RFC Generic DMA bindings helpers for Device Tree

Hi All,

Here is a first RFC to introduce a generic binding for DMA controller and DMA request along with a couple of basic helpers functions.

The support is very limited since the a lot of DMA controllers in ARM SoCs are far for being adapted to dmaengine. At least this is the case for OMAP.

It is thus a little bit harder to handle that the same way GPIO is doing thanks to the gpiolib and provide a dmaengine pointer to the user.

For the moment the API is just returning the DMA controller device_node to the driver + the DMA request number.

I added as well for legacy purpose the dma to resource API, because it is still widely us in ARM SoC in general.

I found at least two custom DMA bindings that could be replaced by a generic one for my point of view.

commit bf55499e6ee927e047feed85349365481289bd75 Stephen Warren <[email protected]>
ASoC: Tegra I2S: Add device tree binding

commit 93ed55441245a39e3935f5cf1af3e22febcce905 Thomas Abraham <[email protected]>
DMA: PL330: Add device tree support

That generic DMA support is indeed pretty basic for the moment, but I think it can still help a couple of platforms.

Comments are welcome.

Thanks,
Benoit

Benoit Cousson (2):
of: Add generic device tree DMA helpers
arm/dts: OMAP4: Add dma-controller and dma-request for I2C

 Documentation/devicetree/bindings/dma/dma.txt |   44 +++++++++
 arch/arm/boot/dts/omap4.dtsi                  |   15 +++
 drivers/of/Kconfig                            |    5 +
 drivers/of/Makefile                           |    1 +
 drivers/of/dma.c                              |  130 +++++++++++++++++++++++++
 include/linux/of_dma.h                        |   49 +++++++++
 6 files changed, 244 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/dma/dma.txt
 create mode 100644 drivers/of/dma.c
 create mode 100644 include/linux/of_dma.h