drm/nouveau: reserve VGA area for the moment

This is to prevent things such as GART tables and other important GPU
structures being allocated there before we take over fbcon ourselves.

This is more of a workaround for the moment, a better solution will
require some more invasive changes, but it'll be done at some point.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -509,6 +509,8 @@ struct drm_nouveau_private {
 	void __iomem *ramin;
 	uint32_t ramin_size;
 
+	struct nouveau_bo *vga_ram;
+
 	struct workqueue_struct *wq;
 	struct work_struct irq_work;
 

drivers/gpu/drm/nouveau/nouveau_mem.c

@@ -383,6 +383,9 @@ void nouveau_mem_close(struct drm_device *dev)
 {
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 
+	nouveau_bo_unpin(dev_priv->vga_ram);
+	nouveau_bo_ref(NULL, &dev_priv->vga_ram);
+
 	ttm_bo_clean_mm(&dev_priv->ttm.bdev, TTM_PL_VRAM);
 	ttm_bo_device_release(&dev_priv->ttm.bdev);
 
@@ -619,6 +622,15 @@ nouveau_mem_init(struct drm_device *dev)
 		return ret;
 	}
 
+	ret = nouveau_bo_new(dev, NULL, 256*1024, 0, TTM_PL_FLAG_VRAM,
+			     0, 0, true, true, &dev_priv->vga_ram);
+	if (ret == 0)
+		ret = nouveau_bo_pin(dev_priv->vga_ram, TTM_PL_FLAG_VRAM);
+	if (ret) {
+		NV_WARN(dev, "failed to reserve VGA memory\n");
+		nouveau_bo_ref(NULL, &dev_priv->vga_ram);
+	}
+
 	/* GART */
 #if !defined(__powerpc__) && !defined(__ia64__)
 	if (drm_device_is_agp(dev) && dev->agp) {
@@ -650,6 +662,7 @@ nouveau_mem_init(struct drm_device *dev)
 	dev_priv->fb_mtrr = drm_mtrr_add(drm_get_resource_start(dev, 1),
 					 drm_get_resource_len(dev, 1),
 					 DRM_MTRR_WC);
+
 	return 0;
 }