Added write_raw function to manipulate the optional divider_by_two
through the scaling attribute out of the available scales.

Signed-off-by: Hector Palacios <hector.palac...@digi.com>
---
 drivers/staging/iio/adc/mxs-lradc.c | 55 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c 
b/drivers/staging/iio/adc/mxs-lradc.c
index c929733..286cde2 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -144,6 +144,7 @@ struct mxs_lradc {
 
        uint32_t                vref_mv[LRADC_MAX_TOTAL_CHANS];
        unsigned int            scale_avail[LRADC_MAX_TOTAL_CHANS][2][2];
+       unsigned int            is_divided[LRADC_MAX_TOTAL_CHANS];
 
        /*
         * Touchscreen LRADC channels receives a private slot in the CTRL4
@@ -202,6 +203,7 @@ struct mxs_lradc {
 #define        LRADC_CTRL1_LRADC_IRQ_OFFSET            0
 
 #define        LRADC_CTRL2                             0x20
+#define        LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET        24
 #define        LRADC_CTRL2_TEMPSENSE_PWD               (1 << 15)
 
 #define        LRADC_STATUS                            0x40
@@ -310,7 +312,8 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
                break;
        case IIO_CHAN_INFO_SCALE:
                *val = lradc->vref_mv[chan->channel];
-               *val2 = chan->scan_type.realbits;
+               *val2 = chan->scan_type.realbits -
+                       lradc->is_divided[chan->channel];
                ret = IIO_VAL_FRACTIONAL_LOG2;
                break;
        default:
@@ -323,6 +326,54 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
        return ret;
 }
 
+static int mxs_lradc_write_raw(struct iio_dev *iio_dev,
+                              const struct iio_chan_spec *chan,
+                              int val, int val2, long m)
+{
+       struct mxs_lradc *lradc = iio_priv(iio_dev);
+       int ret;
+
+       ret = mutex_trylock(&lradc->lock);
+       if (!ret)
+               return -EBUSY;
+
+       switch (m) {
+       case IIO_CHAN_INFO_SCALE:
+               ret = -EINVAL;
+               if (val == lradc->scale_avail[chan->channel][0][0] &&
+                   val2 == lradc->scale_avail[chan->channel][0][1]) {
+                       /* [0] -> divider by two disabled */
+                       writel(1 << LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET,
+                              lradc->base + LRADC_CTRL2 + STMP_OFFSET_REG_CLR);
+                       lradc->is_divided[chan->channel] = 0;
+                       ret = 0;
+               } else if (val == lradc->scale_avail[chan->channel][1][0] &&
+                          val2 == lradc->scale_avail[chan->channel][1][1]) {
+                       /* [1] -> divider by two enabled */
+                       writel(1 << LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET,
+                              lradc->base + LRADC_CTRL2 + STMP_OFFSET_REG_SET);
+                       lradc->is_divided[chan->channel] = 1;
+                       ret = 0;
+               }
+
+               break;
+       default:
+               ret = -EINVAL;
+               break;
+       }
+
+       mutex_unlock(&lradc->lock);
+
+       return ret;
+}
+
+static int mxs_lradc_write_raw_get_fmt(struct iio_dev *iio_dev,
+                                      const struct iio_chan_spec *chan,
+                                      long m)
+{
+       return IIO_VAL_INT_PLUS_NANO;
+}
+
 static ssize_t mxs_lradc_show_scale_available_ch(struct device *dev,
                struct device_attribute *attr,
                char *buf,
@@ -400,6 +451,8 @@ static const struct attribute_group 
mxs_lradc_attribute_group = {
 static const struct iio_info mxs_lradc_iio_info = {
        .driver_module          = THIS_MODULE,
        .read_raw               = mxs_lradc_read_raw,
+       .write_raw              = mxs_lradc_write_raw,
+       .write_raw_get_fmt      = &mxs_lradc_write_raw_get_fmt,
        .attrs                  = &mxs_lradc_attribute_group,
 };
 
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