+
−FreeCalypso loadtools have been designed from the beginning to work through
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−the Calypso chip's own boot ROM.  This approach works great for Openmoko and
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−Pirelli targets, but Compal phones unfortunately have this Calypso boot ROM
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−disabled at the board level.  To run our own code in these phones instead of
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−booting the regular firmware, we need to go through Compal's own boot code.
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−The latter allows loading code into IRAM and jumping to it, but not in the
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−same way as how we do it through the Calypso boot ROM.
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−
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−One could argue that the "proper" way to support these Compal phones would be
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−to build a different version of our loadagent that is designed to be loaded
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−through Compal's boot code instead of the Calypso boot ROM, and then redesign
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−our fc-loadtool and fc-xram utilities to work with different loadagents loaded
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−in different ways on different target devices.  But I don't feel like doing
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−that - too invasive to the once-clean design of loadtools.
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−
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−Hence I am adopting a different solution that works in the same way as
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−OsmocomBB's "chain loading": the IRAM image that is fed to Compal's boot code
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−is not our real loadagent, but a tiny piece of code that enables the Calypso
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−boot ROM and jumps to it.  All loadtools host programs will include this
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−optional "Compal stage" at the beginning, enabled for targets that need it,
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−but will then always fall into the Calypso boot ROM IRAM download path.
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−
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−The approach I'm adopting is doubly inefficient for Mot C139/140 phones whose
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−bootloader effectively requires that the downloaded image be ~15 KiB long
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−even when we only need to download 32 bytes.  But hey, our ultimate goal is to
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−produce our own Calypso phones, rather than hack those made by diabolical
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−manufacturers who do not Respect Your Freedom; running our own gsm-fw on the
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−Mot C139 is only a transitional step, so making fc-loadtool/fc-xram entry
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−slower by a second or two is probably an acceptable price for keeping the
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−code clean for the boot-ROM-enabled free world.
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−
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−In this directory we build the several different versions of compalstage
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−needed for different C1xx models.