[PATCH v2 1/2] iio: Add iio_read_channel_label to inkern API

Sean Anderson
2024-06-24T17:46:27Z

It can be convenient for other in-kernel drivers to reuse IIO channel
labels. Export the iio_read_channel_label function to allow this. The
signature is different depending on where we are calling it from, so
the meat is moved to do_iio_read_channel_label.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---

(no changes since v1)

drivers/iio/iio_core.h | 4 ++++
drivers/iio/industrialio-core.c | 23 ++++++++++++++---------
drivers/iio/inkern.c | 6 ++++++
include/linux/iio/consumer.h | 10 ++++++++++
4 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
index 1a38b1915e7a..b7d5f4f0fada 100644
--- a/drivers/iio/iio_core.h
+++ b/drivers/iio/iio_core.h
@@ -34,6 +34,10 @@ void iio_device_ioctl_handler_register(struct iio_dev *indio_dev,
struct iio_ioctl_handler *h);
void iio_device_ioctl_handler_unregister(struct iio_ioctl_handler *h);

+ssize_t do_iio_read_channel_label(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *c,
+ char *buf);
+
int __iio_add_chan_devattr(const char *postfix,
struct iio_chan_spec const *chan,
ssize_t (*func)(struct device *dev,
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 2f185b386949..0f6cda7ffe45 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -727,22 +727,27 @@ ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals)
}
EXPORT_SYMBOL_GPL(iio_format_value);

-static ssize_t iio_read_channel_label(struct device *dev,
- struct device_attribute *attr,
- char *buf)
+ssize_t do_iio_read_channel_label(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *c,
+ char *buf)
{
- struct iio_dev *indio_dev = dev_to_iio_dev(dev);
- struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
-
if (indio_dev->info->read_label)
- return indio_dev->info->read_label(indio_dev, this_attr->c, buf);
+ return indio_dev->info->read_label(indio_dev, c, buf);

- if (this_attr->c->extend_name)
- return sysfs_emit(buf, "%s\n", this_attr->c->extend_name);
+ if (c->extend_name)
+ return sysfs_emit(buf, "%s\n", c->extend_name);

return -EINVAL;
}

+static ssize_t iio_read_channel_label(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return do_iio_read_channel_label(dev_to_iio_dev(dev),
+ to_iio_dev_attr(attr)->c, buf);
+}
+
static ssize_t iio_read_channel_info(struct device *dev,
struct device_attribute *attr,
char *buf)
diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 39cf26d69d17..9f484c94bc6e 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -1010,3 +1010,9 @@ ssize_t iio_write_channel_ext_info(struct iio_channel *chan, const char *attr,
chan->channel, buf, len);
}
EXPORT_SYMBOL_GPL(iio_write_channel_ext_info);
+
+ssize_t iio_read_channel_label(struct iio_channel *chan, char *buf)
+{
+ return do_iio_read_channel_label(chan->indio_dev, chan->channel, buf);
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_label);
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index e9910b41d48e..333d1d8ccb37 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -441,4 +441,14 @@ ssize_t iio_read_channel_ext_info(struct iio_channel *chan,
ssize_t iio_write_channel_ext_info(struct iio_channel *chan, const char *attr,
const char *buf, size_t len);

+/**
+ * iio_read_channel_label() - read label for a given channel
+ * @chan: The channel being queried.
+ * @buf: Where to store the attribute value. Assumed to hold
+ * at least PAGE_SIZE bytes.
+ *
+ * Returns the number of bytes written to buf, or an error code.
+ */
+ssize_t iio_read_channel_label(struct iio_channel *chan, char *buf);
+
#endif
--
2.35.1.1320.gc452695387.dirty