[RFC PATCH V7 03/10] drm/gpu: Add gpu_buddy_allocated_addr_to_block helper

[Tejas Upadhyay <tejas.upadhyay@intel.com>]

Add helper with primary purpose is to efficiently trace a specific
physical memory address back to its corresponding TTM buffer object.

v2:
- %s/gpu_buddy_addr_to_block/gpu_buddy_allocated_addr_to_block(MattA)
- remove clear->avail and split nodes check(MattA)
- Adapt lockdep(MattB)

Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
---
 drivers/gpu/buddy.c       | 53 +++++++++++++++++++++++++++++++++++++++
 include/linux/gpu_buddy.h |  2 ++
 2 files changed, 55 insertions(+)

diff --git a/drivers/gpu/buddy.c b/drivers/gpu/buddy.c
index 53ff85ac2105..44bf926aca56 100644
--- a/drivers/gpu/buddy.c
+++ b/drivers/gpu/buddy.c
@@ -595,6 +595,59 @@ void gpu_buddy_free_block(struct gpu_buddy *mm,
 }
 EXPORT_SYMBOL(gpu_buddy_free_block);
 
+/**
+ * gpu_buddy_allocated_addr_to_block - given relative address find the allocated block
+ *
+ * @mm: GPU buddy manager
+ * @addr: Relative address
+ *
+ * Returns:
+ * gpu_buddy_block on success, NULL or error code on failure
+ */
+struct gpu_buddy_block *gpu_buddy_allocated_addr_to_block(struct gpu_buddy *mm, u64 addr)
+{
+	struct gpu_buddy_block *block;
+	LIST_HEAD(dfs);
+	u64 end;
+	int i;
+
+	gpu_buddy_driver_lock_held(mm);
+
+	end = addr + SZ_4K - 1;
+	for (i = 0; i < mm->n_roots; ++i)
+		list_add_tail(&mm->roots[i]->tmp_link, &dfs);
+
+	do {
+		u64 block_start;
+		u64 block_end;
+
+		block = list_first_entry_or_null(&dfs,
+						 struct gpu_buddy_block,
+						 tmp_link);
+		if (!block)
+			break;
+
+		list_del(&block->tmp_link);
+
+		block_start = gpu_buddy_block_offset(block);
+		block_end = block_start + gpu_buddy_block_size(mm, block) - 1;
+
+		if (!overlaps(addr, end, block_start, block_end))
+			continue;
+
+		if (gpu_buddy_block_is_allocated(block))
+			return block;
+		else if (gpu_buddy_block_is_free(block))
+			return NULL;
+
+		list_add(&block->right->tmp_link, &dfs);
+		list_add(&block->left->tmp_link, &dfs);
+	} while (1);
+
+	return ERR_PTR(-ENXIO);
+}
+EXPORT_SYMBOL(gpu_buddy_allocated_addr_to_block);
+
 static void __gpu_buddy_free_list(struct gpu_buddy *mm,
 				  struct list_head *objects,
 				  bool mark_clear,
diff --git a/include/linux/gpu_buddy.h b/include/linux/gpu_buddy.h
index c174de80ad72..e42c38a2a9f5 100644
--- a/include/linux/gpu_buddy.h
+++ b/include/linux/gpu_buddy.h
@@ -272,6 +272,8 @@ void gpu_buddy_reset_clear(struct gpu_buddy *mm, bool is_clear);
 
 void gpu_buddy_free_block(struct gpu_buddy *mm, struct gpu_buddy_block *block);
 
+struct gpu_buddy_block *gpu_buddy_allocated_addr_to_block(struct gpu_buddy *mm, u64 addr);
+
 void gpu_buddy_free_list(struct gpu_buddy *mm,
 			 struct list_head *objects,
 			 unsigned int flags);
-- 
2.52.0