Remove a lot of older cruft not needed.
Improve ISR support, but it is still unused since polling is faster
Properly initalize the speed register to get 90kb/s, not 400b/s.
Try to catch NACK
Allow 0 length read transfers to generate start/top pairs.
o Don't delay when checking the done bits. There's no gain other
than a small performance hit.
o calculate the clock divisors better (things are still way slow,
so maybe there's more here?)
o don't always fail reset. Always succeed instead.
o fix inverted logic around at91_twi_wait() return value
o remove debug code
o remove unneeded, unworking junk
is a ARM920T based CPU with a bunch of built-in peripherals. The
inital import supports the SPI bus, the TWI bus (although iicbus
integration is not complete), the uarts, the system timer and the
onboard ethernet. Support for the Kwikbyte KB9202
(http://www.kwikbyte.com) board is also included, although there's no
reason why the 9200 and the 9201 wouldn't also work. Primitive
support for running under the skyeye emulator is also provided
(although skyeye's support for the AT91RM9200 is a little weak).
The code has been structured so that other members of Atmel's arm family can
be supported in the future. The AT91SAM9260 is not presently supported
due to lack of hardware. The arm7tdmi families are also not supported
becasue they lack an MMU.
Many thanks to cognet@ for his help and assistance in bringing up this
board. He did much of the vm work and wrote parts of the uart and
system timer code as well as the bus space implementation.
The system boots to single user w/o problem, although the serial
console is a little slow and the ethernet driver is still in flux.
This work was sponsored by Timing Solutions, Corporation. I am
grateful to their support of the FreeBSD project in this manner.
