At least one person found an SD card that wouldn't work at 2.7v.

Change-Id: I84001f07acc9ce36c71165706cce28c2899ac6bf

Many includes of fat.h are pointless. Some includes are just for
SECTOR_SIZE. Add a file 'firmware/include/fs_defines.h' for that
and to define tuneable values that were scattered amongst various
headers.

Remove some local definitions of SECTOR_SIZE since they have to be
in agreement with the rest of the fs code anyway.

(We'll see what's in fact pointless in a moment ;)

Change-Id: I9ba183bf58bd87f5c45eba7bd675c7e2c1c18ed5

* Remove unused bits like the radio event and simplify basic
radio interface. It can be more self-contained with rds.h only
required by radio and tuner code.

* Add post-processing to text a-la Silicon Labs AN243. The chip's
error correction can only do so much; additional checks are highly
recommended. Simply testing for two identical messages in a row
is extremely effective and I've never seen corrupted text since
doing that, even with mediocre reception.

Groups segments must arrive in order, not randomly; logic change
only accepts them in order, starting at 0.

Time readout was made a bit better but really we'd need to use
verbose mode and ensure that no errors were seen during receiving
of time and more checks would be need to have a stable PI. The
text is the important bit anyway.

* Time out of stale text.

* Text is no longer updated until a complete group has been
received, as is specified in the standard. Perhaps go back to
scrolling text lines in the radio screen?

* Add proper character conversion to UTF-8. Only the default G0
table for the moment. The other two could be added in.

* Add variants "RDS_CFG_PROCESS" and "RDS_CFG_PUSH" to allow
the option for processed RDS data to be pushed to the driver and
still do proper post-processing (only text conversion for now for
the latter).

Change-Id: I4d83f8b2e89a209a5096d15ec266477318c66925

Change-Id: Ic784c72a643546c8e31affa820f701eb7982b7c7

Remove "low power mode clocking" as we stop clocking by hands after each transfer.
Remove CGU_IDE and CGU_MEMSTICK as we don't use them.
Simplify logic in sd_transfer_sectors.

Change-Id: I120396d7ec5c99c62f3a746306aa8edd8686e08a

1. Slightly revised and regularized internal interface. Callback is used
for read and write to provide completion signal instead of having two
mechanisms.

2. Lower overhead for asynchronous or alterate completion callbacks. We
now only init what is required by the transfer. A couple unneeded
structure members were also nixed.

3. Fixes a bug that would neglect a semaphore wait if pumping the I2C
interrupts in a loop when not in thread state or interrupts are masked.

4. Corrects broken initialization order by defining KDEV_INIT, which
makes kernel_init() call kernel_device_init() to initialize additional
devices _after_ the kernel, threading and synchronization objects are
safe to use.

5. Locking set_cpu_frequency has to be done at the highest level in
system.c to ensure the boost counter and the frequency are both set in
agreement. Reconcile the locking inteface between PP and AMS (the only
two currently using locking there) to keep it clean.

Now works fine with voltages in GIT HEAD on my Fuze v2, type 0.
Previously, everything crashed and died instantly. action.c calling
set_cpu_frequency from a tick was part of it. The rest may have been
related to 3. and 4. Honestly, I'm not certain!

Testing by Mihail Zenkov indicates it solves our problems. This will
get the developer builds running again after the kernel assert code
push.

Change-Id: Ie245994fb3e318dd5ef48e383ce61fdd977224d4

Targets: sansaclipplus, samsaclipv2, sansaclipzip, sansafuzev2.

Change-Id: I7773528a4e26707dd33fe9cb8948750d49570701

Change-Id: I839ba2191a5c52ef6f58fd4a273db628b690a05c

Change-Id: I0424d02196a6c5fb6d0185b007df5ece24b10b82

Interrupts version is cause of freeze on USB extraction.
Also non-interrupts version much simpler and faster.

Change-Id: I30a2993cdcaa85abfba77ca06bfacd5b6b4353e2