// 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.device;

using zx;
using fuchsia.hardware.power.statecontrol;

/// Maxmium length for a device name
const uint64 MAX_DEVICE_NAME_LEN = 32;
/// Maximum length of a device path
const uint64 MAX_DEVICE_PATH_LEN = 1024;
/// Maxmium length for a driver name
const uint64 MAX_DRIVER_NAME_LEN = 32;
/// Maximum length for a driver path
const uint64 MAX_DRIVER_PATH_LEN = 1024;
/// Maximum device power states. In future this should account
/// for performance states.
const uint32 MAX_DEVICE_POWER_STATES = 5;
const uint32 MIN_DEVICE_POWER_STATES = 2; // D0 & D3COLD
const uint32 MAX_DEVICE_PERFORMANCE_STATES = 20;
const uint32 MIN_DEVICE_PERFORMANCE_STATES = 1; // Fully performant state

/// Signal that will be active on a device event handle if the device's read() method
/// will return data.
const uint32 DEVICE_SIGNAL_READABLE = 0x01000000; // ZX_USER_SIGNAL_0
/// Signal that will be active on a device event handle if the device has some out-of-band
/// mechanism that needs attention.
/// This is primarily used by the PTY support.
const uint32 DEVICE_SIGNAL_OOB = 0x02000000; // ZX_USER_SIGNAL_1
/// Signal that will be active on a device event handle if the device's write() method
/// will accept data.
const uint32 DEVICE_SIGNAL_WRITABLE = 0x04000000; // ZX_USER_SIGNAL_2
/// Signal that will be active on a device event handle if the device has encountered an error.
/// This is primarily used by the PTY support.
const uint32 DEVICE_SIGNAL_ERROR = 0x08000000; // ZX_USER_SIGNAL_3
/// Signal that will be active on a device event handle if the device has been disconnected.
/// This is primarily used by the PTY support.
const uint32 DEVICE_SIGNAL_HANGUP = 0x10000000; // ZX_USER_SIGNAL_4

enum DevicePowerState : uint8 {
    /// Mandatory Working state. Device is fully functional, can take I/O,
    /// issue interrrupts. This state is mandatory for all devices
    /// The device enters into this state by default, when powered on.
    DEVICE_POWER_STATE_D0 = 0;
    /// [OPTIONAL] Device is not working when in this state. It cannot process
    /// I/O nor issue interrupts, unless it is armed for some special interrupts
    /// that can wake up the system/device. When in this state, the restore time
    /// of getting back to working state is less than other low-power states
    /// Power savings in this state are lesser than other low power states.
    /// Device may retain some hardware context and full initialization
    /// may not be needed when resuming from this state.
    DEVICE_POWER_STATE_D1 = 1;
    /// [OPTIONAL] Device is not working when in this state. It cannot process
    /// I/O nor issue interrupts, unless it is armed for some special interrupts
    /// that can wake up the system/device. When in this state, the restore time
    /// of getting back to working state is more than DEVICE_POWER_STATE_D1 and
    /// less than restore time of getting back from DEVICE_POWER_STATE_D3HOT,
    /// DEVICE_POWER_STATE_D3COLD. Power savings in this state are lesser
    /// than DEVICE_POWER_STATE_D3COLD, DEVICE_POWER_STATE_D3HOT.
    /// Device may retain some hardware context and full initialization
    /// may not be needed when resuming from this state.
    DEVICE_POWER_STATE_D2 = 2;
    /// [OPTIONAL] Device is not working when in this state. It cannot process
    /// I/O nor issue interrupts, unless it is armed for some special interrupts
    /// that can wake up the system/device. When in this state, the restore time
    /// of getting back to working state is more than DEVICE_POWER_STATE_D1,
    /// DEVICE_POWER_STATE_D3HOT and less than restore time of getting back from
    /// DEVICE_POWER_STATE_D3COLD. Power savings in this state are lesser
    /// than DEVICE_POWER_STATE_D3COLD. Device has no context and full initialization
    /// by the device driver when resuming from this state.
    /// Although the device is completely off, it is still powered on and is enumerable.
    DEVICE_POWER_STATE_D3HOT = 3;
    /// [MANDATORY] Device is not working when in this state. It cannot process
    /// I/O nor issue interrupts, unless it is armed for some special interrupts
    /// that can wake up the system/device. When in this state, the restore time
    /// of getting back to working state is more than all other low power states.
    /// Power savings are more compared to all other low-power states.
    /// Device has no context and full initialization by the device driver when
    /// resuming from this state. In this state, the power to this device is turned off.
    /// Device may be powered by other auxiliary supplies to support wake capability.
    DEVICE_POWER_STATE_D3COLD = 4;
};

/// [MANDATORY] Default performance state when the device is in DEVICE_POWER_STATE_D0
const uint32 DEVICE_PERFORMANCE_STATE_P0 = 0;

// TODO(ravoorir): This should be table when the Controller protocol moves off of simple layout.
struct DevicePowerStateInfo {
    DevicePowerState state_id;

    /// Is this state supported?
    bool is_supported;

    /// Restore time for coming out of this state to working D0 state.
    int64 restore_latency;

    /// Is this device wakeup_capable?
    bool wakeup_capable;

    /// Deepest system system sleep state that the device can wake the system from.
    int32 system_wake_state;
};

/// Performance state info for a device. A performance state is relevant only
/// when the device is in non-sleeping working device power state.
struct DevicePerformanceStateInfo {
    int32 state_id;
    /// Restore time for coming out of this state to fully working performance state.
    int64 restore_latency;
    /// Is this state supported?
    bool is_supported;
    // TODO(ravoorir): Explore how more device specific metadata can be saved here.
    // Maybe a union of metadata coming from different devices.
};

struct SystemPowerStateInfo {
    // TODO(ravoorir): This can be removed when all clients move away from the suspend_flag.
    uint32 suspend_flag;
    /// Should wakeup be enabled from this system state?
    bool wakeup_enable;

    /// Device power state that the device should be in, for this system power state.
    DevicePowerState dev_state;
    /// Performance state that the device should be in, for this system power state.
    /// Only applicable, if the dev_state is a working state (DEVICE_POWER_STATE_D0).
    uint32 performance_state;
};

/// Interface for manipulating a device in a devhost
protocol Controller {
    /// Attempt to bind the requested driver to this device. This should just be the name of the
    /// shared object for the driver e.g. "fvm.so". A full path can be specified but this is
    /// deprecated.
    Bind(string:MAX_DRIVER_PATH_LEN driver) -> () error zx.status;

    /// This api will unbind all the children of this device and bind the
    /// requested driver. If the driver is empty, it will autobind.
    /// The Rebind will not return until the bind completes. The name is the same as for the Bind
    /// call.
    Rebind(string:MAX_DRIVER_PATH_LEN driver) -> () error zx.status;

    /// This api will unbind all the children of this device synchronously.
    /// This will avoid watching for device removal by the clients.
    UnbindChildren() -> () error zx.status;

    /// Disconnect this device and allow its parent to be bound again.
    /// This may not complete before it returns.
    ScheduleUnbind() -> () error zx.status;

    /// Return the name of the driver managing this the device
    GetDriverName() -> (zx.status status, string:MAX_DRIVER_NAME_LEN? name);
    /// Return the name of the device
    GetDeviceName() -> (string:MAX_DEVICE_NAME_LEN name);

    /// Return the topological path for this device
    GetTopologicalPath() -> (string:MAX_DEVICE_PATH_LEN path) error zx.status;

    /// Get an event for monitoring device conditions (see `DEVICE_SIGNAL_*` constants)
    GetEventHandle() -> (zx.status status, zx.handle:EVENT? event);

    /// Return the current logging flags for this device's driver
    GetDriverLogFlags() -> (zx.status status, uint32 flags);
    /// Set the logging flags for this device's driver.
    /// Each set bit in `clear_flags` will be cleared in the log flags state.
    /// Each set bit in `set_flags` will then be set in the log flags state.
    SetDriverLogFlags(uint32 clear_flags, uint32 set_flags) -> (zx.status status);

    /// Runs compatibility tests for the driver that binds to this device.
    /// The `hook_wait_time` is the time that the driver expects to take for
    /// each device hook in nanoseconds.
    /// Returns whether the driver passed the compatibility check.
    RunCompatibilityTests(int64 hook_wait_time) -> (uint32 status);

    /// Gets the device power capabilities. Used by the system wide power manager
    /// to manage power for this device.
    GetDevicePowerCaps() -> (array<DevicePowerStateInfo>:MAX_DEVICE_POWER_STATES dpstates) error zx.status;

    /// Gets the current performance state of the device.
    /// out_state is the state_id published via GetDevicePerformanceStates.
    /// If the device is in non-working state, this will be the performance
    /// state that the device will be in, after it is resumed.
    GetCurrentPerformanceState() -> (uint32 out_state);

    /// Gets the device performance states. Used by the system wide power manager
    /// to manage power for this device.
    GetDevicePerformanceStates() -> (array<DevicePerformanceStateInfo>:MAX_DEVICE_PERFORMANCE_STATES states, zx.status status);

    /// Updates the mapping between system power states to device power states. Used by the system
    /// wide power manager to manage power for this device
    UpdatePowerStateMapping(array<SystemPowerStateInfo>:fuchsia.hardware.power.statecontrol.MAX_SYSTEM_POWER_STATES mapping) -> () error zx.status;

    /// Get the mapping between system power states to device power states. Used by the system
    /// wide power manager to manage power for this device.
    GetPowerStateMapping() -> (array<SystemPowerStateInfo>:fuchsia.hardware.power.statecontrol.MAX_SYSTEM_POWER_STATES mapping) error zx.status;

    /// Transition this device from a working to a sleep state or from a sleep state to a deeper sleep
    /// state.
    /// On success, the out_state is same as requested_state.
    /// On failure, the out_state is the state the device is currently in.
    // TODO(ravoorir): At the moment, this will call the suspend hook only on this device.
    // In a future change, this api will result in suspend hook being called on all the children and
    // descendants before transitioning this device.
    Suspend(DevicePowerState requested_state) -> (zx.status status, DevicePowerState out_state);

    /// Transition this device from a sleep state to a working state.
    /// out_power_state is the power state the device is currently in.
    /// out_perf_state is the performance state the device is currently in.
    ///
    /// Returns ZX_OK, if resume is successful. out_power_state will be DEVICE_POWER_STATE_D0
    /// out_perf_state will be the performance state that was previously set(if any) or
    /// DEVICE_PERFORMANCE_STATE_P0.
    ///
    /// Returns error, if the device is unable to resume successfully or unable to resume
    /// to a previously set performance state(if any).
    /// If out_power_state is DEVICE_POWER_STATE_D0, out_perf_state will have the actual
    /// performance state the device is in.
    ///
    /// Returns ZX_ERR_NOT_SUPPORTED if auto-suspend is configured/the resume hook is not
    /// provided by the driver. The out_power_state and out_perf_state do not mean anything
    /// in this case.
    // TODO(ravoorir): At the moment, this will call the resume hook only on this device.
    // In a future change, this api will result in resume hook being called on all the children
    // after the current device is transitioned.
    Resume() -> (zx.status status, DevicePowerState out_power_state, uint32 out_perf_state);

    /// Set the performance state of this device to the requested performance state. This is only
    /// called for the current device and none of the descendants are aware of the state
    /// transition.
    /// Returns ZX_OK if the device is not in working state. When the device resumes
    /// from the non working state, it resumes to the requested performance state. out_state will
    /// be same as the requested state. If the device fails to resume to the performance state
    /// that was set, the resume will fail with an error.
    /// Returns ZX_OK, if the device is in a working state and the performance state is changed to
    /// requested_state successfully. out_state will be same as requested_state.
    /// Returns error status, if switching to the requested_state was unsuccessful. out_state
    /// is the state that the device is currently in.
    SetPerformanceState(uint32 requested_state) -> (zx.status status, uint32 out_state);
    /// Configure autosuspend of device to this deepest sleep state.
    ConfigureAutoSuspend(bool enable,
                         DevicePowerState requested_deepest_sleep_state) -> (zx.status status);
};