[PATCH v2 1/6] dt-bindings: rtc: Convert snps,dw-apb-timer to DT schema

[<Sergey.Semin@baikalelectronics.ru>]

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

Modern device tree bindings are supposed to be created as YAML-files
in accordance with DT schema. This commit replaces Synopsys DW Timer
legacy bare text binding with YAML file. As before the binding file
states that the corresponding dts node is supposed to be compatible
with generic DW APB Timer indicated by the "snps,dw-apb-timer"
compatible string and to provide a mandatory registers memory range,
one timer interrupt, either reference clock source or a fixed clock
rate value. It may also have an optional APB bus reference clock
phandle specified.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: 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: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: linux-rtc@vger.kernel.org

---

I have doubts that this binding file belongs to the bindings/rtc
directory seeing it's a pure timer with no rtc facilities like
days/months/years counting and alarms. What about moving it to the
"Documentation/devicetree/bindings/timer/" directory?

I also don't know who is the corresponding driver maintainer, so I added
Daniel Lezcano to the maintainers schema. Any idea what email should be
specified there instead?

Please also note, that "oneOf: - required: ..." pattern isn't working
here. So if you omit any of the clock-related property the
dt_binding_check procedure won't fail. Seeing the anyOf schema is working
I suppose this happens due to the dtschema/lib.py script, which replaces
the global oneOf with a fixup for the interrupts/interrupts-extended
properties:

> def fixup_interrupts(schema):
>    # Supporting 'interrupts' implies 'interrupts-extended' is also supported.
>    if not 'interrupts' in schema['properties'].keys():
>        return
>
>    # Any node with 'interrupts' can have 'interrupt-parent'
>    schema['properties']['interrupt-parent'] = True
>
>    schema['properties']['interrupts-extended'] = { "$ref": "#/properties/interrupts" };
>
>    if not ('required' in schema.keys() and 'interrupts' in schema['required']):
>        return
>
!>    # Currently no better way to express either 'interrupts' or 'interrupts-extended'
!>    # is required. If this fails validation, the error reporting is the whole
!>    # schema file fails validation
!>    schema['oneOf'] = [ {'required': ['interrupts']}, {'required': ['interrupts-extended']} ]
---
 .../devicetree/bindings/rtc/dw-apb.txt        | 32 -------
 .../bindings/rtc/snps,dw-apb-timer.yaml       | 88 +++++++++++++++++++
 2 files changed, 88 insertions(+), 32 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/rtc/dw-apb.txt
 create mode 100644 Documentation/devicetree/bindings/rtc/snps,dw-apb-timer.yaml

diff --git a/Documentation/devicetree/bindings/rtc/dw-apb.txt b/Documentation/devicetree/bindings/rtc/dw-apb.txt
deleted file mode 100644
index c703d51abb6c..000000000000
--- a/Documentation/devicetree/bindings/rtc/dw-apb.txt
+++ /dev/null
@@ -1,32 +0,0 @@
-* Designware APB timer
-
-Required properties:
-- compatible: One of:
- 	"snps,dw-apb-timer"
-	"snps,dw-apb-timer-sp" <DEPRECATED>
-	"snps,dw-apb-timer-osc" <DEPRECATED>
-- reg: physical base address of the controller and length of memory mapped
-  region.
-- interrupts: IRQ line for the timer.
-- either clocks+clock-names or clock-frequency properties
-
-Optional properties:
-- clocks	: list of clock specifiers, corresponding to entries in
-		  the clock-names property;
-- clock-names	: should contain "timer" and "pclk" entries, matching entries
-		  in the clocks property.
-- clock-frequency: The frequency in HZ of the timer.
-- clock-freq: For backwards compatibility with picoxcell
-
-If using the clock specifiers, the pclk clock is optional, as not all
-systems may use one.
-
-
-Example:
-	timer@ffe00000 {
-		compatible = "snps,dw-apb-timer";
-		interrupts = <0 170 4>;
-		reg = <0xffe00000 0x1000>;
-		clocks = <&timer_clk>, <&timer_pclk>;
-		clock-names = "timer", "pclk";
-	};
diff --git a/Documentation/devicetree/bindings/rtc/snps,dw-apb-timer.yaml b/Documentation/devicetree/bindings/rtc/snps,dw-apb-timer.yaml
new file mode 100644
index 000000000000..88d939ed1b0b
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/snps,dw-apb-timer.yaml
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/snps,dw-apb-timer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Synopsys DesignWare APB Timer
+
+maintainers:
+  - Daniel Lezcano <daniel.lezcano@linaro.org>
+
+properties:
+  compatible:
+    oneOf:
+      - const: snps,dw-apb-timer
+      - enum:
+          - snps,dw-apb-timer-sp
+          - snps,dw-apb-timer-osc
+        deprecated: true
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    minItems: 1
+    items:
+       - description: Timer ticks reference clock source
+       - description: APB interface clock source
+
+  clock-names:
+    minItems: 1
+    items:
+      - const: timer
+      - const: pclk
+
+  clock-frequency: true
+
+  clock-freq:
+    $ref: "/schemas/types.yaml#/definitions/uint32"
+    description: |
+      Has the same meaning as the 'clock-frequency' property - timer clock
+      frequency in HZ, but is defined only for the backwards compatibility
+      with the picoxcell platform.
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+oneOf:
+  - required:
+      - clocks
+      - clock-names
+  - required:
+      - clock-frequency
+  - required:
+      - clock-freq
+
+examples:
+  - |
+    timer@ffe00000 {
+      compatible = "snps,dw-apb-timer";
+      interrupts = <0 170 4>;
+      reg = <0xffe00000 0x1000>;
+      clocks = <&timer_clk>, <&timer_pclk>;
+      clock-names = "timer", "pclk";
+    };
+  - |
+    timer@ffe00000 {
+      compatible = "snps,dw-apb-timer";
+      interrupts = <0 170 4>;
+      reg = <0xffe00000 0x1000>;
+      clocks = <&timer_clk>;
+      clock-names = "timer";
+    };
+  - |
+    timer@ffe00000 {
+      compatible = "snps,dw-apb-timer";
+      interrupts = <0 170 4>;
+      reg = <0xffe00000 0x1000>;
+      clock-frequency = <25000000>;
+    };
+...
-- 
2.25.1