Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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>");