63 lines
1.8 KiB
Plaintext
63 lines
1.8 KiB
Plaintext
|
ADC device binding
|
||
|
|
|
||
|
|
There are no mandatory properties for ADC. However, if Voltage info is required,
|
||
|
|
then there are two options:
|
||
|
|
- use microvolts constraint or
|
||
|
|
- use regulator phandle to enable/read supply's Voltage
|
||
|
|
|
||
|
|
Properties and constraints:
|
||
|
|
*optional and always checked, Voltage polarity info:
|
||
|
|
- vdd-polarity-negative: positive reference Voltage has a negative polarity
|
||
|
|
- vss-polarity-negative: negative reference Voltage has a negative polarity
|
||
|
|
|
||
|
|
Chose one option, for each supply (Vdd/Vss):
|
||
|
|
|
||
|
|
*optional and always checked, supply Voltage constants:
|
||
|
|
- vdd-supply: phandle to Vdd regulator's node
|
||
|
|
- vss-supply: phandle to Vss regulator's node
|
||
|
|
|
||
|
|
*optional and checked only if the above corresponding, doesn't exist:
|
||
|
|
- vdd-microvolts: positive reference Voltage value [uV]
|
||
|
|
- vss-microvolts: negative reference Voltage value [uV]
|
||
|
|
|
||
|
|
Example with constant 'Vdd' value:
|
||
|
|
adc@1000000 {
|
||
|
|
compatible = "some-adc";
|
||
|
|
reg = <0xaabb000 0x100>;
|
||
|
|
status = "enabled";
|
||
|
|
vdd-microvolts = <1800000>;
|
||
|
|
};
|
||
|
|
|
||
|
|
Example of supply phandle usage, for the ADC's VDD/VSS references as below:
|
||
|
|
_______ _______
|
||
|
|
|Sandbox| |Sandbox|
|
||
|
|
: PMIC : : ADC :
|
||
|
|
. . . .
|
||
|
|
| | (Vdd) | AIN0|-->
|
||
|
|
| BUCK2|-------|VDDref |
|
||
|
|
| (3.3V)| _|VSSref |
|
||
|
|
|_______| | |_______|
|
||
|
|
_|_
|
||
|
|
|
||
|
|
For the above PMIC, the node can be defined as follows:
|
||
|
|
sandbox_pmic {
|
||
|
|
compatible = "sandbox,pmic";
|
||
|
|
...
|
||
|
|
buck2: buck2 {
|
||
|
|
regulator-name = "SUPPLY_3.3V";
|
||
|
|
regulator-min-microvolt = <3300000>;
|
||
|
|
regulator-max-microvolt = <3300000>;
|
||
|
|
};
|
||
|
|
...
|
||
|
|
};
|
||
|
|
|
||
|
|
For the above ADC, the node can be defined as follows:
|
||
|
|
adc@0 {
|
||
|
|
compatible = "sandbox,adc";
|
||
|
|
vdd-supply = <&buck2>;
|
||
|
|
vss-microvolts = <0>;
|
||
|
|
};
|
||
|
|
|
||
|
|
The ADC uclass code, will enable the supply before start of the conversion,
|
||
|
|
but it will not configure the regulator settings.
|