On Tue, 12 Nov 2019 07:59:19 +0900
Matt Ranostay <matt.ranostay@xxxxxxxxxxxx> wrote:
> On Tue, Nov 12, 2019 at 12:35 AM Andrea Merello
> <andrea.merello@xxxxxxxxx> wrote:
> >
> > This sensor has an embedded notch filter for reducing interferences caused
> > by the power mains. This filter can be tuned to reject either 50Hz or 60Hz
> > (and harmonics).
> >
> > Currently the said setting is left alone (the sensor defaults to 60Hz).
> > This patch introduces a IIO attribute that allows the user to set the said
> > filter to the desired frequency.
> >
> > NOTE: this has been intentionally not tied to any DT property to allow
> > the configuration of this setting from userspace, e.g. with a GUI or by
> > reading a configuration file, or maybe reading a GPIO tied to a physical
> > switch or accessing some device that can autodetect the line frequency.
> >
>
> Looks good to me. Although this ideal could be a device tree property
> as well, but not a big deal.
>
> Reviewed-by: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
I've no objection to someone following up with DT support for this
as they might have a device that only supports one frequency of powersupply.
However, let's leave it until we have a user that cares.
I'm going to let the patch sit on the list a little longer though as
it introduces new ABI and others may want to review.
If I seem to have lost it in 2 weeks time give me a ping
(normally I don't lose patches, but it's happened a few times in the past!)
Thanks,
Jonathan
>
> > Cc: Hartmut Knaack <knaack.h@xxxxxx>
> > Cc: Lars-Peter Clausen <lars@xxxxxxxxxx>
> > Cc: Peter Meerwald-Stadler <pmeerw@xxxxxxxxxx>
> > Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > Cc: Patrick Havelange <patrick.havelange@xxxxxxxxxxxxx>
> > Cc: Paresh Chaudhary <paresh.chaudhary@xxxxxxxxxxxxxxxxxxx>
> > Cc: Matt Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx>
> > Cc: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
> > Cc: Chuhong Yuan <hslester96@xxxxxxxxx>
> > Cc: Daniel Gomez <dagmcr@xxxxxxxxx>
> > Cc: linux-iio@xxxxxxxxxxxxxxx
> > Signed-off-by: Andrea Merello <andrea.merello@xxxxxxxxx>
> > ---
> > drivers/iio/temperature/max31856.c | 50 ++++++++++++++++++++++++++++++
> > 1 file changed, 50 insertions(+)
> >
> > diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c
> > index 73ed550e3fc9..d97ba9ee1598 100644
> > --- a/drivers/iio/temperature/max31856.c
> > +++ b/drivers/iio/temperature/max31856.c
> > @@ -23,6 +23,7 @@
> > #define MAX31856_CR0_1SHOT BIT(6)
> > #define MAX31856_CR0_OCFAULT BIT(4)
> > #define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4)
> > +#define MAX31856_CR0_FILTER_50HZ BIT(0)
> > #define MAX31856_TC_TYPE_MASK GENMASK(3, 0)
> > #define MAX31856_FAULT_OVUV BIT(1)
> > #define MAX31856_FAULT_OPEN BIT(0)
> > @@ -63,6 +64,7 @@ static const struct iio_chan_spec max31856_channels[] = {
> > struct max31856_data {
> > struct spi_device *spi;
> > u32 thermocouple_type;
> > + bool filter_50hz;
> > };
> >
> > static int max31856_read(struct max31856_data *data, u8 reg,
> > @@ -123,6 +125,11 @@ static int max31856_init(struct max31856_data *data)
> > reg_cr0_val &= ~MAX31856_CR0_1SHOT;
> > reg_cr0_val |= MAX31856_CR0_AUTOCONVERT;
> >
> > + if (data->filter_50hz)
> > + reg_cr0_val |= MAX31856_CR0_FILTER_50HZ;
> > + else
> > + reg_cr0_val &= ~MAX31856_CR0_FILTER_50HZ;
> > +
> > return max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
> > }
> >
> > @@ -249,12 +256,54 @@ static ssize_t show_fault_oc(struct device *dev,
> > return show_fault(dev, MAX31856_FAULT_OPEN, buf);
> > }
> >
> > +static ssize_t show_filter(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > + struct max31856_data *data = iio_priv(indio_dev);
> > +
> > + return sprintf(buf, "%d\n", data->filter_50hz ? 50 : 60);
> > +}
> > +
> > +static ssize_t set_filter(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf,
> > + size_t len)
> > +{
> > + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > + struct max31856_data *data = iio_priv(indio_dev);
> > + unsigned int freq;
> > + int ret;
> > +
> > + ret = kstrtouint(buf, 10, &freq);
> > + if (ret)
> > + return ret;
> > +
> > + switch (freq) {
> > + case 50:
> > + data->filter_50hz = true;
> > + break;
> > + case 60:
> > + data->filter_50hz = false;
> > + break;
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + max31856_init(data);
> > + return len;
> > +}
> > +
> > static IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0);
> > static IIO_DEVICE_ATTR(fault_oc, 0444, show_fault_oc, NULL, 0);
> > +static IIO_DEVICE_ATTR(in_temp_filter_notch_center_frequency, 0644,
> > + show_filter, set_filter, 0);
> >
> > static struct attribute *max31856_attributes[] = {
> > &iio_dev_attr_fault_ovuv.dev_attr.attr,
> > &iio_dev_attr_fault_oc.dev_attr.attr,
> > + &iio_dev_attr_in_temp_filter_notch_center_frequency.dev_attr.attr,
> > NULL,
> > };
> >
> > @@ -280,6 +329,7 @@ static int max31856_probe(struct spi_device *spi)
> >
> > data = iio_priv(indio_dev);
> > data->spi = spi;
> > + data->filter_50hz = false;
> >
> > spi_set_drvdata(spi, indio_dev);
> >
> > --
> > 2.17.1
> >
