+/* Algorithm:
+ *
+ * We store the last allocated bo in "hole", we always try to allocate
+ * after the last allocated bo. Principle is that in a linear GPU ring
+ * progression was is after last is the oldest bo we allocated and
thus
+ * the first one that should no longer be in use by the GPU.
+ *
+ * If it's not the case we skip over the bo after last to the closest
+ * done bo if such one exist. If none exist and we are not asked to
+ * block we report failure to allocate.
+ *
+ * If we are asked to block we wait on all the oldest fence of all
+ * rings. We just wait for any of those fence to complete.
+ */
+
+#include <drm/drm_suballoc.h>
+#include <drm/drm_print.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/dma-fence.h>
+
+static void drm_suballoc_remove_locked(struct drm_suballoc *sa);
+static void drm_suballoc_try_free(struct drm_suballoc_manager
*sa_manager);
+
+/**
+ * drm_suballoc_manager_init() - Initialise the drm_suballoc_manager
+ * @sa_manager: pointer to the sa_manager
+ * @size: number of bytes we want to suballocate
+ * @align: alignment for each suballocated chunk
+ *
+ * Prepares the suballocation manager for suballocations.
+ */
+void drm_suballoc_manager_init(struct drm_suballoc_manager
*sa_manager,
+ u64 size, u64 align)
+{
+ unsigned int i;
+
+ if (!align)
+ align = 1;
+
+ /* alignment must be a power of 2 */
+ if (WARN_ON_ONCE(align & (align - 1)))
+ align = roundup_pow_of_two(align);
+
+ init_waitqueue_head(&sa_manager->wq);
+ sa_manager->size = size;
+ sa_manager->align = align;
+ sa_manager->hole = &sa_manager->olist;
+ INIT_LIST_HEAD(&sa_manager->olist);
+ for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
+ INIT_LIST_HEAD(&sa_manager->flist[i]);
+}
+EXPORT_SYMBOL(drm_suballoc_manager_init);
+
+/**
+ * drm_suballoc_manager_fini() - Destroy the drm_suballoc_manager
+ * @sa_manager: pointer to the sa_manager
+ *
+ * Cleans up the suballocation manager after use. All fences added
+ * with drm_suballoc_free() must be signaled, or we cannot clean up
+ * the entire manager.
+ */
+void drm_suballoc_manager_fini(struct drm_suballoc_manager
*sa_manager)
+{
+ struct drm_suballoc *sa, *tmp;
+
+ if (!sa_manager->size)
+ return;
+
+ if (!list_empty(&sa_manager->olist)) {
+ sa_manager->hole = &sa_manager->olist;
+ drm_suballoc_try_free(sa_manager);
+ if (!list_empty(&sa_manager->olist))
+ DRM_ERROR("sa_manager is not empty, clearing anyway\n");
+ }
+ list_for_each_entry_safe(sa, tmp, &sa_manager->olist, olist) {
+ drm_suballoc_remove_locked(sa);
+ }
+
+ sa_manager->size = 0;
+}
+EXPORT_SYMBOL(drm_suballoc_manager_fini);
+
+static void drm_suballoc_remove_locked(struct drm_suballoc *sa)
+{
+ struct drm_suballoc_manager *sa_manager = sa->manager;
+
+ if (sa_manager->hole == &sa->olist)
+ sa_manager->hole = sa->olist.prev;
+
+ list_del_init(&sa->olist);
+ list_del_init(&sa->flist);
+ dma_fence_put(sa->fence);
+ kfree(sa);
+}
+
+static void drm_suballoc_try_free(struct drm_suballoc_manager
*sa_manager)
+{
+ struct drm_suballoc *sa, *tmp;
+
+ if (sa_manager->hole->next == &sa_manager->olist)
+ return;
+
+ sa = list_entry(sa_manager->hole->next, struct drm_suballoc,
olist);
+ list_for_each_entry_safe_from(sa, tmp, &sa_manager->olist,
olist) {
+ if (!sa->fence || !dma_fence_is_signaled(sa->fence))
+ return;
+
+ drm_suballoc_remove_locked(sa);
+ }
+}
+
+static u64 drm_suballoc_hole_soffset(struct drm_suballoc_manager
*sa_manager)
+{
+ struct list_head *hole = sa_manager->hole;
+
+ if (hole != &sa_manager->olist)
+ return list_entry(hole, struct drm_suballoc, olist)->eoffset;
+
+ return 0;
+}
+
+static u64 drm_suballoc_hole_eoffset(struct drm_suballoc_manager
*sa_manager)
+{
+ struct list_head *hole = sa_manager->hole;
+
+ if (hole->next != &sa_manager->olist)
+ return list_entry(hole->next, struct drm_suballoc,
olist)->soffset;
+ return sa_manager->size;
+}
+
+static bool drm_suballoc_try_alloc(struct drm_suballoc_manager
*sa_manager,
+ struct drm_suballoc *sa,
+ u64 size, u64 align)
+{
+ u64 soffset, eoffset, wasted;
+
+ soffset = drm_suballoc_hole_soffset(sa_manager);
+ eoffset = drm_suballoc_hole_eoffset(sa_manager);
+ wasted = (align - (soffset % align)) % align;
+
+ if ((eoffset - soffset) >= (size + wasted)) {
+ soffset += wasted;
+
+ sa->manager = sa_manager;
+ sa->soffset = soffset;
+ sa->eoffset = soffset + size;
+ list_add(&sa->olist, sa_manager->hole);
+ INIT_LIST_HEAD(&sa->flist);
+ sa_manager->hole = &sa->olist;
+ return true;
+ }
+ return false;
+}
+
+static bool __drm_suballoc_event(struct drm_suballoc_manager
*sa_manager,
+ u64 size, u64 align)
+{
+ u64 soffset, eoffset, wasted;
+ unsigned int i;
+
+ for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
+ if (!list_empty(&sa_manager->flist[i]))
+ return true;
+
+ soffset = drm_suballoc_hole_soffset(sa_manager);
+ eoffset = drm_suballoc_hole_eoffset(sa_manager);
+ wasted = (align - (soffset % align)) % align;
+
+ return ((eoffset - soffset) >= (size + wasted));
+}
+
+/**
+ * drm_suballoc_event() - Check if we can stop waiting
+ * @sa_manager: pointer to the sa_manager
+ * @size: number of bytes we want to allocate
+ * @align: alignment we need to match
+ *
+ * Return: true if either there is a fence we can wait for or
+ * enough free memory to satisfy the allocation directly.
+ * false otherwise.
+ */
+static bool drm_suballoc_event(struct drm_suballoc_manager
*sa_manager,
+ u64 size, u64 align)
+{
+ bool ret;
+
+ spin_lock(&sa_manager->wq.lock);
+ ret = __drm_suballoc_event(sa_manager, size, align);
+ spin_unlock(&sa_manager->wq.lock);
+ return ret;
+}
+
+static bool drm_suballoc_next_hole(struct drm_suballoc_manager
*sa_manager,
+ struct dma_fence **fences,
+ unsigned int *tries)
+{
+ struct drm_suballoc *best_bo = NULL;
+ unsigned int i, best_idx;
+ u64 soffset, best, tmp;
+
+ /* if hole points to the end of the buffer */
+ if (sa_manager->hole->next == &sa_manager->olist) {
+ /* try again with its beginning */
+ sa_manager->hole = &sa_manager->olist;
+ return true;
+ }
+
+ soffset = drm_suballoc_hole_soffset(sa_manager);
+ /* to handle wrap around we add sa_manager->size */
+ best = sa_manager->size * 2;
+ /* go over all fence list and try to find the closest sa
+ * of the current last
+ */
+ for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i) {
+ struct drm_suballoc *sa;
+
+ fences[i] = NULL;
+
+ if (list_empty(&sa_manager->flist[i]))
+ continue;
+
+ sa = list_first_entry(&sa_manager->flist[i],
+ struct drm_suballoc, flist);
+
+ if (!dma_fence_is_signaled(sa->fence)) {
+ fences[i] = sa->fence;
+ continue;
+ }
+
+ /* limit the number of tries each freelist gets */
+ if (tries[i] > 2)
+ continue;
+
+ tmp = sa->soffset;
+ if (tmp < soffset) {
+ /* wrap around, pretend it's after */
+ tmp += sa_manager->size;
+ }
+ tmp -= soffset;
+ if (tmp < best) {
+ /* this sa bo is the closest one */
+ best = tmp;
+ best_idx = i;
+ best_bo = sa;
+ }
+ }
+
+ if (best_bo) {
+ ++tries[best_idx];
+ sa_manager->hole = best_bo->olist.prev;
+
+ /*
+ * We know that this one is signaled,
+ * so it's safe to remove it.
+ */
+ drm_suballoc_remove_locked(best_bo);
+ return true;
+ }
+ return false;
+}
+
+/**
+ * drm_suballoc_new() - Make a suballocation.
+ * @sa_manager: pointer to the sa_manager
+ * @size: number of bytes we want to suballocate.
+ * @gfp: gfp flags used for memory allocation. Typically GFP_KERNEL
but
+ * the argument is provided for suballocations from reclaim
context or
+ * where the caller wants to avoid pipelining rather than
wait for
+ * reclaim.
+ * @intr: Whether to perform waits interruptible. This should
typically
+ * always be true, unless the caller needs to propagate a
+ * non-interruptible context from above layers.
+ * @align: Alignment. Must not exceed the default manager alignment.
+ * If @align is zero, then the manager alignment is used.
+ *
+ * Try to make a suballocation of size @size, which will be rounded
+ * up to the alignment specified in specified in
drm_suballoc_manager_init().
+ *
+ * Return: a new suballocated bo, or an ERR_PTR.
+ */
+struct drm_suballoc *
+drm_suballoc_new(struct drm_suballoc_manager *sa_manager, u64 size,
+ gfp_t gfp, bool intr, u64 align)
+{
+ struct dma_fence *fences[DRM_SUBALLOC_MAX_QUEUES];
+ unsigned int tries[DRM_SUBALLOC_MAX_QUEUES];
+ unsigned int count;
+ int i, r;
+ struct drm_suballoc *sa;
+
+ if (WARN_ON_ONCE(align > sa_manager->align))
+ return ERR_PTR(-EINVAL);
+ if (WARN_ON_ONCE(size > sa_manager->size || !size))
+ return ERR_PTR(-EINVAL);
+
+ if (!align)
+ align = sa_manager->align;
+
+ sa = kmalloc(sizeof(*sa), gfp);
+ if (!sa)
+ return ERR_PTR(-ENOMEM);
+ sa->manager = sa_manager;
+ sa->fence = NULL;
+ INIT_LIST_HEAD(&sa->olist);
+ INIT_LIST_HEAD(&sa->flist);
+
+ spin_lock(&sa_manager->wq.lock);
+ do {
+ for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
+ tries[i] = 0;
+
+ do {
+ drm_suballoc_try_free(sa_manager);
+
+ if (drm_suballoc_try_alloc(sa_manager, sa,
+ size, align)) {
+ spin_unlock(&sa_manager->wq.lock);
+ return sa;
+ }
+
+ /* see if we can skip over some allocations */
+ } while (drm_suballoc_next_hole(sa_manager, fences, tries));
+
+ for (i = 0, count = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
+ if (fences[i])
+ fences[count++] = dma_fence_get(fences[i]);
+
+ if (count) {
+ long t;
+
+ spin_unlock(&sa_manager->wq.lock);
+ t = dma_fence_wait_any_timeout(fences, count, intr,
+ MAX_SCHEDULE_TIMEOUT,
+ NULL);
+ for (i = 0; i < count; ++i)
+ dma_fence_put(fences[i]);
+
+ r = (t > 0) ? 0 : t;
+ spin_lock(&sa_manager->wq.lock);
+ } else if (intr) {
+ /* if we have nothing to wait for block */
+ r = wait_event_interruptible_locked
+ (sa_manager->wq,
+ __drm_suballoc_event(sa_manager, size, align));
+ } else {
+ spin_unlock(&sa_manager->wq.lock);
+ wait_event(sa_manager->wq,
+ drm_suballoc_event(sa_manager, size, align));
+ r = 0;
+ spin_lock(&sa_manager->wq.lock);
+ }
+ } while (!r);
+
+ spin_unlock(&sa_manager->wq.lock);
+ kfree(sa);
+ return ERR_PTR(r);
+}
+EXPORT_SYMBOL(drm_suballoc_new);
+
+/**
+ * drm_suballoc_free - Free a suballocation
+ * @suballoc: pointer to the suballocation
+ * @fence: fence that signals when suballocation is idle
+ *
+ * Free the suballocation. The suballocation can be re-used after
@fence signals.
+ */
+void drm_suballoc_free(struct drm_suballoc *suballoc,
+ struct dma_fence *fence)
+{
+ struct drm_suballoc_manager *sa_manager;
+
+ if (!suballoc)
+ return;
+
+ sa_manager = suballoc->manager;
+
+ spin_lock(&sa_manager->wq.lock);
+ if (fence && !dma_fence_is_signaled(fence)) {
+ u64 idx;
+
+ suballoc->fence = dma_fence_get(fence);
+ idx = fence->context % DRM_SUBALLOC_MAX_QUEUES;
+ list_add_tail(&suballoc->flist, &sa_manager->flist[idx]);
+ } else {
+ drm_suballoc_remove_locked(suballoc);
+ }
+ wake_up_all_locked(&sa_manager->wq);
+ spin_unlock(&sa_manager->wq.lock);
+}
+EXPORT_SYMBOL(drm_suballoc_free);
+
+#ifdef CONFIG_DEBUG_FS
+void drm_suballoc_dump_debug_info(struct drm_suballoc_manager
*sa_manager,
+ struct drm_printer *p, u64 suballoc_base)
+{
+ struct drm_suballoc *i;
+
+ spin_lock(&sa_manager->wq.lock);
+ list_for_each_entry(i, &sa_manager->olist, olist) {
+ u64 soffset = i->soffset;
+ u64 eoffset = i->eoffset;
+
+ if (&i->olist == sa_manager->hole)
+ drm_puts(p, ">");
+ else
+ drm_puts(p, " ");
+
+ drm_printf(p, "[0x%010llx 0x%010llx] size %8lld",
+ suballoc_base + soffset, suballoc_base + eoffset,
+ eoffset - soffset);
+
+ if (i->fence)
+ drm_printf(p, " protected by 0x%016llx on context %llu",
+ i->fence->seqno, i->fence->context);
+
+ drm_puts(p, "\n");
+ }
+ spin_unlock(&sa_manager->wq.lock);
+}
+EXPORT_SYMBOL(drm_suballoc_dump_debug_info);
+#endif
+MODULE_AUTHOR("Multiple");
+MODULE_DESCRIPTION("Range suballocator helper");
+MODULE_LICENSE("Dual MIT/GPL");
diff --git a/include/drm/drm_suballoc.h b/include/drm/drm_suballoc.h
new file mode 100644
index 000000000000..a737f996e5ff
--- /dev/null
+++ b/include/drm/drm_suballoc.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/*
+ * Copyright 2011 Red Hat Inc.
+ * Copyright © 2022 Intel Corporation
+ */
+#ifndef _DRM_SUBALLOC_H_
+#define _DRM_SUBALLOC_H_
+
+#include <drm/drm_mm.h>
+
+#include <linux/dma-fence.h>
+#include <linux/types.h>
+
+#define DRM_SUBALLOC_MAX_QUEUES 32
+/**
+ * struct drm_suballoc_manager - fenced range allocations
+ * @wq: Wait queue for sleeping allocations on contention.
+ * @hole: Pointer to first hole node.
+ * @olist: List of allocated ranges.
+ * @flist: Array[fence context hash] of queues of fenced allocated
ranges.
+ * @size: Size of the managed range.
+ * @align: Default alignment for the managed range.
+ */
+struct drm_suballoc_manager {
+ wait_queue_head_t wq;
+ struct list_head *hole;
+ struct list_head olist;
+ struct list_head flist[DRM_SUBALLOC_MAX_QUEUES];
+ u64 size;
+ u64 align;
+};
+
+/**
+ * struct drm_suballoc - Sub-allocated range
+ * @olist: List link for list of allocated ranges.
+ * @flist: List linkk for the manager fenced allocated ranges queues.
+ * @manager: The drm_suballoc_manager.
+ * @soffset: Start offset.
+ * @eoffset: End offset + 1 so that @eoffset - @soffset = size.
+ * @dma_fence: The fence protecting the allocation.
+ */
+struct drm_suballoc {
+ struct list_head olist;
+ struct list_head flist;
+ struct drm_suballoc_manager *manager;
+ u64 soffset;
+ u64 eoffset;
+ struct dma_fence *fence;
+};
+
+void drm_suballoc_manager_init(struct drm_suballoc_manager
*sa_manager,
+ u64 size, u64 align);
+
+void drm_suballoc_manager_fini(struct drm_suballoc_manager
*sa_manager);
+
+struct drm_suballoc *
+drm_suballoc_new(struct drm_suballoc_manager *sa_manager, u64 size,
gfp_t gfp,
+ bool intr, u64 align);
+
+void drm_suballoc_free(struct drm_suballoc *sa, struct dma_fence
*fence);
+
+/**
+ * drm_suballoc_soffset - Range start.
+ * @sa: The struct drm_suballoc.
+ *
+ * Return: The start of the allocated range.
+ */
+static inline u64 drm_suballoc_soffset(struct drm_suballoc *sa)
+{
+ return sa->soffset;
+}
+
+/**
+ * drm_suballoc_eoffset - Range end.
+ * @sa: The struct drm_suballoc.
+ *
+ * Return: The end of the allocated range + 1.
+ */
+static inline u64 drm_suballoc_eoffset(struct drm_suballoc *sa)
+{
+ return sa->eoffset;
+}
+
+/**
+ * drm_suballoc_size - Range size.
+ * @sa: The struct drm_suballoc.
+ *
+ * Return: The size of the allocated range.
+ */
+static inline u64 drm_suballoc_size(struct drm_suballoc *sa)
+{
+ return sa->eoffset - sa->soffset;
+}
+
+#ifdef CONFIG_DEBUG_FS
+void drm_suballoc_dump_debug_info(struct drm_suballoc_manager
*sa_manager,
+ struct drm_printer *p, u64 suballoc_base);
+#else
+static inline void
+drm_suballoc_dump_debug_info(struct drm_suballoc_manager *sa_manager,
+ struct drm_printer *p, u64 suballoc_base)
+{ }
+
+#endif
+
+#endif /* _DRM_SUBALLOC_H_ */
