[PATCH v2 1/2] spi: renesas,rzv2m-csi: Add CSI (SPI) target related property

[Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>]

The CSI IP found inside the Renesas RZ/V2M SoC can also work
in SPI target mode.
When working in target mode, the IP will make use of the SS
(Slave Selection) pin, with "low" as default active level.
The active level of SS can be changed to "high" upon setting
property "spi-cs-high" to true.
By default, the SS will be used in target mode, unless property
"renesas,csi-no-ss" is set to true, in which case data will be
shifted in and out purely based on clock activity, and the
logic level of the SS pin will be completely ignored.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
---
v1->v2: I have dropped properties renesas,csi-ss and
        renesas,csi-ss-high. I have added property
	renesas,csi-no-ss, and to configure SS as active
	high one now needs to use property spi-cs-high.
	I have also reworded the changelog to use a more
	modern terminology (host and target as opposed to
	master and slave).

 .../devicetree/bindings/spi/renesas,rzv2m-csi.yaml       | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/renesas,rzv2m-csi.yaml b/Documentation/devicetree/bindings/spi/renesas,rzv2m-csi.yaml
index e59183e53690..bed829837df1 100644
--- a/Documentation/devicetree/bindings/spi/renesas,rzv2m-csi.yaml
+++ b/Documentation/devicetree/bindings/spi/renesas,rzv2m-csi.yaml
@@ -39,6 +39,12 @@ properties:
   power-domains:
     maxItems: 1
 
+  renesas,csi-no-ss:
+    type: boolean
+    description:
+      The CSI Slave Selection (SS) pin won't be used to enable transmission and
+      reception. Only available when in target mode.
+
 required:
   - compatible
   - reg
@@ -50,6 +56,9 @@ required:
   - '#address-cells'
   - '#size-cells'
 
+dependencies:
+  renesas,csi-no-ss: [ spi-slave ]
+
 unevaluatedProperties: false
 
 examples:
-- 
2.34.1