Overall, this diff looks fine.  There are numerous little style violations (all of which I did not point out).  Many, many lines also seem to exceed 80 columns.

src/dev/arm/amba_device.hh (Diff revision 1)

Sort #includes

src/dev/arm/amba_device.cc (Diff revision 1)

full #include path please.  Sort includes.

src/dev/arm/pl111.hh (Diff revision 1)

Should be _HH__

src/dev/arm/pl111.hh (Diff revision 1)

Please sort #includes and have system #include separate and at the top

src/dev/arm/pl111.hh (Diff revision 1)

Brace on new line.

src/dev/arm/pl111.hh (Diff revision 1)

Brace on new line.

I'd personally prefer to see a separate declaration of "Header header;" somewhere else, though I won't be stubborn.

src/dev/arm/pl111.hh (Diff revision 1)

Would uint8_t make more sense here?

src/dev/arm/pl111.hh (Diff revision 1)

Brace on new line.

src/dev/arm/pl111.hh (Diff revision 1)

If you're going to keep the "header" here, there should probably be a space after the brace to be consistent with other code. (though I'd rather see the "header" somewhere else.

src/dev/arm/pl111.hh (Diff revision 1)

brace on new line.

src/dev/arm/pl111.hh (Diff revision 1)

Brace on new line.

src/dev/arm/pl111.hh (Diff revision 1)

uint8_t?

src/dev/arm/pl111.cc (Diff revision 1)

space after comma.

src/dev/arm/pl111.cc (Diff revision 1)

Space after for.

src/dev/arm/pl111.cc (Diff revision 1)

Space after for

src/dev/arm/pl111.cc (Diff revision 1)

space after if, no space after (, space before brace

src/dev/arm/pl111.cc (Diff revision 1)

space after switch

src/dev/arm/pl111.cc (Diff revision 1)

I personally like this style, but to be consistent, else should be on line with brace.

src/dev/arm/pl111.cc (Diff revision 1)

and here

src/dev/arm/pl111.cc (Diff revision 1)

and here
and space before brace

src/dev/arm/pl111.cc (Diff revision 1)

else should be on line with brace.

src/dev/arm/pl111.cc (Diff revision 1)

space after if, space before brace.