1 files changed, 304 insertions, 0 deletions
diff --git a/drivers/gpu/drm/msm/adreno/a5xx_preempt.c b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
new file mode 100644
index 000000000000..970c7963ae29
--- /dev/null
+++ b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
@@ -0,0 +1,304 @@
+/* Copyright (c) 2017 The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include "msm_gem.h"
+#include "a5xx_gpu.h"
+
+/*
+ * Try to transition the preemption state from old to new. Return
+ * true on success or false if the original state wasn't 'old'
+ */
+static inline bool try_preempt_state(struct a5xx_gpu *a5xx_gpu,
+		enum preempt_state old, enum preempt_state new)
+{
+	enum preempt_state cur = atomic_cmpxchg(&a5xx_gpu->preempt_state,
+		old, new);
+
+	return (cur == old);
+}
+
+/*
+ * Force the preemption state to the specified state.  This is used in cases
+ * where the current state is known and won't change
+ */
+static inline void set_preempt_state(struct a5xx_gpu *gpu,
+		enum preempt_state new)
+{
+	/*
+	 * preempt_state may be read by other cores trying to trigger a
+	 * preemption or in the interrupt handler so barriers are needed
+	 * before...
+	 */
+	smp_mb__before_atomic();
+	atomic_set(&gpu->preempt_state, new);
+	/* ... and after*/
+	smp_mb__after_atomic();
+}
+
+/* Write the most recent wptr for the given ring into the hardware */
+static inline void update_wptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
+{
+	unsigned long flags;
+	uint32_t wptr;
+
+	if (!ring)
+		return;
+
+	spin_lock_irqsave(&ring->lock, flags);
+	wptr = get_wptr(ring);
+	spin_unlock_irqrestore(&ring->lock, flags);
+
+	gpu_write(gpu, REG_A5XX_CP_RB_WPTR, wptr);
+}
+
+/* Return the highest priority ringbuffer with something in it */
+static struct msm_ringbuffer *get_next_ring(struct msm_gpu *gpu)
+{
+	unsigned long flags;
+	int i;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		bool empty;
+		struct msm_ringbuffer *ring = gpu->rb[i];
+
+		spin_lock_irqsave(&ring->lock, flags);
+		empty = (get_wptr(ring) == ring->memptrs->rptr);
+		spin_unlock_irqrestore(&ring->lock, flags);
+
+		if (!empty)
+			return ring;
+	}
+
+	return NULL;
+}
+
+static void a5xx_preempt_timer(struct timer_list *t)
+{
+	struct a5xx_gpu *a5xx_gpu = from_timer(a5xx_gpu, t, preempt_timer);
+	struct msm_gpu *gpu = &a5xx_gpu->base.base;
+	struct drm_device *dev = gpu->dev;
+	struct msm_drm_private *priv = dev->dev_private;
+
+	if (!try_preempt_state(a5xx_gpu, PREEMPT_TRIGGERED, PREEMPT_FAULTED))
+		return;
+
+	dev_err(dev->dev, "%s: preemption timed out\n", gpu->name);
+	queue_work(priv->wq, &gpu->recover_work);
+}
+
+/* Try to trigger a preemption switch */
+void a5xx_preempt_trigger(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a5xx_gpu *a5xx_gpu = to_a5xx_gpu(adreno_gpu);
+	unsigned long flags;
+	struct msm_ringbuffer *ring;
+
+	if (gpu->nr_rings == 1)
+		return;
+
+	/*
+	 * Try to start preemption by moving from NONE to START. If
+	 * unsuccessful, a preemption is already in flight
+	 */
+	if (!try_preempt_state(a5xx_gpu, PREEMPT_NONE, PREEMPT_START))
+		return;
+
+	/* Get the next ring to preempt to */
+	ring = get_next_ring(gpu);
+
+	/*
+	 * If no ring is populated or the highest priority ring is the current
+	 * one do nothing except to update the wptr to the latest and greatest
+	 */
+	if (!ring || (a5xx_gpu->cur_ring == ring)) {
+		/*
+		 * Its possible that while a preemption request is in progress
+		 * from an irq context, a user context trying to submit might
+		 * fail to update the write pointer, because it determines
+		 * that the preempt state is not PREEMPT_NONE.
+		 *
+		 * Close the race by introducing an intermediate
+		 * state PREEMPT_ABORT to let the submit path
+		 * know that the ringbuffer is not going to change
+		 * and can safely update the write pointer.
+		 */
+
+		set_preempt_state(a5xx_gpu, PREEMPT_ABORT);
+		update_wptr(gpu, a5xx_gpu->cur_ring);
+		set_preempt_state(a5xx_gpu, PREEMPT_NONE);
+		return;
+	}
+
+	/* Make sure the wptr doesn't update while we're in motion */
+	spin_lock_irqsave(&ring->lock, flags);
+	a5xx_gpu->preempt[ring->id]->wptr = get_wptr(ring);
+	spin_unlock_irqrestore(&ring->lock, flags);
+
+	/* Set the address of the incoming preemption record */
+	gpu_write64(gpu, REG_A5XX_CP_CONTEXT_SWITCH_RESTORE_ADDR_LO,
+		REG_A5XX_CP_CONTEXT_SWITCH_RESTORE_ADDR_HI,
+		a5xx_gpu->preempt_iova[ring->id]);
+
+	a5xx_gpu->next_ring = ring;
+
+	/* Start a timer to catch a stuck preemption */
+	mod_timer(&a5xx_gpu->preempt_timer, jiffies + msecs_to_jiffies(10000));
+
+	/* Set the preemption state to triggered */
+	set_preempt_state(a5xx_gpu, PREEMPT_TRIGGERED);
+
+	/* Make sure everything is written before hitting the button */
+	wmb();
+
+	/* And actually start the preemption */
+	gpu_write(gpu, REG_A5XX_CP_CONTEXT_SWITCH_CNTL, 1);
+}
+
+void a5xx_preempt_irq(struct msm_gpu *gpu)
+{
+	uint32_t status;
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a5xx_gpu *a5xx_gpu = to_a5xx_gpu(adreno_gpu);
+	struct drm_device *dev = gpu->dev;
+	struct msm_drm_private *priv = dev->dev_private;
+
+	if (!try_preempt_state(a5xx_gpu, PREEMPT_TRIGGERED, PREEMPT_PENDING))
+		return;
+
+	/* Delete the preemption watchdog timer */
+	del_timer(&a5xx_gpu->preempt_timer);
+
+	/*
+	 * The hardware should be setting CP_CONTEXT_SWITCH_CNTL to zero before
+	 * firing the interrupt, but there is a non zero chance of a hardware
+	 * condition or a software race that could set it again before we have a
+	 * chance to finish. If that happens, log and go for recovery
+	 */
+	status = gpu_read(gpu, REG_A5XX_CP_CONTEXT_SWITCH_CNTL);
+	if (unlikely(status)) {
+		set_preempt_state(a5xx_gpu, PREEMPT_FAULTED);
+		dev_err(dev->dev, "%s: Preemption failed to complete\n",
+			gpu->name);
+		queue_work(priv->wq, &gpu->recover_work);
+		return;
+	}
+
+	a5xx_gpu->cur_ring = a5xx_gpu->next_ring;
+	a5xx_gpu->next_ring = NULL;
+
+	update_wptr(gpu, a5xx_gpu->cur_ring);
+
+	set_preempt_state(a5xx_gpu, PREEMPT_NONE);
+}
+
+void a5xx_preempt_hw_init(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a5xx_gpu *a5xx_gpu = to_a5xx_gpu(adreno_gpu);
+	int i;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		a5xx_gpu->preempt[i]->wptr = 0;
+		a5xx_gpu->preempt[i]->rptr = 0;
+		a5xx_gpu->preempt[i]->rbase = gpu->rb[i]->iova;
+	}
+
+	/* Write a 0 to signal that we aren't switching pagetables */
+	gpu_write64(gpu, REG_A5XX_CP_CONTEXT_SWITCH_SMMU_INFO_LO,
+		REG_A5XX_CP_CONTEXT_SWITCH_SMMU_INFO_HI, 0);
+
+	/* Reset the preemption state */
+	set_preempt_state(a5xx_gpu, PREEMPT_NONE);
+
+	/* Always come up on rb 0 */
+	a5xx_gpu->cur_ring = gpu->rb[0];
+}
+
+static int preempt_init_ring(struct a5xx_gpu *a5xx_gpu,
+		struct msm_ringbuffer *ring)
+{
+	struct adreno_gpu *adreno_gpu = &a5xx_gpu->base;
+	struct msm_gpu *gpu = &adreno_gpu->base;
+	struct a5xx_preempt_record *ptr;
+	struct drm_gem_object *bo = NULL;
+	u64 iova = 0;
+
+	ptr = msm_gem_kernel_new(gpu->dev,
+		A5XX_PREEMPT_RECORD_SIZE + A5XX_PREEMPT_COUNTER_SIZE,
+		MSM_BO_UNCACHED, gpu->aspace, &bo, &iova);
+
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	a5xx_gpu->preempt_bo[ring->id] = bo;
+	a5xx_gpu->preempt_iova[ring->id] = iova;
+	a5xx_gpu->preempt[ring->id] = ptr;
+
+	/* Set up the defaults on the preemption record */
+
+	ptr->magic = A5XX_PREEMPT_RECORD_MAGIC;
+	ptr->info = 0;
+	ptr->data = 0;
+	ptr->cntl = MSM_GPU_RB_CNTL_DEFAULT;
+	ptr->rptr_addr = rbmemptr(ring, rptr);
+	ptr->counter = iova + A5XX_PREEMPT_RECORD_SIZE;
+
+	return 0;
+}
+
+void a5xx_preempt_fini(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a5xx_gpu *a5xx_gpu = to_a5xx_gpu(adreno_gpu);
+	int i;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		if (!a5xx_gpu->preempt_bo[i])
+			continue;
+
+		msm_gem_put_vaddr(a5xx_gpu->preempt_bo[i]);
+
+		if (a5xx_gpu->preempt_iova[i])
+			msm_gem_put_iova(a5xx_gpu->preempt_bo[i], gpu->aspace);
+
+		drm_gem_object_unreference(a5xx_gpu->preempt_bo[i]);
+		a5xx_gpu->preempt_bo[i] = NULL;
+	}
+}
+
+void a5xx_preempt_init(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a5xx_gpu *a5xx_gpu = to_a5xx_gpu(adreno_gpu);
+	int i;
+
+	/* No preemption if we only have one ring */
+	if (gpu->nr_rings <= 1)
+		return;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		if (preempt_init_ring(a5xx_gpu, gpu->rb[i])) {
+			/*
+			 * On any failure our adventure is over. Clean up and
+			 * set nr_rings to 1 to force preemption off
+			 */
+			a5xx_preempt_fini(gpu);
+			gpu->nr_rings = 1;
+
+			return;
+		}
+	}
+
+	timer_setup(&a5xx_gpu->preempt_timer, a5xx_preempt_timer, 0);
+}