Subject: [PATCH v11 12/27] ARM: dts: Add description of System MMU of Exynos SoCs

From: [email-masked] (Tomasz Figa)
Date: Fri, 14 Mar 2014 13:20:23 +0100

Hi KyongHo,

On 14.03.2014 06:06, Cho KyongHo wrote:
> This patch adds dts entries for the System MMU devices found on
> Exynos4 and Exynos5 SoC series and the System MMU binding
> documentation.
>
> CC: Rob Herring <[email-masked]>
> CC: Sylwester Nawrocki <[email-masked]>
> Signed-off-by: Cho KyongHo <[email-masked]>
> ---
>   .../bindings/iommu/samsung,exynos4210-sysmmu.txt   |   86 +++++++
>   arch/arm/boot/dts/exynos4.dtsi                     |  107 ++++++++
>   arch/arm/boot/dts/exynos4210.dtsi                  |   23 +-
>   arch/arm/boot/dts/exynos4x12.dtsi                  |   77 +++++-
>   arch/arm/boot/dts/exynos5250.dtsi                  |  266 +++++++++++++++++++-
>   arch/arm/boot/dts/exynos5420.dtsi                  |  205 ++++++++++++++-
>   6 files changed, 758 insertions(+), 6 deletions(-)
>   create mode 100644 Documentation/devicetree/bindings/iommu/samsung,exynos4210-sysmmu.txt
>
> diff --git a/Documentation/devicetree/bindings/iommu/samsung,exynos4210-sysmmu.txt b/Documentation/devicetree/bindings/iommu/samsung,exynos4210-sysmmu.txt
> new file mode 100644
> index 0000000..e4417bb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iommu/samsung,exynos4210-sysmmu.txt
> @@ -0,0 +1,86 @@
> +Samsung Exynos IOMMU H/W, System MMU (System Memory Management Unit)
> +
> +Samsung's Exynos architecture contains System MMUs that enables scattered
> +physical memory chunks visible as a contiguous region to DMA-capable peripheral
> +devices like MFC, FIMC, FIMD, GScaler, FIMC-IS and so forth.
> +
> +System MMU is an IOMMU and supports identical translation table format to
> +ARMv7 translation tables with minimum set of page properties including access
> +permissions, shareability and security protection. In addition, System MMU has
> +another capabilities like L2 TLB or block-fetch buffers to minimize translation
> +latency.
> +
> +System MMUs are in many to one relation with peripheral devices, i.e. single
> +peripheral device might have multiple System MMUs (usually one for each bus
> +master), but one System MMU can handle transactions from only one peripheral
> +device. The relation between a System MMU and the peripheral device needs to be
> +defined in device node of the peripheral device.
> +
> +MFC in all Exynos SoCs and FIMD, M2M Scalers and G2D in Exynos5420 has 2 System
> +MMUs.
> +* MFC has one System MMU on its left and right bus.
> +* FIMD in Exynos5420 has one System MMU for window 0 and 4, the other system MMU
> +  for window 1, 2 and 3.
> +* M2M Scalers and G2D in Exynos5420 has one System MMU on the read channel and
> +  the other System MMU on the write channel.
> +The drivers must consider how to handle those System MMUs. One of the idea is
> +to implement child devices or sub-devices which are the client devices of the
> +System MMU.
> +
> +Required properties:
> +- compatible: Should be one of:
> +		"samsung,sysmmu-v1"
> +		"samsung,sysmmu-v2"
> +		"samsung,sysmmu-v3.1"
> +		"samsung,sysmmu-v3.2"
> +		"samsung,sysmmu-v3.3"
> +
> +- reg: A tuple of base address and size of System MMU registers.
> +- interrupt-parent: The phandle of the interrupt controller of System MMU
> +- interrupts: An interrupt specifier for interrupt signal of System MMU,
> +	      according to the format defined by a particular interrupt
> +	      controller.
> +- clock-names: Should be "sysmmu" if the System MMU is needed to gate its clock.
> +               Please refer to the following documents:
> +	       Documentation/devicetree/bindings/clock/clock-bindings.txt
> +	       Documentation/devicetree/bindings/clock/exynos4-clock.txt
> +	       Documentation/devicetree/bindings/clock/exynos5250-clock.txt
> +	       Documentation/devicetree/bindings/clock/exynos5420-clock.txt
> +	       Optional "master" if the clock to the System MMU is gated by
> +	       another gate clock other than "sysmmu". The System MMU driver
> +	       sets "master" the parent of "sysmmu".
> +	       Exynos4 SoCs, there needs no "master" clockj.
> +	       Exynos5 SoCs, some System MMUs must have "master" clocks.
> +- clocks: Required if the System MMU is needed to gate its clock.
> +	  Please refer to the documents listed above.
> +- samsung,power-domain: Required if the System MMU is needed to gate its power.
> +	  Please refer to the following document:
> +	  Documentation/devicetree/bindings/arm/exynos/power_domain.txt
> +- mmu-masters: A phandle to device nodes representing the master for which
> +               the System MMU can provide a translation. Any additional values
> +	       after the phandle will be ignored because a System MMU never
> +	       have two or more masters. "#stream-id-cells" specified in the
> +	       master's node will be also ignored.
> +	       If more than one phandle is specified, only the first phandle
> +	       will be treated.
> +
> +Examples:
> +	gsc_0: gsc at 13e00000 {
> +		compatible = "samsung,exynos5-gsc";
> +		reg = <0x13e00000 0x1000>;
> +		interrupts = <0 85 0>;
> +		samsung,power-domain = <&pd_gsc>;
> +		clocks = <&clock 256>;
> +		clock-names = "gscl";
> +	};
> +
> +	sysmmu_gsc0: sysmmu at 13E80000 {
> +		compatible = "samsung,exynos4210-sysmmu";
> +		reg = <0x13E80000 0x1000>;
> +		interrupt-parent = <&combiner>;
> +		interrupts = <2 0>;
> +		clock-names = "sysmmu", "master";
> +		clocks = <&clock 262>, <&clock 256>;
> +		samsung,power-domain = <&pd_gsc>;
> +		mmu-masters = <&gsc_0>;
> +	};

Binding documentation should be added in separate patch in front of the 
series relying on such binding or with the patch adding binding 
implementation to the driver, so DT maintainers can review the binding 
and related code easily.

Changes to dts(i) files should be posted in a separate patch, preferably 
at the end of the series, when any prerequisites are already available.

Best regards,
Tomasz