diff options
Diffstat (limited to 'drivers/hwspinlock/hwspinlock_core.c')
| -rw-r--r-- | drivers/hwspinlock/hwspinlock_core.c | 954 |
1 files changed, 954 insertions, 0 deletions
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c new file mode 100644 index 000000000..fd5f5c5a5 --- /dev/null +++ b/drivers/hwspinlock/hwspinlock_core.c @@ -0,0 +1,954 @@ +// 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> + */ + +#define pr_fmt(fmt) "%s: " fmt, __func__ + +#include <linux/delay.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/spinlock.h> +#include <linux/types.h> +#include <linux/err.h> +#include <linux/jiffies.h> +#include <linux/radix-tree.h> +#include <linux/hwspinlock.h> +#include <linux/pm_runtime.h> +#include <linux/mutex.h> +#include <linux/of.h> + +#include "hwspinlock_internal.h" + +/* retry delay used in atomic context */ +#define HWSPINLOCK_RETRY_DELAY_US 100 + +/* radix tree tags */ +#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */ + +/* + * A radix tree is used to maintain the available hwspinlock instances. + * The tree associates hwspinlock pointers with their integer key id, + * and provides easy-to-use API which makes the hwspinlock core code simple + * and easy to read. + * + * Radix trees are quick on lookups, and reasonably efficient in terms of + * storage, especially with high density usages such as this framework + * requires (a continuous range of integer keys, beginning with zero, is + * used as the ID's of the hwspinlock instances). + * + * The radix tree API supports tagging items in the tree, which this + * framework uses to mark unused hwspinlock instances (see the + * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the + * tree, looking for an unused hwspinlock instance, is now reduced to a + * single radix tree API call. + */ +static RADIX_TREE(hwspinlock_tree, GFP_KERNEL); + +/* + * Synchronization of access to the tree is achieved using this mutex, + * as the radix-tree API requires that users provide all synchronisation. + * A mutex is needed because we're using non-atomic radix tree allocations. + */ +static DEFINE_MUTEX(hwspinlock_tree_lock); + + +/** + * __hwspin_trylock() - attempt to lock a specific hwspinlock + * @hwlock: an hwspinlock which we want to trylock + * @mode: controls whether local interrupts are disabled or not + * @flags: a pointer where the caller's interrupt state will be saved at (if + * requested) + * + * This function attempts to lock an hwspinlock, and will immediately + * fail if the hwspinlock is already taken. + * + * 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 neither HWLOCK_IN_ATOMIC nor 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 + * to choose the appropriate @mode of operation, exactly the same way users + * should decide between spin_trylock, spin_trylock_irq and + * spin_trylock_irqsave. + * + * Returns 0 if we successfully locked the hwspinlock or -EBUSY if + * the hwspinlock was already taken. + * This function will never sleep. + */ +int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags) +{ + int ret; + + if (WARN_ON(!hwlock || (!flags && mode == HWLOCK_IRQSTATE))) + return -EINVAL; + + /* + * This spin_lock{_irq, _irqsave} serves three purposes: + * + * 1. Disable preemption, in order to minimize the period of time + * in which the hwspinlock is taken. This is important in order + * to minimize the possible polling on the hardware interconnect + * by a remote user of this lock. + * 2. Make the hwspinlock SMP-safe (so we can take it from + * additional contexts on the local host). + * 3. Ensure that in_atomic/might_sleep checks catch potential + * problems with hwspinlock usage (e.g. scheduler checks like + * 'scheduling while atomic' etc.) + */ + switch (mode) { + case HWLOCK_IRQSTATE: + ret = spin_trylock_irqsave(&hwlock->lock, *flags); + break; + case HWLOCK_IRQ: + ret = spin_trylock_irq(&hwlock->lock); + break; + case HWLOCK_RAW: + case HWLOCK_IN_ATOMIC: + ret = 1; + break; + default: + ret = spin_trylock(&hwlock->lock); + break; + } + + /* is lock already taken by another context on the local cpu ? */ + if (!ret) + return -EBUSY; + + /* try to take the hwspinlock device */ + ret = hwlock->bank->ops->trylock(hwlock); + + /* if hwlock is already taken, undo spin_trylock_* and exit */ + if (!ret) { + switch (mode) { + case HWLOCK_IRQSTATE: + spin_unlock_irqrestore(&hwlock->lock, *flags); + break; + case HWLOCK_IRQ: + spin_unlock_irq(&hwlock->lock); + break; + case HWLOCK_RAW: + case HWLOCK_IN_ATOMIC: + /* Nothing to do */ + break; + default: + spin_unlock(&hwlock->lock); + break; + } + + return -EBUSY; + } + + /* + * We can be sure the other core's memory operations + * are observable to us only _after_ we successfully take + * the hwspinlock, and we must make sure that subsequent memory + * operations (both reads and writes) will not be reordered before + * we actually took the hwspinlock. + * + * Note: the implicit memory barrier of the spinlock above is too + * early, so we need this additional explicit memory barrier. + */ + mb(); + + return 0; +} +EXPORT_SYMBOL_GPL(__hwspin_trylock); + +/** + * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit + * @hwlock: the hwspinlock to be locked + * @timeout: timeout value in msecs + * @mode: mode which controls whether local interrupts are disabled or not + * @flags: a pointer to where the caller's interrupt state will be saved at (if + * requested) + * + * This function locks the given @hwlock. If the @hwlock + * is already taken, the function will busy loop waiting for it to + * be released, but give up after @timeout msecs have elapsed. + * + * 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 HWLOCK_IN_ATOMIC (called from an atomic context) the timeout + * is handled with busy-waiting delays, hence shall not exceed few msecs. + * + * If the mode is neither HWLOCK_IN_ATOMIC nor 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 + * to choose the appropriate @mode of operation, exactly the same way users + * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave. + * + * Returns 0 when the @hwlock was successfully taken, and an appropriate + * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still + * busy after @timeout msecs). The function will never sleep. + */ +int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to, + int mode, unsigned long *flags) +{ + int ret; + unsigned long expire, atomic_delay = 0; + + expire = msecs_to_jiffies(to) + jiffies; + + for (;;) { + /* Try to take the hwspinlock */ + ret = __hwspin_trylock(hwlock, mode, flags); + if (ret != -EBUSY) + break; + + /* + * The lock is already taken, let's check if the user wants + * us to try again + */ + if (mode == HWLOCK_IN_ATOMIC) { + udelay(HWSPINLOCK_RETRY_DELAY_US); + atomic_delay += HWSPINLOCK_RETRY_DELAY_US; + if (atomic_delay > to * 1000) + return -ETIMEDOUT; + } else { + if (time_is_before_eq_jiffies(expire)) + return -ETIMEDOUT; + } + + /* + * Allow platform-specific relax handlers to prevent + * hogging the interconnect (no sleeping, though) + */ + if (hwlock->bank->ops->relax) + hwlock->bank->ops->relax(hwlock); + } + + return ret; +} +EXPORT_SYMBOL_GPL(__hwspin_lock_timeout); + +/** + * __hwspin_unlock() - unlock a specific hwspinlock + * @hwlock: a previously-acquired hwspinlock which we want to unlock + * @mode: controls whether local interrupts needs to be restored or not + * @flags: previous caller's interrupt state to restore (if requested) + * + * This function will unlock a specific hwspinlock, enable preemption and + * (possibly) enable interrupts or restore their previous state. + * @hwlock must be already locked before calling this function: it is a bug + * to call unlock on a @hwlock that is already unlocked. + * + * The user decides whether local interrupts should be enabled or not, and + * if yes, whether he wants their previous state to be restored. It is up + * to the user to choose the appropriate @mode of operation, exactly the + * same way users decide between spin_unlock, spin_unlock_irq and + * spin_unlock_irqrestore. + * + * The function will never sleep. + */ +void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags) +{ + if (WARN_ON(!hwlock || (!flags && mode == HWLOCK_IRQSTATE))) + return; + + /* + * We must make sure that memory operations (both reads and writes), + * done before unlocking the hwspinlock, will not be reordered + * after the lock is released. + * + * That's the purpose of this explicit memory barrier. + * + * Note: the memory barrier induced by the spin_unlock below is too + * late; the other core is going to access memory soon after it will + * take the hwspinlock, and by then we want to be sure our memory + * operations are already observable. + */ + mb(); + + hwlock->bank->ops->unlock(hwlock); + + /* Undo the spin_trylock{_irq, _irqsave} called while locking */ + switch (mode) { + case HWLOCK_IRQSTATE: + spin_unlock_irqrestore(&hwlock->lock, *flags); + break; + case HWLOCK_IRQ: + spin_unlock_irq(&hwlock->lock); + break; + case HWLOCK_RAW: + case HWLOCK_IN_ATOMIC: + /* Nothing to do */ + break; + default: + spin_unlock(&hwlock->lock); + break; + } +} +EXPORT_SYMBOL_GPL(__hwspin_unlock); + +/** + * of_hwspin_lock_simple_xlate - translate hwlock_spec to return a lock id + * @bank: the hwspinlock device bank + * @hwlock_spec: hwlock specifier as found in the device tree + * + * This is a simple translation function, suitable for hwspinlock platform + * drivers that only has a lock specifier length of 1. + * + * Returns a relative index of the lock within a specified bank on success, + * or -EINVAL on invalid specifier cell count. + */ +static inline int +of_hwspin_lock_simple_xlate(const struct of_phandle_args *hwlock_spec) +{ + if (WARN_ON(hwlock_spec->args_count != 1)) + return -EINVAL; + + return hwlock_spec->args[0]; +} + +/** + * of_hwspin_lock_get_id() - get lock id for an OF phandle-based specific lock + * @np: device node from which to request the specific hwlock + * @index: index of the hwlock in the list of values + * + * This function provides a means for DT users of the hwspinlock module to + * get the global lock id of a specific hwspinlock using the phandle of the + * hwspinlock device, so that it can be requested using the normal + * hwspin_lock_request_specific() API. + * + * Returns the global lock id number on success, -EPROBE_DEFER if the hwspinlock + * device is not yet registered, -EINVAL on invalid args specifier value or an + * appropriate error as returned from the OF parsing of the DT client node. + */ +int of_hwspin_lock_get_id(struct device_node *np, int index) +{ + struct of_phandle_args args; + struct hwspinlock *hwlock; + struct radix_tree_iter iter; + void **slot; + int id; + int ret; + + ret = of_parse_phandle_with_args(np, "hwlocks", "#hwlock-cells", index, + &args); + if (ret) + return ret; + + if (!of_device_is_available(args.np)) { + ret = -ENOENT; + goto out; + } + + /* Find the hwspinlock device: we need its base_id */ + ret = -EPROBE_DEFER; + rcu_read_lock(); + radix_tree_for_each_slot(slot, &hwspinlock_tree, &iter, 0) { + hwlock = radix_tree_deref_slot(slot); + if (unlikely(!hwlock)) + continue; + if (radix_tree_deref_retry(hwlock)) { + slot = radix_tree_iter_retry(&iter); + continue; + } + + if (hwlock->bank->dev->of_node == args.np) { + ret = 0; + break; + } + } + rcu_read_unlock(); + if (ret < 0) + goto out; + + id = of_hwspin_lock_simple_xlate(&args); + if (id < 0 || id >= hwlock->bank->num_locks) { + ret = -EINVAL; + goto out; + } + id += hwlock->bank->base_id; + +out: + of_node_put(args.np); + return ret ? ret : id; +} +EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id); + +/** + * of_hwspin_lock_get_id_byname() - get lock id for an specified hwlock name + * @np: device node from which to request the specific hwlock + * @name: hwlock name + * + * This function provides a means for DT users of the hwspinlock module to + * get the global lock id of a specific hwspinlock using the specified name of + * the hwspinlock device, so that it can be requested using the normal + * hwspin_lock_request_specific() API. + * + * Returns the global lock id number on success, -EPROBE_DEFER if the hwspinlock + * device is not yet registered, -EINVAL on invalid args specifier value or an + * appropriate error as returned from the OF parsing of the DT client node. + */ +int of_hwspin_lock_get_id_byname(struct device_node *np, const char *name) +{ + int index; + + if (!name) + return -EINVAL; + + index = of_property_match_string(np, "hwlock-names", name); + if (index < 0) + return index; + + return of_hwspin_lock_get_id(np, index); +} +EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id_byname); + +static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id) +{ + struct hwspinlock *tmp; + int ret; + + mutex_lock(&hwspinlock_tree_lock); + + ret = radix_tree_insert(&hwspinlock_tree, id, hwlock); + if (ret) { + if (ret == -EEXIST) + pr_err("hwspinlock id %d already exists!\n", id); + goto out; + } + + /* mark this hwspinlock as available */ + tmp = radix_tree_tag_set(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); + + /* self-sanity check which should never fail */ + WARN_ON(tmp != hwlock); + +out: + mutex_unlock(&hwspinlock_tree_lock); + return 0; +} + +static struct hwspinlock *hwspin_lock_unregister_single(unsigned int id) +{ + struct hwspinlock *hwlock = NULL; + int ret; + + mutex_lock(&hwspinlock_tree_lock); + + /* make sure the hwspinlock is not in use (tag is set) */ + ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); + if (ret == 0) { + pr_err("hwspinlock %d still in use (or not present)\n", id); + goto out; + } + + hwlock = radix_tree_delete(&hwspinlock_tree, id); + if (!hwlock) { + pr_err("failed to delete hwspinlock %d\n", id); + goto out; + } + +out: + mutex_unlock(&hwspinlock_tree_lock); + return hwlock; +} + +/** + * hwspin_lock_register() - register a new hw spinlock device + * @bank: the hwspinlock device, which usually provides numerous hw locks + * @dev: the backing device + * @ops: hwspinlock handlers for this device + * @base_id: id of the first hardware spinlock in this bank + * @num_locks: number of hwspinlocks provided by this device + * + * This function should be called from the underlying platform-specific + * implementation, to register a new hwspinlock device instance. + * + * Should be called from a process context (might sleep) + * + * Returns 0 on success, or an appropriate error code on failure + */ +int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev, + const struct hwspinlock_ops *ops, int base_id, int num_locks) +{ + struct hwspinlock *hwlock; + int ret = 0, i; + + if (!bank || !ops || !dev || !num_locks || !ops->trylock || + !ops->unlock) { + pr_err("invalid parameters\n"); + return -EINVAL; + } + + bank->dev = dev; + bank->ops = ops; + bank->base_id = base_id; + bank->num_locks = num_locks; + + for (i = 0; i < num_locks; i++) { + hwlock = &bank->lock[i]; + + spin_lock_init(&hwlock->lock); + hwlock->bank = bank; + + ret = hwspin_lock_register_single(hwlock, base_id + i); + if (ret) + goto reg_failed; + } + + return 0; + +reg_failed: + while (--i >= 0) + hwspin_lock_unregister_single(base_id + i); + return ret; +} +EXPORT_SYMBOL_GPL(hwspin_lock_register); + +/** + * hwspin_lock_unregister() - unregister an hw spinlock device + * @bank: the hwspinlock device, which usually provides numerous hw locks + * + * This function should be called from the underlying platform-specific + * implementation, to unregister an existing (and unused) hwspinlock. + * + * Should be called from a process context (might sleep) + * + * Returns 0 on success, or an appropriate error code on failure + */ +int hwspin_lock_unregister(struct hwspinlock_device *bank) +{ + struct hwspinlock *hwlock, *tmp; + int i; + + for (i = 0; i < bank->num_locks; i++) { + hwlock = &bank->lock[i]; + + tmp = hwspin_lock_unregister_single(bank->base_id + i); + if (!tmp) + return -EBUSY; + + /* self-sanity check that should never fail */ + WARN_ON(tmp != hwlock); + } + + return 0; +} +EXPORT_SYMBOL_GPL(hwspin_lock_unregister); + +static void devm_hwspin_lock_unreg(struct device *dev, void *res) +{ + hwspin_lock_unregister(*(struct hwspinlock_device **)res); +} + +static int devm_hwspin_lock_device_match(struct device *dev, void *res, + void *data) +{ + struct hwspinlock_device **bank = res; + + if (WARN_ON(!bank || !*bank)) + return 0; + + return *bank == data; +} + +/** + * devm_hwspin_lock_unregister() - unregister an hw spinlock device for + * a managed device + * @dev: the backing device + * @bank: the hwspinlock device, which usually provides numerous hw locks + * + * This function should be called from the underlying platform-specific + * implementation, to unregister an existing (and unused) hwspinlock. + * + * Should be called from a process context (might sleep) + * + * Returns 0 on success, or an appropriate error code on failure + */ +int devm_hwspin_lock_unregister(struct device *dev, + struct hwspinlock_device *bank) +{ + int ret; + + ret = devres_release(dev, devm_hwspin_lock_unreg, + devm_hwspin_lock_device_match, bank); + WARN_ON(ret); + + return ret; +} +EXPORT_SYMBOL_GPL(devm_hwspin_lock_unregister); + +/** + * devm_hwspin_lock_register() - register a new hw spinlock device for + * a managed device + * @dev: the backing device + * @bank: the hwspinlock device, which usually provides numerous hw locks + * @ops: hwspinlock handlers for this device + * @base_id: id of the first hardware spinlock in this bank + * @num_locks: number of hwspinlocks provided by this device + * + * This function should be called from the underlying platform-specific + * implementation, to register a new hwspinlock device instance. + * + * Should be called from a process context (might sleep) + * + * Returns 0 on success, or an appropriate error code on failure + */ +int devm_hwspin_lock_register(struct device *dev, + struct hwspinlock_device *bank, + const struct hwspinlock_ops *ops, + int base_id, int num_locks) +{ + struct hwspinlock_device **ptr; + int ret; + + ptr = devres_alloc(devm_hwspin_lock_unreg, sizeof(*ptr), GFP_KERNEL); + if (!ptr) + return -ENOMEM; + + ret = hwspin_lock_register(bank, dev, ops, base_id, num_locks); + if (!ret) { + *ptr = bank; + devres_add(dev, ptr); + } else { + devres_free(ptr); + } + + return ret; +} +EXPORT_SYMBOL_GPL(devm_hwspin_lock_register); + +/** + * __hwspin_lock_request() - tag an hwspinlock as used and power it up + * + * This is an internal function that prepares an hwspinlock instance + * before it is given to the user. The function assumes that + * hwspinlock_tree_lock is taken. + * + * Returns 0 or positive to indicate success, and a negative value to + * indicate an error (with the appropriate error code) + */ +static int __hwspin_lock_request(struct hwspinlock *hwlock) +{ + struct device *dev = hwlock->bank->dev; + struct hwspinlock *tmp; + int ret; + + /* prevent underlying implementation from being removed */ + if (!try_module_get(dev->driver->owner)) { + dev_err(dev, "%s: can't get owner\n", __func__); + return -EINVAL; + } + + /* notify PM core that power is now needed */ + ret = pm_runtime_get_sync(dev); + if (ret < 0 && ret != -EACCES) { + dev_err(dev, "%s: can't power on device\n", __func__); + pm_runtime_put_noidle(dev); + module_put(dev->driver->owner); + return ret; + } + + ret = 0; + + /* mark hwspinlock as used, should not fail */ + tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock), + HWSPINLOCK_UNUSED); + + /* self-sanity check that should never fail */ + WARN_ON(tmp != hwlock); + + return ret; +} + +/** + * hwspin_lock_get_id() - retrieve id number of a given hwspinlock + * @hwlock: a valid hwspinlock instance + * + * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid. + */ +int hwspin_lock_get_id(struct hwspinlock *hwlock) +{ + if (!hwlock) { + pr_err("invalid hwlock\n"); + return -EINVAL; + } + + return hwlock_to_id(hwlock); +} +EXPORT_SYMBOL_GPL(hwspin_lock_get_id); + +/** + * hwspin_lock_request() - request an hwspinlock + * + * This function should be called by users of the hwspinlock device, + * in order to dynamically assign them an unused hwspinlock. + * Usually the user of this lock will then have to communicate the lock's id + * to the remote core before it can be used for synchronization (to get the + * id of a given hwlock, use hwspin_lock_get_id()). + * + * Should be called from a process context (might sleep) + * + * Returns the address of the assigned hwspinlock, or NULL on error + */ +struct hwspinlock *hwspin_lock_request(void) +{ + struct hwspinlock *hwlock; + int ret; + + mutex_lock(&hwspinlock_tree_lock); + + /* look for an unused lock */ + ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock, + 0, 1, HWSPINLOCK_UNUSED); + if (ret == 0) { + pr_warn("a free hwspinlock is not available\n"); + hwlock = NULL; + goto out; + } + + /* sanity check that should never fail */ + WARN_ON(ret > 1); + + /* mark as used and power up */ + ret = __hwspin_lock_request(hwlock); + if (ret < 0) + hwlock = NULL; + +out: + mutex_unlock(&hwspinlock_tree_lock); + return hwlock; +} +EXPORT_SYMBOL_GPL(hwspin_lock_request); + +/** + * hwspin_lock_request_specific() - request for a specific hwspinlock + * @id: index of the specific hwspinlock that is requested + * + * This function should be called by users of the hwspinlock module, + * in order to assign them a specific hwspinlock. + * Usually early board code will be calling this function in order to + * reserve specific hwspinlock ids for predefined purposes. + * + * Should be called from a process context (might sleep) + * + * Returns the address of the assigned hwspinlock, or NULL on error + */ +struct hwspinlock *hwspin_lock_request_specific(unsigned int id) +{ + struct hwspinlock *hwlock; + int ret; + + mutex_lock(&hwspinlock_tree_lock); + + /* make sure this hwspinlock exists */ + hwlock = radix_tree_lookup(&hwspinlock_tree, id); + if (!hwlock) { + pr_warn("hwspinlock %u does not exist\n", id); + goto out; + } + + /* sanity check (this shouldn't happen) */ + WARN_ON(hwlock_to_id(hwlock) != id); + + /* make sure this hwspinlock is unused */ + ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); + if (ret == 0) { + pr_warn("hwspinlock %u is already in use\n", id); + hwlock = NULL; + goto out; + } + + /* mark as used and power up */ + ret = __hwspin_lock_request(hwlock); + if (ret < 0) + hwlock = NULL; + +out: + mutex_unlock(&hwspinlock_tree_lock); + return hwlock; +} +EXPORT_SYMBOL_GPL(hwspin_lock_request_specific); + +/** + * hwspin_lock_free() - free a specific hwspinlock + * @hwlock: the specific hwspinlock to free + * + * This function mark @hwlock as free again. + * Should only be called with an @hwlock that was retrieved from + * an earlier call to hwspin_lock_request{_specific}. + * + * Should be called from a process context (might sleep) + * + * Returns 0 on success, or an appropriate error code on failure + */ +int hwspin_lock_free(struct hwspinlock *hwlock) +{ + struct device *dev; + struct hwspinlock *tmp; + int ret; + + if (!hwlock) { + pr_err("invalid hwlock\n"); + return -EINVAL; + } + + dev = hwlock->bank->dev; + mutex_lock(&hwspinlock_tree_lock); + + /* make sure the hwspinlock is used */ + ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock), + HWSPINLOCK_UNUSED); + if (ret == 1) { + dev_err(dev, "%s: hwlock is already free\n", __func__); + dump_stack(); + ret = -EINVAL; + goto out; + } + + /* notify the underlying device that power is not needed */ + pm_runtime_put(dev); + + /* mark this hwspinlock as available */ + tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock), + HWSPINLOCK_UNUSED); + + /* sanity check (this shouldn't happen) */ + WARN_ON(tmp != hwlock); + + module_put(dev->driver->owner); + +out: + mutex_unlock(&hwspinlock_tree_lock); + return ret; +} +EXPORT_SYMBOL_GPL(hwspin_lock_free); + +static int devm_hwspin_lock_match(struct device *dev, void *res, void *data) +{ + struct hwspinlock **hwlock = res; + + if (WARN_ON(!hwlock || !*hwlock)) + return 0; + + return *hwlock == data; +} + +static void devm_hwspin_lock_release(struct device *dev, void *res) +{ + hwspin_lock_free(*(struct hwspinlock **)res); +} + +/** + * devm_hwspin_lock_free() - free a specific hwspinlock for a managed device + * @dev: the device to free the specific hwspinlock + * @hwlock: the specific hwspinlock to free + * + * This function mark @hwlock as free again. + * Should only be called with an @hwlock that was retrieved from + * an earlier call to hwspin_lock_request{_specific}. + * + * Should be called from a process context (might sleep) + * + * Returns 0 on success, or an appropriate error code on failure + */ +int devm_hwspin_lock_free(struct device *dev, struct hwspinlock *hwlock) +{ + int ret; + + ret = devres_release(dev, devm_hwspin_lock_release, + devm_hwspin_lock_match, hwlock); + WARN_ON(ret); + + return ret; +} +EXPORT_SYMBOL_GPL(devm_hwspin_lock_free); + +/** + * devm_hwspin_lock_request() - request an hwspinlock for a managed device + * @dev: the device to request an hwspinlock + * + * This function should be called by users of the hwspinlock device, + * in order to dynamically assign them an unused hwspinlock. + * Usually the user of this lock will then have to communicate the lock's id + * to the remote core before it can be used for synchronization (to get the + * id of a given hwlock, use hwspin_lock_get_id()). + * + * Should be called from a process context (might sleep) + * + * Returns the address of the assigned hwspinlock, or NULL on error + */ +struct hwspinlock *devm_hwspin_lock_request(struct device *dev) +{ + struct hwspinlock **ptr, *hwlock; + + ptr = devres_alloc(devm_hwspin_lock_release, sizeof(*ptr), GFP_KERNEL); + if (!ptr) + return NULL; + + hwlock = hwspin_lock_request(); + if (hwlock) { + *ptr = hwlock; + devres_add(dev, ptr); + } else { + devres_free(ptr); + } + + return hwlock; +} +EXPORT_SYMBOL_GPL(devm_hwspin_lock_request); + +/** + * devm_hwspin_lock_request_specific() - request for a specific hwspinlock for + * a managed device + * @dev: the device to request the specific hwspinlock + * @id: index of the specific hwspinlock that is requested + * + * This function should be called by users of the hwspinlock module, + * in order to assign them a specific hwspinlock. + * Usually early board code will be calling this function in order to + * reserve specific hwspinlock ids for predefined purposes. + * + * Should be called from a process context (might sleep) + * + * Returns the address of the assigned hwspinlock, or NULL on error + */ +struct hwspinlock *devm_hwspin_lock_request_specific(struct device *dev, + unsigned int id) +{ + struct hwspinlock **ptr, *hwlock; + + ptr = devres_alloc(devm_hwspin_lock_release, sizeof(*ptr), GFP_KERNEL); + if (!ptr) + return NULL; + + hwlock = hwspin_lock_request_specific(id); + if (hwlock) { + *ptr = hwlock; + devres_add(dev, ptr); + } else { + devres_free(ptr); + } + + return hwlock; +} +EXPORT_SYMBOL_GPL(devm_hwspin_lock_request_specific); + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("Hardware spinlock interface"); +MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>"); |