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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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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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