kernel/include/kernel/spinlock.h

// Copyright 2016 The Fuchsia Authors
// Copyright (c) 2014 Travis Geiselbrecht
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#pragma once

#include <arch/spinlock.h>
#include <zircon/compiler.h>
#include <zircon/thread_annotations.h>

__BEGIN_CDECLS

/* interrupts should already be disabled */
static inline void spin_lock(spin_lock_t* lock) {
    arch_spin_lock(lock);
}

/* Returns 0 on success, non-0 on failure */
static inline int spin_trylock(spin_lock_t* lock) {
    return arch_spin_trylock(lock);
}

/* interrupts should already be disabled */
static inline void spin_unlock(spin_lock_t* lock) {
    arch_spin_unlock(lock);
}

static inline void spin_lock_init(spin_lock_t* lock) {
    arch_spin_lock_init(lock);
}

static inline bool spin_lock_held(spin_lock_t* lock) {
    return arch_spin_lock_held(lock);
}

/* which cpu currently holds the spin lock */
/* returns UINT_MAX if not held */
static inline uint spin_lock_holder_cpu(spin_lock_t* lock) {
    return arch_spin_lock_holder_cpu(lock);
}

/* spin lock irq save flags: */

/* Possible future flags:
 * SPIN_LOCK_FLAG_PMR_MASK         = 0x000000ff
 * SPIN_LOCK_FLAG_PREEMPTION       = 0x00000100
 * SPIN_LOCK_FLAG_SET_PMR          = 0x00000200
 */

/* Generic flags */
#define SPIN_LOCK_FLAG_INTERRUPTS ARCH_DEFAULT_SPIN_LOCK_FLAG_INTERRUPTS

/* same as spin lock, but save disable and save interrupt state first */
static inline void spin_lock_save(
    spin_lock_t* lock,
    spin_lock_saved_state_t* statep,
    spin_lock_save_flags_t flags) {
    arch_interrupt_save(statep, flags);
    spin_lock(lock);
}

/* restore interrupt state before unlocking */
static inline void spin_unlock_restore(
    spin_lock_t* lock,
    spin_lock_saved_state_t old_state,
    spin_lock_save_flags_t flags) {
    spin_unlock(lock);
    arch_interrupt_restore(old_state, flags);
}

/* hand(ier) routines */
#define spin_lock_irqsave(lock, statep) spin_lock_save(lock, &(statep), SPIN_LOCK_FLAG_INTERRUPTS)
#define spin_unlock_irqrestore(lock, statep) spin_unlock_restore(lock, statep, SPIN_LOCK_FLAG_INTERRUPTS)

__END_CDECLS

#ifdef __cplusplus
class TA_CAP("mutex") SpinLock {
public:
    SpinLock() { spin_lock_init(&spinlock_); }
    void Acquire() TA_ACQ() { spin_lock(&spinlock_); }
    void TryAcquire() { spin_trylock(&spinlock_); }
    void Release() TA_REL() { spin_unlock(&spinlock_); }
    bool IsHeld() { return spin_lock_held(&spinlock_); }

    void AcquireIrqSave(spin_lock_saved_state_t& state,
                        spin_lock_save_flags_t flags = SPIN_LOCK_FLAG_INTERRUPTS) {
        spin_lock_save(&spinlock_, &state, flags);
    }

    void ReleaseIrqRestore(spin_lock_saved_state_t state,
                           spin_lock_save_flags_t flags = SPIN_LOCK_FLAG_INTERRUPTS) {
        spin_unlock_restore(&spinlock_, state, flags);
    }

    spin_lock_t* GetInternal() { return &spinlock_; }

    // suppress default constructors
    SpinLock(const SpinLock& am) = delete;
    SpinLock& operator=(const SpinLock& am) = delete;
    SpinLock(SpinLock&& c) = delete;
    SpinLock& operator=(SpinLock&& c) = delete;

private:
    spin_lock_t spinlock_;
};
#endif // ifdef __cplusplus