On 23/09/2024 17:50, Angelo Dureghello wrote: > Hi Krzysztof, > > On 22/09/24 23:02, Krzysztof Kozlowski wrote: >> On Thu, Sep 19, 2024 at 11:20:00AM +0200, Angelo Dureghello wrote: >>> From: Angelo Dureghello <adureghello@xxxxxxxxxxxx> >>> >>> There is a version AXI DAC IP block (for FPGAs) that provides >>> a physical bus for AD3552R and similar chips, and acts as >>> an SPI controller. >>> >>> For this case, the binding is modified to include some >>> additional properties. >>> >>> Signed-off-by: Angelo Dureghello <adureghello@xxxxxxxxxxxx> >>> --- >>> .../devicetree/bindings/iio/dac/adi,ad3552r.yaml | 42 ++++++++++++++++++++++ >>> 1 file changed, 42 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml >>> index 41fe00034742..aca4a41c2633 100644 >>> --- a/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml >>> +++ b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml >>> @@ -60,6 +60,18 @@ properties: >>> $ref: /schemas/types.yaml#/definitions/uint32 >>> enum: [0, 1, 2, 3] >>> >>> + io-backends: >>> + description: The iio backend reference. >>> + An example backend can be found at >>> + https://analogdevicesinc.github.io/hdl/library/axi_ad3552r/index.html >>> + maxItems: 1 >>> + >>> + adi,synchronous-mode: >>> + description: Enable waiting for external synchronization signal. >>> + Some AXI IP configuration can implement a dual-IP layout, with internal >>> + wirings for streaming synchronization. >>> + type: boolean >>> + >>> '#address-cells': >>> const: 1 >>> >>> @@ -128,6 +140,7 @@ patternProperties: >>> - custom-output-range-config >>> >>> allOf: >>> + - $ref: /schemas/spi/spi-peripheral-props.yaml# >>> - if: >>> properties: >>> compatible: >>> @@ -238,4 +251,33 @@ examples: >>> }; >>> }; >>> }; >>> + >>> + - | >>> + axi_dac: spi@44a70000 { >>> + compatible = "adi,axi-ad3552r"; >> That is either redundant or entire example should go to the parent node, >> if this device is fixed child of complex device (IOW, adi,ad3552r cannot >> be used outside of adi,axi-ad3552r). > > ad3552r can still be used by a generic "classic" spi > controller (SCLK/CS/MISO) but at a slower samplerate, fpga > controller only (axi-ad3552r) can reach 33MUPS. OK, then this is just redundant. Drop the node. Parent example should contain the children, though. > >> >>> + reg = <0x44a70000 0x1000>; >>> + dmas = <&dac_tx_dma 0>; >>> + dma-names = "tx"; >>> + #io-backend-cells = <0>; >>> + clocks = <&ref_clk>; >>> + >>> + #address-cells = <1>; >>> + #size-cells = <0>; >>> + >>> + dac@0 { >>> + compatible = "adi,ad3552r"; >>> + reg = <0>; >>> + reset-gpios = <&gpio0 92 0>; >> Use standard defines for GPIO flags. > > fixed, thanks > >>> + io-backends = <&axi_dac>; >> Why do you need to point to the parent? How much coupled are these >> devices? Child pointing to parent is not usually expected, because >> that's obvious. > > > "io-backends" is actually the way to refer to the backend module, > (used already for i.e. ad9739a), > it is needed because the backend is not only acting as spi-controller, > but is also providing some APIs for synchronization and bus setup support. But if backend is the parent, then this is redundant. You can take it from the child-parent relationship. Is this pointing to other devices (non-parent) in other ad3552r configurations? Best regards, Krzysztof
