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path: root/drivers/base/kds/kds.c
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Diffstat (limited to 'drivers/base/kds/kds.c')
-rwxr-xr-xdrivers/base/kds/kds.c532
1 files changed, 532 insertions, 0 deletions
diff --git a/drivers/base/kds/kds.c b/drivers/base/kds/kds.c
new file mode 100755
index 00000000000..aada2da646a
--- /dev/null
+++ b/drivers/base/kds/kds.c
@@ -0,0 +1,532 @@
+/*
+ *
+ * (C) COPYRIGHT 2012-2013 ARM Limited. All rights reserved.
+ *
+ * This program is free software and is provided to you under the terms of the
+ * GNU General Public License version 2 as published by the Free Software
+ * Foundation, and any use by you of this program is subject to the terms
+ * of such GNU licence.
+ *
+ * A copy of the licence is included with the program, and can also be obtained
+ * from Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ *
+ */
+
+
+
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/workqueue.h>
+#include <linux/kds.h>
+
+
+#define KDS_LINK_TRIGGERED (1u << 0)
+#define KDS_LINK_EXCLUSIVE (1u << 1)
+
+#define KDS_INVALID (void *)-2
+#define KDS_RESOURCE (void *)-1
+
+struct kds_resource_set
+{
+ unsigned long num_resources;
+ unsigned long pending;
+ struct kds_callback *cb;
+ void *callback_parameter;
+ void *callback_extra_parameter;
+ struct list_head callback_link;
+ struct work_struct callback_work;
+
+ /* This is only initted when kds_waitall() is called. */
+ wait_queue_head_t wake;
+
+ struct kds_link resources[0];
+};
+
+static DEFINE_SPINLOCK(kds_lock);
+
+int kds_callback_init(struct kds_callback *cb, int direct, kds_callback_fn user_cb)
+{
+ int ret = 0;
+
+ cb->direct = direct;
+ cb->user_cb = user_cb;
+
+ if (!direct)
+ {
+ cb->wq = alloc_workqueue("kds", WQ_UNBOUND | WQ_HIGHPRI, WQ_UNBOUND_MAX_ACTIVE);
+ if (!cb->wq)
+ ret = -ENOMEM;
+ }
+ else
+ {
+ cb->wq = NULL;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(kds_callback_init);
+
+void kds_callback_term(struct kds_callback *cb)
+{
+ if (!cb->direct)
+ {
+ BUG_ON(!cb->wq);
+ destroy_workqueue(cb->wq);
+ }
+ else
+ {
+ BUG_ON(cb->wq);
+ }
+}
+
+EXPORT_SYMBOL(kds_callback_term);
+
+static void kds_do_user_callback(struct kds_resource_set *rset)
+{
+ rset->cb->user_cb(rset->callback_parameter, rset->callback_extra_parameter);
+}
+
+static void kds_queued_callback(struct work_struct *work)
+{
+ struct kds_resource_set *rset;
+ rset = container_of(work, struct kds_resource_set, callback_work);
+
+ kds_do_user_callback(rset);
+}
+
+static void kds_callback_perform(struct kds_resource_set *rset)
+{
+ if (rset->cb->direct)
+ kds_do_user_callback(rset);
+ else
+ {
+ int result;
+ result = queue_work(rset->cb->wq, &rset->callback_work);
+ /* if we got a 0 return it means we've triggered the same rset twice! */
+ WARN_ON(!result);
+ }
+}
+
+void kds_resource_init(struct kds_resource * const res)
+{
+ BUG_ON(!res);
+ INIT_LIST_HEAD(&res->waiters.link);
+ res->waiters.parent = KDS_RESOURCE;
+}
+EXPORT_SYMBOL(kds_resource_init);
+
+int kds_resource_term(struct kds_resource *res)
+{
+ unsigned long lflags;
+ BUG_ON(!res);
+ spin_lock_irqsave(&kds_lock, lflags);
+ if (!list_empty(&res->waiters.link))
+ {
+ spin_unlock_irqrestore(&kds_lock, lflags);
+ printk(KERN_ERR "ERROR: KDS resource is still in use\n");
+ return -EBUSY;
+ }
+ res->waiters.parent = KDS_INVALID;
+ spin_unlock_irqrestore(&kds_lock, lflags);
+ return 0;
+}
+EXPORT_SYMBOL(kds_resource_term);
+
+int kds_async_waitall(
+ struct kds_resource_set ** const pprset,
+ struct kds_callback *cb,
+ void *callback_parameter,
+ void *callback_extra_parameter,
+ int number_resources,
+ unsigned long *exclusive_access_bitmap,
+ struct kds_resource **resource_list)
+{
+ struct kds_resource_set *rset = NULL;
+ unsigned long lflags;
+ int i;
+ int triggered;
+ int err = -EFAULT;
+
+ BUG_ON(!pprset);
+ BUG_ON(!resource_list);
+ BUG_ON(!cb);
+
+ WARN_ONCE(number_resources > 10, "Waiting on a high numbers of resources may increase latency, see documentation.");
+
+ rset = kmalloc(sizeof(*rset) + number_resources * sizeof(struct kds_link), GFP_KERNEL);
+ if (!rset)
+ {
+ return -ENOMEM;
+ }
+
+ rset->num_resources = number_resources;
+ rset->pending = number_resources;
+ rset->cb = cb;
+ rset->callback_parameter = callback_parameter;
+ rset->callback_extra_parameter = callback_extra_parameter;
+ INIT_LIST_HEAD(&rset->callback_link);
+ INIT_WORK(&rset->callback_work, kds_queued_callback);
+
+ for (i = 0; i < number_resources; i++)
+ {
+ INIT_LIST_HEAD(&rset->resources[i].link);
+ rset->resources[i].parent = rset;
+ }
+
+ spin_lock_irqsave(&kds_lock, lflags);
+
+ for (i = 0; i < number_resources; i++)
+ {
+ unsigned long link_state = 0;
+
+ if (test_bit(i, exclusive_access_bitmap))
+ {
+ link_state |= KDS_LINK_EXCLUSIVE;
+ }
+
+ /* no-one else waiting? */
+ if (list_empty(&resource_list[i]->waiters.link))
+ {
+ link_state |= KDS_LINK_TRIGGERED;
+ rset->pending--;
+ }
+ /* Adding a non-exclusive and the current tail is a triggered non-exclusive? */
+ else if (((link_state & KDS_LINK_EXCLUSIVE) == 0) &&
+ (((list_entry(resource_list[i]->waiters.link.prev, struct kds_link, link)->state & (KDS_LINK_EXCLUSIVE | KDS_LINK_TRIGGERED)) == KDS_LINK_TRIGGERED)))
+ {
+ link_state |= KDS_LINK_TRIGGERED;
+ rset->pending--;
+ }
+ rset->resources[i].state = link_state;
+
+ /* avoid double wait (hang) */
+ if (!list_empty(&resource_list[i]->waiters.link))
+ {
+ /* adding same rset again? */
+ if (list_entry(resource_list[i]->waiters.link.prev, struct kds_link, link)->parent == rset)
+ {
+ goto roll_back;
+ }
+ }
+ list_add_tail(&rset->resources[i].link, &resource_list[i]->waiters.link);
+ }
+
+ triggered = (rset->pending == 0);
+
+ /* set the pointer before the callback is called so it sees it */
+ *pprset = rset;
+
+ spin_unlock_irqrestore(&kds_lock, lflags);
+
+ if (triggered)
+ {
+ /* all resources obtained, trigger callback */
+ kds_callback_perform(rset);
+ }
+
+ return 0;
+
+roll_back:
+ /* roll back */
+ while (i-- > 0)
+ {
+ list_del(&rset->resources[i].link);
+ }
+ err = -EINVAL;
+
+ spin_unlock_irqrestore(&kds_lock, lflags);
+ kfree(rset);
+ return err;
+}
+EXPORT_SYMBOL(kds_async_waitall);
+
+static void wake_up_sync_call(void *callback_parameter, void *callback_extra_parameter)
+{
+ wait_queue_head_t *wait = (wait_queue_head_t *)callback_parameter;
+ wake_up(wait);
+}
+
+static struct kds_callback sync_cb =
+{
+ wake_up_sync_call,
+ 1,
+ NULL,
+};
+
+struct kds_resource_set *kds_waitall(
+ int number_resources,
+ unsigned long *exclusive_access_bitmap,
+ struct kds_resource **resource_list,
+ unsigned long jiffies_timeout)
+{
+ struct kds_resource_set *rset;
+ unsigned long lflags;
+ int i;
+ int triggered = 0;
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wake);
+
+ rset = kmalloc(sizeof(*rset) + number_resources * sizeof(struct kds_link), GFP_KERNEL);
+ if (!rset)
+ return rset;
+
+ rset->num_resources = number_resources;
+ rset->pending = number_resources;
+ init_waitqueue_head(&rset->wake);
+ INIT_LIST_HEAD(&rset->callback_link);
+ INIT_WORK(&rset->callback_work, kds_queued_callback);
+
+ spin_lock_irqsave(&kds_lock, lflags);
+
+ for (i = 0; i < number_resources; i++)
+ {
+ unsigned long link_state = 0;
+
+ if (test_bit(i, exclusive_access_bitmap))
+ {
+ link_state |= KDS_LINK_EXCLUSIVE;
+ }
+
+ if (list_empty(&resource_list[i]->waiters.link))
+ {
+ link_state |= KDS_LINK_TRIGGERED;
+ rset->pending--;
+ }
+ /* Adding a non-exclusive and the current tail is a triggered non-exclusive? */
+ else if (((link_state & KDS_LINK_EXCLUSIVE) == 0) &&
+ (((list_entry(resource_list[i]->waiters.link.prev, struct kds_link, link)->state & (KDS_LINK_EXCLUSIVE | KDS_LINK_TRIGGERED)) == KDS_LINK_TRIGGERED)))
+ {
+ link_state |= KDS_LINK_TRIGGERED;
+ rset->pending--;
+ }
+
+ INIT_LIST_HEAD(&rset->resources[i].link);
+ rset->resources[i].parent = rset;
+ rset->resources[i].state = link_state;
+
+ /* avoid double wait (hang) */
+ if (!list_empty(&resource_list[i]->waiters.link))
+ {
+ /* adding same rset again? */
+ if (list_entry(resource_list[i]->waiters.link.prev, struct kds_link, link)->parent == rset)
+ {
+ goto roll_back;
+ }
+ }
+
+ list_add_tail(&rset->resources[i].link, &resource_list[i]->waiters.link);
+ }
+
+ if (rset->pending == 0)
+ triggered = 1;
+ else
+ {
+ rset->cb = &sync_cb;
+ rset->callback_parameter = &rset->wake;
+ rset->callback_extra_parameter = NULL;
+ }
+
+ spin_unlock_irqrestore(&kds_lock, lflags);
+
+ if (!triggered)
+ {
+ long wait_res = 0;
+ long timeout = (jiffies_timeout == KDS_WAIT_BLOCKING) ?
+ MAX_SCHEDULE_TIMEOUT : jiffies_timeout;
+
+ if (timeout)
+ {
+ wait_res = wait_event_interruptible_timeout(rset->wake,
+ rset->pending == 0, timeout);
+ }
+
+ if ((wait_res == -ERESTARTSYS) || (wait_res == 0))
+ {
+ /* use \a kds_resource_set_release to roll back */
+ kds_resource_set_release(&rset);
+ return ERR_PTR(wait_res);
+ }
+ }
+ return rset;
+
+roll_back:
+ /* roll back */
+ while (i-- > 0)
+ {
+ list_del(&rset->resources[i].link);
+ }
+
+ spin_unlock_irqrestore(&kds_lock, lflags);
+ kfree(rset);
+ return ERR_PTR(-EINVAL);
+}
+EXPORT_SYMBOL(kds_waitall);
+
+static void __kds_resource_set_release_common(struct kds_resource_set *rset)
+{
+ struct list_head triggered = LIST_HEAD_INIT(triggered);
+ struct kds_resource_set *it;
+ unsigned long lflags;
+ int i;
+
+ spin_lock_irqsave(&kds_lock, lflags);
+
+ for (i = 0; i < rset->num_resources; i++)
+ {
+ struct kds_resource *resource;
+ struct kds_link *it = NULL;
+
+ /* fetch the previous entry on the linked list */
+ it = list_entry(rset->resources[i].link.prev, struct kds_link, link);
+ /* unlink ourself */
+ list_del(&rset->resources[i].link);
+
+ /* any waiters? */
+ if (list_empty(&it->link))
+ continue;
+
+ /* were we the head of the list? (head if prev is a resource) */
+ if (it->parent != KDS_RESOURCE)
+ {
+ if ((it->state & KDS_LINK_TRIGGERED) && !(it->state & KDS_LINK_EXCLUSIVE) )
+ {
+ /*
+ * previous was triggered and not exclusive, so we
+ * trigger non-exclusive until end-of-list or first
+ * exclusive
+ */
+
+ struct kds_link *it_waiting = it;
+
+ list_for_each_entry(it, &it_waiting->link, link)
+ {
+ /* exclusive found, stop triggering */
+ if (it->state & KDS_LINK_EXCLUSIVE)
+ break;
+
+ it->state |= KDS_LINK_TRIGGERED;
+ /* a parent to update? */
+ if ( it->parent != KDS_RESOURCE )
+ {
+ if (0 == --it->parent->pending)
+ {
+ /* new owner now triggered, track for callback later */
+ list_add(&it->parent->callback_link, &triggered);
+ }
+ }
+ }
+ }
+ continue;
+ }
+
+ /* we were the head, find the kds_resource */
+ resource = container_of(it, struct kds_resource, waiters);
+
+ /* we know there is someone waiting from the any-waiters test above */
+
+ /* find the head of the waiting list */
+ it = list_first_entry(&resource->waiters.link, struct kds_link, link);
+
+ /* new exclusive owner? */
+ if (it->state & KDS_LINK_EXCLUSIVE)
+ {
+ /* link now triggered */
+ it->state |= KDS_LINK_TRIGGERED;
+ /* a parent to update? */
+ if (0 == --it->parent->pending)
+ {
+ /* new owner now triggered, track for callback later */
+ list_add(&it->parent->callback_link, &triggered);
+ }
+ }
+ /* exclusive releasing ? */
+ else if (rset->resources[i].state & KDS_LINK_EXCLUSIVE)
+ {
+ /* trigger non-exclusive until end-of-list or first exclusive */
+ list_for_each_entry(it, &resource->waiters.link, link)
+ {
+ /* exclusive found, stop triggering */
+ if (it->state & KDS_LINK_EXCLUSIVE)
+ break;
+
+ it->state |= KDS_LINK_TRIGGERED;
+ /* a parent to update? */
+ if (0 == --it->parent->pending)
+ {
+ /* new owner now triggered, track for callback later */
+ list_add(&it->parent->callback_link, &triggered);
+ }
+ }
+ }
+ }
+
+ spin_unlock_irqrestore(&kds_lock, lflags);
+
+ while (!list_empty(&triggered))
+ {
+ it = list_first_entry(&triggered, struct kds_resource_set, callback_link);
+ list_del(&it->callback_link);
+ kds_callback_perform(it);
+ }
+}
+
+void kds_resource_set_release(struct kds_resource_set **pprset)
+{
+ struct kds_resource_set *rset;
+
+ rset = cmpxchg(pprset,*pprset,NULL);
+
+ if (!rset)
+ {
+ /* caught a race between a cancelation
+ * and a completion, nothing to do */
+ return;
+ }
+
+ __kds_resource_set_release_common(rset);
+
+ /*
+ * Caller is responsible for guaranteeing that callback work is not
+ * pending (i.e. its running or completed) prior to calling release.
+ */
+ BUG_ON(work_pending(&rset->callback_work));
+
+ /* free the resource set */
+ kfree(rset);
+}
+EXPORT_SYMBOL(kds_resource_set_release);
+
+void kds_resource_set_release_sync(struct kds_resource_set **pprset)
+{
+ struct kds_resource_set *rset;
+
+ rset = cmpxchg(pprset,*pprset,NULL);
+ if (!rset)
+ {
+ /* caught a race between a cancelation
+ * and a completion, nothing to do */
+ return;
+ }
+
+ __kds_resource_set_release_common(rset);
+
+ /*
+ * In the case of a kds async wait cancellation ensure the deferred
+ * call back does not get scheduled if a trigger fired at the same time
+ * to release the wait.
+ */
+ cancel_work_sync(&rset->callback_work);
+
+ /* free the resource set */
+ kfree(rset);
+}
+EXPORT_SYMBOL(kds_resource_set_release_sync);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("ARM Ltd.");
+MODULE_VERSION("1.0");
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-26 01:36:17 +0000