[PATCH 2/4] iio: inkern: Add a helper to query an available minimum raw value

Herve Codina
2023-04-21T12:42:34Z

A helper, iio_read_max_channel_raw() exists to read the available
maximum raw value of a channel but nothing similar exists to read the
available minimum raw value.

This new helper, iio_read_min_channel_raw(), fills the hole and can be
used for reading the available minimum raw value of a channel.
It is fully based on the existing iio_read_max_channel_raw().

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
---
drivers/iio/inkern.c | 67 ++++++++++++++++++++++++++++++++++++
include/linux/iio/consumer.h | 11 ++++++
2 files changed, 78 insertions(+)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 872fd5c24147..914fc69c718a 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -912,6 +912,73 @@ int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
}
EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);

+static int iio_channel_read_min(struct iio_channel *chan,
+ int *val, int *val2, int *type,
+ enum iio_chan_info_enum info)
+{
+ int unused;
+ const int *vals;
+ int length;
+ int ret;
+
+ if (!val2)
+ val2 = &unused;
+
+ ret = iio_channel_read_avail(chan, &vals, type, &length, info);
+ switch (ret) {
+ case IIO_AVAIL_RANGE:
+ switch (*type) {
+ case IIO_VAL_INT:
+ *val = vals[0];
+ break;
+ default:
+ *val = vals[0];
+ *val2 = vals[1];
+ }
+ return 0;
+
+ case IIO_AVAIL_LIST:
+ if (length <= 0)
+ return -EINVAL;
+ switch (*type) {
+ case IIO_VAL_INT:
+ *val = vals[--length];
+ while (length) {
+ if (vals[--length] < *val)
+ *val = vals[length];
+ }
+ break;
+ default:
+ /* FIXME: learn about min for other iio values */
+ return -EINVAL;
+ }
+ return 0;
+
+ default:
+ return ret;
+ }
+}
+
+int iio_read_min_channel_raw(struct iio_channel *chan, int *val)
+{
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);
+ int ret;
+ int type;
+
+ mutex_lock(&iio_dev_opaque->info_exist_lock);
+ if (!chan->indio_dev->info) {
+ ret = -ENODEV;
+ goto err_unlock;
+ }
+
+ ret = iio_channel_read_min(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
+err_unlock:
+ mutex_unlock(&iio_dev_opaque->info_exist_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_min_channel_raw);
+
int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
{
struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 6802596b017c..956120d8b5a3 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -297,6 +297,17 @@ int iio_write_channel_raw(struct iio_channel *chan, int val);
*/
int iio_read_max_channel_raw(struct iio_channel *chan, int *val);

+/**
+ * iio_read_min_channel_raw() - read minimum available raw value from a given
+ * channel, i.e. the minimum possible value.
+ * @chan: The channel being queried.
+ * @val: Value read back.
+ *
+ * Note raw reads from iio channels are in adc counts and hence
+ * scale will need to be applied if standard units are required.
+ */
+int iio_read_min_channel_raw(struct iio_channel *chan, int *val);
+
/**
* iio_read_avail_channel_raw() - read available raw values from a given channel
* @chan: The channel being queried.
--
2.39.2