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Diffstat (limited to 'kernel/include/linux/hwspinlock.h')
| -rw-r--r-- | kernel/include/linux/hwspinlock.h | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/kernel/include/linux/hwspinlock.h b/kernel/include/linux/hwspinlock.h new file mode 100644 index 000000000..3343298e4 --- /dev/null +++ b/kernel/include/linux/hwspinlock.h @@ -0,0 +1,313 @@ +/* + * 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 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 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 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 */ |