1 files changed, 294 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
new file mode 100644
index 000000000..4f4c2e15e
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -0,0 +1,294 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef INTEL_WAKEREF_H
+#define INTEL_WAKEREF_H
+
+#include <linux/atomic.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/lockdep.h>
+#include <linux/mutex.h>
+#include <linux/refcount.h>
+#include <linux/stackdepot.h>
+#include <linux/timer.h>
+#include <linux/workqueue.h>
+
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
+#define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
+#else
+#define INTEL_WAKEREF_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
+#endif
+
+struct intel_runtime_pm;
+struct intel_wakeref;
+
+typedef depot_stack_handle_t intel_wakeref_t;
+
+struct intel_wakeref_ops {
+	int (*get)(struct intel_wakeref *wf);
+	int (*put)(struct intel_wakeref *wf);
+};
+
+struct intel_wakeref {
+	atomic_t count;
+	struct mutex mutex;
+
+	intel_wakeref_t wakeref;
+
+	struct intel_runtime_pm *rpm;
+	const struct intel_wakeref_ops *ops;
+
+	struct delayed_work work;
+};
+
+struct intel_wakeref_lockclass {
+	struct lock_class_key mutex;
+	struct lock_class_key work;
+};
+
+void __intel_wakeref_init(struct intel_wakeref *wf,
+			  struct intel_runtime_pm *rpm,
+			  const struct intel_wakeref_ops *ops,
+			  struct intel_wakeref_lockclass *key);
+#define intel_wakeref_init(wf, rpm, ops) do {				\
+	static struct intel_wakeref_lockclass __key;			\
+									\
+	__intel_wakeref_init((wf), (rpm), (ops), &__key);		\
+} while (0)
+
+int __intel_wakeref_get_first(struct intel_wakeref *wf);
+void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
+
+/**
+ * intel_wakeref_get: Acquire the wakeref
+ * @wf: the wakeref
+ *
+ * Acquire a hold on the wakeref. The first user to do so, will acquire
+ * the runtime pm wakeref and then call the @fn underneath the wakeref
+ * mutex.
+ *
+ * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
+ * will be released and the acquisition unwound, and an error reported.
+ *
+ * Returns: 0 if the wakeref was acquired successfully, or a negative error
+ * code otherwise.
+ */
+static inline int
+intel_wakeref_get(struct intel_wakeref *wf)
+{
+	might_sleep();
+	if (unlikely(!atomic_inc_not_zero(&wf->count)))
+		return __intel_wakeref_get_first(wf);
+
+	return 0;
+}
+
+/**
+ * __intel_wakeref_get: Acquire the wakeref, again
+ * @wf: the wakeref
+ *
+ * Increment the wakeref counter, only valid if it is already held by
+ * the caller.
+ *
+ * See intel_wakeref_get().
+ */
+static inline void
+__intel_wakeref_get(struct intel_wakeref *wf)
+{
+	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
+	atomic_inc(&wf->count);
+}
+
+/**
+ * intel_wakeref_get_if_in_use: Acquire the wakeref
+ * @wf: the wakeref
+ *
+ * Acquire a hold on the wakeref, but only if the wakeref is already
+ * active.
+ *
+ * Returns: true if the wakeref was acquired, false otherwise.
+ */
+static inline bool
+intel_wakeref_get_if_active(struct intel_wakeref *wf)
+{
+	return atomic_inc_not_zero(&wf->count);
+}
+
+enum {
+	INTEL_WAKEREF_PUT_ASYNC_BIT = 0,
+	__INTEL_WAKEREF_PUT_LAST_BIT__
+};
+
+static inline void
+intel_wakeref_might_get(struct intel_wakeref *wf)
+{
+	might_lock(&wf->mutex);
+}
+
+/**
+ * intel_wakeref_put_flags: Release the wakeref
+ * @wf: the wakeref
+ * @flags: control flags
+ *
+ * Release our hold on the wakeref. When there are no more users,
+ * the runtime pm wakeref will be released after the @fn callback is called
+ * underneath the wakeref mutex.
+ *
+ * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
+ * is retained and an error reported.
+ *
+ * Returns: 0 if the wakeref was released successfully, or a negative error
+ * code otherwise.
+ */
+static inline void
+__intel_wakeref_put(struct intel_wakeref *wf, unsigned long flags)
+#define INTEL_WAKEREF_PUT_ASYNC BIT(INTEL_WAKEREF_PUT_ASYNC_BIT)
+#define INTEL_WAKEREF_PUT_DELAY \
+	GENMASK(BITS_PER_LONG - 1, __INTEL_WAKEREF_PUT_LAST_BIT__)
+{
+	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
+	if (unlikely(!atomic_add_unless(&wf->count, -1, 1)))
+		__intel_wakeref_put_last(wf, flags);
+}
+
+static inline void
+intel_wakeref_put(struct intel_wakeref *wf)
+{
+	might_sleep();
+	__intel_wakeref_put(wf, 0);
+}
+
+static inline void
+intel_wakeref_put_async(struct intel_wakeref *wf)
+{
+	__intel_wakeref_put(wf, INTEL_WAKEREF_PUT_ASYNC);
+}
+
+static inline void
+intel_wakeref_put_delay(struct intel_wakeref *wf, unsigned long delay)
+{
+	__intel_wakeref_put(wf,
+			    INTEL_WAKEREF_PUT_ASYNC |
+			    FIELD_PREP(INTEL_WAKEREF_PUT_DELAY, delay));
+}
+
+static inline void
+intel_wakeref_might_put(struct intel_wakeref *wf)
+{
+	might_lock(&wf->mutex);
+}
+
+/**
+ * intel_wakeref_lock: Lock the wakeref (mutex)
+ * @wf: the wakeref
+ *
+ * Locks the wakeref to prevent it being acquired or released. New users
+ * can still adjust the counter, but the wakeref itself (and callback)
+ * cannot be acquired or released.
+ */
+static inline void
+intel_wakeref_lock(struct intel_wakeref *wf)
+	__acquires(wf->mutex)
+{
+	mutex_lock(&wf->mutex);
+}
+
+/**
+ * intel_wakeref_unlock: Unlock the wakeref
+ * @wf: the wakeref
+ *
+ * Releases a previously acquired intel_wakeref_lock().
+ */
+static inline void
+intel_wakeref_unlock(struct intel_wakeref *wf)
+	__releases(wf->mutex)
+{
+	mutex_unlock(&wf->mutex);
+}
+
+/**
+ * intel_wakeref_unlock_wait: Wait until the active callback is complete
+ * @wf: the wakeref
+ *
+ * Waits for the active callback (under the @wf->mutex or another CPU) is
+ * complete.
+ */
+static inline void
+intel_wakeref_unlock_wait(struct intel_wakeref *wf)
+{
+	mutex_lock(&wf->mutex);
+	mutex_unlock(&wf->mutex);
+	flush_delayed_work(&wf->work);
+}
+
+/**
+ * intel_wakeref_is_active: Query whether the wakeref is currently held
+ * @wf: the wakeref
+ *
+ * Returns: true if the wakeref is currently held.
+ */
+static inline bool
+intel_wakeref_is_active(const struct intel_wakeref *wf)
+{
+	return READ_ONCE(wf->wakeref);
+}
+
+/**
+ * __intel_wakeref_defer_park: Defer the current park callback
+ * @wf: the wakeref
+ */
+static inline void
+__intel_wakeref_defer_park(struct intel_wakeref *wf)
+{
+	lockdep_assert_held(&wf->mutex);
+	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count));
+	atomic_set_release(&wf->count, 1);
+}
+
+/**
+ * intel_wakeref_wait_for_idle: Wait until the wakeref is idle
+ * @wf: the wakeref
+ *
+ * Wait for the earlier asynchronous release of the wakeref. Note
+ * this will wait for any third party as well, so make sure you only wait
+ * when you have control over the wakeref and trust no one else is acquiring
+ * it.
+ *
+ * Return: 0 on success, error code if killed.
+ */
+int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
+
+struct intel_wakeref_auto {
+	struct intel_runtime_pm *rpm;
+	struct timer_list timer;
+	intel_wakeref_t wakeref;
+	spinlock_t lock;
+	refcount_t count;
+};
+
+/**
+ * intel_wakeref_auto: Delay the runtime-pm autosuspend
+ * @wf: the wakeref
+ * @timeout: relative timeout in jiffies
+ *
+ * The runtime-pm core uses a suspend delay after the last wakeref
+ * is released before triggering runtime suspend of the device. That
+ * delay is configurable via sysfs with little regard to the device
+ * characteristics. Instead, we want to tune the autosuspend based on our
+ * HW knowledge. intel_wakeref_auto() delays the sleep by the supplied
+ * timeout.
+ *
+ * Pass @timeout = 0 to cancel a previous autosuspend by executing the
+ * suspend immediately.
+ */
+void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout);
+
+void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
+			     struct intel_runtime_pm *rpm);
+void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
+
+#endif /* INTEL_WAKEREF_H */