dt-bindings: iio: adc: add Glink ADC bindings

Add bindings for the PMIC Glink ADC device.  This device provides
a mechanism for software to read multiple ADC channels of
Qualcomm Technologies, Inc. PMICs using the Glink interface to
communicate with charger firmware.

Change-Id: I805b13893f80ce993496e35767a89b09ae163254
Signed-off-by: David Collins <quic_collinsd@quicinc.com>

bindings/iio/adc/qcom,glink-adc.yaml

@@ -0,0 +1,90 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/qcom,glink-adc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Technologies, Inc. Glink PMIC ADC
+
+maintainers:
+  - David Collins <quic_collinsd@quicinc.com>
+
+description: |
+  This device provides a mechanism for software to read multiple ADC channels of
+  Qualcomm Technologies, Inc. PMICs using the Glink interface to communicate
+  with charger firmware.  Channel value conversion is performed in firmware.
+  Both converted and raw ADC values can be read.  This device is useful in
+  situations where a charger PMIC is connected via I2C and only accessible to
+  charger firmware.
+
+properties:
+  compatible:
+    const: qcom,glink-adc
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - "#address-cells"
+  - "#size-cells"
+  - "#io-channel-cells"
+
+additionalProperties: false
+
+patternProperties:
+  "@[0-9a-f]+$":
+    type: object
+    description: ADC channel node
+
+    properties:
+      reg:
+        maxItems: 1
+        description: |
+          ADC channel number of the form:
+          (bus_id << 16) | (pmic_id << 8) | adc_channel
+          where:
+          bus_id = which SPMI or I2C bus the PMIC is attached to
+          pmic_id = PMIC address on the bus
+          adc_channel = specific channel within the PMIC
+
+      label:
+        $ref: /schemas/types.yaml#/definitions/string
+        description: ADC channel name
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+examples:
+  - |
+    pmic_glink_log {
+        glink-adc {
+            compatible = "qcom,glink-adc";
+            #address-cells = <1>;
+            #size-cells = <0>;
+            #io-channel-cells = <1>;
+
+            smb1502_iin@1076801 {
+                reg = <0x1076801>;
+                label = "smb1502_iin";
+            };
+
+            smb1502_ichg@1076802 {
+                reg = <0x1076802>;
+                label = "smb1502_ichg";
+            };
+
+            smb1502_die_temp@1076803 {
+                reg = <0x1076803>;
+                label = "smb1502_die_temp";
+            };
+        };
+    };