1 files changed, 349 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_lock.c b/drivers/gpu/drm/drm_lock.c
new file mode 100644
index 000000000..96bb6badb
--- /dev/null
+++ b/drivers/gpu/drm/drm_lock.c
@@ -0,0 +1,349 @@
+/**
+ * \file drm_lock.c
+ * IOCTLs for locking
+ *
+ * \author Rickard E. (Rik) Faith <faith@valinux.com>
+ * \author Gareth Hughes <gareth@valinux.com>
+ */
+
+/*
+ * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
+ *
+ * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
+ * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/export.h>
+#include <linux/sched/signal.h>
+
+#include <drm/drmP.h>
+#include "drm_legacy.h"
+#include "drm_internal.h"
+
+static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);
+
+/**
+ * Take the heavyweight lock.
+ *
+ * \param lock lock pointer.
+ * \param context locking context.
+ * \return one if the lock is held, or zero otherwise.
+ *
+ * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
+ */
+static
+int drm_lock_take(struct drm_lock_data *lock_data,
+		  unsigned int context)
+{
+	unsigned int old, new, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
+
+	spin_lock_bh(&lock_data->spinlock);
+	do {
+		old = *lock;
+		if (old & _DRM_LOCK_HELD)
+			new = old | _DRM_LOCK_CONT;
+		else {
+			new = context | _DRM_LOCK_HELD |
+				((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
+				 _DRM_LOCK_CONT : 0);
+		}
+		prev = cmpxchg(lock, old, new);
+	} while (prev != old);
+	spin_unlock_bh(&lock_data->spinlock);
+
+	if (_DRM_LOCKING_CONTEXT(old) == context) {
+		if (old & _DRM_LOCK_HELD) {
+			if (context != DRM_KERNEL_CONTEXT) {
+				DRM_ERROR("%d holds heavyweight lock\n",
+					  context);
+			}
+			return 0;
+		}
+	}
+
+	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
+		/* Have lock */
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * This takes a lock forcibly and hands it to context.	Should ONLY be used
+ * inside *_unlock to give lock to kernel before calling *_dma_schedule.
+ *
+ * \param dev DRM device.
+ * \param lock lock pointer.
+ * \param context locking context.
+ * \return always one.
+ *
+ * Resets the lock file pointer.
+ * Marks the lock as held by the given context, via the \p cmpxchg instruction.
+ */
+static int drm_lock_transfer(struct drm_lock_data *lock_data,
+			     unsigned int context)
+{
+	unsigned int old, new, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
+
+	lock_data->file_priv = NULL;
+	do {
+		old = *lock;
+		new = context | _DRM_LOCK_HELD;
+		prev = cmpxchg(lock, old, new);
+	} while (prev != old);
+	return 1;
+}
+
+static int drm_legacy_lock_free(struct drm_lock_data *lock_data,
+				unsigned int context)
+{
+	unsigned int old, new, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
+
+	spin_lock_bh(&lock_data->spinlock);
+	if (lock_data->kernel_waiters != 0) {
+		drm_lock_transfer(lock_data, 0);
+		lock_data->idle_has_lock = 1;
+		spin_unlock_bh(&lock_data->spinlock);
+		return 1;
+	}
+	spin_unlock_bh(&lock_data->spinlock);
+
+	do {
+		old = *lock;
+		new = _DRM_LOCKING_CONTEXT(old);
+		prev = cmpxchg(lock, old, new);
+	} while (prev != old);
+
+	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
+		DRM_ERROR("%d freed heavyweight lock held by %d\n",
+			  context, _DRM_LOCKING_CONTEXT(old));
+		return 1;
+	}
+	wake_up_interruptible(&lock_data->lock_queue);
+	return 0;
+}
+
+/**
+ * Lock ioctl.
+ *
+ * \param inode device inode.
+ * \param file_priv DRM file private.
+ * \param cmd command.
+ * \param arg user argument, pointing to a drm_lock structure.
+ * \return zero on success or negative number on failure.
+ *
+ * Add the current task to the lock wait queue, and attempt to take to lock.
+ */
+int drm_legacy_lock(struct drm_device *dev, void *data,
+		    struct drm_file *file_priv)
+{
+	DECLARE_WAITQUEUE(entry, current);
+	struct drm_lock *lock = data;
+	struct drm_master *master = file_priv->master;
+	int ret = 0;
+
+	if (!drm_core_check_feature(dev, DRIVER_LEGACY))
+		return -EINVAL;
+
+	++file_priv->lock_count;
+
+	if (lock->context == DRM_KERNEL_CONTEXT) {
+		DRM_ERROR("Process %d using kernel context %d\n",
+			  task_pid_nr(current), lock->context);
+		return -EINVAL;
+	}
+
+	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
+		  lock->context, task_pid_nr(current),
+		  master->lock.hw_lock ? master->lock.hw_lock->lock : -1,
+		  lock->flags);
+
+	add_wait_queue(&master->lock.lock_queue, &entry);
+	spin_lock_bh(&master->lock.spinlock);
+	master->lock.user_waiters++;
+	spin_unlock_bh(&master->lock.spinlock);
+
+	for (;;) {
+		__set_current_state(TASK_INTERRUPTIBLE);
+		if (!master->lock.hw_lock) {
+			/* Device has been unregistered */
+			send_sig(SIGTERM, current, 0);
+			ret = -EINTR;
+			break;
+		}
+		if (drm_lock_take(&master->lock, lock->context)) {
+			master->lock.file_priv = file_priv;
+			master->lock.lock_time = jiffies;
+			break;	/* Got lock */
+		}
+
+		/* Contention */
+		mutex_unlock(&drm_global_mutex);
+		schedule();
+		mutex_lock(&drm_global_mutex);
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+	}
+	spin_lock_bh(&master->lock.spinlock);
+	master->lock.user_waiters--;
+	spin_unlock_bh(&master->lock.spinlock);
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(&master->lock.lock_queue, &entry);
+
+	DRM_DEBUG("%d %s\n", lock->context,
+		  ret ? "interrupted" : "has lock");
+	if (ret) return ret;
+
+	/* don't set the block all signals on the master process for now 
+	 * really probably not the correct answer but lets us debug xkb
+ 	 * xserver for now */
+	if (!drm_is_current_master(file_priv)) {
+		dev->sigdata.context = lock->context;
+		dev->sigdata.lock = master->lock.hw_lock;
+	}
+
+	if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
+	{
+		if (dev->driver->dma_quiescent(dev)) {
+			DRM_DEBUG("%d waiting for DMA quiescent\n",
+				  lock->context);
+			return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * Unlock ioctl.
+ *
+ * \param inode device inode.
+ * \param file_priv DRM file private.
+ * \param cmd command.
+ * \param arg user argument, pointing to a drm_lock structure.
+ * \return zero on success or negative number on failure.
+ *
+ * Transfer and free the lock.
+ */
+int drm_legacy_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
+{
+	struct drm_lock *lock = data;
+	struct drm_master *master = file_priv->master;
+
+	if (!drm_core_check_feature(dev, DRIVER_LEGACY))
+		return -EINVAL;
+
+	if (lock->context == DRM_KERNEL_CONTEXT) {
+		DRM_ERROR("Process %d using kernel context %d\n",
+			  task_pid_nr(current), lock->context);
+		return -EINVAL;
+	}
+
+	if (drm_legacy_lock_free(&master->lock, lock->context)) {
+		/* FIXME: Should really bail out here. */
+	}
+
+	return 0;
+}
+
+/**
+ * This function returns immediately and takes the hw lock
+ * with the kernel context if it is free, otherwise it gets the highest priority when and if
+ * it is eventually released.
+ *
+ * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
+ * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
+ * a deadlock, which is why the "idlelock" was invented).
+ *
+ * This should be sufficient to wait for GPU idle without
+ * having to worry about starvation.
+ */
+
+void drm_legacy_idlelock_take(struct drm_lock_data *lock_data)
+{
+	int ret;
+
+	spin_lock_bh(&lock_data->spinlock);
+	lock_data->kernel_waiters++;
+	if (!lock_data->idle_has_lock) {
+
+		spin_unlock_bh(&lock_data->spinlock);
+		ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
+		spin_lock_bh(&lock_data->spinlock);
+
+		if (ret == 1)
+			lock_data->idle_has_lock = 1;
+	}
+	spin_unlock_bh(&lock_data->spinlock);
+}
+EXPORT_SYMBOL(drm_legacy_idlelock_take);
+
+void drm_legacy_idlelock_release(struct drm_lock_data *lock_data)
+{
+	unsigned int old, prev;
+	volatile unsigned int *lock = &lock_data->hw_lock->lock;
+
+	spin_lock_bh(&lock_data->spinlock);
+	if (--lock_data->kernel_waiters == 0) {
+		if (lock_data->idle_has_lock) {
+			do {
+				old = *lock;
+				prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
+			} while (prev != old);
+			wake_up_interruptible(&lock_data->lock_queue);
+			lock_data->idle_has_lock = 0;
+		}
+	}
+	spin_unlock_bh(&lock_data->spinlock);
+}
+EXPORT_SYMBOL(drm_legacy_idlelock_release);
+
+static int drm_legacy_i_have_hw_lock(struct drm_device *dev,
+				     struct drm_file *file_priv)
+{
+	struct drm_master *master = file_priv->master;
+	return (file_priv->lock_count && master->lock.hw_lock &&
+		_DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
+		master->lock.file_priv == file_priv);
+}
+
+void drm_legacy_lock_release(struct drm_device *dev, struct file *filp)
+{
+	struct drm_file *file_priv = filp->private_data;
+
+	/* if the master has gone away we can't do anything with the lock */
+	if (!dev->master)
+		return;
+
+	if (drm_legacy_i_have_hw_lock(dev, file_priv)) {
+		DRM_DEBUG("File %p released, freeing lock for context %d\n",
+			  filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
+		drm_legacy_lock_free(&file_priv->master->lock,
+				     _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
+	}
+}