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SubjectRe: [PATCH v2 5/5] iio: mxs-lradc: add write_raw function to modify scale
Date
Dear Hector Palacios,

> 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.palacios@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];

Why not use bitfield ? ;-)

> /*
> * 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 */

This comment is confusing, you use [0] in different dimensions of the array. So
is the stuff below.

Still, how does this even work, can you show me and example how to set the
divider from userland ? Sorry, I'm a bit confused with this 3D-business here,
even if the comment in previous patch made it a bit clearer. Actually you can
use some #define to specify if you're accessing div/2 or div/1 portion of the
array to make it more readable.

Like ... scale_avail[chan->channel][LRADC_DIV_BY_2][LRADC_DECIMAL_PART] ...
would by nice.

> + 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,

Is this & needed here ?

> .attrs = &mxs_lradc_attribute_group,
> };

Best regards,
Marek Vasut


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