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This commit adds:
- new uclass id: UCLASS_ADC
- new uclass driver: drivers/adc/adc-uclass.c
The new uclass's API allows for ADC operation on:
* single-channel with channel selection by a number
* multti-channel with channel selection by bit mask
ADC uclass's functions:
* single-channel:
- adc_start_channel() - start channel conversion
- adc_channel_data() - get conversion data
- adc_channel_single_shot() - start/get conversion data
* multi-channel:
- adc_start_channels() - start selected channels conversion
- adc_channels_data() - get conversion data
- adc_channels_single_shot() - start/get conversion data for channels
selected by bit mask
* general:
- adc_stop() - stop the conversion
- adc_vdd_value() - positive reference Voltage value with polarity [uV]
- adc_vss_value() - negative reference Voltage value with polarity [uV]
- adc_data_mask() - conversion data bit mask
The device tree can provide below constraints/properties:
- vdd-polarity-negative: if true: Vdd = vdd-microvolts * (-1)
- vss-polarity-negative: if true: Vss = vss-microvolts * (-1)
- vdd-supply: phandle to Vdd regulator's node
- vss-supply: phandle to Vss regulator's node
And optional, checked only if the above corresponding, doesn't exist:
- vdd-microvolts: positive reference Voltage [uV]
- vss-microvolts: negative reference Voltage [uV]
Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
63 lines
1.8 KiB
Plaintext
63 lines
1.8 KiB
Plaintext
ADC device binding
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There are no mandatory properties for ADC. However, if Voltage info is required,
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then there are two options:
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- use microvolts constraint or
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- use regulator phandle to enable/read supply's Voltage
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Properties and constraints:
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*optional and always checked, Voltage polarity info:
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- vdd-polarity-negative: positive reference Voltage has a negative polarity
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- vss-polarity-negative: negative reference Voltage has a negative polarity
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Chose one option, for each supply (Vdd/Vss):
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*optional and always checked, supply Voltage constants:
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- vdd-supply: phandle to Vdd regulator's node
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- vss-supply: phandle to Vss regulator's node
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*optional and checked only if the above corresponding, doesn't exist:
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- vdd-microvolts: positive reference Voltage value [uV]
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- vss-microvolts: negative reference Voltage value [uV]
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Example with constant 'Vdd' value:
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adc@1000000 {
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compatible = "some-adc";
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reg = <0xaabb000 0x100>;
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status = "enabled";
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vdd-microvolts = <1800000>;
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};
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Example of supply phandle usage, for the ADC's VDD/VSS references as below:
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_______ _______
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|Sandbox| |Sandbox|
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: PMIC : : ADC :
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. . . .
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| | (Vdd) | AIN0|-->
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| BUCK2|-------|VDDref |
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| (3.3V)| _|VSSref |
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|_______| | |_______|
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_|_
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For the above PMIC, the node can be defined as follows:
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sandbox_pmic {
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compatible = "sandbox,pmic";
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...
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buck2: buck2 {
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regulator-name = "SUPPLY_3.3V";
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regulator-min-microvolt = <3300000>;
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regulator-max-microvolt = <3300000>;
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};
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...
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};
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For the above ADC, the node can be defined as follows:
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adc@0 {
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compatible = "sandbox,adc";
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vdd-supply = <&buck2>;
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vss-microvolts = <0>;
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};
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The ADC uclass code, will enable the supply before start of the conversion,
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but it will not configure the regulator settings.
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