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Subject[PATCH 1/2] dt-bindings: spi: Document binding for generic SPI multiplexer
Date
Add binding documentation for the spi-mux driver. This allows a generic
multiplexer to be used to provide access to multiple SPI devices.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
.../devicetree/bindings/spi/spi-mux.yaml | 82 +++++++++++++++++++
1 file changed, 82 insertions(+)
create mode 100644 Documentation/devicetree/bindings/spi/spi-mux.yaml

diff --git a/Documentation/devicetree/bindings/spi/spi-mux.yaml b/Documentation/devicetree/bindings/spi/spi-mux.yaml
new file mode 100644
index 000000000000..1026d03a69c7
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-mux.yaml
@@ -0,0 +1,82 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/spi-mux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic SPI Multiplexer
+
+description: |
+ This binding describes a SPI bus multiplexer to route the SPI chip select
+ signals. This can be used when you need more devices than the SPI controller
+ has chip selects available. An example setup is shown in ASCII art; the actual
+ setting of the multiplexer to a channel needs to be done by a specific SPI mux
+ driver.
+
+ MOSI /--------------------------------+--------+--------+--------\
+ MISO |/------------------------------+|-------+|-------+|-------\|
+ SCL ||/----------------------------+||------+||------+||------\||
+ ||| ||| ||| ||| |||
+ +------------+ ||| ||| ||| |||
+ | SoC ||| | +-+++-+ +-+++-+ +-+++-+ +-+++-+
+ | ||| | | dev | | dev | | dev | | dev |
+ | +--+++-+ | CS-X +------+\ +--+--+ +--+--+ +--+--+ +--+--+
+ | | SPI +-|-------+ Mux |\\ CS-0 | | | |
+ | +------+ | +--+---+\\\-------/ CS-1 | | |
+ | | | \\\----------------/ CS-2 | |
+ | +------+ | | \\-------------------------/ CS-3 |
+ | | ? +-|----------/ \----------------------------------/
+ | +------+ |
+ +------------+
+
+allOf:
+ - $ref: "/schemas/spi/spi-controller.yaml#"
+
+properties:
+ compatible:
+ const: spi-mux
+
+ mux-control:
+ $ref: "/schemas/mux/mux-controller.yaml#"
+
+required:
+ - compatible
+ - reg
+ - spi-max-frequency
+ - mux-control
+
+examples:
+ - |
+ mux: mux-controller {
+ compatible = "gpio-mux";
+ #mux-control-cells = <0>;
+
+ mux-gpios = <&gpio0 3 GPIO_ACTIVE_HIGH>;
+ };
+
+ spi {
+ spi-mux {
+ compatible = "spi-mux";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ reg = <0>;
+ spi-max-frequency = <100000000>;
+
+ mux-control = <&mux>
+ mux-control-names = "spi";
+
+ spi-flash@0 {
+ compatible = "jedec,spi-nor";
+ #address-cells = <1>;
+ #size-cells = <1>;
+ reg = <0>;
+ spi-max-frequency = <40000000>;
+ };
+
+ spi-device@1 {
+ compatible = "spidev";
+ reg = <1>;
+ spi-max-frequency = <10000000>;
+ };
+ };
+ };
--
2.25.0
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