// Copyright 2019 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.clock;

using zx;

const NAME_LEN uint32 = 30;

type FrequencyInfo = struct {
    name array<uint8, NAME_LEN>;
    frequency uint64;
};

/// Used for driver-to-non-driver communication.
closed protocol Device {
    strict Measure(struct {
        clock uint32;
    }) -> (struct {
        info FrequencyInfo;
    });
    strict GetCount() -> (struct {
        count uint32;
    });

    // For debugging
    strict Enable(struct {
        clock uint32;
    }) -> () error zx.Status;

    strict Disable(struct {
        clock uint32;
    }) -> () error zx.Status;
};

/// Used for driver-to-driver communication.
@discoverable
closed protocol Clock {

    /// Enables (ungates) this clock.
    /// Drivers *must* call enable on all clocks they depend upon.
    strict Enable() -> () error zx.Status;

    /// Disables (gates) this clock.
    /// Drivers should call this method to indicate to the clock subsystem that
    /// a particular clock signal is no longer necessary.
    strict Disable() -> () error zx.Status;

    /// Returns `true` if a given clock is running.
    /// May query the hardware or return a cached value.
    strict IsEnabled() -> (struct {
        enabled bool;
    }) error zx.Status;

    /// Attempt to set the rate of the clock provider.
    strict SetRate(struct {
        hz uint64;
    }) -> () error zx.Status;

    /// Query the hardware for the highest supported rate that does not
    /// exceed hz_in.
    strict QuerySupportedRate(struct {
        hz_in uint64;
    }) -> (struct {
        hz_out uint64;
    }) error zx.Status;

    /// Returns the current rate that a given clock is running at.
    strict GetRate() -> (struct {
        hz uint64;
    }) error zx.Status;

    /// Sets the input of this clock by index. I.e. by selecting a mux.
    /// This clock has N inputs defined 0 through N-1, which are valid arguemts
    /// as the index to SetInput.
    strict SetInput(struct {
        idx uint32;
    }) -> () error zx.Status;

    /// Returns the number of inputs this clock has.
    /// Any value between 0 and UINT32_MAX is a valid return for this method.
    /// A Root Oscillator may return 0 for instance, if it has no inputs.
    strict GetNumInputs() -> (struct {
        n uint32;
    }) error zx.Status;

    /// Returns the index of the current input of this clock.
    strict GetInput() -> (struct {
        index uint32;
    }) error zx.Status;
};

service Service {
    clock client_end:Clock;
};