[PATCH 04/13] spi: dt-bindings: adi,axi-spi-engine: add offload bindings

[David Lechner <dlechner@baylibre.com>]

The ADI AXI SPI Engine driver supports offloading SPI transfers to
hardware. This is essentially a feature that allows recording an
arbitrary sequence of SPI transfers and then playing them back with
no CPU intervention via a hardware trigger.

This adds the bindings for this feature. Each SPI Engine instance
can have from 0 to 32 offload instances. Each offload instance has a
trigger input and a data stream output. As an example, this could be
used with an ADC SPI peripheral. In this case the trigger is connected
to a PWM/clock to determine the sampling rate for the ADC and the output
stream is connected to a DMA channel to pipe the sample data to memory.

SPI peripherals act as consumers of the offload instances. Typically,
one SPI peripheral will be connected to one offload instance. But to
make the bindings future-proof, the property is an array.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 .../spi/adi,axi-spi-engine-peripheral-props.yaml   | 24 +++++++++++
 .../bindings/spi/adi,axi-spi-engine.yaml           | 49 +++++++++++++++++++++-
 .../bindings/spi/spi-peripheral-props.yaml         |  1 +
 3 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/spi/adi,axi-spi-engine-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine-peripheral-props.yaml
new file mode 100644
index 000000000000..19b685fc3b39
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine-peripheral-props.yaml
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/adi,axi-spi-engine-peripheral-props.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Peripheral properties for Analog Devices AXI SPI Engine Controller
+
+maintainers:
+  - Michael Hennerich <Michael.Hennerich@analog.com>
+  - Nuno Sá <nuno.sa@analog.com>
+
+properties:
+  adi,offloads:
+    description:
+      List of AXI SPI Engine offload instances assigned to this peripheral.
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    maxItems: 32
+    items:
+      items:
+        - minimum: 0
+          maximum: 31
+
+additionalProperties: true
diff --git a/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
index d48faa42d025..69f3261bab47 100644
--- a/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
+++ b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
@@ -21,6 +21,23 @@ maintainers:
 allOf:
   - $ref: /schemas/spi/spi-controller.yaml#
 
+$defs:
+  offload:
+    description:
+      Describes the connections of the trigger input and the data output stream
+      of one or more offload instances.
+
+    properties:
+      reg:
+        description:
+          Index of the offload instance.
+        items:
+          - minimum: 0
+            maximum: 31
+
+    required:
+      - reg
+
 properties:
   compatible:
     const: adi,axi-spi-engine-1.00.a
@@ -41,6 +58,22 @@ properties:
       - const: s_axi_aclk
       - const: spi_clk
 
+  offloads:
+    type: object
+    description: Zero or more offloads supported by the controller.
+
+    properties:
+      "#address-cells":
+        const: 1
+
+      "#size-cells":
+        const: 0
+
+    patternProperties:
+      "^offload@[0-8a-f]+$":
+        type: object
+        $ref: '#/$defs/offload'
+
 required:
   - compatible
   - reg
@@ -62,5 +95,19 @@ examples:
         #address-cells = <1>;
         #size-cells = <0>;
 
-        /* SPI devices */
+        offloads {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            offload@0 {
+                compatible = "adi,example-offload";
+                reg = <0>;
+            };
+        };
+
+        adc@0 {
+            compatible = "adi,example-adc";
+            reg = <0>;
+            adi,offloads = <0>;
+        };
     };
diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
index 1c8e71c18234..7beb5a3798a5 100644
--- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
@@ -132,6 +132,7 @@ properties:
 
 # The controller specific properties go here.
 allOf:
+  - $ref: adi,axi-spi-engine-peripheral-props.yaml#
   - $ref: arm,pl022-peripheral-props.yaml#
   - $ref: cdns,qspi-nor-peripheral-props.yaml#
   - $ref: samsung,spi-peripheral-props.yaml#

-- 
2.43.0