drm/cma-helper: Implement mmap as GEM CMA object functions

The new GEM object function drm_gem_cma_mmap() sets the VMA flags
and offset as in the old implementation and immediately maps in the
buffer's memory pages.

Changing CMA helpers to use the GEM object function allows for the
removal of the special implementations for mmap and gem_prime_mmap
callbacks. The regular functions drm_gem_mmap() and drm_gem_prime_mmap()
are now used.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201123115646.11004-3-tzimmermann@suse.de

drivers/gpu/drm/drm_file.c

@@ -113,8 +113,7 @@ bool drm_dev_needs_global_mutex(struct drm_device *dev)
  * The memory mapping implementation will vary depending on how the driver
  * manages memory. Legacy drivers will use the deprecated drm_legacy_mmap()
  * function, modern drivers should use one of the provided memory-manager
- * specific implementations. For GEM-based drivers this is drm_gem_mmap(), and
+ * specific implementations. For GEM-based drivers this is drm_gem_mmap().
- * for drivers which use the CMA GEM helpers it's drm_gem_cma_mmap().
  *
  * No other file operations are supported by the DRM userspace API. Overall the
  * following is an example &file_operations structure::

drivers/gpu/drm/drm_gem_cma_helper.c

@@ -38,6 +38,7 @@ static const struct drm_gem_object_funcs drm_gem_cma_default_funcs = {
 	.print_info = drm_gem_cma_print_info,
 	.get_sg_table = drm_gem_cma_get_sg_table,
 	.vmap = drm_gem_cma_vmap,
+	.mmap = drm_gem_cma_mmap,
 	.vm_ops = &drm_gem_cma_vm_ops,
 };
 
@@ -277,62 +278,6 @@ const struct vm_operations_struct drm_gem_cma_vm_ops = {
 };
 EXPORT_SYMBOL_GPL(drm_gem_cma_vm_ops);
 
-static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
-				struct vm_area_struct *vma)
-{
-	int ret;
-
-	/*
-	 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
-	 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
-	 * the whole buffer.
-	 */
-	vma->vm_flags &= ~VM_PFNMAP;
-	vma->vm_pgoff = 0;
-
-	ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
-			  cma_obj->paddr, vma->vm_end - vma->vm_start);
-	if (ret)
-		drm_gem_vm_close(vma);
-
-	return ret;
-}
-
-/**
- * drm_gem_cma_mmap - memory-map a CMA GEM object
- * @filp: file object
- * @vma: VMA for the area to be mapped
- *
- * This function implements an augmented version of the GEM DRM file mmap
- * operation for CMA objects: In addition to the usual GEM VMA setup it
- * immediately faults in the entire object instead of using on-demaind
- * faulting. Drivers which employ the CMA helpers should use this function
- * as their ->mmap() handler in the DRM device file's file_operations
- * structure.
- *
- * Instead of directly referencing this function, drivers should use the
- * DEFINE_DRM_GEM_CMA_FOPS().macro.
- *
- * Returns:
- * 0 on success or a negative error code on failure.
- */
-int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
-{
-	struct drm_gem_cma_object *cma_obj;
-	struct drm_gem_object *gem_obj;
-	int ret;
-
-	ret = drm_gem_mmap(filp, vma);
-	if (ret)
-		return ret;
-
-	gem_obj = vma->vm_private_data;
-	cma_obj = to_drm_gem_cma_obj(gem_obj);
-
-	return drm_gem_cma_mmap_obj(cma_obj, vma);
-}
-EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
-
 #ifndef CONFIG_MMU
 /**
  * drm_gem_cma_get_unmapped_area - propose address for mapping in noMMU cases
@@ -500,33 +445,6 @@ drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_import_sg_table);
 
-/**
- * drm_gem_cma_prime_mmap - memory-map an exported CMA GEM object
- * @obj: GEM object
- * @vma: VMA for the area to be mapped
- *
- * This function maps a buffer imported via DRM PRIME into a userspace
- * process's address space. Drivers that use the CMA helpers should set this
- * as their &drm_driver.gem_prime_mmap callback.
- *
- * Returns:
- * 0 on success or a negative error code on failure.
- */
-int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
-			   struct vm_area_struct *vma)
-{
-	struct drm_gem_cma_object *cma_obj;
-	int ret;
-
-	ret = drm_gem_mmap_obj(obj, obj->size, vma);
-	if (ret < 0)
-		return ret;
-
-	cma_obj = to_drm_gem_cma_obj(obj);
-	return drm_gem_cma_mmap_obj(cma_obj, vma);
-}
-EXPORT_SYMBOL_GPL(drm_gem_cma_prime_mmap);
-
 /**
  * drm_gem_cma_vmap - map a CMA GEM object into the kernel's virtual
  *     address space
@@ -553,6 +471,43 @@ int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_vmap);
 
+/**
+ * drm_gem_cma_mmap - memory-map an exported CMA GEM object
+ * @obj: GEM object
+ * @vma: VMA for the area to be mapped
+ *
+ * This function maps a buffer into a userspace process's address space.
+ * In addition to the usual GEM VMA setup it immediately faults in the entire
+ * object instead of using on-demand faulting. Drivers that use the CMA
+ * helpers should set this as their &drm_gem_object_funcs.mmap callback.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+{
+	struct drm_gem_cma_object *cma_obj;
+	int ret;
+
+	/*
+	 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
+	 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
+	 * the whole buffer.
+	 */
+	vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
+	vma->vm_flags &= ~VM_PFNMAP;
+
+	cma_obj = to_drm_gem_cma_obj(obj);
+
+	ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
+			  cma_obj->paddr, vma->vm_end - vma->vm_start);
+	if (ret)
+		drm_gem_vm_close(vma);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
+
 /**
  * drm_gem_cma_prime_import_sg_table_vmap - PRIME import another driver's
  *	scatter/gather table and get the virtual address of the buffer

drivers/gpu/drm/pl111/pl111_drv.c

@@ -228,7 +228,7 @@ static const struct drm_driver pl111_drm_driver = {
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_import_sg_table = pl111_gem_import_sg_table,
-	.gem_prime_mmap = drm_gem_cma_prime_mmap,
+	.gem_prime_mmap = drm_gem_prime_mmap,
 
 #if defined(CONFIG_DEBUG_FS)
 	.debugfs_init = pl111_debugfs_init,

drivers/gpu/drm/vc4/vc4_bo.c

@@ -782,7 +782,7 @@ int vc4_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 		return -EINVAL;
 	}
 
-	return drm_gem_cma_prime_mmap(obj, vma);
+	return drm_gem_prime_mmap(obj, vma);
 }
 
 int vc4_prime_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)

include/drm/drm_gem_cma_helper.h

@@ -59,7 +59,7 @@ struct drm_gem_cma_object {
 		.poll		= drm_poll,\
 		.read		= drm_read,\
 		.llseek		= noop_llseek,\
-		.mmap		= drm_gem_cma_mmap,\
+		.mmap		= drm_gem_mmap,\
 		DRM_GEM_CMA_UNMAPPED_AREA_FOPS \
 	}
 
@@ -76,9 +76,6 @@ int drm_gem_cma_dumb_create(struct drm_file *file_priv,
 			    struct drm_device *drm,
 			    struct drm_mode_create_dumb *args);
 
-/* set vm_flags and we can change the VM attribute to other one at here */
-int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma);
-
 /* allocate physical memory */
 struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
 					      size_t size);
@@ -101,9 +98,8 @@ struct drm_gem_object *
 drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
 				  struct dma_buf_attachment *attach,
 				  struct sg_table *sgt);
-int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
-			   struct vm_area_struct *vma);
 int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
 
 /**
  * DRM_GEM_CMA_DRIVER_OPS_WITH_DUMB_CREATE - CMA GEM driver operations
@@ -123,7 +119,7 @@ int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
 	.prime_handle_to_fd	= drm_gem_prime_handle_to_fd, \
 	.prime_fd_to_handle	= drm_gem_prime_fd_to_handle, \
 	.gem_prime_import_sg_table = drm_gem_cma_prime_import_sg_table, \
-	.gem_prime_mmap		= drm_gem_cma_prime_mmap
+	.gem_prime_mmap		= drm_gem_prime_mmap
 
 /**
  * DRM_GEM_CMA_DRIVER_OPS - CMA GEM driver operations