drivers: soc: sunxi: Introduce SoC driver to map SRAMs

Allwinnner SoC SRAM controllers

-----------------------------------------------------

The SRAM controller found on most Allwinner devices is represented by

a regular node for the SRAM controller itself, with sub-nodes

reprensenting the SRAM handled by the SRAM controller.

Controller Node

---------------

Required properties:

- compatible : "allwinner,sun4i-a10-sram-controller"

- reg : sram controller register offset + length

SRAM nodes

----------

Each SRAM is described using the mmio-sram bindings documented in

Documentation/devicetree/bindings/misc/sram.txt

Each SRAM will have SRAM sections that are going to be handled by the

SRAM controller as subnodes. These sections are represented following

once again the representation described in the mmio-sram binding.

The valid sections compatible are:

    - allwinner,sun4i-a10-sram-a3-a4

    - allwinner,sun4i-a10-sram-d

Devices using SRAM sections

---------------------------

Some devices need to request to the SRAM controller to map an SRAM for

their exclusive use.

The relationship between such a device and an SRAM section is

expressed through the allwinner,sram property, that will take a

phandle and an argument.

This valid values for this argument are:

  - 0: CPU

  - 1: Device

Example

-------

sram-controller@01c00000 {

	compatible = "allwinner,sun4i-a10-sram-controller";

	reg = <0x01c00000 0x30>;

	#address-cells = <1>;

	#size-cells = <1>;

	ranges;

	sram_a: sram@00000000 {

		compatible = "mmio-sram";

		reg = <0x00000000 0xc000>;

		#address-cells = <1>;

		#size-cells = <1>;

		ranges = <0 0x00000000 0xc000>;

		emac_sram: sram-section@8000 {

			compatible = "allwinner,sun4i-a10-sram-a3-a4";

			reg = <0x8000 0x4000>;

			status = "disabled";

		};

	};

};

emac: ethernet@01c0b000 {

	compatible = "allwinner,sun4i-a10-emac";

	...

	allwinner,sram = <&emac_sram 1>;

};

source "drivers/soc/mediatek/Kconfig"

source "drivers/soc/qcom/Kconfig"

source "drivers/soc/sunxi/Kconfig"

source "drivers/soc/ti/Kconfig"

source "drivers/soc/versatile/Kconfig"

obj-$(CONFIG_ARCH_MEDIATEK)	+= mediatek/

obj-$(CONFIG_ARCH_QCOM)		+= qcom/

obj-$(CONFIG_ARCH_SUNXI)	+= sunxi/

obj-$(CONFIG_ARCH_TEGRA)	+= tegra/

obj-$(CONFIG_SOC_TI)		+= ti/

obj-$(CONFIG_PLAT_VERSATILE)	+= versatile/

#

# Allwinner sunXi SoC drivers

#

config SUNXI_SRAM

	bool

	default ARCH_SUNXI

	help

	  Say y here to enable the SRAM controller support. This

	  device is responsible on mapping the SRAM in the sunXi SoCs

	  whether to the CPU/DMA, or to the devices.

obj-$(CONFIG_SUNXI_SRAM) +=	sunxi_sram.o