xref: /linux/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc-common.yaml (revision cb4eb6771c0f8fd1c52a8f6fdec7762fb087380a) 
1# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/iio/adc/qcom,spmi-vadc-common.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: Qualcomm Technologies, Inc. SPMI PMIC ADC channels
8
9maintainers:
10  - Jishnu Prakash <jishnu.prakash@oss.qualcomm.com>
11
12description:
13  This defines the common properties used to define Qualcomm VADC channels.
14
15properties:
16  reg:
17    description:
18      ADC channel number (PMIC-specific for versions after PMIC5 ADC).
19    maxItems: 1
20
21  label:
22    description:
23      ADC input of the platform as seen in the schematics.
24      For thermistor inputs connected to generic AMUX or GPIO inputs
25      these can vary across platform for the same pins. Hence select
26      the platform schematics name for this channel.
27
28  qcom,decimation:
29    $ref: /schemas/types.yaml#/definitions/uint32
30    description:
31      This parameter is used to decrease ADC sampling rate.
32      Quicker measurements can be made by reducing decimation ratio.
33
34  qcom,pre-scaling:
35    $ref: /schemas/types.yaml#/definitions/uint32-array
36    description:
37      Used for scaling the channel input signal before the signal is
38      fed to VADC. The configuration for this node is to know the
39      pre-determined ratio and use it for post scaling. It is a pair of
40      integers, denoting the numerator and denominator of the fraction by which
41      input signal is multiplied. For example, <1 3> indicates the signal is scaled
42      down to 1/3 of its value before ADC measurement.
43      If property is not found default value depending on chip will be used.
44    oneOf:
45      - items:
46          - const: 1
47          - enum: [ 1, 3, 4, 6, 20, 8, 10, 16 ]
48      - items:
49          - const: 10
50          - const: 81
51
52  qcom,ratiometric:
53    type: boolean
54    description: |
55      Channel calibration type.
56      - For compatible property "qcom,spmi-vadc", if this property is
57        specified VADC will use the VDD reference (1.8V) and GND for
58        channel calibration. If property is not found, channel will be
59        calibrated with 0.625V and 1.25V reference channels, also
60        known as absolute calibration.
61      - For other compatible properties, if this property is specified
62        VADC will use the VDD reference (1.875V) and GND for channel
63        calibration. If property is not found, channel will be calibrated
64        with 0V and 1.25V reference channels, also known as absolute calibration.
65
66  qcom,hw-settle-time:
67    $ref: /schemas/types.yaml#/definitions/uint32
68    description: |
69      Time between AMUX getting configured and the ADC starting
70      conversion. The 'hw_settle_time' is an index used from valid values
71      and programmed in hardware to achieve the hardware settling delay.
72
73  qcom,avg-samples:
74    $ref: /schemas/types.yaml#/definitions/uint32
75    description: |
76      Number of samples to be used for measurement.
77      Averaging provides the option to obtain a single measurement
78      from the ADC that is an average of multiple samples. The value
79      selected is 2^(value).
80
81required:
82  - reg
83
84additionalProperties: true
85