Add backend support for obtaining the interface type used.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
no changes in v6.
 drivers/iio/industrialio-backend.c | 24 ++++++++++++++++++++++++
 include/linux/iio/backend.h        | 11 +++++++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index 20b3b5212da7..c792cd1e24e8 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -636,6 +636,30 @@ ssize_t iio_backend_ext_info_set(struct iio_dev *indio_dev, uintptr_t private,
 }
 EXPORT_SYMBOL_NS_GPL(iio_backend_ext_info_set, IIO_BACKEND);
 
+/**
+ * iio_backend_interface_type_get - get the interface type used.
+ * @back: Backend device
+ * @type: Interface type
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_interface_type_get(struct iio_backend *back,
+				   enum iio_backend_interface_type *type)
+{
+	int ret;
+
+	ret = iio_backend_op_call(back, interface_type_get, type);
+	if (ret)
+		return ret;
+
+	if (*type >= IIO_BACKEND_INTERFACE_MAX)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_interface_type_get, IIO_BACKEND);
+
 /**
  * iio_backend_extend_chan_spec - Extend an IIO channel
  * @back: Backend device
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index 37d56914d485..e5ea90f1c3e0 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -68,6 +68,12 @@ enum iio_backend_sample_trigger {
 	IIO_BACKEND_SAMPLE_TRIGGER_MAX
 };
 
+enum iio_backend_interface_type {
+	IIO_BACKEND_INTERFACE_SERIAL_LVDS,
+	IIO_BACKEND_INTERFACE_SERIAL_CMOS,
+	IIO_BACKEND_INTERFACE_MAX
+};
+
 /**
  * struct iio_backend_ops - operations structure for an iio_backend
  * @enable: Enable backend.
@@ -86,6 +92,7 @@ enum iio_backend_sample_trigger {
  * @extend_chan_spec: Extend an IIO channel.
  * @ext_info_set: Extended info setter.
  * @ext_info_get: Extended info getter.
+ * @interface_type_get: Interface type.
  * @read_raw: Read a channel attribute from a backend device
  * @debugfs_print_chan_status: Print channel status into a buffer.
  * @debugfs_reg_access: Read or write register value of backend.
@@ -121,6 +128,8 @@ struct iio_backend_ops {
 			    const char *buf, size_t len);
 	int (*ext_info_get)(struct iio_backend *back, uintptr_t private,
 			    const struct iio_chan_spec *chan, char *buf);
+	int (*interface_type_get)(struct iio_backend *back,
+				  enum iio_backend_interface_type *type);
 	int (*read_raw)(struct iio_backend *back,
 			struct iio_chan_spec const *chan, int *val, int *val2,
 			long mask);
@@ -169,6 +178,8 @@ ssize_t iio_backend_ext_info_set(struct iio_dev *indio_dev, uintptr_t private,
 				 const char *buf, size_t len);
 ssize_t iio_backend_ext_info_get(struct iio_dev *indio_dev, uintptr_t private,
 				 const struct iio_chan_spec *chan, char *buf);
+int iio_backend_interface_type_get(struct iio_backend *back,
+				   enum iio_backend_interface_type *type);
 int iio_backend_read_raw(struct iio_backend *back,
 			 struct iio_chan_spec const *chan, int *val, int *val2,
 			 long mask);
-- 
2.47.0