This sensor can perform samples averaging in hardware, but currently the
driver leaves this setting alone (default is no averaging).
This patch introduces a new IIO attribute that allows the user to set the
averaging as desired (the HW supports averaging of 2, 5, 8 or 16 samples)
Signed-off-by: Andrea Merello <andrea.merello@xxxxxxxxx>
---
drivers/iio/temperature/max31856.c | 43 ++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c
index d12613f7ba3c..8b2e0102fa5c 100644
--- a/drivers/iio/temperature/max31856.c
+++ b/drivers/iio/temperature/max31856.c
@@ -24,6 +24,8 @@
#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)
@@ -65,6 +67,7 @@ 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 +112,10 @@ 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;
@@ -295,14 +302,50 @@ static ssize_t set_filter(struct device *dev,
return len;
}
+static ssize_t show_averaging(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", 1 << data->averaging);
+}
+
+static ssize_t set_averaging(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 nsamples;
+ int shift;
+ int ret;
+
+ ret = kstrtouint(buf, 10, &nsamples);
+ if (ret)
+ return ret;
+
+ shift = fls(nsamples) - 1;
+ if (nsamples > 16 || BIT(shift) != nsamples)
+ return -EINVAL;
+
+ data->averaging = shift;
+ 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(filter, 0644, show_filter, set_filter, 0);
+static IIO_DEVICE_ATTR(averaging, 0644, show_averaging, set_averaging, 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_filter.dev_attr.attr,
+ &iio_dev_attr_averaging.dev_attr.attr,
NULL,
};
--
2.17.1
