// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library fuchsia.hardware.gpio;

using zx;

/// Maximum length of the GPIO name.
const MAX_GPIO_NAME_LEN uint32 = 256;

/// Flags for `ConfigIn`.
type GpioFlags = strict enum : uint32 {
    PULL_DOWN = 0x0;
    PULL_UP = 0x1;
    NO_PULL = 0x2;
};

/// Values for `SetPolarity`.
type GpioPolarity = strict enum : uint32 {
    LOW = 0x0;
    HIGH = 0x1;
};

closed protocol Gpio {
    /// Get the pin of a GPIO
    strict GetPin() -> (struct {
        pin uint32;
    }) error zx.Status;

    /// Get the name of a GPIO.
    strict GetName() -> (struct {
        name string:MAX_GPIO_NAME_LEN;
    }) error zx.Status;

    /// Configures a GPIO for input.
    strict ConfigIn(struct {
        flags GpioFlags;
    }) -> () error zx.Status;

    /// Configures a GPIO for output.
    strict ConfigOut(struct {
        initial_value uint8;
    }) -> () error zx.Status;

    /// Configures the GPIO pin for an alternate function (I2C, SPI, etc)
    /// the interpretation of "function" is platform dependent.
    strict SetAltFunction(struct {
        function uint64;
    }) -> () error zx.Status;

    /// Reads the current value of a GPIO (0 or 1).
    strict Read() -> (struct {
        value uint8;
    }) error zx.Status;

    /// Sets the current value of the GPIO (any non-zero value maps to 1).
    strict Write(struct {
        value uint8;
    }) -> () error zx.Status;

    /// Set GPIO polarity.
    strict SetPolarity(struct {
        polarity GpioPolarity;
    }) -> () error zx.Status;

    /// Sets the drive strength of the GPIO.
    /// actual_ds_ua is always >= ds_ua. If ds_ua is larger than max value, the drive strength will be set to the max value.
    /// Return error if unable to set drive strength. actual_ds_ua is not set in this case.
    strict SetDriveStrength(struct {
        ds_ua uint64;
    }) -> (struct {
        actual_ds_ua uint64;
    }) error zx.Status;

    /// Gets the configured drive strength of the GPIO in microamps (ua).
    strict GetDriveStrength() -> (struct {
        result_ua uint64;
    }) error zx.Status;

    /// Gets an interrupt object pertaining to a particular GPIO pin. `flags`
    /// is passed as the `options` parameter when
    /// [creating the interrupt](https://fuchsia.dev/fuchsia-src/reference/syscalls/interrupt_create).
    strict GetInterrupt(struct {
        flags uint32;
    }) -> (resource struct {
        irq zx.Handle:INTERRUPT;
    }) error zx.Status;

    /// Release the interrupt.
    strict ReleaseInterrupt() -> () error zx.Status;
};

closed protocol Device {
    /// Opens a new session on the device.
    ///
    /// At most one session is permitted at one time; the server end will be
    /// closed with `ZX_ERR_ALREADY_BOUND` if a session already exists.
    strict OpenSession(resource struct {
        session server_end:Gpio;
    });
};

service Service {
    device client_end:Gpio;
};