+static resource_size_t simple_align_resource(void *data,
+ const struct resource *avail,
+ resource_size_t size,
+ resource_size_t align)
+{
+ return avail->start;
+}
+
+static void resource_clip(struct resource *res, resource_size_t min,
+ resource_size_t max)
+{
+ if (res->start < min)
+ res->start = min;
+ if (res->end > max)
+ res->end = max;
+}
+
+static bool resource_contains(struct resource *res1, struct resource *res2)
+{
+ return res1->start <= res2->start && res1->end >= res2->end;
+}
+
+/*
+ * Find the resource before "child" in the sibling list of "root" children.
+ */
+static struct resource *find_sibling_prev(struct resource *root, struct resource *child)
+{
+ struct resource *this;
+
+ for (this = root->child; this; this = this->sibling)
+ if (this->sibling == child)
+ return this;
+
+ return NULL;
+}
+
+/*
+ * Find empty slot in the resource tree given range and alignment.
+ * This version allocates from the end of the root resource first.
+ */
+static int find_resource_from_top(struct resource *root, struct resource *new,
+ resource_size_t size, resource_size_t min,
+ resource_size_t max, resource_size_t align,
+ resource_size_t (*alignf)(void *,
+ const struct resource *,
+ resource_size_t,
+ resource_size_t),
+ void *alignf_data)
+{
+ struct resource *this;
+ struct resource tmp, avail, alloc;
+
+ tmp.start = root->end;
+ tmp.end = root->end;
+
+ this = find_sibling_prev(root, NULL);
+ for (;;) {
+ if (this) {
+ if (this->end < root->end)
+ tmp.start = this->end + 1;
+ } else
+ tmp.start = root->start;
+
+ resource_clip(&tmp, min, max);
+
+ /* Check for overflow after ALIGN() */
+ avail = *new;
+ avail.start = ALIGN(tmp.start, align);
+ avail.end = tmp.end;
+ if (avail.start >= tmp.start) {
+ alloc.start = alignf(alignf_data, &avail, size, align);
+ alloc.end = alloc.start + size - 1;
+ if (resource_contains(&avail, &alloc)) {
+ new->start = alloc.start;
+ new->end = alloc.end;
+ return 0;
+ }
+ }
+
+ if (!this || this->start == root->start)
+ break;
+
+ tmp.end = this->start - 1;
+ this = find_sibling_prev(root, this);
+ }
+ return -EBUSY;
+}
+