[Letux-kernel] [PATCH v7 4/9] drivers:input:tsc2007: add iio interface to read external ADC input and temperature

[H. Nikolaus Schaller]

Hi Dmitry and Jonathan,

> Am 19.11.2016 um 21:09 schrieb Jonathan Cameron <jic23 at jic23.retrosnub.co.uk>:
> 
> 
> 
>>> 
>>> The IS_ENABLED macro takes care of both cases.
>> 
>> No it doesn't. Have you tried building the driver into the kernel with
>> IIO as a module?

I have tried and it indeed fails to compile.

> Fair point. Is there a clean way of handling this?
>> 

This seems to basically work and I have included it in [PATCH v8]:

obj-$(CONFIG_TOUCHSCREEN_TSC2004)	+= tsc2004.o
obj-$(CONFIG_TOUCHSCREEN_TSC2005)	+= tsc2005.o
tsc2007-y				:= tsc2007_core.o
ifeq ($(CONFIG_IIO),y)
tsc2007-y				+= tsc2007_iio.o
endif
ifeq ($(CONFIG_IIO),m)
tsc2007-y				+= tsc2007_iio.o
endif
obj-$(CONFIG_TOUCHSCREEN_TSC2007)	+= tsc2007.o
obj-$(CONFIG_TOUCHSCREEN_UCB1400)	+= ucb1400_ts.o
obj-$(CONFIG_TOUCHSCREEN_WACOM_W8001)	+= wacom_w8001.o

but still has a problem because it is not possible to
reference functions from the iio core with CONFIG_IIO=m
from a driver built into the kernel:

drivers/built-in.o: In function `tsc2007_iio_unconfigure':
/Users/hns/Sources/System/Kernel/Linux/src/master/drivers/input/touchscreen/tsc2007_iio.c:148: undefined reference to `iio_device_unregister'
drivers/built-in.o: In function `tsc2007_iio_configure':
/Users/hns/Sources/System/Kernel/Linux/src/master/drivers/input/touchscreen/tsc2007_iio.c:115: undefined reference to `devm_iio_device_alloc'
/Users/hns/Sources/System/Kernel/Linux/src/master/drivers/input/touchscreen/tsc2007_iio.c:133: undefined reference to `iio_device_register'

So it would mean that we have to dynamically locate
and bind iio_device_(un)register and devm_iio_device_alloc.

BR and thanks,
Nikolaus