drm/amd: add basic scheduling framework

run queue:
A set of entities scheduling commands for the same ring. It
implements the scheduling policy that selects the next entity to
emit commands from.

entity:
A scheduler entity is a wrapper around a job queue or a group of
other entities. This can be used to build hierarchies of entities.
For example all job queue entities belonging to the same process
may be placed in a higher level entity and scheduled against other
process entities.
Entities take turns emitting jobs from their job queue to the
corresponding hardware ring, in accordance with the scheduler policy.

Signed-off-by: Shaoyun Liu <Shaoyun.Liu@amd.com>
Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Signed-off-by: Jammy Zhou <Jammy.Zhou@amd.com>
Acked-by: Christian K?nig <christian.koenig@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>

1 files changed, 531 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
new file mode 100644
index 0000000..296496c
--- /dev/null
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
@@ -0,0 +1,531 @@
+/*
+ * Copyright 2015 Advanced Micro Devices, Inc.
+ *
+ * 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 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
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) 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/kthread.h>
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <drm/drmP.h>
+#include "gpu_scheduler.h"
+
+/* Initialize a given run queue struct */
+static void init_rq(struct amd_run_queue *rq)
+{
+	INIT_LIST_HEAD(&rq->head.list);
+	rq->head.belongto_rq = rq;
+	mutex_init(&rq->lock);
+	atomic_set(&rq->nr_entity, 0);
+	rq->current_entity = &rq->head;
+}
+
+/* Note: caller must hold the lock or in a atomic context */
+static void rq_remove_entity(struct amd_run_queue *rq,
+			     struct amd_sched_entity *entity)
+{
+	if (rq->current_entity == entity)
+		rq->current_entity = list_entry(entity->list.prev,
+						typeof(*entity), list);
+	list_del_init(&entity->list);
+	atomic_dec(&rq->nr_entity);
+}
+
+static void rq_add_entity(struct amd_run_queue *rq,
+			  struct amd_sched_entity *entity)
+{
+	list_add_tail(&entity->list, &rq->head.list);
+	atomic_inc(&rq->nr_entity);
+}
+
+/**
+ * Select next entity from a specified run queue with round robin policy.
+ * It could return the same entity as current one if current is the only
+ * available one in the queue. Return NULL if nothing available.
+ */
+static struct amd_sched_entity *rq_select_entity(struct amd_run_queue *rq)
+{
+	struct amd_sched_entity *p = rq->current_entity;
+	int i = atomic_read(&rq->nr_entity) + 1; /*real count + dummy head*/
+	while (i) {
+		p = list_entry(p->list.next, typeof(*p), list);
+		if (!rq->check_entity_status(p)) {
+			rq->current_entity = p;
+			break;
+		}
+		i--;
+	}
+	return i ? p : NULL;
+}
+
+static bool context_entity_is_waiting(struct amd_context_entity *entity)
+{
+	/* TODO: sync obj for multi-ring synchronization */
+	return false;
+}
+
+static int gpu_entity_check_status(struct amd_sched_entity *entity)
+{
+	struct amd_context_entity *tmp = NULL;
+
+	if (entity == &entity->belongto_rq->head)
+		return -1;
+
+	tmp = container_of(entity, typeof(*tmp), generic_entity);
+	if (kfifo_is_empty(&tmp->job_queue) ||
+	    context_entity_is_waiting(tmp))
+		return -1;
+
+	return 0;
+}
+
+/**
+ * Note: This function should only been called inside scheduler main
+ * function for thread safety, there is no other protection here.
+ * return ture if scheduler has something ready to run.
+ *
+ * For active_hw_rq, there is only one producer(scheduler thread) and
+ * one consumer(ISR). It should be safe to use this function in scheduler
+ * main thread to decide whether to continue emit more IBs.
+*/
+static bool is_scheduler_ready(struct amd_gpu_scheduler *sched)
+{
+	return !kfifo_is_full(&sched->active_hw_rq);
+}
+
+/**
+ * Select next entity from the kernel run queue, if not available,
+ * return null.
+*/
+static struct amd_context_entity *kernel_rq_select_context(
+	struct amd_gpu_scheduler *sched)
+{
+	struct amd_sched_entity *sched_entity = NULL;
+	struct amd_context_entity *tmp = NULL;
+	struct amd_run_queue *rq = &sched->kernel_rq;
+
+	mutex_lock(&rq->lock);
+	sched_entity = rq_select_entity(rq);
+	if (sched_entity)
+		tmp = container_of(sched_entity,
+				   typeof(*tmp),
+				   generic_entity);
+	mutex_unlock(&rq->lock);
+	return tmp;
+}
+
+/**
+ * Select next entity containing real IB submissions
+*/
+static struct amd_context_entity *select_context(
+	struct amd_gpu_scheduler *sched)
+{
+	struct amd_context_entity *wake_entity = NULL;
+	struct amd_context_entity *tmp;
+	struct amd_run_queue *rq;
+
+	if (!is_scheduler_ready(sched))
+		return NULL;
+
+	/* Kernel run queue has higher priority than normal run queue*/
+	tmp = kernel_rq_select_context(sched);
+	if (tmp != NULL)
+		goto exit;
+
+	WARN_ON(offsetof(struct amd_context_entity, generic_entity) != 0);
+
+	rq = &sched->sched_rq;
+	mutex_lock(&rq->lock);
+	tmp = container_of(rq_select_entity(rq),
+			   typeof(*tmp), generic_entity);
+	mutex_unlock(&rq->lock);
+exit:
+	if (sched->current_entity && (sched->current_entity != tmp))
+		wake_entity = sched->current_entity;
+	sched->current_entity = tmp;
+	if (wake_entity)
+		wake_up(&wake_entity->wait_queue);
+	return tmp;
+}
+
+/**
+ * Init a context entity used by scheduler when submit to HW ring.
+ *
+ * @sched	The pointer to the scheduler
+ * @entity	The pointer to a valid amd_context_entity
+ * @parent	The parent entity of this amd_context_entity
+ * @rq		The run queue this entity belongs
+ * @context_id	The context id for this entity
+ *
+ * return 0 if succeed. negative error code on failure
+*/
+int amd_context_entity_init(struct amd_gpu_scheduler *sched,
+			    struct amd_context_entity *entity,
+			    struct amd_sched_entity *parent,
+			    struct amd_run_queue *rq,
+			    uint32_t context_id)
+{
+	uint64_t seq_ring = 0;
+
+	if (!(sched && entity && rq))
+		return -EINVAL;
+
+	memset(entity, 0, sizeof(struct amd_context_entity));
+	seq_ring = ((uint64_t)sched->ring_id) << 60;
+	spin_lock_init(&entity->lock);
+	entity->generic_entity.belongto_rq = rq;
+	entity->generic_entity.parent = parent;
+	entity->scheduler = sched;
+	init_waitqueue_head(&entity->wait_queue);
+	init_waitqueue_head(&entity->wait_emit);
+	if(kfifo_alloc(&entity->job_queue,
+		       AMD_MAX_JOB_ENTRY_PER_CONTEXT * sizeof(void *),
+		       GFP_KERNEL))
+		return -EINVAL;
+
+	spin_lock_init(&entity->queue_lock);
+	entity->tgid = (context_id == AMD_KERNEL_CONTEXT_ID) ?
+		AMD_KERNEL_PROCESS_ID : current->tgid;
+	entity->context_id = context_id;
+	atomic64_set(&entity->last_emitted_v_seq, seq_ring);
+	atomic64_set(&entity->last_queued_v_seq, seq_ring);
+	atomic64_set(&entity->last_signaled_v_seq, seq_ring);
+
+	/* Add the entity to the run queue */
+	mutex_lock(&rq->lock);
+	rq_add_entity(rq, &entity->generic_entity);
+	mutex_unlock(&rq->lock);
+	return 0;
+}
+
+/**
+ * Query if entity is initialized
+ *
+ * @sched       Pointer to scheduler instance
+ * @entity	The pointer to a valid scheduler entity
+ *
+ * return true if entity is initialized, false otherwise
+*/
+static bool is_context_entity_initialized(struct amd_gpu_scheduler *sched,
+					  struct amd_context_entity *entity)
+{
+	return entity->scheduler == sched &&
+		entity->generic_entity.belongto_rq != NULL;
+}
+
+static bool is_context_entity_idle(struct amd_gpu_scheduler *sched,
+				   struct amd_context_entity *entity)
+{
+	/**
+	 * Idle means no pending IBs, and the entity is not
+	 * currently being used.
+	*/
+	barrier();
+	if ((sched->current_entity != entity) &&
+	    kfifo_is_empty(&entity->job_queue))
+		return true;
+
+	return false;
+}
+
+/**
+ * Destroy a context entity
+ *
+ * @sched       Pointer to scheduler instance
+ * @entity	The pointer to a valid scheduler entity
+ *
+ * return 0 if succeed. negative error code on failure
+ */
+int amd_context_entity_fini(struct amd_gpu_scheduler *sched,
+			    struct amd_context_entity *entity)
+{
+	int r = 0;
+	struct amd_run_queue *rq = entity->generic_entity.belongto_rq;
+
+	if (!is_context_entity_initialized(sched, entity))
+		return 0;
+
+	/**
+	 * The client will not queue more IBs during this fini, consume existing
+	 * queued IBs
+	*/
+	r = wait_event_timeout(
+		entity->wait_queue,
+		is_context_entity_idle(sched, entity),
+		msecs_to_jiffies(AMD_GPU_WAIT_IDLE_TIMEOUT_IN_MS)
+		) ?  0 : -1;
+
+	if (r) {
+		if (entity->is_pending)
+			DRM_INFO("Entity %u is in waiting state during fini,\
+				all pending ibs will be canceled.\n",
+				 entity->context_id);
+	}
+
+	mutex_lock(&rq->lock);
+	rq_remove_entity(rq, &entity->generic_entity);
+	mutex_unlock(&rq->lock);
+	kfifo_free(&entity->job_queue);
+	return r;
+}
+
+/**
+ * Submit a normal job to the job queue
+ *
+ * @sched	The pointer to the scheduler
+ * @c_entity    The pointer to amd_context_entity
+ * @job		The pointer to job required to submit
+ * return 0 if succeed. -1 if failed.
+ *        -2 indicate queue is full for this client, client should wait untill
+ *	     scheduler consum some queued command.
+ *	  -1 other fail.
+*/
+int amd_sched_push_job(struct amd_gpu_scheduler *sched,
+		       struct amd_context_entity *c_entity,
+		       void *job)
+{
+	while (kfifo_in_spinlocked(&c_entity->job_queue, &job, sizeof(void *),
+				   &c_entity->queue_lock) != sizeof(void *)) {
+		/**
+		 * Current context used up all its IB slots
+		 * wait here, or need to check whether GPU is hung
+		*/
+		schedule();
+	}
+
+	wake_up_interruptible(&sched->wait_queue);
+	return 0;
+}
+
+/**
+ * Check the virtual sequence number for specified context
+ *
+ * @seq		The virtual sequence number to check
+ * @c_entity	The pointer to a valid amd_context_entity
+ *
+ * return 0 if signaled, -1 else.
+*/
+int amd_sched_check_ts(struct amd_context_entity *c_entity, uint64_t seq)
+{
+	return (seq <= atomic64_read(&c_entity->last_signaled_v_seq)) ? 0 : -1;
+}
+
+/**
+ * Wait for a virtual sequence number to be signaled or timeout
+ *
+ * @c_entity	The pointer to a valid context entity
+ * @seq         The virtual sequence number to wait
+ * @intr	Interruptible or not
+ * @timeout	Timeout in ms, wait infinitely if <0
+ * @emit        wait for emit or signal
+ *
+ * return =0 signaled ,  <0 failed
+*/
+static int amd_sched_wait(struct amd_context_entity *c_entity,
+			  uint64_t seq,
+			  bool intr,
+			  long timeout,
+			  bool emit)
+{
+	atomic64_t *v_seq = emit ? &c_entity->last_emitted_v_seq :
+		&c_entity->last_signaled_v_seq;
+	wait_queue_head_t *wait_queue = emit ? &c_entity->wait_emit :
+		&c_entity->wait_queue;
+
+	if (intr && (timeout < 0)) {
+		wait_event_interruptible(
+			*wait_queue,
+			seq <= atomic64_read(v_seq));
+		return 0;
+	} else if (intr && (timeout >= 0)) {
+		wait_event_interruptible_timeout(
+			*wait_queue,
+			seq <= atomic64_read(v_seq),
+			msecs_to_jiffies(timeout));
+		return (seq <= atomic64_read(v_seq)) ?
+			0 : -1;
+	} else if (!intr && (timeout < 0)) {
+		wait_event(
+			*wait_queue,
+			seq <= atomic64_read(v_seq));
+		return 0;
+	} else if (!intr && (timeout >= 0)) {
+		wait_event_timeout(
+			*wait_queue,
+			seq <= atomic64_read(v_seq),
+			msecs_to_jiffies(timeout));
+		return (seq <= atomic64_read(v_seq)) ?
+			0 : -1;
+	}
+	return 0;
+}
+
+int amd_sched_wait_signal(struct amd_context_entity *c_entity,
+			  uint64_t seq,
+			  bool intr,
+			  long timeout)
+{
+	return amd_sched_wait(c_entity, seq, intr, timeout, false);
+}
+
+int amd_sched_wait_emit(struct amd_context_entity *c_entity,
+			uint64_t seq,
+			bool intr,
+			long timeout)
+{
+	return amd_sched_wait(c_entity, seq, intr, timeout, true);
+}
+
+static int amd_sched_main(void *param)
+{
+	int r;
+	void *job;
+	struct sched_param sparam = {.sched_priority = 1};
+	struct amd_context_entity *c_entity = NULL;
+	struct amd_gpu_scheduler *sched = (struct amd_gpu_scheduler *)param;
+
+	sched_setscheduler(current, SCHED_FIFO, &sparam);
+
+	while (!kthread_should_stop()) {
+		wait_event_interruptible(sched->wait_queue,
+					 is_scheduler_ready(sched) &&
+					 (c_entity = select_context(sched)));
+		r = kfifo_out(&c_entity->job_queue, &job, sizeof(void *));
+		if (r != sizeof(void *))
+			continue;
+		r = sched->ops->prepare_job(sched, c_entity, job);
+		if (!r)
+			WARN_ON(kfifo_in_spinlocked(
+					&sched->active_hw_rq,
+					&job,
+					sizeof(void *),
+					&sched->queue_lock) != sizeof(void *));
+		mutex_lock(&sched->sched_lock);
+		sched->ops->run_job(sched, c_entity, job);
+		mutex_unlock(&sched->sched_lock);
+	}
+	return 0;
+}
+
+uint64_t amd_sched_get_handled_seq(struct amd_gpu_scheduler *sched)
+{
+	return sched->last_handled_seq;
+}
+
+/**
+ * ISR to handle EOP inetrrupts
+ *
+ * @sched: gpu scheduler
+ *
+*/
+void amd_sched_isr(struct amd_gpu_scheduler *sched)
+{
+	int r;
+	void *job;
+	r = kfifo_out_spinlocked(&sched->active_hw_rq,
+				 &job, sizeof(void *),
+				 &sched->queue_lock);
+
+	if (r != sizeof(void *))
+		job = NULL;
+
+	sched->ops->process_job(sched, job);
+	sched->last_handled_seq++;
+	wake_up_interruptible(&sched->wait_queue);
+}
+
+/**
+ * Create a gpu scheduler
+ *
+ * @device	The device context for this scheduler
+ * @ops		The backend operations for this scheduler.
+ * @id	        The scheduler is per ring, here is ring id.
+ * @granularity	The minumum ms unit the scheduler will scheduled.
+ * @preemption  Indicate whether this ring support preemption, 0 is no.
+ *
+ * return the pointer to scheduler for success, otherwise return NULL
+*/
+struct amd_gpu_scheduler *amd_sched_create(void *device,
+					   struct amd_sched_backend_ops *ops,
+					   unsigned ring,
+					   unsigned granularity,
+					   unsigned preemption)
+{
+	struct amd_gpu_scheduler *sched;
+	char name[20] = "gpu_sched[0]";
+
+	sched = kzalloc(sizeof(struct amd_gpu_scheduler), GFP_KERNEL);
+	if (!sched)
+		return NULL;
+
+	sched->device = device;
+	sched->ops = ops;
+	sched->granularity = granularity;
+	sched->ring_id = ring;
+	sched->preemption = preemption;
+	sched->last_handled_seq = 0;
+
+	snprintf(name, sizeof(name), "gpu_sched[%d]", ring);
+	mutex_init(&sched->sched_lock);
+	spin_lock_init(&sched->queue_lock);
+	init_rq(&sched->sched_rq);
+	sched->sched_rq.check_entity_status = gpu_entity_check_status;
+
+	init_rq(&sched->kernel_rq);
+	sched->kernel_rq.check_entity_status = gpu_entity_check_status;
+
+	init_waitqueue_head(&sched->wait_queue);
+	if(kfifo_alloc(&sched->active_hw_rq,
+		       AMD_MAX_ACTIVE_HW_SUBMISSION * sizeof(void *),
+		       GFP_KERNEL)) {
+		kfree(sched);
+		return NULL;
+	}
+
+	/* Each scheduler will run on a seperate kernel thread */
+	sched->thread = kthread_create(amd_sched_main, sched, name);
+	if (sched->thread) {
+		wake_up_process(sched->thread);
+		DRM_INFO("Create gpu scheduler for id %d successfully.\n",
+			 ring);
+		return sched;
+	}
+
+	DRM_ERROR("Failed to create scheduler for id %d.\n", ring);
+	kfifo_free(&sched->active_hw_rq);
+	kfree(sched);
+	return NULL;
+}
+
+/**
+ * Destroy a gpu scheduler
+ *
+ * @sched	The pointer to the scheduler
+ *
+ * return 0 if succeed. -1 if failed.
+ */
+int amd_sched_destroy(struct amd_gpu_scheduler *sched)
+{
+	kthread_stop(sched->thread);
+	kfifo_free(&sched->active_hw_rq);
+	kfree(sched);
+	return  0;
+}
+