In CPU definitions we should not be explicilty naming peripheral modules to use
via USEMODULE (one should use FEATURES_PROVIDED instead).
Plus add missing cpu_init() and periph_init() methods.
This commit removes periph_hwrng support from the pic32mx cpu builds as
pic32mx does not have hwrng only pic32mz does.
- Copied the relevant parts of mipshal.mk from the toolchain
- Cleaned up CFLAGS and more in Makefile.include
- Added empty syscalls implementation which can be used to interface
with the UHI system
- Added a note on why -std=gnu99 is necessary for this CPU presently
cpu/mips32r2_common adds base architecture support for mips32r2 cores it can be
built in it own right as a 'CPU', but is dependant on a bootloader (like
u-boot) to have bootstrapped the system, this has been tested on a 'malta'
FPGA system (BOARD=mips-malta) with various mips32r2 compliant cores
(interAptiv, P5600, etc).
