite_Send (XUartLite *InstancePtr, Xuint8 *DataBufferPtr, unsigned int NumBytes)– unsigned int XUartLite_Recv (XUartLite *InstancePtr, Xuint8 *DataBufferPtr, unsigned int NumBytes)– Xboolean XUartLite_IsSending (XUartLite *InstancePtr)– void XUartLite_GetStats (XUartLite *InstancePtr, XUartLite_Stats *StatsPtr)– void XUartLite_ClearStats (XUartLite *InstancePtr)– XStatus XUartLite_SelfTest (XUartLite *InstancePtr)– void XUartLite_EnableInterrupt (XUartLite *InstancePtr)– void XUartLite_DisableInterrupt (XUartLite *InstancePtr)– void XUartLite_SetRecvHandler (XUartLite *InstancePtr, XUartLite_Handler FuncPtr, void *CallBackRef)– void XUartLite_SetSendHandler (XUartLite *InstancePtr, XUartLite_Handler FuncPtr, void *CallBackRef)– void XUartLite_InterruptHandler (XUartLite *InstancePtr)

• Uartlite Level 0 – void XUartLite_SendByte (Xuint32 BaseAddress, Xuint8 Data)– Xuint8 XUartLite_RecvByte (Xuint32 BaseAddress)

Software Design 38

Outline







Software Design 39

Exceptions and Interrupts

• Exceptions are events detected by the processor that require action by the system software– Typically, the result of unexpected error conditions (e.g., bus error)– Some exceptions can be programmed to occur (e.g., FIT, PIT)– Some exceptions are generated by external devices (e.g., CritInt)

• Interrupts are automatic control transfers as a result of an exception– Execution of the current program is suspended after the current instruction– Some context info is saved so execution can return to the current program – Execution is transferred to the interrupt handler to service the interrupt– The interrupt handler must be registered– The interrupt must be enabled

Software Design 40

Hardware Interrupt Inputs

• Two external inputs to the IBM PowerPC 405 processor core:– Critical interrupt– External interrupt

• Enabled and disabled through the Machine State Register (MSR)– MSR(CE) and MSR(EE)– Default @RESET is disabled

• FPGA design adds an interrupt controller for application-specific requirements– Supports 32 interrupts

Software Design 41


Entry Point

Save State

Call Handler

Restore State

Return to Program

Exception Code

HANDLER

Registered Handler

Software Design 42


• Exception library function calls support:– void XExc_Init(void);

• Initializes vector table, default handlers– void XExc_RegisterHandler (Xuint8 ExceptionId, XExceptionHandler

Handler, void *DataPtr);• Allows the registration of a handler

– void XExc_RemoveHandler (Xuint8 ExceptionId)• Replaces the current handler with a default handler

– void XExc_mEnableExceptions (EnableMask);• Enables Crit, NonCrit interrupts

– void XExc_mDisableExceptions (DisableMask);• Disables Crit, NonCrit interrupts

Software Design 43

Timer Facilities

• Features:– Time base– Fixed Interval Timer (FIT)– Programmable Interval Timer (PIT)– Watchdog timer– These timers share the same time-base clock frequency

• Uses:– Time-of-day– Data logging– Peripherals requiring periodic service– Recover from faulty hardware or firmware

PowerPC Processor: Sleep• Sleep BSP library function calls:

– unsigned int usleep(unsigned int __useconds);– unsigned int sleep(unsigned int __seconds);

• The sleep() or usleep() function in sleep.c delays the execution of a program by __seconds or __useconds seconds

• Set CORE_CLOCK_FREQUENCY as sleep() and usleep() functions use it compute the delay

PowerPC: Time

• The xtime_l.c file and corresponding xtime_l.h include file provide access to the 64-bit time-base counter inside the PowerPC processor core

• The counter increases by one every processor cycle• Declarations:

– void XTime_SetTime(XTime xtime);• Sets the time-base register to the value in xtime

– void XTime_GetTime(XTime *xtime);• Writes the current value of the time-base register to variable xtime

– void XTime_TSRClearStatusBits(unsigned long Bitmask);• Used to clear bits in the Timer Status Register (TSR). The parameter Bitmask

designates the bits to be cleared. A one in any position of the Bitmask parameter clears the corresponding bit in the TSR

Software Design 46

Outline




– Level 0, Level 1– PowerPC Processor: Exceptions, Sleep, and Time– Integration in EDK



Integration in EDK• When the interrupt generating device is connected to the processor interrupt pin, either

through an opb interrupt controller or directly, only the interrupt handler function must be developed (for example, you do not need to explicitly write code to set up the interrupt mechanism)

• In the Software Platform Setting dialog box, enter the interrupt handler function name for the corresponding device

• The Interrupt Handler Function section in Interrupt Handler panel provides an entry for the Interrupt function name associated with that peripheral

Software Design 48

Outline







Libraries

• Xilinx provides three libraries– Math library (libm)

• The math library is an improvement over the newlib math library

– Standard C language support (libc)• The functions of this library are automatically available

– Xilinx C drivers and libraries (libxil)• Xilinx file support functions LibXilFile• Xilinx memory file system LibXilMfs• Xilinx networking support LibXilNet

Software Design 50

Outline







Software Design 51

What is a BSP?

• Board Support Package (BSP):– A set of software modules combined into the libxil.a library– Allows you to use the low-level PowerPC processor core

functions• Enable, disable, and flush caches• Read/write time-base registers

– Allows you to use IP peripheral-device drivers• GPIO, IIC controller, PCI controller, UART

– Offers glue functionality to link code against standard libraries• Time, sleep• Files• Memory

Software Design 52

Hardware IP Device Drivers

• Driver– Provides an interface for the software to communicate with the

hardware– Designed to be portable across processor architectures and

operating systems

• Delivery format– Delivered as source code, allowing it to be built and optimized– Minimized assembly language– C programming language

Software Design 53

Outline







Software Design 54

PowerPC Processor Boot Files

• Files: boot.S, boot0.S, crt0.S, eabi.S– Application entry point at label _boot in

boot.S– _boot is single jump instruction to

_boot0 – _boot0 is a few instructions that do a

jump to _start in crt0.S– _start

• Clears .bss and .sbss sections• Sets up stack on an eight byte

alignment• Initializes time-base registers to zero• Optionally, enable FPU bit in MSR• Calls main()

– Calls _eabi to set R13 and R2 registers to point to .sdata and .sdata2 sections respectively

– Performs user tasks

Software Design 56

Review Questions

• What is included in a BSP?

• What are some of the differences between a Level 0 and a Level 1 driver?

Software Design 57

Answers

• What is included in a BSP?– IP drivers– Processor functions– Library functions

• What are some of the differences between a Level 0 and a Level 1 driver?– Size– Functionality– Ease of use

Where Can I Learn More?

• Tool documentation– Platform Specification Format Reference Manual

• Microprocessor Software Specifications• Microprocessor Driver Definition• Microprocessor Library Definition • EDK OS and Libraries Reference Guide LibXil File, Net, and Kernel • Processor IP Reference Guide• Xilinx Drivers

• Processor documentation– PowerPC Processor Reference Guide– PowerPC 405 Processor Block Reference Guide

• Support website– EDK Home Page: support.xilinx.com/edk

Documents

This material exempt per Department of Commerce license exception TSU Software Development