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Re: MCF5282 - bits for DACRx registers
- From: Bart Veer <bartv at ecoscentric dot com>
- To: Christian Meusel <christian dot meusel at inf dot tu-dresden dot de>
- Cc: ecos-discuss at ecos dot sourceware dot org
- Date: Mon, 09 Feb 2009 20:39:20 +0000
- Subject: Re: [ECOS] MCF5282 - bits for DACRx registers
- References: <49907B2D.1060609@inf.tu-dresden.de>
>>>>> "Christian" == Christian Meusel <christian.meusel@inf.tu-dresden.de> writes:
Christian> I'm currently backporting our eCos port for the
Christian> ColdFire MCF5282 (based= on the old coldfire
Christian> architecture) to the MCF52xx processor HAL (based on=
Christian> m68k) contributed by eCosCentric.
Christian> The archictecture HAL for MCF52xx processors provides
Christian> quite a lot of definitions for the MCF5282. Amongst
Christian> others, bit definitions for the SDRAM controller's DACR
Christian> registers where the motivation behind is not clear to
Christian> me. For example, the port size bits
Christian> (HAL_MCFxxxx_SDRAMC_DACRx_PS_32, ...) are alredy
Christian> shifted to the appropriate position within a DACR
Christian> register where the command and bank MUX bits
Christian> (HAL_MCFxxxx_SDRAMC_DACRx_CBM) are not.
Christian> Is there a special intention for not shifting the
Christian> command and bank MUX bits to their appropriate
Christian> position? Has these definitions be made for allowing to
Christian> redefine HAL_MCFxxxx_SDRAMC_DACRx_CBM_SHIFT for other
Christian> ColdFire processors? Is there already productive code
Christian> out there which relies on this definition of the
Christian> command and bank MUX bits?
Christian> If not, I would like to change the bit defintions for
Christian> the command and bank MUX bits in var_io.h. If there is
Christian> a reason for not doing so, our MCF5282 port will live
Christian> with the definitions already provided for this bits. We
Christian> are planning to contribute this port when it is
Christian> finished and therefor we would like to minimize the
Christian> impact of such "global" changes.
The definitions in var_io.h are not necessarily 100% consistent,
partly because the Freescale reference manuals are not 100% consistent
especially between processors, and partly because it is actually quite
hard to avoid mistakes when typing in very large numbers of these
definitions. The particular case of the _CBM settings does look an
oversight and can be fixed with relatively low risk, so I'll make the
change. If there are other problems it may or may not be possible to
fix them. It will depend on the risk to existing production systems.
Bart
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Bart Veer eCos Configuration Architect
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