3 files changed, 149 insertions, 0 deletions

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 29df11572858..b0f4630a163f 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -716,6 +716,110 @@ int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
 }
 EXPORT_SYMBOL_GPL(iio_read_channel_scale);
 
+static int iio_channel_read_avail(struct iio_channel *chan,
+				  const int **vals, int *type, int *length,
+				  enum iio_chan_info_enum info)
+{
+	if (!iio_channel_has_available(chan->channel, info))
+		return -EINVAL;
+
+	return chan->indio_dev->info->read_avail(chan->indio_dev, chan->channel,
+						 vals, type, length, info);
+}
+
+int iio_read_avail_channel_raw(struct iio_channel *chan,
+			       const int **vals, int *length)
+{
+	int ret;
+	int type;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (!chan->indio_dev->info) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_read_avail(chan,
+				     vals, &type, length, IIO_CHAN_INFO_RAW);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	if (ret >= 0 && type != IIO_VAL_INT) {
+		/* raw values are assumed to be IIO_VAL_INT */
+		ret = -EINVAL;
+		goto err_unlock;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_avail_channel_raw);
+
+static int iio_channel_read_max(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[2];
+			break;
+		default:
+			*val = vals[4];
+			*val2 = vals[5];
+		}
+		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 max for other iio values */
+			return -EINVAL;
+		}
+		return 0;
+
+	default:
+		return ret;
+	}
+}
+
+int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
+{
+	int ret;
+	int type;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (!chan->indio_dev->info) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_read_max(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);
+
 int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
 {
 	int ret = 0;
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 638157234357..47eeec3218b5 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -226,6 +226,34 @@ int iio_read_channel_processed(struct iio_channel *chan, int *val);
 int iio_write_channel_raw(struct iio_channel *chan, int val);
 
 /**
+ * iio_read_max_channel_raw() - read maximum available raw value from a given
+ *				channel, i.e. the maximum 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_max_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.
+ * @vals:		Available values read back.
+ * @length:		Number of entries in vals.
+ *
+ * Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
+ *
+ * For ranges, three vals are always returned; min, step and max.
+ * For lists, all the possible values are enumerated.
+ *
+ * Note raw available values from iio channels are in adc counts and
+ * hence scale will need to be applied if standard units are required.
+ */
+int iio_read_avail_channel_raw(struct iio_channel *chan,
+			       const int **vals, int *length);
+
+/**
  * iio_get_channel_type() - get the type of a channel
  * @channel:		The channel being queried.
  * @type:		The type of the channel.
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 849d524645e8..3f5ea2e9a39e 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -315,6 +315,23 @@ static inline bool iio_channel_has_info(const struct iio_chan_spec *chan,
 		(chan->info_mask_shared_by_all & BIT(type));
 }
 
+/**
+ * iio_channel_has_available() - Checks if a channel has an available attribute
+ * @chan: The channel to be queried
+ * @type: Type of the available attribute to be checked
+ *
+ * Returns true if the channel supports reporting available values for the
+ * given attribute type, false otherwise.
+ */
+static inline bool iio_channel_has_available(const struct iio_chan_spec *chan,
+					     enum iio_chan_info_enum type)
+{
+	return (chan->info_mask_separate_available & BIT(type)) |
+		(chan->info_mask_shared_by_type_available & BIT(type)) |
+		(chan->info_mask_shared_by_dir_available & BIT(type)) |
+		(chan->info_mask_shared_by_all_available & BIT(type));
+}
+
 #define IIO_CHAN_SOFT_TIMESTAMP(_si) {					\
 	.type = IIO_TIMESTAMP,						\
 	.channel = -1,							\