158 lines
4.4 KiB
Plaintext
158 lines
4.4 KiB
Plaintext
Qualcomm's PM8xxx voltage XOADC
|
|
|
|
The Qualcomm PM8xxx PMICs contain a HK/XO ADC (Housekeeping/Crystal
|
|
oscillator ADC) encompassing PM8018, PM8038, PM8058 and PM8921.
|
|
|
|
Required properties:
|
|
|
|
- compatible: should be one of:
|
|
"qcom,pm8018-adc"
|
|
"qcom,pm8038-adc"
|
|
"qcom,pm8058-adc"
|
|
"qcom,pm8921-adc"
|
|
|
|
- reg: should contain the ADC base address in the PMIC, typically
|
|
0x197.
|
|
|
|
- xoadc-ref-supply: should reference a regulator that can supply
|
|
a reference voltage on demand. The reference voltage may vary
|
|
with PMIC variant but is typically something like 2.2 or 1.8V.
|
|
|
|
The following required properties are standard for IO channels, see
|
|
iio-bindings.txt for more details, but notice that this particular
|
|
ADC has a special addressing scheme that require two cells for
|
|
identifying each ADC channel:
|
|
|
|
- #address-cells: should be set to <2>, the first cell is the
|
|
prescaler (on PM8058) or premux (on PM8921) with two valid bits
|
|
so legal values are 0x00, 0x01 or 0x02. The second cell
|
|
is the main analog mux setting (0x00..0x0f). The combination
|
|
of prescaler/premux and analog mux uniquely addresses a hardware
|
|
channel on all systems.
|
|
|
|
- #size-cells: should be set to <0>
|
|
|
|
- #io-channel-cells: should be set to <2>, again the cells are
|
|
precaler or premux followed by the analog muxing line.
|
|
|
|
- interrupts: should refer to the parent PMIC interrupt controller
|
|
and reference the proper ADC interrupt.
|
|
|
|
Required subnodes:
|
|
|
|
The ADC channels are configured as subnodes of the ADC.
|
|
|
|
Since some of them are used for calibrating the ADC, these nodes are
|
|
compulsory:
|
|
|
|
adc-channel@c {
|
|
reg = <0x00 0x0c>;
|
|
};
|
|
|
|
adc-channel@d {
|
|
reg = <0x00 0x0d>;
|
|
};
|
|
|
|
adc-channel@f {
|
|
reg = <0x00 0x0f>;
|
|
};
|
|
|
|
These three nodes are used for absolute and ratiometric calibration
|
|
and only need to have these reg values: they are by hardware definition
|
|
1:1 ratio converters that sample 625, 1250 and 0 milliV and create
|
|
an interpolation calibration for all other ADCs.
|
|
|
|
Optional subnodes: any channels other than channels [0x00 0x0c],
|
|
[0x00 0x0d] and [0x00 0x0f] are optional.
|
|
|
|
Required channel node properties:
|
|
|
|
- reg: should contain the hardware channel number in the range
|
|
0 .. 0xff (8 bits).
|
|
|
|
Optional channel node properties:
|
|
|
|
- qcom,decimation:
|
|
Value type: <u32>
|
|
Definition: This parameter is used to decrease the ADC sampling rate.
|
|
Quicker measurements can be made by reducing the decimation ratio.
|
|
Valid values are 512, 1024, 2048, 4096.
|
|
If the property is not found, a default value of 512 will be used.
|
|
|
|
- qcom,ratiometric:
|
|
Value type: <u32>
|
|
Definition: Channel calibration type. If this property is specified
|
|
VADC will use a special voltage references for channel
|
|
calibration. The available references are specified in the
|
|
as a u32 value setting (see below) and it is compulsory
|
|
to also specify this reference if ratiometric calibration
|
|
is selected.
|
|
|
|
If the property is not found, the channel will be
|
|
calibrated with the 0.625V and 1.25V reference channels, also
|
|
known as an absolute calibration.
|
|
The reference voltage pairs when using ratiometric calibration:
|
|
0 = XO_IN/XOADC_GND
|
|
1 = PMIC_IN/XOADC_GND
|
|
2 = PMIC_IN/BMS_CSP
|
|
3 (invalid)
|
|
4 = XOADC_GND/XOADC_GND
|
|
5 = XOADC_VREF/XOADC_GND
|
|
|
|
Example:
|
|
|
|
xoadc: xoadc@197 {
|
|
compatible = "qcom,pm8058-adc";
|
|
reg = <0x197>;
|
|
interrupts-extended = <&pm8058 76 IRQ_TYPE_EDGE_RISING>;
|
|
#address-cells = <2>;
|
|
#size-cells = <0>;
|
|
#io-channel-cells = <2>;
|
|
|
|
vcoin: adc-channel@0 {
|
|
reg = <0x00 0x00>;
|
|
};
|
|
vbat: adc-channel@1 {
|
|
reg = <0x00 0x01>;
|
|
};
|
|
dcin: adc-channel@2 {
|
|
reg = <0x00 0x02>;
|
|
};
|
|
ichg: adc-channel@3 {
|
|
reg = <0x00 0x03>;
|
|
};
|
|
vph_pwr: adc-channel@4 {
|
|
reg = <0x00 0x04>;
|
|
};
|
|
usb_vbus: adc-channel@a {
|
|
reg = <0x00 0x0a>;
|
|
};
|
|
die_temp: adc-channel@b {
|
|
reg = <0x00 0x0b>;
|
|
};
|
|
ref_625mv: adc-channel@c {
|
|
reg = <0x00 0x0c>;
|
|
};
|
|
ref_1250mv: adc-channel@d {
|
|
reg = <0x00 0x0d>;
|
|
};
|
|
ref_325mv: adc-channel@e {
|
|
reg = <0x00 0x0e>;
|
|
};
|
|
ref_muxoff: adc-channel@f {
|
|
reg = <0x00 0x0f>;
|
|
};
|
|
};
|
|
|
|
/* IIO client node */
|
|
iio-hwmon {
|
|
compatible = "iio-hwmon";
|
|
io-channels = <&xoadc 0x00 0x01>, /* Battery */
|
|
<&xoadc 0x00 0x02>, /* DC in (charger) */
|
|
<&xoadc 0x00 0x04>, /* VPH the main system voltage */
|
|
<&xoadc 0x00 0x0b>, /* Die temperature */
|
|
<&xoadc 0x00 0x0c>, /* Reference voltage 1.25V */
|
|
<&xoadc 0x00 0x0d>, /* Reference voltage 0.625V */
|
|
<&xoadc 0x00 0x0e>; /* Reference voltage 0.325V */
|
|
};
|