/*
* Hardware spinlock public header
*
* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
*
* Contact: Ohad Ben-Cohen <ohad@wizery.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef __LINUX_HWSPINLOCK_H
#define __LINUX_HWSPINLOCK_H
#include <linux/err.h>
#include <linux/sched.h>
/* hwspinlock mode argument */
#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */
#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */
struct hwspinlock;
#if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE)
int hwspin_lock_register(struct hwspinlock *lock);
struct hwspinlock *hwspin_lock_unregister(unsigned int id);
struct hwspinlock *hwspin_lock_request(void);
struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
int hwspin_lock_free(struct hwspinlock *hwlock);
int hwspin_lock_get_id(struct hwspinlock *hwlock);
int __hwspin_lock_timeout(struct hwspinlock *, unsigned int, int,
unsigned long *);
int __hwspin_trylock(struct hwspinlock *, int, unsigned long *);
void __hwspin_unlock(struct hwspinlock *, int, unsigned long *);
#else /* !CONFIG_HWSPINLOCK */
/*
* We don't want these functions to fail if CONFIG_HWSPINLOCK is not
* enabled. We prefer to silently succeed in this case, and let the
* code path get compiled away. This way, if CONFIG_HWSPINLOCK is not
* required on a given setup, users will still work.
*
* The only exception is hwspin_lock_register/hwspin_lock_unregister, with which
* we _do_ want users to fail (no point in registering hwspinlock instances if
* the framework is not available).
*
* Note: ERR_PTR(-ENODEV) will still be considered a success for NULL-checking
* users. Others, which care, can still check this with IS_ERR.
*/
static inline struct hwspinlock *hwspin_lock_request(void)
{
return ERR_PTR(-ENODEV);
}
static inline struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
{
return ERR_PTR(-ENODEV);
}
static inline int hwspin_lock_free(struct hwspinlock *hwlock)
{
return 0;
}
static inline
int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to,
int mode, unsigned long *flags)
{
return 0;
}
static inline
int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
{
return 0;
}
static inline
void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
{
return 0;
}
static inline int hwspin_lock_get_id(struct hwspinlock *hwlock)
{
return 0;
}
static inline int hwspin_lock_register(struct hwspinlock *hwlock)
{
return -ENODEV;
}
static inline struct hwspinlock *hwspin_lock_unregister(unsigned int id)
{
return NULL;
}
#endif /* !CONFIG_HWSPINLOCK */
/**
* hwspin_trylock_irqsave() - try to lock an hwspinlock, disable interrupts
* @hwlock: an hwspinlock which we want to trylock
* @flags: a pointer to where the caller's interrupt state will be saved at
*
* This function attempts to lock the underlying hwspinlock, and will
* immediately fail if the hwspinlock is already locked.
*
* Upon a successful return from this function, preemption and local
* interrupts are disabled (previous interrupts state is saved at @flags),
* so the caller must not sleep, and is advised to release the hwspinlock
* as soon as possible.
*
* Returns 0 if we successfully locked the hwspinlock, -EBUSY if
* the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
*/
static inline
int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags)
{
return __hwspin_trylock(hwlock, HWLOCK_IRQSTATE, flags);
}
/**
* hwspin_trylock_irq() - try to lock an hwspinlock, disable interrupts
* @hwlock: an hwspinlock which we want to trylock
*
* This function attempts to lock the underlying hwspinlock, and will
* immediately fail if the hwspinlock is already locked.
*
* Upon a successful return from this function, preemption and local
* interrupts are disabled, so the caller must not sleep, and is advised
* to release the hwspinlock as soon as possible.
*
* Returns 0 if we successfully locked the hwspinlock, -EBUSY if
* the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
*/
static inline int hwspin_trylock_irq(struct hwspinlock *hwlock)
{
return __hwspin_trylock(hwlock, HWLOCK_IRQ, NULL);
}
/**
* hwspin_trylock() - attempt to lock a specific hwspinlock
* @hwlock: an hwspinlock which we want to trylock
*
* This function attempts to lock an hwspinlock, and will immediately fail
* if the hwspinlock is already taken.
*
* Upon a successful return from this function, preemption is disabled,
* so the caller must not sleep, and is advised to release the hwspinlock
* as soon as possible. This is required in order to minimize remote cores
* polling on the hardware interconnect.
*
* Returns 0 if we successfully locked the hwspinlock, -EBUSY if
* the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
*/
static inline int hwspin_trylock(struct hwspinlock *hwlock)
{
return __hwspin_trylock(hwlock, 0, NULL);
}
/**
* hwspin_lock_timeout_irqsave() - lock hwspinlock, with timeout, disable irqs
* @hwlock: the hwspinlock to be locked
* @to: timeout value in msecs
* @flags: a pointer to where the caller's interrupt state will be saved at
*
* This function locks the underlying @hwlock. If the @hwlock
* is already taken, the function will busy loop waiting for it to
* be released, but give up when @timeout msecs have elapsed.
*
* Upon a successful return from this function, preemption and local interrupts
* are disabled (plus previous interrupt state is saved), so the caller must
* not sleep, and is advised to release the hwspinlock as soon as possible.
*
* Returns 0 when the @hwlock was successfully taken, and an appropriate
* error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
* busy after @timeout msecs). The function will never sleep.
*/
static inline int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock,
unsigned int to, unsigned long *flags)
{
return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQSTATE, flags);
}
/**
* hwspin_lock_timeout_irq() - lock hwspinlock, with timeout, disable irqs
* @hwlock: the hwspinlock to be locked
* @to: timeout value in msecs
*
* This function locks the underlying @hwlock. If the @hwlock
* is already taken, the function will busy loop waiting for it to
* be released, but give up when @timeout msecs have elapsed.
*
* Upon a successful return from this function, preemption and local interrupts
* are disabled so the caller must not sleep, and is advised to release the
* hwspinlock as soon as possible.
*
* Returns 0 when the @hwlock was successfully taken, and an appropriate
* error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
* busy after @timeout msecs). The function will never sleep.
*/
static inline
int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, unsigned int to)
{
return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQ, NULL);
}
/**
* hwspin_lock_timeout() - lock an hwspinlock with timeout limit
* @hwlock: the hwspinlock to be locked
* @to: timeout value in msecs
*
* This function locks the underlying @hwlock. If the @hwlock
* is already taken, the function will busy loop waiting for it to
* be released, but give up when @timeout msecs have elapsed.
*
* Upon a successful return from this function, preemption is disabled
* so the caller must not sleep, and is advised to release the hwspinlock
* as soon as possible.
* This is required in order to minimize remote cores polling on the
* hardware interconnect.
*
* Returns 0 when the @hwlock was successfully taken, and an appropriate
* error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
* busy after @timeout msecs). The function will never sleep.
*/
static inline
int hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to)
{
return __hwspin_lock_timeout(hwlock, to, 0, NULL);
}
/**
* hwspin_unlock_irqrestore() - unlock hwspinlock, restore irq state
* @hwlock: a previously-acquired hwspinlock which we want to unlock
* @flags: previous caller's interrupt state to restore
*
* This function will unlock a specific hwspinlock, enable preemption and
* restore the previous state of the local interrupts. It should be used
* to undo, e.g., hwspin_trylock_irqsave().
*
* @hwlock must be already locked before calling this function: it is a bug
* to call unlock on a @hwlock that is already unlocked.
*/
static inline void hwspin_unlock_irqrestore(struct hwspinlock *hwlock,
unsigned long *flags)
{
__hwspin_unlock(hwlock, HWLOCK_IRQSTATE, flags);
}
/**
* hwspin_unlock_irq() - unlock hwspinlock, enable interrupts
* @hwlock: a previously-acquired hwspinlock which we want to unlock
*
* This function will unlock a specific hwspinlock, enable preemption and
* enable local interrupts. Should be used to undo hwspin_lock_irq().
*
* @hwlock must be already locked (e.g. by hwspin_trylock_irq()) before
* calling this function: it is a bug to call unlock on a @hwlock that is
* already unlocked.
*/
static inline void hwspin_unlock_irq(struct hwspinlock *hwlock)
{
__hwspin_unlock(hwlock, HWLOCK_IRQ, NULL);
}
/**
* hwspin_unlock() - unlock hwspinlock
* @hwlock: a previously-acquired hwspinlock which we want to unlock
*
* This function will unlock a specific hwspinlock and enable preemption
* back.
*
* @hwlock must be already locked (e.g. by hwspin_trylock()) before calling
* this function: it is a bug to call unlock on a @hwlock that is already
* unlocked.
*/
static inline void hwspin_unlock(struct hwspinlock *hwlock)
{
__hwspin_unlock(hwlock, 0, NULL);
}
#endif /* __LINUX_HWSPINLOCK_H */
