| /* |
| * 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; |
| |
| /** |
| * struct hwspinlock_pdata - platform data for hwspinlock drivers |
| * @base_id: base id for this hwspinlock device |
| * |
| * hwspinlock devices provide system-wide hardware locks that are used |
| * by remote processors that have no other way to achieve synchronization. |
| * |
| * To achieve that, each physical lock must have a system-wide id number |
| * that is agreed upon, otherwise remote processors can't possibly assume |
| * they're using the same hardware lock. |
| * |
| * Usually boards have a single hwspinlock device, which provides several |
| * hwspinlocks, and in this case, they can be trivially numbered 0 to |
| * (num-of-locks - 1). |
| * |
| * In case boards have several hwspinlocks devices, a different base id |
| * should be used for each hwspinlock device (they can't all use 0 as |
| * a starting id!). |
| * |
| * This platform data structure should be used to provide the base id |
| * for each device (which is trivially 0 when only a single hwspinlock |
| * device exists). It can be shared between different platforms, hence |
| * its location. |
| */ |
| struct hwspinlock_pdata { |
| int base_id; |
| }; |
| |
| #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; |
| } |
| |
| #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 */ |