Generic DMA-capable streaming device driver looking for home

[Alex Williams <alex.williams@ni.com>]

Hi all,

We're writing a device driver and having some difficulty matching a
subsystem to the driver/device properties. Can anyone help with
direction?

These are some basic properties:
1) Device is used to carry generic data to/from userspace. It's a pair
   of dumb streams with one sink and one source for each direction (no
   addressable endpoints for the other side).
2) Data goes to/from a DMA engine in an FPGA at high throughput.
3) The driver enables userspace to queue multiple DMA-able buffers for
   asynchronous, pipelined data transfer. We currently use the
   videobuf2 API to provide the feature. We're not carrying video data
   in general, though.

It's a piece of a software-defined radio system, and while it can carry
data from DACs/ADCs, the device is only a generic transport. It doesn't
know what data it's carrying, so neither would the driver.

Some guidance would be greatly appreciated. Thanks!
--Alex