diff options
Diffstat (limited to 'drivers/hwspinlock/hwspinlock_core.c')
| -rw-r--r-- | drivers/hwspinlock/hwspinlock_core.c | 77 |
1 files changed, 52 insertions, 25 deletions
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c index 4074441444fe..d16e6a3d38e8 100644 --- a/drivers/hwspinlock/hwspinlock_core.c +++ b/drivers/hwspinlock/hwspinlock_core.c @@ -1,18 +1,10 @@ +// SPDX-License-Identifier: GPL-2.0 /* * Hardware spinlock framework * * 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. */ #define pr_fmt(fmt) "%s: " fmt, __func__ @@ -71,10 +63,16 @@ static DEFINE_MUTEX(hwspinlock_tree_lock); * 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 (and possibly - * interrupts) 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. + * Caution: If the mode is HWLOCK_RAW, that means user must protect the routine + * of getting hardware lock with mutex or spinlock. Since in some scenarios, + * user need some time-consuming or sleepable operations under the hardware + * lock, they need one sleepable lock (like mutex) to protect the operations. + * + * If the mode is not HWLOCK_RAW, upon a successful return from this function, + * preemption (and possibly interrupts) 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. * * The user decides whether local interrupts are disabled or not, and if yes, * whether he wants their previous state to be saved. It is up to the user @@ -106,12 +104,20 @@ int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags) * problems with hwspinlock usage (e.g. scheduler checks like * 'scheduling while atomic' etc.) */ - if (mode == HWLOCK_IRQSTATE) + switch (mode) { + case HWLOCK_IRQSTATE: ret = spin_trylock_irqsave(&hwlock->lock, *flags); - else if (mode == HWLOCK_IRQ) + break; + case HWLOCK_IRQ: ret = spin_trylock_irq(&hwlock->lock); - else + break; + case HWLOCK_RAW: + ret = 1; + break; + default: ret = spin_trylock(&hwlock->lock); + break; + } /* is lock already taken by another context on the local cpu ? */ if (!ret) @@ -122,12 +128,20 @@ int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags) /* if hwlock is already taken, undo spin_trylock_* and exit */ if (!ret) { - if (mode == HWLOCK_IRQSTATE) + switch (mode) { + case HWLOCK_IRQSTATE: spin_unlock_irqrestore(&hwlock->lock, *flags); - else if (mode == HWLOCK_IRQ) + break; + case HWLOCK_IRQ: spin_unlock_irq(&hwlock->lock); - else + break; + case HWLOCK_RAW: + /* Nothing to do */ + break; + default: spin_unlock(&hwlock->lock); + break; + } return -EBUSY; } @@ -160,9 +174,14 @@ EXPORT_SYMBOL_GPL(__hwspin_trylock); * is already taken, the function will busy loop waiting for it to * be released, but give up after @timeout msecs have elapsed. * - * Upon a successful return from this function, preemption is disabled - * (and possibly local interrupts, too), so the caller must not sleep, - * and is advised to release the hwspinlock as soon as possible. + * Caution: If the mode is HWLOCK_RAW, that means user must protect the routine + * of getting hardware lock with mutex or spinlock. Since in some scenarios, + * user need some time-consuming or sleepable operations under the hardware + * lock, they need one sleepable lock (like mutex) to protect the operations. + * + * If the mode is not HWLOCK_RAW, upon a successful return from this function, + * preemption is disabled (and possibly local interrupts, too), 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. * @@ -249,12 +268,20 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags) hwlock->bank->ops->unlock(hwlock); /* Undo the spin_trylock{_irq, _irqsave} called while locking */ - if (mode == HWLOCK_IRQSTATE) + switch (mode) { + case HWLOCK_IRQSTATE: spin_unlock_irqrestore(&hwlock->lock, *flags); - else if (mode == HWLOCK_IRQ) + break; + case HWLOCK_IRQ: spin_unlock_irq(&hwlock->lock); - else + break; + case HWLOCK_RAW: + /* Nothing to do */ + break; + default: spin_unlock(&hwlock->lock); + break; + } } EXPORT_SYMBOL_GPL(__hwspin_unlock); |