[U-Boot] Environment and SPI drivers

[Wolfgang Denk]

Dear Albin Tonnerre,

In message <20100315192914.GA14032 at pc-ran3241> you wrote:
> 
> The SPI framework provided by u-boot (spi_setup_slave, spi_xfer and the like)
> cannot currently be used to read the environment from SPI devices. The reason is

This depends on what sort of SPI devices you are talking about. Do you
have plain simple EEPROM in mind, or things like SPI flash, or
eventually MMC/SDCard?  These are pretty different thinngs...

> I'm wondering what would be a proper fix for this. I don't think it is OK to say
> 'drivers reading the environment should not use the SPI framework', as those
> drivers might be used to do others things - that would make the SPI framework
> unsuitable for (e.g.) any SPI EEPROM. The only sane alternative I can see is
> that we introduce spi_setup_slave_$whatever, which would work the same way as
> spi_setup_slave, with the difference that it should be given caller-allocated
> storage, so that we avoid the use for malloc().

If you are talking about SPI EEPROM, then just enable EEPROM support
and environment in EEPROM, and set CONFIG_SPI. The EEPROM framework in
"common/cmd_eeprom.c" includes support for SPI EEPROM (this actually
predates the SPI framework).

Best regards,

Wolfgang Denk

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