[PATCH 2/6] dt-bindings: Add Baikal-T1 APB-bus EHB dts bindings file

[<Sergey.Semin@baikalelectronics.ru>]

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

This is a specific block embedded into the Baikal-T1 SoC, which is
dedicated to detect APB-bus protocol errors and tune the peripheral
access timeout. So the dts bindings implies that corresponding dts
node would be equipped with "be,bt1-apb-ehb" compatible string, MMIO
region of registers space and of space with no device mapped,
interrupts property and with an APB-reference clock handler.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: soc@kernel.org
---
 .../soc/baikal-t1/be,bt1-apb-ehb.yaml         | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml

diff --git a/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml
new file mode 100644
index 000000000000..e262aead2fb5
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml
@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2019 - 2020 BAIKAL ELECTRONICS, JSC
+#
+# Baikal-T1 APB-bus Errors Handler Block Device Tree Bindings.
+#
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/baikal-t1/be,bt1-apb-ehb.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Baikal-T1 APB-bus Errors Handler Block
+
+maintainers:
+  - Serge Semin <fancer.lancer@gmail.com>
+
+description: |
+  Configuration registers of Baikal-T1 SoC peripheral interfaces are accessed
+  by means of the APB-bus. In case of any APB protocol collisions, slave device
+  not responding on timeout an IRQ is raised with an erroneous address reported
+  to the APB terminator (EHB) sub-block described by this bindings file.
+
+properties:
+  compatible:
+    const: be,bt1-apb-ehb
+
+  reg:
+    items:
+      - description: APB EHB MMIO registers.
+      - description: APB MMIO region with no any device mapped.
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    description: APB reference clock.
+    maxItems: 1
+
+  clock-names:
+    const: ref
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/mips-gic.h>
+    #include <dt-bindings/clock/bt1-ccu.h>
+
+    apb_ehb: ehb@1F059000 {
+      compatible = "be,bt1-apb-ehb";
+      reg = <0x1F059000 0x1000>,
+            <0x1D000000 0x2040000>;
+
+      interrupts = <GIC_SHARED 16 IRQ_TYPE_LEVEL_HIGH>;
+
+      clocks = <&ccu_sys CCU_SYS_APB_CLK>;
+      clock-names = "ref";
+    };
+...
-- 
2.25.1