[PATCH v3 3/6] dt-bindings: bus: add STM32 System Bus

[Gatien Chevallier <gatien.chevallier@foss.st.com>]

Document STM32 System Bus. This bus is intended to control firewall
access for the peripherals connected to it.

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Signed-off-by: Loic PALLARDY <loic.pallardy@st.com>
---

Changes in V2: 
	- Corrected errors highlighted by Rob's robot
	- Re-ordered Signed-off-by tags
	
Changes in V3:
	- Correct #feature-domain-cells
	- Declare 1 as minimum number of arguments for feature-domains property
	in bus subnodes and 3 as maximum.
	- Change example to be a real usecase.

 .../devicetree/bindings/bus/st,sys-bus.yaml   | 127 ++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/st,sys-bus.yaml

diff --git a/Documentation/devicetree/bindings/bus/st,sys-bus.yaml b/Documentation/devicetree/bindings/bus/st,sys-bus.yaml
new file mode 100644
index 000000000000..c1510784b79b
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/st,sys-bus.yaml
@@ -0,0 +1,127 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/st,sys-bus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STM32 System Bus
+
+description: |
+  The STM32 System Bus is an internal bus to which some internal peripherals
+  are connected. STM32 System Bus integrates a firewall controlling access to each
+  device. This bus prevents non-accessible devices to be probed.
+
+  To see which peripherals are securable, please check the SoC reference manual.
+
+maintainers:
+  - Gatien Chevallier <gatien.chevallier@foss.st.com>
+
+allOf:
+  - $ref: /schemas/feature-controllers/feature-domain-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - st,stm32mp13-sys-bus
+      - st,stm32mp15-sys-bus
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+  "#feature-domain-cells":
+    const: 1
+
+  ranges: true
+
+  feature-domain-controller: true
+
+patternProperties:
+  "^.*@[0-9a-f]+$":
+    description: Devices attached to system bus
+    type: object
+    properties:
+      feature-domains:
+        $ref: /schemas/feature-controllers/feature-domain-controller.yaml#/properties/feature-domains
+        minItems: 1
+        maxItems: 3
+
+required:
+  - compatible
+  - reg
+  - "#address-cells"
+  - "#size-cells"
+  - feature-domain-controller
+  - "#feature-domain-cells"
+  - ranges
+
+additionalProperties: false
+
+examples:
+  - |
+    // In this example, the rng1 device refers to etzpc as its domain controller.
+    // Same goes for fmc.
+    // Access rights are verified before creating devices.
+
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/stm32mp1-clks.h>
+    #include <dt-bindings/reset/stm32mp1-resets.h>
+
+    etzpc: bus@5c007000 {
+        compatible = "st,stm32mp15-sys-bus";
+        reg = <0x5c007000 0x400>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges;
+        feature-domain-controller;
+        #feature-domain-cells = <1>;
+
+        rng1: rng@54003000 {
+          compatible = "st,stm32-rng";
+          reg = <0x54003000 0x400>;
+          clocks = <&rcc RNG1_K>;
+          resets = <&rcc RNG1_R>;
+          feature-domains = <&etzpc 7>;
+          status = "disabled";
+        };
+
+        fmc: memory-controller@58002000 {
+          #address-cells = <2>;
+          #size-cells = <1>;
+          compatible = "st,stm32mp1-fmc2-ebi";
+          reg = <0x58002000 0x1000>;
+          clocks = <&rcc FMC_K>;
+          resets = <&rcc FMC_R>;
+          feature-domains = <&etzpc 91>;
+          status = "disabled";
+
+          ranges = <0 0 0x60000000 0x04000000>, /* EBI CS 1 */
+                   <1 0 0x64000000 0x04000000>, /* EBI CS 2 */
+                   <2 0 0x68000000 0x04000000>, /* EBI CS 3 */
+                   <3 0 0x6c000000 0x04000000>, /* EBI CS 4 */
+                   <4 0 0x80000000 0x10000000>; /* NAND */
+
+          nand-controller@4,0 {
+            #address-cells = <1>;
+            #size-cells = <0>;
+            compatible = "st,stm32mp1-fmc2-nfc";
+            reg = <4 0x00000000 0x1000>,
+                  <4 0x08010000 0x1000>,
+                  <4 0x08020000 0x1000>,
+                  <4 0x01000000 0x1000>,
+                  <4 0x09010000 0x1000>,
+                  <4 0x09020000 0x1000>;
+            interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
+            dmas = <&mdma1 20 0x2 0x12000a02 0x0 0x0>,
+                   <&mdma1 20 0x2 0x12000a08 0x0 0x0>,
+                   <&mdma1 21 0x2 0x12000a0a 0x0 0x0>;
+            dma-names = "tx", "rx", "ecc";
+            status = "disabled";
+          };
+        };
+    };
-- 
2.35.3