[PATCH 2/6] drm/xe: Add generic dependecy jobs / scheduler

[Matthew Brost]

Add generic dependecy jobs / scheduler which serves as wrapper for DRM
scheduler. Useful when we want delay a generic operation until a
dma-fence signals.

Existing use cases could be destroying of resources based fences /
dma-resv, the preempt rebind worker, and pipelined GT TLB invalidations.

Written in such a way it could be moved to DRM subsystem if needed.

Signed-off-by: Matthew Brost <matthew.brost at intel.com>
---
 drivers/gpu/drm/xe/Makefile           |   1 +
 drivers/gpu/drm/xe/xe_dep_job_types.h |  29 ++++++
 drivers/gpu/drm/xe/xe_dep_scheduler.c | 145 ++++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_dep_scheduler.h |  21 ++++
 4 files changed, 196 insertions(+)
 create mode 100644 drivers/gpu/drm/xe/xe_dep_job_types.h
 create mode 100644 drivers/gpu/drm/xe/xe_dep_scheduler.c
 create mode 100644 drivers/gpu/drm/xe/xe_dep_scheduler.h

diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
index f5f5775acdc0..3523bd093b7a 100644
--- a/drivers/gpu/drm/xe/Makefile
+++ b/drivers/gpu/drm/xe/Makefile
@@ -28,6 +28,7 @@ $(obj)/generated/%_wa_oob.c $(obj)/generated/%_wa_oob.h: $(obj)/xe_gen_wa_oob \
 xe-y += xe_bb.o \
 	xe_bo.o \
 	xe_bo_evict.o \
+	xe_dep_scheduler.o \
 	xe_devcoredump.o \
 	xe_device.o \
 	xe_device_sysfs.o \
diff --git a/drivers/gpu/drm/xe/xe_dep_job_types.h b/drivers/gpu/drm/xe/xe_dep_job_types.h
new file mode 100644
index 000000000000..c6a484f24c8c
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_dep_job_types.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2025 Intel Corporation
+ */
+
+#ifndef _XE_DEP_JOB_TYPES_H_
+#define _XE_DEP_JOB_TYPES_H_
+
+#include <drm/gpu_scheduler.h>
+
+struct xe_dep_job;
+
+/** struct xe_dep_job_ops - Generic Xe dependency job operations */
+struct xe_dep_job_ops {
+	/** @run_job: Run generic Xe dependency job */
+	struct dma_fence *(*run_job)(struct xe_dep_job *job);
+	/** @free_job: Free generic Xe dependency job */
+	void (*free_job)(struct xe_dep_job *job);
+};
+
+/** struct xe_dep_job - Generic dependency Xe job */
+struct xe_dep_job {
+	/** @drm: base DRM scheduler job */
+	struct drm_sched_job drm;
+	/** @ops: dependency job operations */
+	const struct xe_dep_job_ops *ops;
+};
+
+#endif
diff --git a/drivers/gpu/drm/xe/xe_dep_scheduler.c b/drivers/gpu/drm/xe/xe_dep_scheduler.c
new file mode 100644
index 000000000000..fbd55577d787
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_dep_scheduler.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2025 Intel Corporation
+ */
+
+#include <linux/slab.h>
+
+#include <drm/gpu_scheduler.h>
+
+#include "xe_dep_job_types.h"
+#include "xe_dep_scheduler.h"
+#include "xe_device_types.h"
+
+/**
+ * DOC: Xe Dependency Scheduler
+ *
+ * The Xe dependency scheduler is a simple wrapper built around the DRM
+ * scheduler to execute jobs once their dependencies are resolved (i.e., all
+ * input fences specified as dependencies are signaled). The jobs that are
+ * executed contain virtual functions to run (execute) and free the job,
+ * allowing a single dependency scheduler to handle jobs performing different
+ * operations.
+ *
+ * Example use cases include deferred resource freeing, TLB invalidations after
+ * bind jobs, etc.
+ */
+
+/** struct xe_dep_scheduler - Generic Xe dependency scheduler */
+struct xe_dep_scheduler {
+	/** @sched: DRM GPU scheduler */
+	struct drm_gpu_scheduler sched;
+	/** @entity: DRM scheduler entity  */
+	struct drm_sched_entity entity;
+	/** @rcu: For safe freeing of exported dma fences */
+	struct rcu_head rcu;
+};
+
+static struct dma_fence *xe_dep_scheduler_run_job(struct drm_sched_job *drm_job)
+{
+	struct xe_dep_job *dep_job =
+		container_of(drm_job, typeof(*dep_job), drm);
+
+	return dep_job->ops->run_job(dep_job);
+}
+
+static void xe_dep_scheduler_free_job(struct drm_sched_job *drm_job)
+{
+	struct xe_dep_job *dep_job =
+		container_of(drm_job, typeof(*dep_job), drm);
+
+	dep_job->ops->free_job(dep_job);
+}
+
+static const struct drm_sched_backend_ops sched_ops = {
+	.run_job = xe_dep_scheduler_run_job,
+	.free_job = xe_dep_scheduler_free_job,
+};
+
+/**
+ * xe_dep_scheduler_create() - Generic Xe dependency scheduler create
+ * @xe: Xe device
+ * @submit_wq: Submit workqueue struct (can be NULL)
+ * @name: Name of dependency scheduler
+ * @job_limit: Max dependency jobs that can be scheduled
+ *
+ * Create a generic Xe dependency scheduler and initialize internal DRM
+ * scheduler objects.
+ *
+ * Return: Generic Xe dependency scheduler object or ERR_PTR
+ */
+struct xe_dep_scheduler *
+xe_dep_scheduler_create(struct xe_device *xe,
+			struct workqueue_struct *submit_wq,
+			const char *name, u32 job_limit)
+{
+	struct xe_dep_scheduler *dep_scheduler;
+	struct drm_gpu_scheduler *sched;
+	const struct drm_sched_init_args args = {
+		.ops = &sched_ops,
+		.submit_wq = submit_wq,
+		.num_rqs = 1,
+		.credit_limit = job_limit,
+		.timeout = MAX_SCHEDULE_TIMEOUT,
+		.name = name,
+		.dev = xe->drm.dev,
+	};
+	int err;
+
+	dep_scheduler = kzalloc(sizeof(*dep_scheduler), GFP_KERNEL);
+	if (!dep_scheduler)
+		return ERR_PTR(-ENOMEM);
+
+	err = drm_sched_init(&dep_scheduler->sched, &args);
+	if (err)
+		goto err_free;
+
+	sched = &dep_scheduler->sched;
+	err = drm_sched_entity_init(&dep_scheduler->entity, 0,
+				    (struct drm_gpu_scheduler **)&sched, 1,
+				    NULL);
+	if (err)
+		goto err_sched;
+
+	init_rcu_head(&dep_scheduler->rcu);
+
+	return dep_scheduler;
+
+err_sched:
+	drm_sched_fini(&dep_scheduler->sched);
+err_free:
+	kfree(dep_scheduler);
+
+	return ERR_PTR(err);
+}
+
+/**
+ * xe_dep_scheduler_fini() - Generic Xe dependency scheduler finalize
+ * @dep_scheduler: Generic Xe dependency scheduler object
+ *
+ * Finalize internal DRM scheduler objects and free generic Xe dependency
+ * scheduler object
+ */
+void xe_dep_scheduler_fini(struct xe_dep_scheduler *dep_scheduler)
+{
+	drm_sched_entity_fini(&dep_scheduler->entity);
+	drm_sched_fini(&dep_scheduler->sched);
+	/*
+	 * RCU free due sched being exported via DRM scheduler fences
+	 * (timeline name).
+	 */
+	kfree_rcu(dep_scheduler, rcu);
+}
+
+/**
+ * xe_dep_scheduler_entity() - Retrieve a generic Xe dependency scheduler
+ *                             DRM scheduler entity
+ * @dep_scheduler: Generic Xe dependency scheduler object
+ *
+ * Return: The generic Xe dependency scheduler's DRM scheduler entity
+ */
+struct drm_sched_entity *
+xe_dep_scheduler_entity(struct xe_dep_scheduler *dep_scheduler)
+{
+	return &dep_scheduler->entity;
+}
diff --git a/drivers/gpu/drm/xe/xe_dep_scheduler.h b/drivers/gpu/drm/xe/xe_dep_scheduler.h
new file mode 100644
index 000000000000..853961eec64b
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_dep_scheduler.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2025 Intel Corporation
+ */
+
+#include <linux/types.h>
+
+struct drm_sched_entity;
+struct workqueue_struct;
+struct xe_dep_scheduler;
+struct xe_device;
+
+struct xe_dep_scheduler *
+xe_dep_scheduler_create(struct xe_device *xe,
+			struct workqueue_struct *submit_wq,
+			const char *name, u32 job_limit);
+
+void xe_dep_scheduler_fini(struct xe_dep_scheduler *dep_scheduler);
+
+struct drm_sched_entity *
+xe_dep_scheduler_entity(struct xe_dep_scheduler *dep_scheduler);
-- 
2.34.1