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GPIO controller requirements checklist

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This topic summarizes the hardware, firmware, and software requirements for General Purpose IO (GPIO) controller devices that are exposed to Windows.

GPIO controller hardware requirements

  • The GPIO controller is integrated into the SoC (not connected by an SPB bus).

    Increases reliability of Emulated ActiveBoth.

  • Level-mode interrupts are supported.

    Required for both Emulated ActiveBoth and Debounce Emulation features.

  • Both High and Low interrupt polarities are supported.

    Required for both Emulated ActiveBoth and Debounce Emulation features.

  • Interrupt polarity can be re-programmed at run time.

    Required for both Emulated ActiveBoth and Debounce Emulation features.

GPIO controller firmware requirements

  • GPIO controller _CRS includes all resources for all pin banks in the controller.

  • GPIO controller _CRS resource ordering provides bank-to-system interrupt mapping.

  • _AEI method, and event method(s) (_Exx, _Lxx or _EVT) exist for any GPIO-signaled ACPI events.

  • GPIO controller _DSM included if any ActiveBoth interrupts connected to the controller are asserted logic high instead of logic low.

  • Implement _REG methods for each GPIO controller and prevent use of GeneralPurposeIO OpRegions if _REG indicates that the region handler is not available.

  • Debounce timeout is included in the GPIOInt resource descriptor for any interrupt that requires debouncing.

GPIO controller driver requirements

  • Support version 2 of the interface between GpioClx and the GPIO controller driver:

    • Implement the CLIENT_QueryEnabledInterrupts callback function. This greatly assists in diagnosing interrupt storms.

    • If the BankIdlePowerMgmtSupported flag is set in the CONTROLLER_BASIC_INFORMATION structure, the GPIO controller driver must implement the CLIENT_SaveBankHardwareContext and CLIENT_RestoreBankHardwareContext callback functions, and these functions must save/restore bank context appropriately, including the masked/unmasked state of the interrupts. Note that interrupts are not guaranteed to be disconnected at the time this function is called, but, if they are still connected, they are guaranteed to be masked.

    • If the DeviceIdlePowerMgmtSupported flag is set in the CONTROLLER_BASIC_INFORMATION structure, the CLIENT_StartController and CLIENT_StopController callback functions must save/restore context for all banks appropriately, including the masked/unmasked state of the interrupts. Note that interrupts are not guaranteed to be disconnected at the time this function is called, but, if they are still connected, they are guaranteed to be masked.

  • Set the EmulateDebouncing flag in the CONTROLLER_BASIC_INFORMATION structure. This significantly increases noise immunity for devices whose interrupts are subject to electrostatic discharge (such as buttons, plugs, and so on).

  • Set the EmulateActiveBoth flag in the CONTROLLER_BASIC_INFORMATION structure, and implement the CLIENT_ReconfigureInterrupt callback function. This ensures reliable edge detection for ActiveBoth interrupts.