Hello, Thanks for explaining it. Now I understand better why read_raw is formatted in that manner. I have some questions in-line:
On Fri, Nov 11, 2016 at 03:18:37PM +0100, Lars-Peter Clausen wrote: > On 11/11/2016 07:34 AM, Eva Rachel Retuya wrote: > > Eliminate the non-standard attribute in_voltage_range and move its > > functionality under the scale attribute. read_raw() has been taken care > > of previously so only write_raw() is handled here. > > > > Additionally, rename the attribute in_voltage_range_available into > > in_voltage_scale_available. > > > > Suggested-by: Lars-Peter Clausen <[email protected]> > > Signed-off-by: Eva Rachel Retuya <[email protected]> > > Hi, > > Thanks for the patch. Unfortunately this is not quite this straight forward. > > The scale is what you multiply the raw with to get the value in the standard > IIO unit. Range as implemented in this driver is the maximum output voltage. > > To get the scale we need to look at the transfer function of the ADC [1]. > The transfer function tells us that 1 LSB is 305uV for the 10V range and > 152uV for the 5V range. Instead of 10000 and 5000, these will be the values for the scale_available attribute? > > More specifically this is $RANGE*2/2**16 (times two since the ADC is bipolar). > > Since the default unit for IIO is mV for voltages we need to multiply this > by 1000. > > The other thing we need to handle is the case where the RANGE pin is not > connected to a GPIO but either hardwired to 1 or 0. Which we need to handle > somehow. Will this be on the same patch or a separate one? Can you please give a hint on how to check if it is hardwired? Eva > > [1] > http://www.analog.com/media/en/technical-documentation/data-sheets/AD7606_7606-6_7606-4.pdf#page=23 > (right bottom) > > > --- > > drivers/staging/iio/adc/ad7606.c | 56 > > ++++++++++++---------------------------- > > 1 file changed, 16 insertions(+), 40 deletions(-) > > > > diff --git a/drivers/staging/iio/adc/ad7606.c > > b/drivers/staging/iio/adc/ad7606.c > > index 4531908..cceb18c 100644 > > --- a/drivers/staging/iio/adc/ad7606.c > > +++ b/drivers/staging/iio/adc/ad7606.c > > @@ -161,42 +161,7 @@ static int ad7606_read_raw(struct iio_dev *indio_dev, > > return -EINVAL; > > } > > > > -static ssize_t ad7606_show_range(struct device *dev, > > - struct device_attribute *attr, char *buf) > > -{ > > - struct iio_dev *indio_dev = dev_to_iio_dev(dev); > > - struct ad7606_state *st = iio_priv(indio_dev); > > - > > - return sprintf(buf, "%u\n", st->range); > > -} > > - > > -static ssize_t ad7606_store_range(struct device *dev, > > - struct device_attribute *attr, > > - const char *buf, size_t count) > > -{ > > - struct iio_dev *indio_dev = dev_to_iio_dev(dev); > > - struct ad7606_state *st = iio_priv(indio_dev); > > - unsigned long lval; > > - int ret; > > - > > - ret = kstrtoul(buf, 10, &lval); > > - if (ret) > > - return ret; > > - > > - if (!(lval == 5000 || lval == 10000)) > > - return -EINVAL; > > - > > - mutex_lock(&indio_dev->mlock); > > - gpiod_set_value(st->gpio_range, lval == 10000); > > - st->range = lval; > > - mutex_unlock(&indio_dev->mlock); > > - > > - return count; > > -} > > - > > -static IIO_DEVICE_ATTR(in_voltage_range, S_IRUGO | S_IWUSR, > > - ad7606_show_range, ad7606_store_range, 0); > > -static IIO_CONST_ATTR(in_voltage_range_available, "5000 10000"); > > +static IIO_CONST_ATTR(in_voltage_scale_available, "5000 10000"); > > > > static int ad7606_oversampling_get_index(unsigned int val) > > { > > @@ -221,6 +186,19 @@ static int ad7606_write_raw(struct iio_dev *indio_dev, > > int ret; > > > > switch (mask) { > > + case IIO_CHAN_INFO_SCALE: > > + if (val2) > > + return -EINVAL; > > + > > + if (!(val == 5000 || val == 10000)) > > + return -EINVAL; > > + > > + mutex_lock(&indio_dev->mlock); > > + gpiod_set_value(st->gpio_range, val == 10000); > > + st->range = val; > > + mutex_unlock(&indio_dev->mlock); > > + > > + return 0; > > case IIO_CHAN_INFO_OVERSAMPLING_RATIO: > > if (val2) > > return -EINVAL; > > @@ -247,8 +225,7 @@ static int ad7606_write_raw(struct iio_dev *indio_dev, > > static IIO_CONST_ATTR(oversampling_ratio_available, "1 2 4 8 16 32 64"); > > > > static struct attribute *ad7606_attributes_os_and_range[] = { > > - &iio_dev_attr_in_voltage_range.dev_attr.attr, > > - &iio_const_attr_in_voltage_range_available.dev_attr.attr, > > + &iio_const_attr_in_voltage_scale_available.dev_attr.attr, > > &iio_const_attr_oversampling_ratio_available.dev_attr.attr, > > NULL, > > }; > > @@ -267,8 +244,7 @@ static const struct attribute_group > > ad7606_attribute_group_os = { > > }; > > > > static struct attribute *ad7606_attributes_range[] = { > > - &iio_dev_attr_in_voltage_range.dev_attr.attr, > > - &iio_const_attr_in_voltage_range_available.dev_attr.attr, > > + &iio_const_attr_in_voltage_scale_available.dev_attr.attr, > > NULL, > > }; > > > > >
