[RFC PATCH 5/7] drm/ttm: add range busy check for range manager

[Robert Beckett]

RFC: do we want this to become a generic interface in
ttm_resource_manager_func?

RFC: would we prefer a different interface? e.g.
for_each_resource_in_range or for_each_bo_in_range

Signed-off-by: Robert Beckett <bob.beckett at collabora.com>
---
 drivers/gpu/drm/ttm/ttm_range_manager.c | 21 +++++++++++++++++++++
 include/drm/ttm/ttm_range_manager.h     |  3 +++
 2 files changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_range_manager.c b/drivers/gpu/drm/ttm/ttm_range_manager.c
index 8cd4f3fb9f79..5662627bb933 100644
--- a/drivers/gpu/drm/ttm/ttm_range_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_range_manager.c
@@ -206,3 +206,24 @@ int ttm_range_man_fini_nocheck(struct ttm_device *bdev,
 	return 0;
 }
 EXPORT_SYMBOL(ttm_range_man_fini_nocheck);
+
+/**
+ * ttm_range_man_range_busy - Check whether anything is allocated with a range
+ *
+ * @man: memory manager to check
+ * @fpfn: first page number to check
+ * @lpfn: last page number to check
+ *
+ * Return: true if anything allocated within the range, false otherwise.
+ */
+bool ttm_range_man_range_busy(struct ttm_resource_manager *man,
+			      unsigned fpfn, unsigned lpfn)
+{
+	struct ttm_range_manager *rman = to_range_manager(man);
+	struct drm_mm *mm = &rman->mm;
+
+	if (__drm_mm_interval_first(mm, PFN_PHYS(fpfn), PFN_PHYS(lpfn + 1) - 1))
+		return true;
+	return false;
+}
+EXPORT_SYMBOL(ttm_range_man_range_busy);
diff --git a/include/drm/ttm/ttm_range_manager.h b/include/drm/ttm/ttm_range_manager.h
index 7963b957e9ef..86794a3f9101 100644
--- a/include/drm/ttm/ttm_range_manager.h
+++ b/include/drm/ttm/ttm_range_manager.h
@@ -53,4 +53,7 @@ static __always_inline int ttm_range_man_fini(struct ttm_device *bdev,
 	BUILD_BUG_ON(__builtin_constant_p(type) && type >= TTM_NUM_MEM_TYPES);
 	return ttm_range_man_fini_nocheck(bdev, type);
 }
+
+bool ttm_range_man_range_busy(struct ttm_resource_manager *man,
+			      unsigned fpfn, unsigned lpfn);
 #endif
-- 
2.25.1