314 lines
11 KiB
C
314 lines
11 KiB
C
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/*
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* Hardware spinlock public header
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*
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* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
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*
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* Contact: Ohad Ben-Cohen <ohad@wizery.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __LINUX_HWSPINLOCK_H
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#define __LINUX_HWSPINLOCK_H
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#include <linux/err.h>
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#include <linux/sched.h>
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/* hwspinlock mode argument */
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#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */
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#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */
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struct device;
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struct hwspinlock;
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struct hwspinlock_device;
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struct hwspinlock_ops;
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/**
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* struct hwspinlock_pdata - platform data for hwspinlock drivers
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* @base_id: base id for this hwspinlock device
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*
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* hwspinlock devices provide system-wide hardware locks that are used
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* by remote processors that have no other way to achieve synchronization.
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*
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* To achieve that, each physical lock must have a system-wide id number
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* that is agreed upon, otherwise remote processors can't possibly assume
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* they're using the same hardware lock.
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*
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* Usually boards have a single hwspinlock device, which provides several
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* hwspinlocks, and in this case, they can be trivially numbered 0 to
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* (num-of-locks - 1).
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*
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* In case boards have several hwspinlocks devices, a different base id
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* should be used for each hwspinlock device (they can't all use 0 as
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* a starting id!).
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*
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* This platform data structure should be used to provide the base id
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* for each device (which is trivially 0 when only a single hwspinlock
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* device exists). It can be shared between different platforms, hence
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* its location.
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*/
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struct hwspinlock_pdata {
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int base_id;
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};
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#if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE)
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int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
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const struct hwspinlock_ops *ops, int base_id, int num_locks);
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int hwspin_lock_unregister(struct hwspinlock_device *bank);
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struct hwspinlock *hwspin_lock_request(void);
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struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
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int hwspin_lock_free(struct hwspinlock *hwlock);
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int hwspin_lock_get_id(struct hwspinlock *hwlock);
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int __hwspin_lock_timeout(struct hwspinlock *, unsigned int, int,
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unsigned long *);
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int __hwspin_trylock(struct hwspinlock *, int, unsigned long *);
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void __hwspin_unlock(struct hwspinlock *, int, unsigned long *);
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#else /* !CONFIG_HWSPINLOCK */
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/*
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* We don't want these functions to fail if CONFIG_HWSPINLOCK is not
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* enabled. We prefer to silently succeed in this case, and let the
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* code path get compiled away. This way, if CONFIG_HWSPINLOCK is not
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* required on a given setup, users will still work.
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*
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* The only exception is hwspin_lock_register/hwspin_lock_unregister, with which
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* we _do_ want users to fail (no point in registering hwspinlock instances if
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* the framework is not available).
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*
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* Note: ERR_PTR(-ENODEV) will still be considered a success for NULL-checking
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* users. Others, which care, can still check this with IS_ERR.
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*/
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static inline struct hwspinlock *hwspin_lock_request(void)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline int hwspin_lock_free(struct hwspinlock *hwlock)
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{
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return 0;
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}
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static inline
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int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to,
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int mode, unsigned long *flags)
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{
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return 0;
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}
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static inline
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int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
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{
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return 0;
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}
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static inline
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void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
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{
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}
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static inline int hwspin_lock_get_id(struct hwspinlock *hwlock)
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{
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return 0;
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}
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#endif /* !CONFIG_HWSPINLOCK */
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/**
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* hwspin_trylock_irqsave() - try to lock an hwspinlock, disable interrupts
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* @hwlock: an hwspinlock which we want to trylock
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* @flags: a pointer to where the caller's interrupt state will be saved at
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*
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* This function attempts to lock the underlying hwspinlock, and will
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* immediately fail if the hwspinlock is already locked.
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*
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* Upon a successful return from this function, preemption and local
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* interrupts are disabled (previous interrupts state is saved at @flags),
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* so the caller must not sleep, and is advised to release the hwspinlock
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* as soon as possible.
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*
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* Returns 0 if we successfully locked the hwspinlock, -EBUSY if
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* the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
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*/
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static inline
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int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags)
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{
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return __hwspin_trylock(hwlock, HWLOCK_IRQSTATE, flags);
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}
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/**
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* hwspin_trylock_irq() - try to lock an hwspinlock, disable interrupts
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* @hwlock: an hwspinlock which we want to trylock
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*
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* This function attempts to lock the underlying hwspinlock, and will
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* immediately fail if the hwspinlock is already locked.
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*
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* Upon a successful return from this function, preemption and local
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* interrupts are disabled, so the caller must not sleep, and is advised
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* to release the hwspinlock as soon as possible.
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*
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* Returns 0 if we successfully locked the hwspinlock, -EBUSY if
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* the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
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*/
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static inline int hwspin_trylock_irq(struct hwspinlock *hwlock)
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{
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return __hwspin_trylock(hwlock, HWLOCK_IRQ, NULL);
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}
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/**
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* hwspin_trylock() - attempt to lock a specific hwspinlock
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* @hwlock: an hwspinlock which we want to trylock
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*
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* This function attempts to lock an hwspinlock, and will immediately fail
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* if the hwspinlock is already taken.
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*
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* Upon a successful return from this function, preemption is disabled,
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* so the caller must not sleep, and is advised to release the hwspinlock
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* as soon as possible. This is required in order to minimize remote cores
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* polling on the hardware interconnect.
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*
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* Returns 0 if we successfully locked the hwspinlock, -EBUSY if
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* the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
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*/
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static inline int hwspin_trylock(struct hwspinlock *hwlock)
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{
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return __hwspin_trylock(hwlock, 0, NULL);
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}
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/**
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* hwspin_lock_timeout_irqsave() - lock hwspinlock, with timeout, disable irqs
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* @hwlock: the hwspinlock to be locked
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* @to: timeout value in msecs
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* @flags: a pointer to where the caller's interrupt state will be saved at
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*
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* This function locks the underlying @hwlock. If the @hwlock
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* is already taken, the function will busy loop waiting for it to
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* be released, but give up when @timeout msecs have elapsed.
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*
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* Upon a successful return from this function, preemption and local interrupts
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* are disabled (plus previous interrupt state is saved), so the caller must
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* not sleep, and is advised to release the hwspinlock as soon as possible.
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*
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* Returns 0 when the @hwlock was successfully taken, and an appropriate
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* error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
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* busy after @timeout msecs). The function will never sleep.
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*/
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static inline int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock,
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unsigned int to, unsigned long *flags)
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{
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return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQSTATE, flags);
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}
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/**
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* hwspin_lock_timeout_irq() - lock hwspinlock, with timeout, disable irqs
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* @hwlock: the hwspinlock to be locked
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* @to: timeout value in msecs
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*
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* This function locks the underlying @hwlock. If the @hwlock
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* is already taken, the function will busy loop waiting for it to
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* be released, but give up when @timeout msecs have elapsed.
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*
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* Upon a successful return from this function, preemption and local interrupts
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* are disabled so the caller must not sleep, and is advised to release the
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* hwspinlock as soon as possible.
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*
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* Returns 0 when the @hwlock was successfully taken, and an appropriate
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* error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
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* busy after @timeout msecs). The function will never sleep.
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*/
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static inline
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int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, unsigned int to)
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{
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return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQ, NULL);
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}
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/**
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* hwspin_lock_timeout() - lock an hwspinlock with timeout limit
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* @hwlock: the hwspinlock to be locked
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* @to: timeout value in msecs
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*
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* This function locks the underlying @hwlock. If the @hwlock
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* is already taken, the function will busy loop waiting for it to
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* be released, but give up when @timeout msecs have elapsed.
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*
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* Upon a successful return from this function, preemption is disabled
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* so the caller must not sleep, and is advised to release the hwspinlock
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* as soon as possible.
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* This is required in order to minimize remote cores polling on the
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* hardware interconnect.
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*
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* Returns 0 when the @hwlock was successfully taken, and an appropriate
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* error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
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* busy after @timeout msecs). The function will never sleep.
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*/
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static inline
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int hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to)
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{
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return __hwspin_lock_timeout(hwlock, to, 0, NULL);
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}
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/**
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* hwspin_unlock_irqrestore() - unlock hwspinlock, restore irq state
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* @hwlock: a previously-acquired hwspinlock which we want to unlock
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* @flags: previous caller's interrupt state to restore
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*
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* This function will unlock a specific hwspinlock, enable preemption and
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* restore the previous state of the local interrupts. It should be used
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* to undo, e.g., hwspin_trylock_irqsave().
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*
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* @hwlock must be already locked before calling this function: it is a bug
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* to call unlock on a @hwlock that is already unlocked.
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*/
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static inline void hwspin_unlock_irqrestore(struct hwspinlock *hwlock,
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unsigned long *flags)
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{
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__hwspin_unlock(hwlock, HWLOCK_IRQSTATE, flags);
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}
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/**
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* hwspin_unlock_irq() - unlock hwspinlock, enable interrupts
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* @hwlock: a previously-acquired hwspinlock which we want to unlock
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*
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* This function will unlock a specific hwspinlock, enable preemption and
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* enable local interrupts. Should be used to undo hwspin_lock_irq().
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*
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* @hwlock must be already locked (e.g. by hwspin_trylock_irq()) before
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* calling this function: it is a bug to call unlock on a @hwlock that is
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* already unlocked.
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*/
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static inline void hwspin_unlock_irq(struct hwspinlock *hwlock)
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{
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__hwspin_unlock(hwlock, HWLOCK_IRQ, NULL);
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}
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/**
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* hwspin_unlock() - unlock hwspinlock
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* @hwlock: a previously-acquired hwspinlock which we want to unlock
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*
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* This function will unlock a specific hwspinlock and enable preemption
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* back.
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*
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* @hwlock must be already locked (e.g. by hwspin_trylock()) before calling
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* this function: it is a bug to call unlock on a @hwlock that is already
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* unlocked.
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*/
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static inline void hwspin_unlock(struct hwspinlock *hwlock)
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{
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__hwspin_unlock(hwlock, 0, NULL);
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}
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#endif /* __LINUX_HWSPINLOCK_H */
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