The toolchain should be easy to install on OSX platforms. Below are a few troubleshooting items found on Mountain Lion (10.8.2).
See https://github.com/ddm/icetools for a set of shell scripts to build IceStorm on OSX (using brew for dependencies).
The libftdi package (.so lib binary and the ftdi.h header) has been renamed to libftdi0, so either do:
port install libftdi0
(note that ports installs the tool to /opt instead of /usr, see next note)
brew install libftdi0
Note that Mac Ports installs to /opt instead of /usr, so change the first two lines in iceprog/Makefile to:
LDLIBS = -L/usr/local/lib -L/opt/local/lib -lftdi -lm CFLAGS = -MD -O0 -ggdb -Wall -std=c99 -I/usr/local/include -I/opt/local/include/
Basically you are indicating where to find the lib with -L/opt/local/lib and where to find the .h with -I/opt/local/include/.
This is a compiler issue, i.e., you are probably running on clang and you can circumvent this error by compiling against another compiler. Edit the Makefile of yosys and replace the two first lines for this, i.e., comment the first line (clang) and uncomment the second (gcc):
#CONFIG := clang CONFIG := gcc
You need to unload the FTDI driver (notes below are from Mountain Lion, 10.8.2). First check if it is running:
kextstat | grep FTDIUSBSerialDriver
If you see it on the kextstat, we need to unload it:
sudo kextunload -b com.FTDI.driver.FTDIUSBSerialDriver
Repeat the kextstat command and check that the driver was successfully unloaded.
Try running iceprog example.bin again. It should be working now.
Note: On newer OSes perhaps you need to also kextunload the com.apple.driver.AppleUSBFTDI driver.