On 17/11/2015 14:39, jic23@xxxxxxxxxxxxxxxxxxxxx wrote:
On 17.11.2015 10:44, Marc Titinger wrote:
Some ADC devices allow averaging/downsampling. The minimal parameter
set for this will be the number of taps used for computing a mean value.
In some cases the ratio will hold discrete values for instance "1, 4, 16"
hence an averaging_ratio_available property is useful. The possible ratio
values are less likely to changing with the device settings, so this
patch
only provides a CONST version of the definition helper.
Tested with ina226:
# ls /sys/bus/iio/devices/iio\:device0/
averaging_ratio_available in_voltage0_raw
dev in_voltage1_raw
in_averaging_ratio name
in_calibscale power
in_current2_raw sampling_frequency_available
in_power3_raw subsystem
in_sampling_frequency uevent
# cat averaging_ratio_available
1, 4, 16, 64, 128, 256, 512, 1024
Signed-off-by: Marc Titinger <mtitinger@xxxxxxxxxxxx>
Having just noted the previous element we added was oversampling_ratio,
in a sense they are somewhat similar.
To play Devil's advocate...
Could we in theory just use that as it is existing ABI?
oversampling_ratio was introduced for the bmc150.
That particular part doesn't have the worlds clearest datasheet
but it seems like it's effectively specifying how many repeat measurements
to average.
I'm afraid I'd completely forgotten about this or
I would have mentioned it earlier!
I saw that oversampling setting, but I my memories, oversampling was
sometimes related to increasing the samplerate, i.e creating more
samples possibly through interpolation, in order to allow for filtering.
If there is a consensus about this being ok to mean 'averaging' I'm
happy to use this ABI!
M.
Jonathan
---
Documentation/ABI/testing/sysfs-bus-iio | 13 +++++++++++++
drivers/iio/industrialio-core.c | 1 +
include/linux/iio/iio.h | 1 +
include/linux/iio/sysfs.h | 9 +++++++++
4 files changed, 24 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-iio
b/Documentation/ABI/testing/sysfs-bus-iio
index 42d360f..a208dfe 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -56,6 +56,19 @@ Description:
When the internal sampling clock can only take a small
discrete set of values, this file lists those available.
+What: /sys/bus/iio/devices/iio:deviceX/averaging_ratio
+KernelVersion: 4.x.x
+Contact: linux-iio@xxxxxxxxxxxxxxx
+Description:
+ Hardware dependent ADC averaging. Controls the averaging ratio
+ of the digital filter if available.
+
+What: /sys/bus/iio/devices/iio:deviceX/averaging_ratio_available
+KernelVersion: 4.x.x
+Contact: linux-iio@xxxxxxxxxxxxxxx
+Description:
+ Hardware dependent values supported by the averaging filter.
+
What: /sys/bus/iio/devices/iio:deviceX/oversampling_ratio
KernelVersion: 2.6.38
Contact: linux-iio@xxxxxxxxxxxxxxx
diff --git a/drivers/iio/industrialio-core.c
b/drivers/iio/industrialio-core.c
index b3fcc2c..e4745f0 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -142,6 +142,7 @@ static const char * const iio_chan_info_postfix[] = {
[IIO_CHAN_INFO_DEBOUNCE_TIME] = "debounce_time",
[IIO_CHAN_INFO_CALIBEMISSIVITY] = "calibemissivity",
[IIO_CHAN_INFO_OVERSAMPLING_RATIO] = "oversampling_ratio",
+ [IIO_CHAN_INFO_AVERAGING_RATIO] = "averaging_ratio",
};
/**
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 7bb7f67..4c84de5 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -46,6 +46,7 @@ enum iio_chan_info_enum {
IIO_CHAN_INFO_DEBOUNCE_TIME,
IIO_CHAN_INFO_CALIBEMISSIVITY,
IIO_CHAN_INFO_OVERSAMPLING_RATIO,
+ IIO_CHAN_INFO_AVERAGING_RATIO,
};
enum iio_shared_by {
diff --git a/include/linux/iio/sysfs.h b/include/linux/iio/sysfs.h
index 9cd8f74..4478ba1 100644
--- a/include/linux/iio/sysfs.h
+++ b/include/linux/iio/sysfs.h
@@ -76,6 +76,15 @@ struct iio_const_attr {
/* Generic attributes of onetype or another */
/**
+ * IIO_CONST_ATTR_AVERAGING_RATIO_AVAIL - list available averaging
ratios
+ * @_string: ratio string for the attribute
+ *
+ * Constant version
+ **/
+#define IIO_CONST_ATTR_AVERAGING_RATIO_AVAIL(_string) \
+ IIO_CONST_ATTR(averaging_ratio_available, _string)
+
+/**
* IIO_DEV_ATTR_SAMP_FREQ - sets any internal clock frequency
* @_mode: sysfs file mode/permissions
* @_show: output method for the attribute
--
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