Building with attached random configuration file,

drivers/built-in.o: In function `mxs_lradc_ts_unregister':
/home/jim/linux/drivers/staging/iio/adc/mxs-lradc.c:905: undefined
reference to `input_unregister_device'
drivers/built-in.o: In function `input_report_abs':
/home/jim/linux/include/linux/input.h:399: undefined reference to `input_event'
/home/jim/linux/include/linux/input.h:399: undefined reference to `input_event'
/home/jim/linux/include/linux/input.h:399: undefined reference to `input_event'
drivers/built-in.o: In function `input_report_key':
/home/jim/linux/include/linux/input.h:389: undefined reference to `input_event'
drivers/built-in.o: In function `input_sync':
/home/jim/linux/include/linux/input.h:414: undefined reference to `input_event'
drivers/built-in.o:/home/jim/linux/include/linux/input.h:389: more
undefined references to `input_event' follow
make: *** [vmlinux] Error 1