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
