[PATCH 1/3] dt-bindings: soc: ti: Document the ti,tda54-mcu-scm-conf binding

[Moteen Shah]

TDA54's MCU domain exposes a shared scm_conf syscon region that other
peripherals, including chipid, access into rather than owning a
dedicated register window. Rather than a bare fallback entry in the
generic syscon compatible list, give it a dedicated binding
describing the region and the proxy/claim/lock arbitration scheme
that gates write access to a subset of its registers.

Some of the claimable registers are gate clock controls, so also
document the required "#clock-cells" property that lets the node be
referenced directly as a clock provider for those gates. The clock
specifier selects the ePWM time-base gate by instance number.

Signed-off-by: Moteen Shah <m-shah at ti.com>
Signed-off-by: Aniket Limaye <a-limaye at ti.com>
---
 .../soc/ti/ti,tda54-mcu-scm-conf.yaml         | 78 +++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/ti/ti,tda54-mcu-scm-conf.yaml

diff --git a/Documentation/devicetree/bindings/soc/ti/ti,tda54-mcu-scm-conf.yaml b/Documentation/devicetree/bindings/soc/ti/ti,tda54-mcu-scm-conf.yaml
new file mode 100644
index 0000000000000..111cbb739b5f1
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/ti/ti,tda54-mcu-scm-conf.yaml
@@ -0,0 +1,78 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/ti/ti,tda54-mcu-scm-conf.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments TDA54 SoC MCU Domain System Control Module Configuration registers
+
+maintainers:
+  - Aniket Limaye <a-limaye at ti.com>
+  - Moteen Shah <m-shah at ti.com>
+
+description: |
+  The TDA54 SoC's MCU domain exposes a System Control Module configuration
+  register region (scm_conf) containing miscellaneous control and status
+  registers for MCU domain peripherals, including the JTAGID/device
+  identification registers, boot configuration and status registers, and
+  device feature registers.
+
+  A subset of these registers is write-protected by a proxy/claim scheme:
+  each register is mirrored across 8 proxy regions, and a host must unlock
+  via LOCK_KICK. Any proxy other than proxy-0 must also claim a register
+  through its CLAIM register before writing through that proxy. Proxy-0 is
+  the default access proxy: its claim bits are tied low, so it needs no
+  claim and can write any register that is not claimed by another proxy.
+  For example: Proxy0's CLAIM0 register sits at offset 0x3100, while the
+  same register mirrored at ProxyN sits at N * 0x4000 + 0x3100.
+
+  Each of the 8 proxy regions also has its own fault status and
+  interrupt registers, but a fault can only be handled through proxy-0.
+  Hence, interrupt/fault handling is not described by this binding.
+
+  Some of the claimable registers are gate clock controls (e.g. the
+  ehrpwm_tbclk gates). This node is the clock provider for those gates;
+  writes to them are still routed through the proxy claim scheme described
+  above.
+
+properties:
+  compatible:
+    const: ti,tda54-mcu-scm-conf
+
+  reg:
+    maxItems: 1
+
+  ti,proxy-id:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 7
+    description:
+      Proxy region (0-7) through which this node's clients access
+      claimable registers and their fault status registers.
+
+  "#clock-cells":
+    const: 1
+    description:
+      The cell selects the ePWM time-base clock gate. Values 0 to 12 select
+      ehrpwm_tbclk0 to ehrpwm_tbclk12, i.e. the gate for ePWM instance N is
+      specifier N.
+
+required:
+  - compatible
+  - reg
+  - ti,proxy-id
+  - "#clock-cells"
+
+additionalProperties: false
+
+examples:
+
+  - |
+    scm_conf1: syscon at 5e800000 {
+        compatible = "ti,tda54-mcu-scm-conf";
+        reg = <0x5e800000 0x20000>;
+        ti,proxy-id = <0>;
+        #clock-cells = <1>;
+    };
+
+...
-- 
2.34.1