WLAN from SDIO to SPI: battle plan

[Werner Almesberger]

I wrote:
> To be continued ...

After getting nowhere with trying to talk to the prototype board, and
seeing no end of those short pulses on MISO (*), I decided that my
suspicion that poor signal integrity was to blame even at this
moderate clock speed was probably more than a convenient excuse.

(*) Here's a beautiful one. D5 is the clock, D2 is MISO:
    http://people.openmoko.org/werner/wlan-spi/3.png

Then it occurred to me that I could just as well use the WLAN module
that's already in the device: after turning off the SDIO driver,
switching to mmc_spi over s3c24xx_spi_gpio, and adapting all the GPIO
definitions, the mainline SDIO stack happily welcomed the new member
with SDIO_ID=0271:010A :-)

I'll just go ahead with s3c24xx_spi_gpio for now, then rework and
switch to s3c24xx_spi when the Atheros stack talks to the module as
well.

I'll give "pure" SPI (G_SPI) a try when the EVB arrives.

To be continued ...

- Werner