Missing:

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

Missing:

+ * $FreeBSD$
  */

Not sure what does "*<" in the comment mean :)

Nope, this should be the following before your first #include, unless you are in the ".h" file:

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

You already have cdefs.h, so just do the following and remove $FreeBSD from the comment here.

  #include <sys/cdefs.h>
+ __FBSDID("$FreeBSD$");
+ 
  #include <sys/param.h>

I'd add just to make sure that later on if some changes are made to the code you won't get with the bogus pointer in the cleanup:

          struct mipscore_regs *regs;

+         regs = NULL;

Not a critical code path (only run once per boot), so it won't hurt anything.

Missing \n before mipscore_probe and another one between ) and {, should be

static int
mipscore_probe(device_t dev)
{

Extra blank line.

See a note above for mipscore_probe.

Move uint16_t devid declaration up two lines.

Move int error declaration together with other vars.

Another space is missing before (.

Another space is missing before (.

Variable definition should probably go to the beginning of the function and separated from the initialization:

From style(9):

Be careful to not obfuscate the code by initializing variables in the
declarations.  Use this feature only thoughtfully.  DO NOT use function
calls in initializers.

@mizhka_gmail.com speaking of this I am not 100% sure about merits of M_NOWAIT ms. M_WAITOK here. Conceptually I'd rather wait for a while and attach, than run without core driver with CPU in broken state (e.g. that TI interrupt issue). That being said, I also understand that in practice it would be hard to construct a plausible case for that to fail. Maybe check what other low-level drivers do to avoid spreading bad code around via copy-pasto.