This patch adds the option for the user to select the sampling frequency.
Also, the user can read the available frequencies and read the currently
set frequency via the read_raw function. The frequency can be set via the
write_raw function.
When the frequency is set, the bandwidth is also checked and ensured
that it is constrained to at most half of the sampling frequency.
Signed-off-by: Stefan Popa <stefan.popa@xxxxxxxxxx>
---
drivers/iio/accel/adxl372.c | 60 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 59 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/accel/adxl372.c b/drivers/iio/accel/adxl372.c
index 645902d..498c740 100644
--- a/drivers/iio/accel/adxl372.c
+++ b/drivers/iio/accel/adxl372.c
@@ -205,7 +205,8 @@ static const int adxl372_samp_freq_tbl[5] = {
.modified = 1, \
.channel2 = IIO_MOD_##axis, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
- .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
+ BIT(IIO_CHAN_INFO_SAMP_FREQ), \
.scan_index = index, \
.scan_type = { \
.sign = 's', \
@@ -291,6 +292,19 @@ static int adxl372_set_odr(struct adxl372_state *st,
return ret;
}
+static int adxl372_find_closest_match(const int *array,
+ unsigned int size, int val)
+{
+ int i;
+
+ for (i = 0; i < size; i++) {
+ if (val <= array[i])
+ return i;
+ }
+
+ return size - 1;
+}
+
static int adxl372_set_bandwidth(struct adxl372_state *st,
enum adxl372_bandwidth bw)
{
@@ -568,6 +582,37 @@ static int adxl372_read_raw(struct iio_dev *indio_dev,
*val = 0;
*val2 = ADXL372_USCALE;
return IIO_VAL_INT_PLUS_MICRO;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ *val = adxl372_samp_freq_tbl[st->odr];
+ return IIO_VAL_INT;
+ }
+
+ return -EINVAL;
+}
+
+static int adxl372_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long info)
+{
+ struct adxl372_state *st = iio_priv(indio_dev);
+ int odr_index, ret;
+
+ switch (info) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ odr_index = adxl372_find_closest_match(adxl372_samp_freq_tbl,
+ ARRAY_SIZE(adxl372_samp_freq_tbl),
+ val);
+ ret = adxl372_set_odr(st, odr_index);
+ if (ret < 0)
+ return ret;
+ /*
+ * The maximum bandwidth is constrained to at most half of
+ * the ODR to ensure that the Nyquist criteria is not violated
+ */
+ if (st->bw > odr_index)
+ ret = adxl372_set_bandwidth(st, odr_index);
+
+ return ret;
default:
return -EINVAL;
}
@@ -722,8 +767,21 @@ static const struct iio_trigger_ops adxl372_trigger_ops = {
.set_trigger_state = adxl372_dready_trig_set_state,
};
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("400 800 1600 3200 6400");
+
+static struct attribute *adxl372_attributes[] = {
+ &iio_const_attr_sampling_frequency_available.dev_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group adxl372_attrs_group = {
+ .attrs = adxl372_attributes,
+};
+
static const struct iio_info adxl372_info = {
+ .attrs = &adxl372_attrs_group,
.read_raw = adxl372_read_raw,
+ .write_raw = adxl372_write_raw,
.debugfs_reg_access = &adxl372_reg_access,
.hwfifo_set_watermark = adxl372_set_watermark,
};
--
2.7.4
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