STM32 - I/O pullup and EXTI issues, plus new SPI driver.

[Chris Holgate <chris@zynaptic.com>]

Hi folks,

I came across a couple of HAL issues while putting together my new SPI
driver for the STM32.  I appreciate that the maintainers are overloaded
with eCos 3.0 work at the moment, so I'll defer to them as to whether
any of this needs fixing now and can provide more information/patches on
request.

1) It's not possible to set pullups on I/Os using the provided
functions.  This is a trivial one-line fix to stm32-misc.c.

2) External interrupts don't work as they stand.  This requires a few
changes to the STM32 var_intr.h.  If required I can tidy up my changes
there and provide a patch which I've tested using a single I/O
(EXTINT0), but which would probably benefit from a bit more testing
using other I/O configurations.

3) I've now got full register maps for the AFIO, DMA and SPI blocks.
For development purposes I've kept these in a separate file from the
STM32 var_io.h, but can provide the file for merging if required.

FYI, I now have a DMA-based SPI driver that is fully functional in
kernel mode, but will need one or two changes (and some testing!) to
make it play nicely in non-kernel mode.  Probably best to leave that
until the 3.0 release is done, though.

Chris.