From: Rodrigo Alencar <[email protected]> Add parent-child relationship between iio channels by creating a parent pointer field in iio_chan_spec struct and exposing a sysfs attribute that returns the parent channel label.
Signed-off-by: Rodrigo Alencar <[email protected]> --- drivers/iio/industrialio-core.c | 44 +++++++++++++++++++++++++++++++++++++++++ include/linux/iio/iio.h | 5 +++++ 2 files changed, 49 insertions(+) diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 9373006235c8..3d12269f26f4 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -854,6 +854,21 @@ static ssize_t iio_read_channel_label(struct device *dev, to_iio_dev_attr(attr)->c, buf); } +static ssize_t iio_read_channel_parent(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + const struct iio_chan_spec *parent = to_iio_dev_attr(attr)->c->parent; + int len; + + len = __iio_chan_prefix_emit(parent, IIO_SEPARATE, buf, PAGE_SIZE - 1); + if (len < 0) + return len; + + buf[len - 1] = '\n'; /* replace underscore termination with newline */ + return len; +} + static ssize_t iio_read_channel_info(struct device *dev, struct device_attribute *attr, char *buf) @@ -1263,6 +1278,30 @@ static int iio_device_add_channel_label(struct iio_dev *indio_dev, return 1; } +static int iio_device_add_channel_parent(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan) +{ + struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); + int ret; + + if (!chan->parent) + return 0; + + ret = __iio_add_chan_devattr("parent", + chan, + &iio_read_channel_parent, + NULL, + 0, + IIO_SEPARATE, + &indio_dev->dev, + NULL, + &iio_dev_opaque->channel_attr_list); + if (ret < 0) + return ret; + + return 1; +} + static int iio_device_add_info_mask_type(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, enum iio_shared_by shared_by, @@ -1401,6 +1440,11 @@ static int iio_device_add_channel_sysfs(struct iio_dev *indio_dev, return ret; attrcount += ret; + ret = iio_device_add_channel_parent(indio_dev, chan); + if (ret < 0) + return ret; + attrcount += ret; + if (chan->ext_info) { unsigned int i = 0; diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index 1c7d12af22da..9470ab8eb726 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -264,6 +264,10 @@ struct iio_scan_type { * @ext_info: Array of extended info attributes for this channel. * The array is NULL terminated, the last element should * have its name field set to NULL. + * @parent: Optional pointer to the parent channel spec for + * hierarchical channel relationships. When set, a read-only + * "parent" sysfs attribute is created containing the + * parent channel's sysfs name prefix (e.g. "in_voltage0"). * @extend_name: Allows labeling of channel attributes with an * informative name. Note this has no effect codes etc, * unlike modifiers. @@ -309,6 +313,7 @@ struct iio_chan_spec { const struct iio_event_spec *event_spec; unsigned int num_event_specs; const struct iio_chan_spec_ext_info *ext_info; + const struct iio_chan_spec *parent; const char *extend_name; const char *datasheet_name; unsigned int modified:1; -- 2.43.0
