linux-kernel - [PATCH RFC v3 1/9] spi: dt-bindings: add spi-offload properties

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Message-ID: <20240722-dlech-mainline-spi-engine-offload-2-v3-1-7420e45df69b@baylibre.com>
Date: Mon, 22 Jul 2024 16:57:08 -0500
From: David Lechner <dlechner@...libre.com>
To: Mark Brown <broonie@...nel.org>,
	Jonathan Cameron <jic23@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Nuno Sá <nuno.sa@...log.com>
Cc: David Lechner <dlechner@...libre.com>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	David Jander <david@...tonic.nl>,
	Martin Sperl <kernel@...tin.sperl.org>,
	linux-spi@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org
Subject: [PATCH RFC v3 1/9] spi: dt-bindings: add spi-offload properties

This adds a new provider/consumer property pair to the generic SPI
bindings for use with peripherals connected to controllers that support
offloading.

Here, offloading means that the controller has the ability to perform
SPI transactions without any CPU intervention in some shape or form.

The spi-offloads property will be used to assign controller offload
resources to each peripheral that needs them. What these resources are
will be defined by each specific controller binding by specifying the
value of the #spi-offload-cells property.

SPI peripherals that use multiple offload instances at the same time
for different functions can describe the functions using the
spi-offload-names property, for example, for a SPI flash memory, this
might be "read", "erase" and "write" functions.

Signed-off-by: David Lechner <dlechner@...libre.com>
---

v3 changes:
* Added #spi-offload-cells property to the controller binding.
* Changed spi-offloads to phandle-array.
* Added spi-offload-names property.

v2 changes:

In v1, instead of generic SPI bindings, there were only controller-
specific bindings, so this is a new patch.
---
 Documentation/devicetree/bindings/spi/spi-controller.yaml     |  5 +++++
 .../devicetree/bindings/spi/spi-peripheral-props.yaml         | 11 +++++++++++
 2 files changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-controller.yaml b/Documentation/devicetree/bindings/spi/spi-controller.yaml
index 093150c0cb87..0af9cce80be9 100644
--- a/Documentation/devicetree/bindings/spi/spi-controller.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-controller.yaml
@@ -105,6 +105,11 @@ properties:
     required:
       - compatible
 
+  '#spi-offload-cells':
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Number of cells in a SPI offload specifier.
+
 patternProperties:
   "^.*@[0-9a-f]+$":
     type: object
diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
index 0bb443b8decd..e27577bdae48 100644
--- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
@@ -113,6 +113,17 @@ properties:
     minItems: 2
     maxItems: 4
 
+  spi-offloads:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description:
+      Array of SPI offload instances that are used by the peripheral.
+
+  spi-offload-names:
+    $ref: /schemas/types.yaml#/definitions/string-array
+    description:
+      Describes the function of each offload instance. Can be omitted if there
+      is only one item allowed in the spi-offloads array.
+
   st,spi-midi-ns:
     description: |
       Only for STM32H7, (Master Inter-Data Idleness) minimum time

-- 
2.43.0