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Subject[PATCH v3 2/6] dt-bindings: bus: Add Baikal-T1 APB-bus binding
Date
Baikal-T1 CPU or DMAC MMIO requests are handled by the AMBA 3 AXI
Interconnect which routes them to the AXI-APB bridge, which in turn
serializes accesses and routes them to the corresponding APB slave device.
This binding describes the AXI-APB bridge considered as the APB-bus. It is
supposed to be compatible with "be,bt1-apb" and "simple-bus" drivers,
should be equipped with EHB MMIO region and a region with no slave device
mapped, interrupts line number, APB reference clock and domain reset line.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Olof Johansson <olof@lixom.net>
Cc: linux-mips@vger.kernel.org
Cc: soc@kernel.org

---

Changelog v2:
- Move driver to the bus subsystem.
- Don't use a multi-arg clock phandle reference in the examples dt-bindings
property. Thus redundant include statement can be removed.
- Use dual GPL/BSD license.
- Use single lined copyright header.
- Lowercase the unit-address.
- Convert a dedicated EHB block binding to the Baikal-T1 APB-bus one.
- Add APB reference clock and reset support.
- Replace "additionalProperties: false" property with
"unevaluatedProperties: false".
- Add reg-names property.
---
.../bindings/bus/baikal,bt1-apb.yaml | 90 +++++++++++++++++++
1 file changed, 90 insertions(+)
create mode 100644 Documentation/devicetree/bindings/bus/baikal,bt1-apb.yaml

diff --git a/Documentation/devicetree/bindings/bus/baikal,bt1-apb.yaml b/Documentation/devicetree/bindings/bus/baikal,bt1-apb.yaml
new file mode 100644
index 000000000000..d6a3b71ea835
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/baikal,bt1-apb.yaml
@@ -0,0 +1,90 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/baikal,bt1-apb.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Baikal-T1 APB-bus
+
+maintainers:
+ - Serge Semin <fancer.lancer@gmail.com>
+
+description: |
+ Baikal-T1 CPU or DMAC MMIO requests are handled by the AMBA 3 AXI Interconnect
+ which routes them to the AXI-APB bridge. This interface is a single master
+ multiple slaves bus in turn serializing IO accesses and routing them to the
+ addressed APB slave devices. 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 (APB Errors Handler Block).
+
+allOf:
+ - $ref: /schemas/simple-bus.yaml#
+
+properties:
+ compatible:
+ contains:
+ const: baikal,bt1-apb
+
+ reg:
+ items:
+ - description: APB EHB MMIO registers
+ - description: APB MMIO region with no any device mapped
+
+ reg-names:
+ items:
+ - const: ehb
+ - const: nodev
+
+ interrupts:
+ maxItems: 1
+
+ clocks:
+ items:
+ - description: APB reference clock
+
+ clock-names:
+ items:
+ - const: pclk
+
+ resets:
+ items:
+ - description: APB domain reset line
+
+ reset-names:
+ items:
+ - const: prst
+
+unevaluatedProperties: false
+
+required:
+ - compatible
+ - reg
+ - reg-names
+ - interrupts
+ - clocks
+ - clock-names
+
+examples:
+ - |
+ #include <dt-bindings/interrupt-controller/mips-gic.h>
+
+ bus@1f059000 {
+ compatible = "baikal,bt1-apb", "simple-bus";
+ reg = <0 0x1f059000 0 0x1000>,
+ <0 0x1d000000 0 0x2040000>;
+ reg-names = "ehb", "nodev";
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ ranges;
+
+ interrupts = <GIC_SHARED 16 IRQ_TYPE_LEVEL_HIGH>;
+
+ clocks = <&ccu_sys 1>;
+ clock-names = "pclk";
+
+ resets = <&ccu_sys 1>;
+ reset-names = "prst";
+ };
+...
--
2.26.2
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