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U-Boot for ARM Integrator Development Platforms
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Peter Pearse, ARM Ltd.
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peter.pearse@arm.com
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www.arm.com
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Manuals available from :-
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http://www.arm.com/products/DevTools/Hardware_Platforms.html
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Overview :
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--------
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There are two Integrator variants - Integrator/AP and Integrator/CP.
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Each may be fitted with a variety of core modules (CMs).
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Each CM consists of a ARM processor core and associated hardware e.g
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FPGA implementing various controllers and/or register
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SSRAM
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SDRAM
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RAM controllers
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clock generators etc.
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CMs may be fitted with varying amounts of SDRAM using a DIMM socket.
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Boot Methods :
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------------
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Integrator platforms can be configured to use U-Boot in at least three ways :-
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a) Run ARM boot monitor, manually run U-Boot image from flash
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b) Run ARM boot monitor, automatically run U-Boot image from flash
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c) Run U-Boot image direct from flash.
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In cases a) and b) the ARM boot monitor will have configured the CM and mapped
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writeable memory to 0x00000000 in the Integrator address space.
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U-Boot has to carry out minimal configration before standard code is run.
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In case c) it may be necessary for U-Boot to perform CM dependent initialization.
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Configuring U-Boot :
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------------------
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The makefile contains targets for Integrator platforms of both types
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fitted with all current variants of CM. If these targets are to be used with
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boot process c) above then CONFIG_INIT_CRITICAL may need to be defined to ensure
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that the CM is correctly configured.
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There are also targets independent of CM. These may not be suitable for
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boot process c) above. They have been preserved for backward compatibility with
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existing build processes.
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Code Hierarchy Applied :
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----------------------
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Code specific to initialization of a particular ARM processor has been placed in
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cpu/arm<>/start.S so that it may be used by other boards.
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However, to avoid duplicating code through all processor files, a generic core
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for ARM Integrator CMs has been added
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arch/arm/cpu/arm_intcm
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Otherwise. for example, the standard CM reset via the CM control register would
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need placing in each CM processor file......
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Code specific to the initialization of the CM, rather than the cpu, and initialization
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of the Integrator board itself, has been placed in
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board/integrator<>/platform.S
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board/integrator<>/integrator<>.c
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Targets
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=======
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The U-Boot make targets map to the available core modules as below.
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Integrator/AP is no longer available from ARM.
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Core modules marked ** are also no longer available.
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ap720t_config ** CM720T
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ap920t_config ** CM920T
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ap926ejs_config Integrator Core Module for ARM926EJ-STM
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ap946es_config Integrator Core Module for ARM946E-STM
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cp920t_config ** CM920T
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cp926ejs_config Integrator Core Module for ARM926EJ-STM
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cp946es_config Integrator Core Module for ARM946E-STM
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cp1136_config Integrator Core Module ARM1136JF-S TM
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The final groups of targets are for core modules where no explicit cpu
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code has yet been added to U-Boot i.e. they all use the same U-Boot binary
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using the generic "arm_intcm" core:
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ap966_config Integrator Core Module for ARM966E-S TM
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ap922_config Integrator Core Module for ARM922T TM with ETM
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ap922_XA10_config Integrator Core Module for ARM922T using Altera Excalibur
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ap7_config ** CM7TDMI
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integratorap_config
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ap_config
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cp966_config Integrator Core Module for ARM966E-S TM
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cp922_config Integrator Core Module for ARM922T TM with ETM
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cp922_XA10_config Integrator Core Module for ARM922T using Altera Excalibur
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cp1026_config Integrator Core Module ARM1026EJ-S TM
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integratorcp_config
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cp_config
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The Makefile targets call board/integrator<>/split_by_variant.sh
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to configure various defines in include/configs/integrator<>.h
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to indicate the core module & core configuration and ensure that
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board/integrator<>/u-boot.lds loads the cpu object first in the U-Boot image.
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*********************************
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Because of this mechanism
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> make clean
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must be run before each change in configuration
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*********************************
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