Some of the DMA controllers are capable of issuing the commands
to peripheral by the DMA. These commands can be list of register
reads/writes and its different from normal data reads/writes.
This patch adds new flag DMA_PREP_CMD in DMA API which tells
the driver that the data passed to DMA API is command data
and DMA controller driver will form descriptor in the required
format.

This flag can be used by any DMA controller driver which requires
the descriptor in different format for non-Data descriptors.

Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

There are no in kernel consumers for DMA_SG op. Removing operation,
dead code, and test code in dmatest.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Gary Hook <gary.hook@amd.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: Kedareswara rao Appana <appana.durga.rao@xilinx.com>
Cc: Li Yang <leoyang.li@nxp.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Adding documentation in dmaengine/provider.txt on the usage of callback
with result, callback_result, function pointer to retrieve transanction
result from a DMA submission.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>