dt-bindings: spi: Add Tegra Quad SPI device tree binding

This patch adds YAML based device tree binding document for Tegra
Quad SPI driver.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Link: https://lore.kernel.org/r/1608585459-17250-3-git-send-email-skomatineni@nvidia.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml

@@ -0,0 +1,117 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/nvidia,tegra210-quad.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Tegra Quad SPI Controller
+
+maintainers:
+  - Thierry Reding <thierry.reding@gmail.com>
+  - Jonathan Hunter <jonathanh@nvidia.com>
+
+allOf:
+  - $ref: "spi-controller.yaml#"
+
+properties:
+  compatible:
+    enum:
+      - nvidia,tegra210-qspi
+      - nvidia,tegra186-qspi
+      - nvidia,tegra194-qspi
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: qspi
+      - const: qspi_out
+
+  clocks:
+    maxItems: 2
+
+  resets:
+    maxItems: 1
+
+  dmas:
+    maxItems: 2
+
+  dma-names:
+    items:
+      - const: rx
+      - const: tx
+
+patternProperties:
+  "@[0-9a-f]+":
+    type: object
+
+    properties:
+      spi-rx-bus-width:
+        enum: [1, 2, 4]
+
+      spi-tx-bus-width:
+        enum: [1, 2, 4]
+
+      nvidia,tx-clk-tap-delay:
+        description:
+          Delays the clock going out to device with this tap value.
+          Tap value varies based on platform design trace lengths from Tegra
+          QSPI to corresponding slave device.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 31
+
+      nvidia,rx-clk-tap-delay:
+        description:
+          Delays the clock coming in from the device with this tap value.
+          Tap value varies based on platform design trace lengths from Tegra
+          QSPI to corresponding slave device.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 255
+
+    required:
+      - reg
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clock-names
+  - clocks
+  - resets
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/tegra210-car.h>
+    #include <dt-bindings/reset/tegra210-car.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    spi@70410000 {
+            compatible = "nvidia,tegra210-qspi";
+            reg = <0x70410000 0x1000>;
+            interrupts = <GIC_SPI 10 IRQ_TYPE_LEVEL_HIGH>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            clocks = <&tegra_car TEGRA210_CLK_QSPI>,
+                     <&tegra_car TEGRA210_CLK_QSPI_PM>;
+            clock-names = "qspi", "qspi_out";
+            resets = <&tegra_car 211>;
+            dmas = <&apbdma 5>, <&apbdma 5>;
+            dma-names = "rx", "tx";
+
+            flash@0 {
+                    compatible = "spi-nor";
+                    reg = <0>;
+                    spi-max-frequency = <104000000>;
+                    spi-tx-bus-width = <2>;
+                    spi-rx-bus-width = <2>;
+                    nvidia,tx-clk-tap-delay = <0>;
+                    nvidia,rx-clk-tap-delay = <0>;
+            };
+    };