Question on Platform Device/Driver

[anish singh]

On Nov 9, 2013 4:18 AM, "sanchayan maity" <victorascroft at gmail.com> wrote:
>
> Can someone give me some pointers or tell me as to how can one use a
platform driver for reading and writing?
>
> For example, if i have a wm97xx codec IC, a core platform driver is
provided (as on the below link).
>
http://lxr.free-electrons.com/sourcep/drivers/input/touchscreen/wm97xx-core.c
This is a touch driver\input driver.
So this driver comes under input subsystem.It interacts with input core to
send events to it using report api's.
>
> If i wanted to use this core driver to read the auxilary ADC's of wm97xx
codec how do i go about using the register read, write functions or read
auxiliary adc functions provided by this driver file?
What is the original problem you are trying to solve?You can do read\write
just by a small hack.Write a kernel module and make the read\write function
in this driver as exported.Use those in your own driver but make sure you
export other variables also to give the right inputs for those api's.I am
sure you are just looking for writing a device driver by doing an actual
read\write.Remember this will just be a bad code i.e. hack.
>
> I have gone through the documentation provided here
http://lxr.free-electrons.com/source/Documentation/driver-model/ but it is
still not clear to me. I understand the concept of why a platform driver is
required and how each device registers itself with the pseudo platform bus,
but, i do not understand how to use such a driver or make my driver based
on it and then use it for reading/writing.
>
> I understand character device drivers but, i am at a loss when it comes
to understand these platform drivers. I come from embedded domain and these
drivers seem are ubiquitous.
>
> Thanks.
>
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