[PATCH v5 07/16] spi: dt-bindings: axi-spi-engine: add SPI offload properties

[David Lechner <dlechner@xxxxxxxxxxxx>]

The AXI SPI Engine has support for hardware offloading capabilities.
This includes a connection to a DMA controller for streaming RX data
and a trigger input for starting execution of the SPI message programmed
in the offload.

Each SPI Engine may have up to 1 offload. The spec actually says that
it could support up to 32, so we are using an index number in the
dma-names (e.g. offload0-rx) to allow for this possibility in the
future.

Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
---

v5 changes:
* Also document offload0-tx DMA names since the hardware can support
  that now.
* Limit the number of offloads to 1 for now since it would require
  significant hardware changes to actually support more than that.

v4 changes:
* Dropped #spi-offload-cells property.
* Changed subject line.

v3 changes:
* Added #spi-offload-cells property.
* Added properties for triggers and RX data stream connected to DMA.

v2 changes:
* This is basically a new patch. It partially replaces "dt-bindings:
  iio: offload: add binding for PWM/DMA triggered buffer".
* The controller no longer has an offloads object node and the
  spi-offloads property is now a standard SPI peripheral property.
---
 .../bindings/spi/adi,axi-spi-engine.yaml           | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
index d48faa42d025..d703b47eb498 100644
--- a/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
+++ b/Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml
@@ -41,6 +41,26 @@ properties:
       - const: s_axi_aclk
       - const: spi_clk
 
+  trigger-sources:
+    description:
+      An array of trigger source phandles for offload instances. The index in
+      the array corresponds to the offload instance number.
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    maxItems: 1
+
+  dmas:
+    description:
+      DMA channels connected to the input or output stream interface of an
+      offload instance.
+    minItems: 1
+    maxItems: 2
+
+  dma-names:
+    items:
+      pattern: "^offload0-[tr]x$"
+    minItems: 1
+    maxItems: 2
+
 required:
   - compatible
   - reg
@@ -59,6 +79,10 @@ examples:
         clocks = <&clkc 15>, <&clkc 15>;
         clock-names = "s_axi_aclk", "spi_clk";
 
+        trigger-sources = <&trigger_clock>;
+        dmas = <&dma 0>;
+        dma-names = "offload0-rx";
+
         #address-cells = <1>;
         #size-cells = <0>;
 

-- 
2.43.0