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iio: buffer: Expose data available 

Add a sysfs attribute that exposes buffer data available to userspace.
This attribute can be checked at runtime to determine the overall buffer
fill level (across all allocated buffers).

Signed-off-by: Matt Fornero <matt.fornero@mathworks.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Matt Fornero 2017-12-06 14:43:30 -05:00 committed by Greg Kroah-Hartman
parent 80e3f0103e
commit 350f6c75f6
2 changed files with 25 additions and 0 deletions
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10
Documentation/ABI/testing/sysfs-bus-iio
View File

@ -1413,6 +1413,16 @@ Description:
the available samples after the timeout expires and thus have a
maximum delay guarantee.
What: /sys/bus/iio/devices/iio:deviceX/buffer/data_available
KernelVersion: 4.16
Contact: linux-iio@vger.kernel.org
Description:
A read-only value indicating the bytes of data available in the
buffer. In the case of an output buffer, this indicates the
amount of empty space available to write data to. In the case of
an input buffer, this indicates the amount of data available for
reading.
What: /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_enabled
KernelVersion: 4.2
Contact: linux-iio@vger.kernel.org

15
drivers/iio/industrialio-buffer.c
View File

@ -1198,6 +1198,18 @@ out:
return ret ? ret : len;
}
static ssize_t iio_dma_show_data_available(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
size_t bytes;
bytes = iio_buffer_data_available(indio_dev->buffer);
return sprintf(buf, "%zu\n", bytes);
}
static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
iio_buffer_write_length);
static struct device_attribute dev_attr_length_ro = __ATTR(length,
@ -1208,11 +1220,14 @@ static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
iio_buffer_show_watermark, iio_buffer_store_watermark);
static struct device_attribute dev_attr_watermark_ro = __ATTR(watermark,
S_IRUGO, iio_buffer_show_watermark, NULL);
static DEVICE_ATTR(data_available, S_IRUGO,
iio_dma_show_data_available, NULL);
static struct attribute *iio_buffer_attrs[] = {
&dev_attr_length.attr,
&dev_attr_enable.attr,
&dev_attr_watermark.attr,
&dev_attr_data_available.attr,
};
int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)