Hello everyone,
You will find a small series that add the support of processed values
for iio-rescale driver.
Thanks to that, it is possible to read processed values in sysfs instead
of getting only raw and scale values.
Here is an example for a 3v3 voltage reading:
# cat /sys/bus/iio/devices/iio\:device1/in_voltage0_scale
3.791015625
# cat /sys/bus/iio/devices/iio\:device1/in_voltage0_raw
879
# cat /sys/bus/iio/devices/iio\:device1/in_voltage0_input
3332
It is also possible to read directly the processed values using iio-hwmon
driver (see example in patch03):
# cat /sys/class/hwmon/hwmon0/in1_input
3328
I seperated my series in 3 patches:
- Patch01: Move the scale conversion into a function to prepare the
support of IIO_CHAN_INFO_PROCESSED.
- Patch02: Add the support of IIO_CHAN_INFO_PROCESSED.
- Patch03: Add an example of the use of hwmon and voltage-divider nodes
in device-tree.
If you have any feedbacks on it, I will be pleased to read them!
Best regards,
Mylène
Mylène Josserand (3):
iio: afe: rescale: Move scale conversion to new function
iio: afe: rescale: Add support of CHAN_INFO_PROCESSED
dt-bindings: iio: afe: Add hwmon example
.../bindings/iio/afe/voltage-divider.txt | 24 ++++++
drivers/iio/afe/iio-rescale.c | 96 ++++++++++++++++------
2 files changed, 96 insertions(+), 24 deletions(-)
--
2.11.0
Add the support of the CHAN_INFO_PROCESSED to have directly
the processed value (raw * scale). It will be exported as
in_voltage0_input in sysfs.
Signed-off-by: Mylène Josserand <[email protected]>
---
drivers/iio/afe/iio-rescale.c | 42 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 41 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index 3e689d6eb501..2275571fff64 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -63,14 +63,54 @@ static int rescale_convert_scale(struct rescale *rescale, int *val, int *val2)
}
}
+static int rescale_convert_processed(struct rescale *rescale, int raw,
+ int *val, int *val2)
+{
+ unsigned long long tmp, scaled;
+ int ret;
+
+ ret = rescale_convert_scale(rescale, val, val2);
+ switch (ret) {
+ case IIO_VAL_FRACTIONAL:
+ tmp = div_s64((s64)*val * 1000000000LL, *val2);
+ scaled = tmp * raw;
+ *val = (int)div_s64_rem(scaled, 1000000000, val2);
+ return ret;
+ case IIO_VAL_INT:
+ return IIO_VAL_FRACTIONAL;
+ case IIO_VAL_FRACTIONAL_LOG2:
+ tmp = shift_right((s64)*val * 1000000000LL, *val2);
+ scaled = tmp * raw;
+ *val = (int)div_s64_rem(scaled, 1000000000LL, val2);
+ return ret;
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
static int rescale_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct rescale *rescale = iio_priv(indio_dev);
+ unsigned int raw;
int ret;
switch (mask) {
+ case IIO_CHAN_INFO_PROCESSED:
+ /* Read the raw value and the scale */
+ ret = iio_read_channel_raw(rescale->source, &raw);
+ if (!ret)
+ return ret;
+ ret = iio_read_channel_scale(rescale->source, val, val2);
+ if (!ret)
+ return ret;
+ /* Process the correct value with raw * scale */
+ ret = rescale_convert_processed(rescale, raw, val, val2);
+ if (!ret)
+ return ret;
+ return IIO_VAL_INT;
+
case IIO_CHAN_INFO_RAW:
return iio_read_channel_raw(rescale->source, val);
@@ -145,7 +185,7 @@ static int rescale_configure_channel(struct device *dev,
}
chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
- BIT(IIO_CHAN_INFO_SCALE);
+ BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_PROCESSED);
if (iio_channel_has_available(schan, IIO_CHAN_INFO_RAW))
chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW);
--
2.11.0
On 2019-06-11 11:56, Mylène Josserand wrote:
> Hello everyone,
>
> You will find a small series that add the support of processed values
> for iio-rescale driver.
> Thanks to that, it is possible to read processed values in sysfs instead
> of getting only raw and scale values.
>
> Here is an example for a 3v3 voltage reading:
> # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_scale
> 3.791015625
> # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_raw
> 879
> # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_input
> 3332
>
> It is also possible to read directly the processed values using iio-hwmon
> driver (see example in patch03):
>
> # cat /sys/class/hwmon/hwmon0/in1_input
> 3328
>
> I seperated my series in 3 patches:
> - Patch01: Move the scale conversion into a function to prepare the
> support of IIO_CHAN_INFO_PROCESSED.
> - Patch02: Add the support of IIO_CHAN_INFO_PROCESSED.
> - Patch03: Add an example of the use of hwmon and voltage-divider nodes
> in device-tree.
>
> If you have any feedbacks on it, I will be pleased to read them!
The last patch about hwmon has nothing to do with this series, and
should be possible as-is without any code changes. No? AFAICT,
iio_hwmon calls iio_read_channel_processed, which calls
iio_convert_raw_to_processed_unlocked in case IIO_CHAN_INFO_PROCESSES
is not handled by the driver. Is that not working?
There is also libiio in userspace that provides the scale as a double
and makes the conversion to a processed value trivial, so the series
is really mostly about the convenience of having a human directly
seeing the processed value in sysfs. Right?
If that is deemed valuable, then I think it should be fixed in a
central location, and not individually for each and every driver.
Anyway, not my call, just stating my opinion, but those are the
reasons for me not adding a processed channel from the very beginning.
Cheers,
Peter
> Best regards,
> Mylène
>
> Mylène Josserand (3):
> iio: afe: rescale: Move scale conversion to new function
> iio: afe: rescale: Add support of CHAN_INFO_PROCESSED
> dt-bindings: iio: afe: Add hwmon example
>
> .../bindings/iio/afe/voltage-divider.txt | 24 ++++++
> drivers/iio/afe/iio-rescale.c | 96 ++++++++++++++++------
> 2 files changed, 96 insertions(+), 24 deletions(-)
>
On Tue, 11 Jun 2019 11:02:14 +0000
Peter Rosin <[email protected]> wrote:
> On 2019-06-11 11:56, Myl?ne Josserand wrote:
> > Hello everyone,
> >
> > You will find a small series that add the support of processed values
> > for iio-rescale driver.
> > Thanks to that, it is possible to read processed values in sysfs instead
> > of getting only raw and scale values.
> >
> > Here is an example for a 3v3 voltage reading:
> > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_scale
> > 3.791015625
> > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_raw
> > 879
> > # cat /sys/bus/iio/devices/iio\:device1/in_voltage0_input
> > 3332
> >
> > It is also possible to read directly the processed values using iio-hwmon
> > driver (see example in patch03):
> >
> > # cat /sys/class/hwmon/hwmon0/in1_input
> > 3328
> >
> > I seperated my series in 3 patches:
> > - Patch01: Move the scale conversion into a function to prepare the
> > support of IIO_CHAN_INFO_PROCESSED.
> > - Patch02: Add the support of IIO_CHAN_INFO_PROCESSED.
> > - Patch03: Add an example of the use of hwmon and voltage-divider nodes
> > in device-tree.
> >
> > If you have any feedbacks on it, I will be pleased to read them!
>
>
> The last patch about hwmon has nothing to do with this series, and
> should be possible as-is without any code changes. No? AFAICT,
> iio_hwmon calls iio_read_channel_processed, which calls
> iio_convert_raw_to_processed_unlocked in case IIO_CHAN_INFO_PROCESSES
> is not handled by the driver. Is that not working?
>
> There is also libiio in userspace that provides the scale as a double
> and makes the conversion to a processed value trivial, so the series
> is really mostly about the convenience of having a human directly
> seeing the processed value in sysfs. Right?
>
> If that is deemed valuable, then I think it should be fixed in a
> central location, and not individually for each and every driver.
>
> Anyway, not my call, just stating my opinion, but those are the
> reasons for me not adding a processed channel from the very beginning.
I definitely want to fully understand the reasoning behind this proposal.
My gut feeling is that it doesn't make sense a sit ends up with two
interfaces to the same thing in userspace, which we generally want to
avoid.
It's really trivial to do the maths in userspace and often doing it in
kernel is less accurate, or much more complex.
Jonathan
>
> Cheers,
> Peter
>
> > Best regards,
> > Myl?ne
> >
> > Myl?ne Josserand (3):
> > iio: afe: rescale: Move scale conversion to new function
> > iio: afe: rescale: Add support of CHAN_INFO_PROCESSED
> > dt-bindings: iio: afe: Add hwmon example
> >
> > .../bindings/iio/afe/voltage-divider.txt | 24 ++++++
> > drivers/iio/afe/iio-rescale.c | 96 ++++++++++++++++------
> > 2 files changed, 96 insertions(+), 24 deletions(-)
> >
>