Add backend support for enabling/disabling oversampling.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
changes in v7:
 - implement 2 callbacks
	iio_backend_oversampling_enable()
	iio_backend_oversampling_disable()
 drivers/iio/industrialio-backend.c | 26 ++++++++++++++++++++++++++
 include/linux/iio/backend.h        |  6 ++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index ea184fc2c838..86237c1e7ab4 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -681,6 +681,32 @@ int iio_backend_data_size_set(struct iio_backend *back, unsigned int size)
 }
 EXPORT_SYMBOL_NS_GPL(iio_backend_data_size_set, IIO_BACKEND);
 
+/**
+ * iio_backend_oversampling_enable - oversampling enable
+ * @back: Backend device
+ *
+ * Return:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_oversampling_enable(struct iio_backend *back)
+{
+	return iio_backend_op_call(back, oversampling_enable);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_oversampling_enable, IIO_BACKEND);
+
+/**
+ * iio_backend_oversampling_disable - oversampling disable
+ * @back: Backend device
+ *
+ * Return:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_oversampling_disable(struct iio_backend *back)
+{
+	return iio_backend_op_call(back, oversampling_disable);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_oversampling_disable, 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 59b6651b7eaf..789fa9b586ec 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -94,6 +94,8 @@ enum iio_backend_interface_type {
  * @ext_info_get: Extended info getter.
  * @interface_type_get: Interface type.
  * @data_size_set: Data size.
+ * @oversampling_enable: Oversampling enable.
+ * @oversampling_disable: Oversampling disable.
  * @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.
@@ -132,6 +134,8 @@ struct iio_backend_ops {
 	int (*interface_type_get)(struct iio_backend *back,
 				  enum iio_backend_interface_type *type);
 	int (*data_size_set)(struct iio_backend *back, unsigned int size);
+	int (*oversampling_enable)(struct iio_backend *back);
+	int (*oversampling_disable)(struct iio_backend *back);
 	int (*read_raw)(struct iio_backend *back,
 			struct iio_chan_spec const *chan, int *val, int *val2,
 			long mask);
@@ -183,6 +187,8 @@ ssize_t iio_backend_ext_info_get(struct iio_dev *indio_dev, uintptr_t private,
 int iio_backend_interface_type_get(struct iio_backend *back,
 				   enum iio_backend_interface_type *type);
 int iio_backend_data_size_set(struct iio_backend *back, unsigned int size);
+int iio_backend_oversampling_enable(struct iio_backend *back);
+int iio_backend_oversampling_disable(struct iio_backend *back);
 int iio_backend_read_raw(struct iio_backend *back,
 			 struct iio_chan_spec const *chan, int *val, int *val2,
 			 long mask);
-- 
2.47.1

On 11/29/24 9:35 AM, Antoniu Miclaus wrote:
> Add backend support for enabling/disabling oversampling.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---
> changes in v7:
>  - implement 2 callbacks
> 	iio_backend_oversampling_enable()
> 	iio_backend_oversampling_disable()

I think Jonathan's suggestion from a previous review to pass the
oversampling ratio instead of enable/disable seems like a good idea
for making this more generic.

int iio_backend_set_oversampling_ratio(struct iio_backend *back, u32 ratio);

To answer Jonathan's question [1] about why does the backend need to
know if oversampling is enabled or not... In this case, it looks
like it changes some timing (the conversion quiet time) on the LVDS/CMOS
serial data lines depending on if oversampling is enabled or not.

[1]: https://lore.kernel.org/linux-iio/20241123160559.56c57fc7@jic23-huawei/