On Tue, Nov 12, 2019 at 12:35 AM Andrea Merello
<andrea.merello@xxxxxxxxx> wrote:
>
> This sensor can perform samples averaging in hardware, but currently the
> driver leaves this setting alone (default is no averaging).
>
> This patch binds this HW setting to the "oversampling_ratio" IIO attribute
> and allows the user to set the averaging as desired (the HW supports
> averaging of 2, 5, 8 or 16 samples; in-between values are rounded up).
>
> 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 | 46 +++++++++++++++++++++++++++++-
> 1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c
> index d97ba9ee1598..9f0f4f65dccd 100644
> --- a/drivers/iio/temperature/max31856.c
> +++ b/drivers/iio/temperature/max31856.c
> @@ -12,6 +12,7 @@
> #include <linux/spi/spi.h>
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
> +#include <linux/util_macros.h>
> #include <dt-bindings/iio/temperature/thermocouple.h>
> /*
> * The MSB of the register value determines whether the following byte will
> @@ -24,6 +25,8 @@
> #define MAX31856_CR0_OCFAULT BIT(4)
> #define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4)
> #define MAX31856_CR0_FILTER_50HZ BIT(0)
> +#define MAX31856_AVERAGING_MASK GENMASK(6, 4)
> +#define MAX31856_AVERAGING_SHIFT 4
> #define MAX31856_TC_TYPE_MASK GENMASK(3, 0)
> #define MAX31856_FAULT_OVUV BIT(1)
> #define MAX31856_FAULT_OPEN BIT(0)
> @@ -50,7 +53,10 @@ static const struct iio_chan_spec max31856_channels[] = {
> { /* Thermocouple Temperature */
> .type = IIO_TEMP,
> .info_mask_separate =
> - BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
Adding IIO_CHAN_INFO_THERMOCOUPLE_TYPE shouldn't happen in this
patchset, since it isn't related
to the oversampling.
- Matt
> + .info_mask_shared_by_type =
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO)
> },
> { /* Cold Junction Temperature */
> .type = IIO_TEMP,
> @@ -58,6 +64,8 @@ static const struct iio_chan_spec max31856_channels[] = {
> .modified = 1,
> .info_mask_separate =
> BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> + .info_mask_shared_by_type =
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO)
> },
> };
>
> @@ -65,6 +73,7 @@ struct max31856_data {
> struct spi_device *spi;
> u32 thermocouple_type;
> bool filter_50hz;
> + int averaging;
> };
>
> static int max31856_read(struct max31856_data *data, u8 reg,
> @@ -109,6 +118,10 @@ static int max31856_init(struct max31856_data *data)
>
> reg_cr1_val &= ~MAX31856_TC_TYPE_MASK;
> reg_cr1_val |= data->thermocouple_type;
> +
> + reg_cr1_val &= ~MAX31856_AVERAGING_MASK;
> + reg_cr1_val |= data->averaging << MAX31856_AVERAGING_SHIFT;
> +
> ret = max31856_write(data, MAX31856_CR1_REG, reg_cr1_val);
> if (ret)
> return ret;
> @@ -217,6 +230,9 @@ static int max31856_read_raw(struct iio_dev *indio_dev,
> return IIO_VAL_INT_PLUS_MICRO;
> }
> break;
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + *val = 1 << data->averaging;
> + return IIO_VAL_INT;
> default:
> ret = -EINVAL;
> break;
> @@ -225,6 +241,33 @@ static int max31856_read_raw(struct iio_dev *indio_dev,
> return ret;
> }
>
> +static int max31856_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct max31856_data *data = iio_priv(indio_dev);
> + int msb;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + if (val > 16 || val < 1)
> + return -EINVAL;
> + msb = fls(val) - 1;
> + /* Round up to next 2pow if needed */
> + if (BIT(msb) < val)
> + msb++;
> +
> + data->averaging = msb;
> + max31856_init(data);
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf)
> {
> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> @@ -313,6 +356,7 @@ static const struct attribute_group max31856_group = {
>
> static const struct iio_info max31856_info = {
> .read_raw = max31856_read_raw,
> + .write_raw = max31856_write_raw,
> .attrs = &max31856_group,
> };
>
> --
> 2.17.1
>
