/* * 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 device; struct device_node; struct hwspinlock; struct hwspinlock_device; struct hwspinlock_ops; /** * 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_device *bank, struct device *dev, const struct hwspinlock_ops *ops, int base_id, int num_locks); int hwspin_lock_unregister(struct hwspinlock_device *bank); struct hwspinlock *hwspin_lock_request(void); struct hwspinlock *hwspin_lock_request_specific(unsigned int id); int hwspin_lock_free(struct hwspinlock *hwlock); int of_hwspin_lock_get_id(struct device_node *np, int index); 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) { } static inline int of_hwspin_lock_get_id(struct device_node *np, int index) { 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 */