[PATCH v2 1/8] iio: add read raw service to iio backend framework

[Olivier Moysan <olivier.moysan@xxxxxxxxxxx>]

Add iio_backend_read_raw() service to support attributes read
from an IIO backend.

Signed-off-by: Olivier Moysan <olivier.moysan@xxxxxxxxxxx>
Reviewed-by: Nuno Sa <nuno.sa@xxxxxxxxxx>
---
 drivers/iio/industrialio-backend.c | 21 +++++++++++++++++++++
 include/linux/iio/backend.h        |  6 +++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index 929aff4040ed..0e2653de1956 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -357,6 +357,27 @@ int devm_iio_backend_request_buffer(struct device *dev,
 }
 EXPORT_SYMBOL_NS_GPL(devm_iio_backend_request_buffer, IIO_BACKEND);
 
+/**
+ * iio_backend_read_raw - Request a channel attribute from the IIO backend.
+ * @back:	Backend device
+ * @chan:	IIO channel reference
+ * @val:	First element of the returned value
+ * @val2:	Second element of the returned value
+ * @mask:	Specify value to retrieve
+ *
+ * This callback replicates the read_raw callback of the IIO framework, and is intended to
+ * request miscellaneous channel attributes from the backend device.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_read_raw(struct iio_backend *back, struct iio_chan_spec const *chan, int *val,
+			 int *val2, long mask)
+{
+	return iio_backend_op_call(back, read_raw, chan, val, val2, mask);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_read_raw, IIO_BACKEND);
+
 static struct iio_backend *iio_backend_from_indio_dev_parent(const struct device *dev)
 {
 	struct iio_backend *back = ERR_PTR(-ENODEV), *iter;
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index 8099759d7242..24185718b20d 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -81,6 +81,7 @@ enum iio_backend_sample_trigger {
  * @extend_chan_spec: Extend an IIO channel.
  * @ext_info_set: Extended info setter.
  * @ext_info_get: Extended info getter.
+ * @read_raw: Read value from a backend device
  **/
 struct iio_backend_ops {
 	int (*enable)(struct iio_backend *back);
@@ -113,6 +114,8 @@ 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 (*read_raw)(struct iio_backend *back, struct iio_chan_spec const *chan, int *val,
+			int *val2, long mask);
 };
 
 int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan);
@@ -141,7 +144,8 @@ 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_read_raw(struct iio_backend *back, struct iio_chan_spec const *chan, int *val,
+			 int *val2, long mask);
 int iio_backend_extend_chan_spec(struct iio_dev *indio_dev,
 				 struct iio_backend *back,
 				 struct iio_chan_spec *chan);
-- 
2.25.1