[PATCH] IIO: Add basic MXS LRADC driver

[Marek Vasut]

Dear Juergen Beisert,

> Hi Marek,
> 
> Marek Vasut wrote:
> > > > > When I try to compile
> > > > > your code I get:
> > > > > 
> > > > > drivers/staging/iio/adc/mxs-lradc.c:42:40: fatal error:
> > > > > linux/iio/triggered_buffer.h: No such file or directory
> > > > 
> > > > You need this patches:
> > > >     iio:kfifo_buf Take advantage of the fixed record size used in IIO
> > > >     iio: kfifo - add poll support.
> > > > 
> > > > And use latest -next.
> > > 
> > > Thanks for the hints. Now it compiles and the driver seems to work.
> > > 
> > > One thing I do not understand: It does not matter what channel I read
> > > ('in_voltage*_raw'), only interrupt 16 ('mxs-lradc-channel0') counts
> > > up. Intended?
> > > Or did I a mistake by adding interrupt numbers "<13 14 15 16 17 18 19
> > > 20 21 22 23 24 25>" to the corresponding device tree entry?
> > 
> > They're wrong
> > 
> > lradc at 80050000 {
> > 
> >         compatible = "fsl,imx28-lradc";
> >         reg = <0x80050000 2000>;
> >         interrupts = <10 14 15 16 17 18 19
> >         
> >                         20 21 22 23 24 25>;
> >         
> >         status = "disabled";
> > 
> > };
> 
> Ups, thanks. But still the same behaviour:
> 
> $ cat /proc/interrupts
> [...]
>  10:          0         -  mxs-lradc-touchscreen
>  14:          0         -  mxs-lradc-thresh0
>  15:          0         -  mxs-lradc-thresh1
>  16:          0         -  mxs-lradc-channel0
>  17:          0         -  mxs-lradc-channel1
>  18:          0         -  mxs-lradc-channel2
>  19:          0         -  mxs-lradc-channel3
>  20:          0         -  mxs-lradc-channel4
>  21:          0         -  mxs-lradc-channel5
>  22:          0         -  mxs-lradc-channel6
>  23:          0         -  mxs-lradc-channel7
>  24:          0         -  mxs-lradc-button0
>  25:          0         -  mxs-lradc-button1
> [...]
> 
> $ cat in_voltage0_raw
> 524
> $ cat in_voltage1_raw
> 96
> $ cat in_voltage2_raw
> 1261
> 
> $ cat /proc/interrupts
> [...]
>  10:          0         -  mxs-lradc-touchscreen
>  14:          0         -  mxs-lradc-thresh0
>  15:          0         -  mxs-lradc-thresh1
>  16:          3         -  mxs-lradc-channel0
>  17:          0         -  mxs-lradc-channel1
>  18:          0         -  mxs-lradc-channel2
>  19:          0         -  mxs-lradc-channel3
>  20:          0         -  mxs-lradc-channel4
>  21:          0         -  mxs-lradc-channel5
>  22:          0         -  mxs-lradc-channel6
>  23:          0         -  mxs-lradc-channel7
>  24:          0         -  mxs-lradc-button0
>  25:          0         -  mxs-lradc-button1
> [...]
> 
> Intended in this way?

But wait, you're getting interrupts on channel 0. Doesn't seem quite right. Did 
you happen to poke into the code and see where the issue might be?

> Regards,
> Juergen

Best regards,
Marek Vasut