[PATCH v7 1/5] iio: core: Add IIO_VAL_EMPTY type

[Ben Collins <bcollins@kernel.org>]

In certain situations it may be necessary to return nothing when reading
an attribute.

For example, when a driver has a filter_type of "none" it should not
print any information for frequency or available frequencies.

Signed-off-by: Ben Collins <bcollins@kernel.org>
---
 drivers/iio/industrialio-core.c | 1 +
 include/linux/iio/types.h       | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 159d6c5ca3cec3f5c37ee9b85ef1681cca36f5c7..e4ff5b940223ab58bf61b394cc9357cd3674cfda 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -702,6 +702,7 @@ static ssize_t __iio_format_value(char *buf, size_t offset, unsigned int type,
 	case IIO_VAL_INT_64:
 		tmp2 = (s64)((((u64)vals[1]) << 32) | (u32)vals[0]);
 		return sysfs_emit_at(buf, offset, "%lld", tmp2);
+	case IIO_VAL_EMPTY:
 	default:
 		return 0;
 	}
diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
index ad2761efcc8315e1f9907d2a7159447fb463333e..261745c2d94e582bcca1a2abb297436e8314c930 100644
--- a/include/linux/iio/types.h
+++ b/include/linux/iio/types.h
@@ -32,6 +32,7 @@ enum iio_event_info {
 #define IIO_VAL_FRACTIONAL 10
 #define IIO_VAL_FRACTIONAL_LOG2 11
 #define IIO_VAL_CHAR 12
+#define IIO_VAL_EMPTY 13
 
 enum iio_available_type {
 	IIO_AVAIL_LIST,

-- 
2.39.5