From: Qipan Li <Qipan.Li@csr.com>
Date: Mon, 19 Aug 2013 03:47:53 +0000 (+0800)
Subject: serial: sirf: add DMA support using dmaengine APIs
X-Git-Tag: v3.12-rc1~182^2~47
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8316d04c42b94e94c8e54027d7c77ebe098ab5fa;p=pandora-kernel.git

serial: sirf: add DMA support using dmaengine APIs

if we get the valid dma channels from dts, move to use dmaengine to do
rx/tx. because the dma hardware requires dma address and length to be
4bytes aligned, in this driver, we will still use PIO for non-aligned
bytes, and use dma for aligned bytes.

for rx, to keep the dmaengine always active, we use double-buffer, so
we issue two dma_desc at first, and maintain the status of both
1. dma transfer done: update in rx dma finish callback
2. dma buffer is inserted into tty: update in rx dma finish tasklet and
   rx timeout tasklet
so we re-issue the dma_desc only if both 1&2 are finished.

for tx, as we know the actual length for every transfer, we don't need
the above double buffering.

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

Reading git-diff-tree failed