// Copyright 2018 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 ddk.protocol.clock;

using zx;

[Layout = "ddk-protocol"]
protocol Clock {

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

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

    /// Returns `true` if a given clock is running.
    /// May query the hardware or return a cached value.
    IsEnabled() -> (zx.status s, bool enabled);

    /// Attempt to set the rate of the clock provider.
    SetRate(uint64 hz) -> (zx.status s);

    /// Query the hardware for the highest supported rate that does not
    /// exceed hz_in.
    QuerySupportedRate(uint64 hz_in) -> (zx.status s, uint64 hz_out);

    /// Returns the current rate that a given clock is running at.
    GetRate() -> (zx.status s, uint64 hz);

    /// 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.
    SetInput(uint32 idx) -> (zx.status s);

    /// 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.
    GetNumInputs() -> (zx.status s, uint32 n);

    /// Returns the index of the current input of this clock.
    GetInput() -> (zx.status s, uint32 index);
};