iio: adc: ti_am335x_adc: Add the scale information

Without the scale, the values returned to the user are just a picture of
the input voltage against the full scale range of the ADC. We need to
provide the actual conversion factor to get milli-Volts values.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211015081506.933180-45-miquel.raynal@bootlin.com

diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index e7dba10b29b47e6ccae07e2501ab063b1ea7940a..867690b6c2dd056171b50d1e8c3467d6aa0eab7e 100644 (file)
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -417,6 +417,7 @@ static int tiadc_channel_init(struct device *dev, struct iio_dev *indio_dev,
                chan->indexed = 1;
                chan->channel = adc_dev->channel_line[i];
                chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+               chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
                chan->datasheet_name = chan_name_ain[chan->channel];
                chan->scan_index = i;
                chan->scan_type.sign = 'u';
@@ -441,6 +442,23 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
        unsigned long timeout;
        int ret;
 
+       switch (mask) {
+       case IIO_CHAN_INFO_RAW:
+               break;
+       case IIO_CHAN_INFO_SCALE:
+               switch (chan->type) {
+               case IIO_VOLTAGE:
+                       *val = 1800;
+                       *val2 = chan->scan_type.realbits;
+                       return IIO_VAL_FRACTIONAL_LOG2;
+               default:
+                       return -EINVAL;
+               }
+               break;
+       default:
+               return -EINVAL;
+       }
+
        if (iio_buffer_enabled(indio_dev))
                return -EBUSY;