[PATCH v3 1/2] dt-bindings: iio: adc: Add Nuvoton MA35D1 EADC

[Chi-Wen Weng <cwweng.linux@gmail.com>]

From: Chi-Wen Weng <cwweng@nuvoton.com>

Add a devicetree binding for the Enhanced Analog-to-Digital Converter
(EADC) found on Nuvoton MA35D1 SoCs.

The controller provides eight external analog inputs which can be used
as single-ended channels or as four fixed differential pairs: 0-4,
1-5, 2-6 and 3-7.

Describe the four hardware interrupt outputs, ADINT0 through ADINT3.
ADINT0 through ADINT2 are associated with the corresponding conversion
interrupt flags, while ADINT3 is shared by the ADIF3 conversion
interrupt and the ADCMPF0 through ADCMPF3 result-compare interrupt
sources.

Also describe the functional clock, optional reset, optional external
reference supply and optional DMA request.

Expose the controller as an IIO channel provider through the
DT #io-channel-cells property. The cell identifies the logical EADC
channel selected by the reg value of the corresponding channel child
node.

Restrict the channel binding to features supported by the MA35D1 EADC
hardware and use the common single-channel representation for
single-ended inputs.

Signed-off-by: Chi-Wen Weng <cwweng@nuvoton.com>
---
 .../bindings/iio/adc/nuvoton,ma35d1-eadc.yaml | 175 ++++++++++++++++++
 1 file changed, 175 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/nuvoton,ma35d1-eadc.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/nuvoton,ma35d1-eadc.yaml b/Documentation/devicetree/bindings/iio/adc/nuvoton,ma35d1-eadc.yaml
new file mode 100644
index 000000000000..97144a8eeb5c
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/nuvoton,ma35d1-eadc.yaml
@@ -0,0 +1,175 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/nuvoton,ma35d1-eadc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton MA35D1 Enhanced Analog-to-Digital Converter
+
+maintainers:
+  - Chi-Wen Weng <cwweng@nuvoton.com>
+
+description: |
+  The Nuvoton MA35D1 Enhanced Analog-to-Digital Converter (EADC) is a
+  12-bit successive approximation converter with eight external analog
+  inputs and one internally connected VBAT input.
+
+  The external inputs can be used as eight single-ended channels or as
+  four fixed differential pairs: 0-4, 1-5, 2-6 and 3-7. The internally
+  connected VBAT input is not described by a channel child node.
+
+  The controller provides four interrupt outputs, ADINT0 through ADINT3.
+  ADINT0, ADINT1 and ADINT2 are generated by the corresponding ADIF0,
+  ADIF1 and ADIF2 conversion interrupt flags. ADINT3 is shared by the
+  ADIF3 conversion interrupt flag and the ADCMPF0 through ADCMPF3 result
+  compare flags.
+
+properties:
+  compatible:
+    const: nuvoton,ma35d1-eadc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: ADINT0 conversion interrupt output generated by ADIF0
+      - description: ADINT1 conversion interrupt output generated by ADIF1
+      - description: ADINT2 conversion interrupt output generated by ADIF2
+      - description: >
+          ADINT3 shared interrupt output generated by ADIF3 or by the
+          ADCMPF0 through ADCMPF3 result compare flags
+
+  interrupt-names:
+    items:
+      - const: adint0
+      - const: adint1
+      - const: adint2
+      - const: adint3
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  vref-supply:
+    description:
+      Optional external reference voltage connected to the VREF pin. If this
+      supply is absent, the controller uses its internal 1.6 V reference.
+
+  dmas:
+    maxItems: 1
+
+  dma-names:
+    const: rx
+
+  '#io-channel-cells':
+    const: 1
+    description:
+      The cell selects the logical EADC channel identified by the reg value
+      of the corresponding channel child node.
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  '^channel@[0-7]$':
+    type: object
+    $ref: /schemas/iio/adc/adc.yaml#
+    unevaluatedProperties: false
+    description: |
+      External EADC channel description.
+
+      For a single-ended channel, single-channel specifies the external
+      analog input number (0 through 7), while reg provides the logical IIO
+      channel index.
+
+      For a differential channel, omit single-channel. The reg value selects
+      one of the four fixed hardware differential pairs: reg 0 selects 0-4,
+      reg 1 selects 1-5, reg 2 selects 2-6 and reg 3 selects 3-7.
+
+    properties:
+      reg:
+        maximum: 7
+
+      single-channel:
+        maximum: 7
+
+      # Differential pairs are fixed in hardware and are selected by reg.
+      diff-channels: false
+
+      bipolar: false
+
+      common-mode-channel: false
+
+      settling-time-us: false
+
+      oversampling-ratio: false
+
+    allOf:
+      - if:
+          not:
+            required:
+              - single-channel
+        then:
+          properties:
+            reg:
+              maximum: 3
+
+    required:
+      - reg
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - interrupt-names
+  - clocks
+  - '#io-channel-cells'
+  - '#address-cells'
+  - '#size-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/nuvoton,ma35d1-clk.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/reset/nuvoton,ma35d1-reset.h>
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        adc@40430000 {
+            compatible = "nuvoton,ma35d1-eadc";
+            reg = <0x0 0x40430000 0x0 0x10000>;
+            interrupts = <GIC_SPI 65 IRQ_TYPE_LEVEL_HIGH>,
+                         <GIC_SPI 66 IRQ_TYPE_LEVEL_HIGH>,
+                         <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>,
+                         <GIC_SPI 68 IRQ_TYPE_LEVEL_HIGH>;
+            interrupt-names = "adint0", "adint1", "adint2", "adint3";
+            clocks = <&clk EADC_GATE>;
+            resets = <&reset MA35D1_RESET_EADC0>;
+
+            #io-channel-cells = <1>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+                single-channel = <0>;
+            };
+
+            channel@1 {
+                reg = <1>;
+            };
+        };
+    };
+
+...
-- 
2.25.1