1 files changed, 138 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
new file mode 100644
index 000000000000..3db6fa682823
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref.c
@@ -0,0 +1,138 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include "intel_runtime_pm.h"
+#include "i915_gem.h"
+
+static void rpm_get(struct intel_runtime_pm *rpm, struct intel_wakeref *wf)
+{
+	wf->wakeref = intel_runtime_pm_get(rpm);
+}
+
+static void rpm_put(struct intel_runtime_pm *rpm, struct intel_wakeref *wf)
+{
+	intel_wakeref_t wakeref = fetch_and_zero(&wf->wakeref);
+
+	intel_runtime_pm_put(rpm, wakeref);
+	GEM_BUG_ON(!wakeref);
+}
+
+int __intel_wakeref_get_first(struct intel_runtime_pm *rpm,
+			      struct intel_wakeref *wf,
+			      int (*fn)(struct intel_wakeref *wf))
+{
+	/*
+	 * Treat get/put as different subclasses, as we may need to run
+	 * the put callback from under the shrinker and do not want to
+	 * cross-contanimate that callback with any extra work performed
+	 * upon acquiring the wakeref.
+	 */
+	mutex_lock_nested(&wf->mutex, SINGLE_DEPTH_NESTING);
+	if (!atomic_read(&wf->count)) {
+		int err;
+
+		rpm_get(rpm, wf);
+
+		err = fn(wf);
+		if (unlikely(err)) {
+			rpm_put(rpm, wf);
+			mutex_unlock(&wf->mutex);
+			return err;
+		}
+
+		smp_mb__before_atomic(); /* release wf->count */
+	}
+	atomic_inc(&wf->count);
+	mutex_unlock(&wf->mutex);
+
+	return 0;
+}
+
+int __intel_wakeref_put_last(struct intel_runtime_pm *rpm,
+			     struct intel_wakeref *wf,
+			     int (*fn)(struct intel_wakeref *wf))
+{
+	int err;
+
+	err = fn(wf);
+	if (likely(!err))
+		rpm_put(rpm, wf);
+	else
+		atomic_inc(&wf->count);
+	mutex_unlock(&wf->mutex);
+
+	return err;
+}
+
+void __intel_wakeref_init(struct intel_wakeref *wf, struct lock_class_key *key)
+{
+	__mutex_init(&wf->mutex, "wakeref", key);
+	atomic_set(&wf->count, 0);
+	wf->wakeref = 0;
+}
+
+static void wakeref_auto_timeout(struct timer_list *t)
+{
+	struct intel_wakeref_auto *wf = from_timer(wf, t, timer);
+	intel_wakeref_t wakeref;
+	unsigned long flags;
+
+	if (!refcount_dec_and_lock_irqsave(&wf->count, &wf->lock, &flags))
+		return;
+
+	wakeref = fetch_and_zero(&wf->wakeref);
+	spin_unlock_irqrestore(&wf->lock, flags);
+
+	intel_runtime_pm_put(wf->rpm, wakeref);
+}
+
+void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
+			     struct intel_runtime_pm *rpm)
+{
+	spin_lock_init(&wf->lock);
+	timer_setup(&wf->timer, wakeref_auto_timeout, 0);
+	refcount_set(&wf->count, 0);
+	wf->wakeref = 0;
+	wf->rpm = rpm;
+}
+
+void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout)
+{
+	unsigned long flags;
+
+	if (!timeout) {
+		if (del_timer_sync(&wf->timer))
+			wakeref_auto_timeout(&wf->timer);
+		return;
+	}
+
+	/* Our mission is that we only extend an already active wakeref */
+	assert_rpm_wakelock_held(wf->rpm);
+
+	if (!refcount_inc_not_zero(&wf->count)) {
+		spin_lock_irqsave(&wf->lock, flags);
+		if (!refcount_inc_not_zero(&wf->count)) {
+			GEM_BUG_ON(wf->wakeref);
+			wf->wakeref = intel_runtime_pm_get_if_in_use(wf->rpm);
+			refcount_set(&wf->count, 1);
+		}
+		spin_unlock_irqrestore(&wf->lock, flags);
+	}
+
+	/*
+	 * If we extend a pending timer, we will only get a single timer
+	 * callback and so need to cancel the local inc by running the
+	 * elided callback to keep the wf->count balanced.
+	 */
+	if (mod_timer(&wf->timer, jiffies + timeout))
+		wakeref_auto_timeout(&wf->timer);
+}
+
+void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf)
+{
+	intel_wakeref_auto(wf, 0);
+	GEM_BUG_ON(wf->wakeref);
+}