Re: [PATCH v3 05/12] dt-bindings: soc: Add Aspeed XDMA Engine

[Eddie James]

On 12/18/19 5:12 PM, Andrew Jeffery wrote:
> On Thu, 19 Dec 2019, at 01:39, Eddie James wrote:
> > Document the bindings for the Aspeed AST25XX and AST26XX XDMA engine.
> >
> > Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > ---
> > Changes since v2:
> >   - Remove 'sdmc', rename 'vga-mem' to 'memory'
> >
> >   .../devicetree/bindings/soc/aspeed/xdma.txt   | 40 +++++++++++++++++++
> >   MAINTAINERS                                   |  6 +++
> >   2 files changed, 46 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/soc/aspeed/xdma.txt
> >
> > diff --git a/Documentation/devicetree/bindings/soc/aspeed/xdma.txt
> > b/Documentation/devicetree/bindings/soc/aspeed/xdma.txt
> > new file mode 100644
> > index 000000000000..58253ea1587b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/soc/aspeed/xdma.txt
> > @@ -0,0 +1,40 @@
> > +Aspeed AST25XX and AST26XX XDMA Engine
> > +
> > +The XDMA Engine embedded in the AST2500 and AST2600 SOCs can perform
> > automatic
> > +DMA operations over PCI between the SOC (acting as a BMC) and a host
> > processor.
> > +
> > +Required properties:
> > + - compatible		: must be "aspeed,ast2500-xdma" or
> > +			  "aspeed,ast2600-xdma"
> > + - reg			: contains the address and size of the memory region
> > +			  associated with the XDMA engine registers
> > + - clocks		: clock specifier for the clock associated with the
> > +			  XDMA engine
> > + - resets		: reset specifier for the syscon reset associated with
> > +			  the XDMA engine
> > + - interrupts-extended	: two interrupt cells; the first specifies the
> > global
> > +			  interrupt for the XDMA engine and the second
> > +			  specifies the PCI-E reset or PERST interrupt.
> > + - scu			: a phandle to the syscon node for the system control
> > +			  unit of the SOC
> I think this should be aspeed,scu.


Sure.


> > + - memory		: contains the address and size of the memory area to
> > +			  be used by the XDMA engine for DMA operations
> Hmm, I was thinking more like a phandle to a reserved memory region,
> like we have in the aspeed-lpc-ctrl binding.


I think I mentioned before, but that doesn't work with the VGA memory. 
Linux can't reserve it. I haven't quite understood what happens in the 
memory system but I've tried it and it didn't work.


> > +
> > +Optional properties:
> > + - pcie-device		: should be either "bmc" or "vga", corresponding to
> > +			  which device should be used by the XDMA engine for
> > +			  DMA operations. If this property is not set, the XDMA
> > +			  engine will use the BMC PCI-E device.
> > +
> > +Example:
> > +
> > +    xdma@1e6e7000 {
> > +        compatible = "aspeed,ast2500-xdma";
> > +        reg = <0x1e6e7000 0x100>;
> > +        clocks = <&syscon ASPEED_CLK_GATE_BCLK>;
> > +        resets = <&syscon ASPEED_RESET_XDMA>;
> > +        interrupts-extended = <&vic 6>, <&scu_ic
> > ASPEED_AST2500_SCU_IC_PCIE_RESET_LO_TO_HI>;
> > +        scu = <&syscon>;
> > +        pcie-device = "bmc";
> > +        memory = <0x9f000000 0x01000000>;
> > +    };
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index ac9c120d192b..8a14d4268bdc 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -2708,6 +2708,12 @@ S:	Maintained
> >   F:	drivers/media/platform/aspeed-video.c
> >   F:	Documentation/devicetree/bindings/media/aspeed-video.txt
> >   
> > +ASPEED XDMA ENGINE DRIVER
> > +M:	Eddie James <eajames@xxxxxxxxxxxxx>
> > +L:	linux-aspeed@xxxxxxxxxxxxxxxx (moderated for non-subscribers)
> > +S:	Maintained
> > +F:	Documentation/devicetree/bindings/soc/aspeed/xdma.txt
> > +
> >   ASUS NOTEBOOKS AND EEEPC ACPI/WMI EXTRAS DRIVERS
> >   M:	Corentin Chary <corentin.chary@xxxxxxxxx>
> >   L:	acpi4asus-user@xxxxxxxxxxxxxxxxxxxxx
> > --
> > 2.24.0