From 353438b3107d56e36a642f117c2b4accc963abbd Mon Sep 17 00:00:00 2001 From: Herman van Hazendonk Date: Fri, 5 Jun 2026 11:18:12 +0200 Subject: [PATCH] dt-bindings: power: supply: maxim,max8903: add DC and USB input current-limit controls Add three optional properties to the MAX8903 charger binding to describe board-level GPIO control of the DC and USB input current limits: DC input (TA / DOK pin): - dc-current-limit-gpios (1..4 GPIOs): mux control lines feeding the MAX8903 IDC resistor mux; - dc-current-limit-mapping (uint32-matrix of {microamps, gpio_bit_pattern} pairs): the available current levels and the GPIO bit pattern that selects each level. USB input (USB / UOK pin): - usb-current-limit-gpios: a single GPIO driving the IUSB pin. The IUSB pin is silicon-fixed by the MAX8903 datasheet (Pin Description): low selects 100 mA, high selects 500 mA. Only the GPIO mapping is board-specific; the current values are not exposed in DT. A dependentRequired block ties dc-current-limit-gpios and dc-current-limit-mapping together so an incomplete DT cannot pass validation with only one half of the pair. These let userspace clamp the input draw via the standard POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT power_supply attribute. The HP TouchPad uses both: two TLMM lines select between 0.5 A, 1.0 A, 1.5 A and 2.0 A DC input current limits behind the MAX8903B charger, and a third TLMM line picks the IUSB 100 mA / 500 mA limit. These are purely additive; existing platforms remain unaffected. Signed-off-by: Herman van Hazendonk Reviewed-by: Rob Herring (Arm) Link: https://patch.msgid.link/20260605-submit-power-max8903-dc-limit-v2-1-0c5396e98f14@herrie.org Signed-off-by: Sebastian Reichel --- .../bindings/power/supply/maxim,max8903.yaml | 53 +++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml b/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml index 86af38378999..b3d8c0a5f214 100644 --- a/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml +++ b/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml @@ -44,9 +44,40 @@ properties: maxItems: 1 description: USB suspend pin (active high, output) + dc-current-limit-gpios: + minItems: 1 + maxItems: 4 + description: + GPIOs controlling DC input current limit via resistor mux. + Used with dc-current-limit-mapping to select charging current. + + dc-current-limit-mapping: + $ref: /schemas/types.yaml#/definitions/uint32-matrix + minItems: 2 + maxItems: 16 + description: | + Array of (current_microamps, gpio_bit_pattern) pairs defining available + DC current limits. The gpio_bit_pattern is applied to dc-current-limit-gpios + to select that current level. + items: + items: + - description: Current limit in microamps + - description: GPIO bit pattern value + + usb-current-limit-gpios: + maxItems: 1 + description: + GPIO driving the MAX8903 IUSB pin. IUSB is a silicon-fixed + two-state input - low selects 100 mA, high selects 500 mA. + Only the GPIO mapping is board-specific. + required: - compatible +dependentRequired: + dc-current-limit-gpios: [dc-current-limit-mapping] + dc-current-limit-mapping: [dc-current-limit-gpios] + anyOf: - required: - dok-gpios @@ -65,3 +96,25 @@ examples: chg-gpios = <&gpio3 15 GPIO_ACTIVE_LOW>; cen-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>; }; + - | + /* Example with DC and USB current limit control */ + #include + charger { + compatible = "maxim,max8903"; + dok-gpios = <&gpio2 3 GPIO_ACTIVE_LOW>; + flt-gpios = <&gpio2 2 GPIO_ACTIVE_LOW>; + chg-gpios = <&gpio3 15 GPIO_ACTIVE_LOW>; + cen-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>; + dcm-gpios = <&gpio2 6 GPIO_ACTIVE_HIGH>; + + /* DC input current limit via IDC resistor mux */ + dc-current-limit-gpios = <&gpio1 0 GPIO_ACTIVE_HIGH>, + <&gpio1 1 GPIO_ACTIVE_HIGH>; + dc-current-limit-mapping = <750000 0>, /* GPIO[1:0]=0b00 */ + <900000 1>, /* GPIO[1:0]=0b01 */ + <1400000 3>, /* GPIO[1:0]=0b11 */ + <2000000 2>; /* GPIO[1:0]=0b10 */ + + /* USB current limit: IUSB pin, 100 mA (low) / 500 mA (high) */ + usb-current-limit-gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>; + };