[PATCH v3 1/2] cxl: Add mechanism for delivering AFU driver specific events

[Matt Ochs]

> On Mar 7, 2016, at 7:48 PM, Ian Munsie <imunsie at au1.ibm.com> wrote:
> 
> From: Ian Munsie <imunsie at au1.ibm.com>
> 
> This adds an afu_driver_ops structure with event_pending and
> deliver_event callbacks. An AFU driver such as cxlflash can fill these
> out and associate it with a context to enable passing custom AFU
> specific events to userspace.
> 
> The cxl driver will call event_pending() during poll, select, read, etc.
> calls to check if an AFU driver specific event is pending, and will call
> deliver_event() to deliver that event. This way, the cxl driver takes
> care of all the usual locking semantics around these calls and handles
> all the generic cxl events, so that the AFU driver only needs to worry
> about it's own events.
> 
> The deliver_event() call is passed a struct cxl_event buffer to fill in.
> The header will already be filled in for an AFU driver event, and the
> AFU driver is expected to expand the header.size as necessary (up to
> max_size, defined by struct cxl_event_afu_driver_reserved) and fill out
> it's own information.
> 
> Since AFU drivers provide their own means for userspace to obtain the
> AFU file descriptor (i.e. cxlflash uses an ioctl on their scsi file
> descriptor to obtain the AFU file descriptor) and the generic cxl driver
> will never use this event, the ABI of the event is up to each individual
> AFU driver.
> 
> Signed-off-by: Ian Munsie <imunsie at au1.ibm.com>

Reviewed-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>