dt-bindings: smb1398: Add binding documents for SMB1398 charger

Qualcomm Technologies, Inc. SMB1398 Charger Specific Bindings

SMB1398 combo charge chip can be working in different modes:

(1) DIV2 charge pump mode to work as a companion charger that can be paired

    with Qualcomm Technologies, Inc. family of standalone chargers;

(2) DIV2 and 3-level buck combo mode to regulate output power from wireless

    charger receiver and provide input power for downstream chargers.

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Required Node Structure

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SMB1398 Charger must be described in two levels of device nodes.

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First Level Node - SMB1398 Charger

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Charger specific properties:

- compatible

  Usage:      required

  Value type: <string>

  Definition: "qcom,smb1396-div2-cp-master" for SMB1396 working in DIV2

	      mode as a companion master charger.

	      "qcom,smb1396-div2-cp-slave" for SMB1396 working in DIV2

	      mode as a companion slave charger.

	      "qcom,smb1398-pre-regulator" for SMB1398 working in combo

	      mode (auto transition between DIV2 CP and 3-level buck) as a

	      pre-regulator stand between wireless receiver and downstream

	      chargers.

- interrupts

  Usage:      optional

  Value type: <prop-encoded-array>

  Definition: Peripheral interrupt specifier. This is required when SMB1396

	      working as a DIV2 CP master.

- interrupt-names

  Usage:      optional

  Value type: <stringlist>

  Definition: Interrupt names.  This list must match up 1-to-1 with the

	      interrupts specified in the 'interrupts' property. This is

	      required when SMB1396 working as a DIV2 CP master.

- io-channels

- io-channel-names

  Usage:      optional

  Value type: <phandle>

  Definition: The IIO channel for measuring SMB1398 die temperature,

	      io-channel-names should be "die-temp". For other details about

	      IIO bindings see:

	             Documentation/devicetree/bindings/iio/iio-bindings.txt

	      These properties are required when SMB1396 working as a DIV2 CP

	      master.

- qcom,div2-cp-min-ilim-ua

  Usage:      optional

  Value type: <u32>

  Definition: The minimum ILIM settings to enable SMB1398 working in DIV2 mode.

	      The switcher is disabled when ILIM is below this value.

	      If this values is not specified, the default minimum ILIM is 1A.

	      This is only applicable when SMB1396 working as a DIV2 CP master.

- qcom,max-cutoff-soc

  Usage:      optional

  Value type: <u32>

  Definition: SOC beyond which SMB1398 is kept disabled.

	      If this value is not specified then default value is 85%.

	      This is only applicable when SMB1396 working as a DIV2 CP master.

- qcom,ilim-ua-disable-slave

  Usage:      optional

  Value type: <u32>

  Definition: The minimum ILIM setting to disable slave CP after hitting taper.

	      If this value is not specified, the default value is 3 times of

	      "qcom,div2-cp-min-ilim-ua". This is only applicable when both

	      SMB1396 DIV2 CP master and slave are present.

Peripheral specific properties:

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Example

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smb1398_charger: qcom,combo_charger {

	compatible = "qcom,smb1396-div2-cp-master";

	interrupt-parent = <&smb1398>;

	status = "disabled";

	io-channels = <&pm8150b_vadc ADC_AMUX_THM2>;

	io-channel-names = "die_temp";

	interrupts = <0x26 0x1 IRQ_TYPE_EDGE_RISING>,

		     <0x26 0x3 IRQ_TYPE_EDGE_RISING>,

		     <0x26 0x5 IRQ_TYPE_EDGE_RISING>,

		     <0x26 0x7 IRQ_TYPE_EDGE_RISING>,

		     <0x27 0x5 IRQ_TYPE_EDGE_RISING>,

		     <0x27 0x6 IRQ_TYPE_EDGE_RISING>,

		     <0x27 0x7 IRQ_TYPE_EDGE_RISING>;

	interrupt-names = "temp-shdwn",

			  "div2-irev",

			  "usbin-uv",

			  "usbin-ov",

			  "div2-ilim",

			  "div2-win-uv",

			  "div2-win-ov";

};