drm/vram: add vram-mm debugfs file

Wire up drm_mm_print() for vram helpers, using a new
debugfs file, so one can see how vram is used:

   # cat /sys/kernel/debug/dri/0/vram-mm
   0x0000000000000000-0x0000000000000300: 768: used
   0x0000000000000300-0x0000000000000600: 768: used
   0x0000000000000600-0x0000000000000900: 768: used
   0x0000000000000900-0x0000000000000c00: 768: used
   0x0000000000000c00-0x0000000000004000: 13312: free
   total: 16384, used 3072 free 13312
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20190904054740.20817-5-kraxel@redhat.com

drivers/gpu/drm/drm_vram_mm_helper.c

 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <drm/drm_debugfs.h>
 #include <drm/drm_device.h>
 #include <drm/drm_file.h>
+#include <drm/drm_gem_ttm_helper.h>
 #include <drm/drm_vram_mm_helper.h>
 
 #include <drm/ttm/ttm_page_alloc.h>
@@ -160,6 +162,48 @@ static struct ttm_bo_driver bo_driver = {
  * struct drm_vram_mm
  */
 
+#if defined(CONFIG_DEBUG_FS)
+static int drm_vram_mm_debugfs(struct seq_file *m, void *data)
+{
+	struct drm_info_node *node = (struct drm_info_node *) m->private;
+	struct drm_vram_mm *vmm = node->minor->dev->vram_mm;
+	struct drm_mm *mm = vmm->bdev.man[TTM_PL_VRAM].priv;
+	struct ttm_bo_global *glob = vmm->bdev.glob;
+	struct drm_printer p = drm_seq_file_printer(m);
+
+	spin_lock(&glob->lru_lock);
+	drm_mm_print(mm, &p);
+	spin_unlock(&glob->lru_lock);
+	return 0;
+}
+
+static const struct drm_info_list drm_vram_mm_debugfs_list[] = {
+	{ "vram-mm", drm_vram_mm_debugfs, 0, NULL },
+};
+#endif
+
+/**
+ * drm_vram_mm_debugfs_init() - Register VRAM MM debugfs file.
+ *
+ * @minor: drm minor device.
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative error code otherwise.
+ */
+int drm_vram_mm_debugfs_init(struct drm_minor *minor)
+{
+	int ret = 0;
+
+#if defined(CONFIG_DEBUG_FS)
+	ret = drm_debugfs_create_files(drm_vram_mm_debugfs_list,
+				       ARRAY_SIZE(drm_vram_mm_debugfs_list),
+				       minor->debugfs_root, minor);
+#endif
+	return ret;
+}
+EXPORT_SYMBOL(drm_vram_mm_debugfs_init);
+
 /**
  * drm_vram_mm_init() - Initialize an instance of VRAM MM.
  * @vmm:	the VRAM MM instance to initialize

include/drm/drm_gem_vram_helper.h

@@ -140,6 +140,7 @@ int drm_gem_vram_driver_dumb_mmap_offset(struct drm_file *file,
  * &struct drm_driver with default functions.
  */
 #define DRM_GEM_VRAM_DRIVER \
+	.debugfs_init             = drm_vram_mm_debugfs_init, \
 	.dumb_create		  = drm_gem_vram_driver_dumb_create, \
 	.dumb_map_offset	  = drm_gem_vram_driver_dumb_mmap_offset, \
 	.gem_prime_mmap		  = drm_gem_prime_mmap

include/drm/drm_vram_mm_helper.h

@@ -64,6 +64,7 @@ static inline struct drm_vram_mm *drm_vram_mm_of_bdev(
 	return container_of(bdev, struct drm_vram_mm, bdev);
 }
 
+int drm_vram_mm_debugfs_init(struct drm_minor *minor);
 int drm_vram_mm_init(struct drm_vram_mm *vmm, struct drm_device *dev,
 		     uint64_t vram_base, size_t vram_size,
 		     const struct drm_vram_mm_funcs *funcs);