Introduction to ARM A15 Linux

DSP Platform Software Apps Team 04/19/2013

TI Confidential - NDA Restrictions

Outline

1. ARM Cortex-A15 Overview 2. ARM A15 Linux Overview     U-boot Two Stage Bootloading Boot Monitor SMP Boot Sequence   LPAE Linux Drivers TI Confidential - NDA Restrictions

ARM A15 Overview

        ARMv7-A Cortex - the latest member of the Cortex-A series of processors 1-4x SMP within a single processor cluster and low power consumption Thumb-2 Technology TrustZone Security Floating Point NEON Hardware Virtualization Large Physical Address Extension (LPAE) TI Confidential - NDA Restrictions

Thumb-2 Technology

 Thumb Mode   16-bit Thumb instructions vs 32-bit ARM instructions Thumb-2 extends with additional 32-bit instructions  Code density similar to Thumb  up to a 30% reduction in memory to store instructions  Performance similar to the ARM instruction set on 32-bit memory 4

TrustZone Security

 2 virtual processors backed by hardware based access control  Enable application core to switch between 2 states (worlds)  Each world can operate independently while using the same core.  Memory and peripherals are made aware of the operating world and provide access control  Secure Monitor is code that runs in secure Monitor mode and processes switches to and from the secure world 5

Floating Point

 Vector Floating Point (VFP) is an FPU coprocessor extension to the ARM architecture  Hardware support for FP operations in half-, single- and double-precision floating point arithmetic .

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NEON

 Advanced SIMD extension, or Media Processing Engine (MPE)  A combined 64- and 128-bit SIMD instruction set  Provides acceleration for media and signal application  NEON hardware shares the same floating-point registers as used in VFP. Linux version: 3.6.0, GCC version: Linaro 4.6.3

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Hardware Virtualization

 Hardware support for multiple software environments available on the same physical processor  Software applications can access the system capabilities simultaneously  Virtual envrionments are isolated from each other 8

LPAE

 64 bit “long-descriptor” format for page tables  Supports 40-bit physical address – up to 1TB of memory 9

ARM A15 Linux Overview

      U-boot Two Stage Bootloading Boot Monitor SMP Boot Sequence LPAE Linux Drivers 10

U-Boot

 Based on the Universal Boot Loader public project  Program that moves executable from non-volatile memory to memory and then transfers CPU control to the newly “loaded” executable  Minimal drivers       SPI I2C UART NAND ETH USB 11

Two Stage Bootloading

 ROM Boot Loader(RBL) loads Secondary Program Loader (SPL) from SPI NOR flash  SPL loads and run the second stage boot loader, a full version of U-Boot) from NOR or NAND  Keystone II – SPI boot mode   The first 64K of the SPI NOR flash is flashed with SPL Followed by U-Boot image 12

Boot Monitor

 ARM Cortex A15 requires certain functions to be executed in the PL1 privilege level  Provides secure privilege level execution service for Linux Kernel code through SMC calls 13

Boot Monitor – High level architecture

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Boot Sequence – Primary Core

 RBL is run on Power On reset  After completion, load and run u-boot in non-secure mode  Boot Monitor gets installed  As part of non-secure entry, boot monitor calls the RBL API through SMC call (SMC #0) passing _init() entry point address.

 RBL enters monitor mode, _init() inits the monitor vector and calls init() to init Core/CPU specific inits, set the primary/secondary flag, the Set the secondary core non-secure entry point address   Back to non-secure mode and booting of linux kernel At linux start up, primary core make SMC call to power on each of the secondary cores  Primary core waits for secondary cores to boot up and then proceeds to rest of booting sequence 15 TI Confidential - NDA Restrictions

Boot Sequence – Secondary Core

 On Power On reset, RBL initializes and enters the secondary entry point address of the Boot Monitor core through SMC call (SMC #0)  RBL enters monitor mode, _init() inits the monitor vector and calls init() to init Core/CPU specific inits.

 On return from _init(), it jumps to secondary kernel entry point address and start booting 2 nd of Linux kernel instance 16

LPAE

    DDR3A memory address space 0x08 0000 0000 – 0x09 FFFF FFFF Cortex-A15 LPAE with 40-bit address bus may access if MMU is on ARM has only 32-bit effective address bus if MMU is off To access DDR3A when MMU is off   MSMC maps first 2GB to 0x00 8000 0000 – 0x00 FFFF FFFF The aliased address space can be used when MMU is on or off  Keystone II does not support cache coherency for the aliased address space  Default memory property of TCI6638 is 0x8000 0000 size 0x2000 0000  When U-boot boots the kernel, it can modify the default start address.

  If mem_lpae=0, U-boot does not modify If mem_lpae=1, U-boot sets the start address to 0x08 0000 0000 17

Linux Drivers

               GIC IRQ chip driver Keystone IPC IRQ chip driver SMP AEMIF driver NAND driver SPI and SPI NOR flash drivers I2C and EEPROM drivers Keystone GPIO driver Keystone IPC GPIO driver Network driver (NetCP), PktDMA, Packet Accelerator SGMII driver QoS driver USB driver 10Gig Ethernet driver (not validated due to test hardware) PCIe driver 18

Getting Started with MCSDK

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Prerequisite

 K2EVM-HK (Follow Hardware setup guide to make sure you have the latest BMC updates) http://processors.wiki.ti.com/index.php/EVMK2H_Hardware_Setup  User guide: (getting started guide & exploring as well) http://processors.wiki.ti.com/index.php/MCSDK_User_Guide_for_KeyStone_II  Download MCSDK: http://software-dl.ti.com/sdoemb/sdoemb_public_sw/mcsdk/latest/index_FDS.html

 Ubuntu Linux 12.04 LTS machine, set up Proxy (consult IT) 20

Install CCS & MCSDK

 1. Install CCSv5.3.0 at . For processor architecture, make sure "C6x DSP + ARM processors" is selected.

 2. Install TI KeyStone2 Emupack, ti_emupack_keystone2_setup_1.0.0.2

If installed on Linux, replace \ with / in this file /opt/ti/ccsv5/ccs_base/common/targetdb/devices/TCI6638.xml  3. Install MCSDK 3.00.00.09, same directory as CCS, e.g.: /opt/ti  4. copy the file tci6638-evm.ccxml from mcsdk_linux_3_00_00_09/host-tools/loadlin folder to ~//ti/CCSTargetConfiguration folder where the CCS saves the user specific configuration file.

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Build Prerequisite

 Toolchain installation: Download the gcc-linaro-arm-linux-gnueabi-2012.03-20120326_linux.tar.bz2 from https://launchpad.net/linaro-toolchain-binaries/trunk/2012.03

cd ~/ tar xjf gcc-linaro-arm-linux-gnueabi-2012.03-20120326_linux.tar.bz2 export CROSS_COMPILE=arm-linux-gnueabi export ARCH=arm PATH=$HOME/gcc-linaro-arm-linux-gnueabi-2012.03-20120326_linux/bin:$PATH  Configure git and install packages needed at build time: sudo apt-get install git-core sudo apt-get install build-essential subversion ccache sed wget cvs coreutils unzip texinfo docbook-utils gawk help2man diffstat file g++ texi2html bison flex htmldoc chrpath libxext-dev xserver-xorg-dev doxygen bitbake uboot-mkimage libncurses5-dev 22

Getting started with MCSDK

 Either use prebuilt images or build Uboot, boot monitor, kernel & file system on your own.

 File systems supported: ramfs, Net mounted file system, UBIFS. Configure environment variable as per user’s guide.

 Getting Kernel & file system to boot  Run applications 23