[lkml]   [2020]   [Jan]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v6 07/12] soc: aspeed: xdma: Add user interface

On Thu, 16 Jan 2020, at 07:59, Eddie James wrote:
> This commits adds a miscdevice to provide a user interface to the XDMA
> engine. The interface provides the write operation to start DMA
> operations. The DMA parameters are passed as the data to the write call.
> The actual data to transfer is NOT passed through write. Note that both
> directions of DMA operation are accomplished through the write command;
> BMC to host and host to BMC.
> The XDMA driver reserves an area of physical memory for DMA operations,
> as the XDMA engine is restricted to accessing certain physical memory
> areas on some platforms. This memory forms a pool from which users can
> allocate pages for their usage with calls to mmap. The space allocated
> by a client will be the space used in the DMA operation. For an
> "upstream" (BMC to host) operation, the data in the client's area will
> be transferred to the host. For a "downstream" (host to BMC) operation,
> the host data will be placed in the client's memory area.
> Poll is also provided in order to determine when the DMA operation is
> complete for non-blocking IO.
> Signed-off-by: Eddie James <>

Reviewed-by: Andrew Jeffery <>

 \ /
  Last update: 2020-01-17 01:10    [W:0.144 / U:7.744 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site