[PATCH 1/3] [RFC] dt-bindings: nvmem: syscon: Add syscon backed nvmem bindings

[Marek Vasut <marex@denx.de>]

Add trivial bindings for driver which permits exposing syscon backed
register to userspace. This is useful e.g. to expose U-Boot boot
counter on various platforms where the boot counter is stored in
random volatile register, like STM32MP15xx TAMP_BKPxR register.

Signed-off-by: Marek Vasut <marex@denx.de>
---
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Rafał Miłecki <rafal@milecki.pl>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: devicetree@vger.kernel.org
Cc: linux-stm32@st-md-mailman.stormreply.com
To: linux-arm-kernel@lists.infradead.org
---
 .../bindings/nvmem/nvmem-syscon.yaml          | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml

diff --git a/Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml b/Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml
new file mode 100644
index 0000000000000..3035a0b2cd24a
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/nvmem-syscon.yaml
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/nvmem-syscon.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic syscon backed nvmem
+
+maintainers:
+  - Marek Vasut <marex@denx.de>
+
+allOf:
+  - $ref: "nvmem.yaml#"
+
+properties:
+  compatible:
+    enum:
+      - nvmem-syscon
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    tamp@5c00a000 {
+        compatible = "st,stm32-tamp", "syscon", "simple-mfd";
+        reg = <0x5c00a000 0x400>;
+
+        nvmem-syscon {
+            compatible = "nvmem-syscon";
+            reg = <0x14c 0x4>;
+        };
+    };
-- 
2.35.1