Dear Hector Palacios,
> Dear Marek,
>
> On 07/05/2013 01:41 PM, Marek Vasut wrote:
> > Dear Hector Palacios,
> >
> >> Some LRADC channels have a fixed pre-divider, and all can have enabled
> >> an optional divisor by two which allows a maximum input voltage of
> >> VDDIO - 50mV.
> >>
> >> This patch
> >>
> >> - adds the scaling info flag to all channels
> >> - adds a lookup table with max reference voltage per channel
> >>
> >> (where the fixed pre-dividers apply)
> >>
> >> - allows to read the scaling attribute (computed from the Vref)
> >>
> >> Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
> >> ---
> >>
> >> drivers/staging/iio/adc/mxs-lradc.c | 122
> >>
> >> +++++++++++++++++++++++++++--------- 1 file changed, 93 insertions(+),
> >> 29 deletions(-)
> >>
> >> diff --git a/drivers/staging/iio/adc/mxs-lradc.c
> >> b/drivers/staging/iio/adc/mxs-lradc.c index d65a594..012c42e 100644
> >> --- a/drivers/staging/iio/adc/mxs-lradc.c
> >> +++ b/drivers/staging/iio/adc/mxs-lradc.c
> >> @@ -107,19 +107,63 @@ static const char * const mx28_lradc_irq_names[] =
> >> {
> >>
> >> "mxs-lradc-button1",
> >>
> >> };
> >>
> >> +/*
> >> + * Max reference voltage (mV) for each channel
> >> + */
> >> +static const int mx23_vref_mv[LRADC_MAX_TOTAL_CHANS] = {
> >> + 1850, /* CH0 */
> >> + 1850, /* CH1 */
> >> + 1850, /* CH2 */
> >> + 1850, /* CH3 */
> >> + 1850, /* CH4 */
> >> + 1850, /* CH5 */
> >> + 1850 * 2, /* CH6 VDDIO */
> >> + 1850 * 4, /* CH7 VBATT */
> >> + 1850, /* CH8 Temp sense 0 */
> >> + 1850, /* CH9 Temp sense 1 */
> >> + 1850, /* CH10 */
> >> + 1850, /* CH11 */
> >> + 1850, /* CH12 USB_DP */
> >> + 1850, /* CH13 USB_DN */
> >> + 1850, /* CH14 VBG */
> >> + 1850 * 4, /* CH15 VDD5V */
> >> +};
> >> +
> >> +static const int mx28_vref_mv[LRADC_MAX_TOTAL_CHANS] = {
> >> + 1850, /* CH0 */
> >> + 1850, /* CH1 */
> >> + 1850, /* CH2 */
> >> + 1850, /* CH3 */
> >> + 1850, /* CH4 */
> >> + 1850, /* CH5 */
> >> + 1850, /* CH6 */
> >> + 1850 * 4, /* CH7 VBATT */
> >> + 1850, /* CH8 Temp sense 0 */
> >> + 1850, /* CH9 Temp sense 1 */
> >> + 1850 * 2, /* CH10 VDDIO */
> >> + 1850, /* CH11 VTH */
> >> + 1850 * 2, /* CH12 VDDA */
> >> + 1850, /* CH13 VDDD */
> >> + 1850, /* CH14 VBG */
> >> + 1850 * 4, /* CH15 VDD5V */
> >> +};
> >
> > Should the above not be in DT ?
>
> Do you mean for example:
>
> lradc@80050000 {
> compatible = "fsl,imx28-lradc";
> reg = <0x80050000 0x2000>;
> interrupts = <10 14 15 16 17 18 19
> 20 21 22 23 24 25>;
> vref = <1850 1850 1850 1850
> 1850 1850 1850 7400
> 1850 1850 3700 1850
> 3700 1850 1850 7400>
> };
>
> I'm ok with it, but are there other examples of driver using a similar
> approach? I see for example the spear-adc which reads:
>
> Optional properties:
> - vref-external: External voltage reference in milli-volts. If omitted
> the internal voltage reference will be used.
>
> which makes me believe the 'internal voltage reference' is hardcoded in the
> driver. More opinions?
I'd duke this one out on devicetree-discuss@ list. In general, I'd use something
like fsl,vref prop, but this really better be discussed in a separate thread.
On the other hand, I'd hate to keep these patches here waiting , so maybe we
should apply them as-is and remove this part from the driver in a subsequent
patch? What do you say, Lars ?
Best regards,
Marek Vasut
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