[PATCH 1/3] iio: kfifo: add iio_device_attach_kfifo_buffer() helper

[Alexandru Ardelean <alexandru.ardelean@analog.com>]

This change adds the iio_device_attach_kfifo_buffer() helper/short-hand,
which groups the simple routine of allocating a kfifo buffers via
devm_iio_kfifo_allocate() and calling iio_device_attach_buffer().

The mode_flags parameter is required. The setup_ops parameter is optional.

This function will be a bit more useful when needing to define multiple
buffers per IIO device.

One requirement [that is more a recommendation] for this helper, is to call
it after 'indio_dev' has been populated.

Also, one consequence related to using this helper is that the resource
management of the buffer will be tied to 'indio_dev->dev'. Previously it
was open-coded, and each driver does it slightly differently. Most of them
tied it to the parent device, some of them to 'indio_dev->dev'.
This shouldn't be a problem, and may be a good idea when adding more
buffers per-device.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
 drivers/iio/buffer/kfifo_buf.c | 37 ++++++++++++++++++++++++++++++++++
 include/linux/iio/kfifo_buf.h  |  4 ++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/iio/buffer/kfifo_buf.c b/drivers/iio/buffer/kfifo_buf.c
index 3150f8ab984b..05b7c5fc6f1d 100644
--- a/drivers/iio/buffer/kfifo_buf.c
+++ b/drivers/iio/buffer/kfifo_buf.c
@@ -228,4 +228,41 @@ void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
 }
 EXPORT_SYMBOL(devm_iio_kfifo_free);
 
+/**
+ * iio_device_attach_kfifo_buffer - Allocate a kfifo buffer & attach it to an IIO device
+ * @indio_dev: The device the buffer should be attached to
+ * @mode_flags: The mode flags for this buffer (INDIO_BUFFER_SOFTWARE and/or
+ *		INDIO_BUFFER_TRIGGERED).
+ * @setup_ops: The setup_ops required to configure the HW part of the buffer (optional)
+ *
+ * This function allocates a kfifo buffer via devm_iio_kfifo_allocate() and
+ * attaches it to the IIO device via iio_device_attach_buffer().
+ * This is meant to be a bit of a short-hand/helper function as many driver
+ * seem to do this.
+ */
+int iio_device_attach_kfifo_buffer(struct iio_dev *indio_dev,
+				   int mode_flags,
+				   const struct iio_buffer_setup_ops *setup_ops)
+{
+	struct iio_buffer *buffer;
+
+	if (mode_flags)
+		mode_flags &= kfifo_access_funcs.modes;
+
+	if (!mode_flags)
+		return -EINVAL;
+
+	buffer = devm_iio_kfifo_allocate(&indio_dev->dev);
+	if (!buffer)
+		return -ENOMEM;
+
+	iio_device_attach_buffer(indio_dev, buffer);
+
+	indio_dev->modes |= mode_flags;
+	indio_dev->setup_ops = setup_ops;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iio_device_attach_kfifo_buffer);
+
 MODULE_LICENSE("GPL");
diff --git a/include/linux/iio/kfifo_buf.h b/include/linux/iio/kfifo_buf.h
index 764659e01b68..2363a931be14 100644
--- a/include/linux/iio/kfifo_buf.h
+++ b/include/linux/iio/kfifo_buf.h
@@ -11,4 +11,8 @@ void iio_kfifo_free(struct iio_buffer *r);
 struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev);
 void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r);
 
+int iio_device_attach_kfifo_buffer(struct iio_dev *indio_dev,
+				   int mode_flags,
+				   const struct iio_buffer_setup_ops *setup_ops);
+
 #endif
-- 
2.17.1