@Peter Yes, i have read that. It says directly addressable but it's not like i can access those addresses straight from user space. So how do i access them . In the above case how do i access the register of the wm97 codec ic which is on an AC97 bus?
@Anish Yes, wm97xx-core is a touch driver falling in the input subsystem. Though i did not look at the input core, but, i guess the touch screen functionality is provided that way as it includes the input.h file. Your suggestion is not exactly clear. I understand i have to write a kernel module. I guess the functions you are referring to are already exported by that driver code. ---------------------------------------------------------------------------------------------------------------------------------------- For my case, i was interested in reading the ADC values using four auxiliary ADC's provided by the WM97 codec IC. If you look at the driver code file, it has a function for reading the WM97 registers as well as the auxiliary ADC's. I wanted to use them. My specific question is how do i write a driver using this wm97xx_core.c to read the auxiliary ADC's? My general question will be how does a device use a platform driver to provide any kind of read write functionality access to it's register or any other functionality. A character driver provides explicit read write functions which are used through an open /dev node. How do i do something similar using a platform driver like the one above? Thanks & Regards, Sanchayan. On Sun, Nov 10, 2013 at 2:02 AM, anish singh <anish198519851...@gmail.com>wrote: > > On Nov 9, 2013 4:18 AM, "sanchayan maity" <victorascr...@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. > > > > _______________________________________________ > > Kernelnewbies mailing list > > Kernelnewbies@kernelnewbies.org > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > >
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