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authorPrzemyslaw Marczak <p.marczak@samsung.com>2015-10-27 13:08:00 +0100
committerMinkyu Kang <mk7.kang@samsung.com>2015-11-02 10:38:00 +0900
commit5decbf53006c8e2aed8e5506b3961810c1544b3c (patch)
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dm: adc: add simple ADC uclass implementation
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>
Diffstat (limited to 'doc')
-rw-r--r--doc/device-tree-bindings/adc/adc.txt62
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diff --git a/doc/device-tree-bindings/adc/adc.txt b/doc/device-tree-bindings/adc/adc.txt
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+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.