[PATCH v3 01/12] drm: add gem array helpers

[Gerd Hoffmann]

Add struct and helper functions to manage an array of gem objects.
See added kernel docs for details.

Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
 include/drm/drm_gem_array_helper.h     | 15 +++++
 drivers/gpu/drm/drm_gem_array_helper.c | 76 ++++++++++++++++++++++++++
 drivers/gpu/drm/Makefile               |  3 +-
 3 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 include/drm/drm_gem_array_helper.h
 create mode 100644 drivers/gpu/drm/drm_gem_array_helper.c

diff --git a/include/drm/drm_gem_array_helper.h b/include/drm/drm_gem_array_helper.h
new file mode 100644
index 000000000000..adf7961247b3
--- /dev/null
+++ b/include/drm/drm_gem_array_helper.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __DRM_GEM_ARRAY_HELPER_H__
+#define __DRM_GEM_ARRAY_HELPER_H__
+
+struct drm_gem_object_array {
+	u32 nents;
+	struct drm_gem_object *objs[];
+};
+
+struct drm_gem_object_array *drm_gem_array_alloc(u32 nents);
+struct drm_gem_object_array *
+drm_gem_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents);
+void drm_gem_array_put_free(struct drm_gem_object_array *objs);
+
+#endif /* __DRM_GEM_ARRAY_HELPER_H__ */
diff --git a/drivers/gpu/drm/drm_gem_array_helper.c b/drivers/gpu/drm/drm_gem_array_helper.c
new file mode 100644
index 000000000000..d35c77c4a02d
--- /dev/null
+++ b/drivers/gpu/drm/drm_gem_array_helper.c
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <drm/drm_gem.h>
+#include <drm/drm_gem_array_helper.h>
+
+/**
+ * drm_gem_array_alloc -- allocate gem object array of the given size.
+ *
+ * @nents: number of entries needed.
+ *
+ * Returns: An array of gem objects on success, NULL on failure.
+ */
+struct drm_gem_object_array *drm_gem_array_alloc(u32 nents)
+{
+	struct drm_gem_object_array *objs;
+	size_t size = sizeof(*objs) + sizeof(objs->objs[0]) * nents;
+
+	objs = kzalloc(size, GFP_KERNEL);
+	if (!objs)
+		return NULL;
+
+	objs->nents = nents;
+	return objs;
+}
+EXPORT_SYMBOL(drm_gem_array_alloc);
+
+static void drm_gem_array_free(struct drm_gem_object_array *objs)
+{
+	kfree(objs);
+}
+
+/**
+ * drm_gem_array_from_handles -- lookup an array of gem handles.
+ *
+ * @drm_file: drm file-private structure to use for the handle look up
+ * @handles: the array of handles to lookup.
+ * @nents: the numer of handles.
+ *
+ * Returns: An array of gem objects on success, NULL on failure.
+ */
+struct drm_gem_object_array*
+drm_gem_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents)
+{
+	struct drm_gem_object_array *objs;
+	u32 i;
+
+	objs = drm_gem_array_alloc(nents);
+	if (!objs)
+		return NULL;
+
+	for (i = 0; i < nents; i++) {
+		objs->objs[i] = drm_gem_object_lookup(drm_file, handles[i]);
+		if (!objs->objs[i]) {
+			drm_gem_array_put_free(objs);
+			return NULL;
+		}
+	}
+	return objs;
+}
+
+/**
+ * drm_gem_array_put_free -- put gem objects and free array.
+ *
+ * @objs: the gem object array.
+ */
+void drm_gem_array_put_free(struct drm_gem_object_array *objs)
+{
+	u32 i;
+
+	for (i = 0; i < objs->nents; i++) {
+		if (!objs->objs[i])
+			continue;
+		drm_gem_object_put_unlocked(objs->objs[i]);
+	}
+	drm_gem_array_free(objs);
+}
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 9d630a28a788..d32e7de0937b 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -43,7 +43,8 @@ drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_dsc.o drm_probe_helper
 		drm_simple_kms_helper.o drm_modeset_helper.o \
 		drm_scdc_helper.o drm_gem_framebuffer_helper.o \
 		drm_atomic_state_helper.o drm_damage_helper.o \
-		drm_format_helper.o drm_self_refresh_helper.o
+		drm_format_helper.o drm_self_refresh_helper.o \
+		drm_gem_array_helper.o
 
 drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
 drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
-- 
2.18.1