The MBUS (and its associated controller) is the bus in the Allwinner SoCs that DMA devices use in the system to access the memory.
Among other things (and depending on the SoC generation), it can also enforce priorities or report bandwidth usages on a per-master basis.
One of the most notable thing is that instead of having the same mapping for the RAM than the CPU, it maps it at address 0, which means we'll have to do address translation thanks to the dma-ranges property.
Signed-off-by: Maxime Ripard maxime.ripard@bootlin.com --- arch/arm/boot/dts/sun5i.dtsi | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/arch/arm/boot/dts/sun5i.dtsi b/arch/arm/boot/dts/sun5i.dtsi index 07f2248ed5f8..acb24e537e0b 100644 --- a/arch/arm/boot/dts/sun5i.dtsi +++ b/arch/arm/boot/dts/sun5i.dtsi @@ -112,6 +112,7 @@ compatible = "simple-bus"; #address-cells = <1>; #size-cells = <1>; + dma-ranges; ranges;
sram-controller@1c00000 { @@ -150,6 +151,14 @@ }; };
+ mbus: dram-controller@1c01000 { + compatible = "allwinner,sun5i-a13-mbus"; + reg = <0x01c01000 0x1000>; + clocks = <&ccu CLK_MBUS>; + dma-ranges = <0x00000000 0x40000000 0x20000000>; + #dma-parent-cells = <1>; + }; + dma: dma-controller@1c02000 { compatible = "allwinner,sun4i-a10-dma"; reg = <0x01c02000 0x1000>; @@ -677,6 +686,7 @@ clock-names = "ahb", "mod", "ram"; resets = <&ccu RST_DE_FE>; + dma-parent = <&mbus 19>; status = "disabled";
ports { @@ -705,6 +715,7 @@ clock-names = "ahb", "mod", "ram"; resets = <&ccu RST_DE_BE>; + dma-parent = <&mbus 18>; status = "disabled";
assigned-clocks = <&ccu CLK_DE_BE>;