[PATCH v2 1/9] dt-bindings: iio: dac: ad3552r: add io-backend property

[Angelo Dureghello <adureghello@xxxxxxxxxxxx>]

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. This can be used
instead of a typical SPI controller to be able to use the chip
in ways that typical SPI controllers are not capable of.

The binding is modified so that either the device is a SPI
peripheral or it uses an io-backend.

Signed-off-by: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
---
 .../devicetree/bindings/iio/dac/adi,ad3552r.yaml   | 42 ++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
index fc8b97f82077..a6ce863ca93c 100644
--- a/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
+++ b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
@@ -60,12 +60,30 @@ 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
+
   '#address-cells':
     const: 1
 
   '#size-cells':
     const: 0
 
+if:
+  required:
+    - reg
+
+then:
+  $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+  properties:
+    io-backends: false
+
+  required: [ spi-max-frequency ]
+
 patternProperties:
   "^channel@([0-1])$":
     type: object
@@ -207,8 +225,6 @@ allOf:
 
 required:
   - compatible
-  - reg
-  - spi-max-frequency
 
 additionalProperties: false
 
@@ -238,4 +254,26 @@ examples:
             };
         };
     };
+
+  - |
+    backend: axi_dac@44a70000 {
+        compatible = "adi,axi-dac-ad3552r";
+        reg = <0x44a70000 0x1000>;
+        dmas = <&dac_tx_dma 0>;
+        dma-names = "tx";
+        #io-backend-cells = <0>;
+        clocks = <&ref_clk>;
+        dac {
+            compatible = "adi,ad3552r";
+            reset-gpios = <&gpio0 92 1>;
+            io-backends = <&backend>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            channel@0 {
+                reg = <0>;
+                adi,output-range-microvolt = <(-10000000) (10000000)>;
+            };
+        };
+    };
+
 ...

-- 
2.45.0.rc1