Re: [PATCH 3/3] stagging:iio:meter: Add ade7854_write_raw function

John Syne
2018-04-21T18:15:32Z

> On Apr 21, 2018, at 10:26 AM, Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Sat, 21 Apr 2018 08:56:19 -0300
> Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> wrote:
>
>> This patch adds the ade7854_write_raw() function which is responsible
>> for handling the write operation for registers: AIGAIN, BIGAIN, CIGAIN,
>> NIGAIN, AVGAIN, BVGAIN, and CVGAIN. Finally, this patch completely
>> removes the old ABI used for handling the registers mentioned above.
>>
>> Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> The baby steps approach here is good, but with all 3 patches as one it
> would have been a lot easier to follow.
>
> This is almost fine except for the issue I had with how the channels
> were defined in the first place.
>
> Also a question about scales inline...
>
>> ---
>> drivers/staging/iio/meter/ade7854.c | 60 ++++++++++++-----------------
>> 1 file changed, 25 insertions(+), 35 deletions(-)
>>
>> diff --git a/drivers/staging/iio/meter/ade7854.c b/drivers/staging/iio/meter/ade7854.c
>> index 242ecde75900..df19c8b4b5d7 100644
>> --- a/drivers/staging/iio/meter/ade7854.c
>> +++ b/drivers/staging/iio/meter/ade7854.c
>> @@ -228,34 +228,6 @@ static int ade7854_reset(struct device *dev)
>> return st->write_reg(dev, ADE7854_CONFIG, val, 16);
>> }
>>
>> -static IIO_DEV_ATTR_AIGAIN(0644,
>> - NULL,
>> - ade7854_write_24bit,
>> - ADE7854_AIGAIN);
>> -static IIO_DEV_ATTR_BIGAIN(0644,
>> - NULL,
>> - ade7854_write_24bit,
>> - ADE7854_BIGAIN);
>> -static IIO_DEV_ATTR_CIGAIN(0644,
>> - NULL,
>> - ade7854_write_24bit,
>> - ADE7854_CIGAIN);
>> -static IIO_DEV_ATTR_NIGAIN(0644,
>> - NULL,
>> - ade7854_write_24bit,
>> - ADE7854_NIGAIN);
>> -static IIO_DEV_ATTR_AVGAIN(0644,
>> - NULL,
>> - ade7854_write_24bit,
>> - ADE7854_AVGAIN);
>> -static IIO_DEV_ATTR_BVGAIN(0644,
>> - NULL,
>> - ade7854_write_24bit,
>> - ADE7854_BVGAIN);
>> -static IIO_DEV_ATTR_CVGAIN(0644,
>> - NULL,
>> - ade7854_write_24bit,
>> - ADE7854_CVGAIN);
>> static IIO_DEV_ATTR_APPARENT_POWER_A_GAIN(0644,
>> ade7854_read_24bit,
>> ade7854_write_24bit,
>> @@ -497,6 +469,30 @@ static int ade7854_read_raw(struct iio_dev *indio_dev,
>> return -EINVAL;
>> }
>>
>> +static int ade7854_write_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int val, int val2, long mask)
>> +{
>> + struct ade7854_state *st = iio_priv(indio_dev);
>> + int ret;
>> +
>> + if (mask != IIO_CHAN_INFO_SCALE)
>> + return -EINVAL;
>> +
>> + switch (chan->type) {
>> + case IIO_CURRENT:
>> + case IIO_VOLTAGE:
> Probably need some range checking to make sure we have a sane value.
>
> Also, I'm curious about units here.
>
> you are using CHAN_INFO_SCALE which would mean this is linked to
> the _RAW value (the actual reading of the channel) by _RAW*_SCALE = value in
> defined base units for the channel type. So I'd expect to see some
> code here doing a conversion to the internal format for the device.
These should be IIO_CHAN_INFO_HARDWAREGAIN as they are used to correct
any imperfections of the sensors. A user space application calculates the error and
based on a formula determines the correct register value.

Meter values such as Voltage, Current, Power, Energy use a value/LSB method,
which is determined while applying a known voltage and current. After that, any
parameter is multiplied by the respective value/LSB to get a real world value.

Regards,
John
>
> I wouldn't expect to see a value from userspace written unconverted
> into the register.
>
> (I missed this in the previous patch - sorry).
>
> Jonathan
>
>> + ret = st->write_reg(&indio_dev->dev, chan->address, val, 24);
>> + if (ret < 0)
>> + return ret;
>> + return 0;
>> + default:
>> + break;
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +
>> static int ade7854_initial_setup(struct iio_dev *indio_dev)
>> {
>> int ret;
>> @@ -521,13 +517,6 @@ static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("8000");
>> static IIO_CONST_ATTR(name, "ade7854");
>>
>> static struct attribute *ade7854_attributes[] = {
>> - &iio_dev_attr_aigain.dev_attr.attr,
>> - &iio_dev_attr_bigain.dev_attr.attr,
>> - &iio_dev_attr_cigain.dev_attr.attr,
>> - &iio_dev_attr_nigain.dev_attr.attr,
>> - &iio_dev_attr_avgain.dev_attr.attr,
>> - &iio_dev_attr_bvgain.dev_attr.attr,
>> - &iio_dev_attr_cvgain.dev_attr.attr,
>> &iio_dev_attr_linecyc.dev_attr.attr,
>> &iio_dev_attr_sagcyc.dev_attr.attr,
>> &iio_dev_attr_cfcyc.dev_attr.attr,
>> @@ -599,6 +588,7 @@ static const struct attribute_group ade7854_attribute_group = {
>> static const struct iio_info ade7854_info = {
>> .attrs = &ade7854_attribute_group,
>> .read_raw = &ade7854_read_raw,
>> + .write_raw = &ade7854_write_raw,
>> };
>>
>> int ade7854_probe(struct iio_dev *indio_dev, struct device *dev)