Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1162 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
new file mode 100644
index 000000000..928e08e0b
--- /dev/null
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -0,0 +1,1162 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/iosys-map.h>
+#include <linux/module.h>
+
+#include <drm/drm_debugfs.h>
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_ttm_helper.h>
+#include <drm/drm_gem_vram_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_mode.h>
+#include <drm/drm_plane.h>
+#include <drm/drm_prime.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#include <drm/ttm/ttm_range_manager.h>
+
+static const struct drm_gem_object_funcs drm_gem_vram_object_funcs;
+
+/**
+ * DOC: overview
+ *
+ * This library provides &struct drm_gem_vram_object (GEM VRAM), a GEM
+ * buffer object that is backed by video RAM (VRAM). It can be used for
+ * framebuffer devices with dedicated memory.
+ *
+ * The data structure &struct drm_vram_mm and its helpers implement a memory
+ * manager for simple framebuffer devices with dedicated video memory. GEM
+ * VRAM buffer objects are either placed in the video memory or remain evicted
+ * to system memory.
+ *
+ * With the GEM interface userspace applications create, manage and destroy
+ * graphics buffers, such as an on-screen framebuffer. GEM does not provide
+ * an implementation of these interfaces. It's up to the DRM driver to
+ * provide an implementation that suits the hardware. If the hardware device
+ * contains dedicated video memory, the DRM driver can use the VRAM helper
+ * library. Each active buffer object is stored in video RAM. Active
+ * buffer are used for drawing the current frame, typically something like
+ * the frame's scanout buffer or the cursor image. If there's no more space
+ * left in VRAM, inactive GEM objects can be moved to system memory.
+ *
+ * To initialize the VRAM helper library call drmm_vram_helper_init().
+ * The function allocates and initializes an instance of &struct drm_vram_mm
+ * in &struct drm_device.vram_mm . Use &DRM_GEM_VRAM_DRIVER to initialize
+ * &struct drm_driver and  &DRM_VRAM_MM_FILE_OPERATIONS to initialize
+ * &struct file_operations; as illustrated below.
+ *
+ * .. code-block:: c
+ *
+ *	struct file_operations fops ={
+ *		.owner = THIS_MODULE,
+ *		DRM_VRAM_MM_FILE_OPERATION
+ *	};
+ *	struct drm_driver drv = {
+ *		.driver_feature = DRM_ ... ,
+ *		.fops = &fops,
+ *		DRM_GEM_VRAM_DRIVER
+ *	};
+ *
+ *	int init_drm_driver()
+ *	{
+ *		struct drm_device *dev;
+ *		uint64_t vram_base;
+ *		unsigned long vram_size;
+ *		int ret;
+ *
+ *		// setup device, vram base and size
+ *		// ...
+ *
+ *		ret = drmm_vram_helper_init(dev, vram_base, vram_size);
+ *		if (ret)
+ *			return ret;
+ *		return 0;
+ *	}
+ *
+ * This creates an instance of &struct drm_vram_mm, exports DRM userspace
+ * interfaces for GEM buffer management and initializes file operations to
+ * allow for accessing created GEM buffers. With this setup, the DRM driver
+ * manages an area of video RAM with VRAM MM and provides GEM VRAM objects
+ * to userspace.
+ *
+ * You don't have to clean up the instance of VRAM MM.
+ * drmm_vram_helper_init() is a managed interface that installs a
+ * clean-up handler to run during the DRM device's release.
+ *
+ * For drawing or scanout operations, rsp. buffer objects have to be pinned
+ * in video RAM. Call drm_gem_vram_pin() with &DRM_GEM_VRAM_PL_FLAG_VRAM or
+ * &DRM_GEM_VRAM_PL_FLAG_SYSTEM to pin a buffer object in video RAM or system
+ * memory. Call drm_gem_vram_unpin() to release the pinned object afterwards.
+ *
+ * A buffer object that is pinned in video RAM has a fixed address within that
+ * memory region. Call drm_gem_vram_offset() to retrieve this value. Typically
+ * it's used to program the hardware's scanout engine for framebuffers, set
+ * the cursor overlay's image for a mouse cursor, or use it as input to the
+ * hardware's drawing engine.
+ *
+ * To access a buffer object's memory from the DRM driver, call
+ * drm_gem_vram_vmap(). It maps the buffer into kernel address
+ * space and returns the memory address. Use drm_gem_vram_vunmap() to
+ * release the mapping.
+ */
+
+/*
+ * Buffer-objects helpers
+ */
+
+static void drm_gem_vram_cleanup(struct drm_gem_vram_object *gbo)
+{
+	/* We got here via ttm_bo_put(), which means that the
+	 * TTM buffer object in 'bo' has already been cleaned
+	 * up; only release the GEM object.
+	 */
+
+	WARN_ON(gbo->vmap_use_count);
+	WARN_ON(iosys_map_is_set(&gbo->map));
+
+	drm_gem_object_release(&gbo->bo.base);
+}
+
+static void drm_gem_vram_destroy(struct drm_gem_vram_object *gbo)
+{
+	drm_gem_vram_cleanup(gbo);
+	kfree(gbo);
+}
+
+static void ttm_buffer_object_destroy(struct ttm_buffer_object *bo)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_bo(bo);
+
+	drm_gem_vram_destroy(gbo);
+}
+
+static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo,
+				   unsigned long pl_flag)
+{
+	u32 invariant_flags = 0;
+	unsigned int i;
+	unsigned int c = 0;
+
+	if (pl_flag & DRM_GEM_VRAM_PL_FLAG_TOPDOWN)
+		invariant_flags = TTM_PL_FLAG_TOPDOWN;
+
+	gbo->placement.placement = gbo->placements;
+	gbo->placement.busy_placement = gbo->placements;
+
+	if (pl_flag & DRM_GEM_VRAM_PL_FLAG_VRAM) {
+		gbo->placements[c].mem_type = TTM_PL_VRAM;
+		gbo->placements[c++].flags = invariant_flags;
+	}
+
+	if (pl_flag & DRM_GEM_VRAM_PL_FLAG_SYSTEM || !c) {
+		gbo->placements[c].mem_type = TTM_PL_SYSTEM;
+		gbo->placements[c++].flags = invariant_flags;
+	}
+
+	gbo->placement.num_placement = c;
+	gbo->placement.num_busy_placement = c;
+
+	for (i = 0; i < c; ++i) {
+		gbo->placements[i].fpfn = 0;
+		gbo->placements[i].lpfn = 0;
+	}
+}
+
+/**
+ * drm_gem_vram_create() - Creates a VRAM-backed GEM object
+ * @dev:		the DRM device
+ * @size:		the buffer size in bytes
+ * @pg_align:		the buffer's alignment in multiples of the page size
+ *
+ * GEM objects are allocated by calling struct drm_driver.gem_create_object,
+ * if set. Otherwise kzalloc() will be used. Drivers can set their own GEM
+ * object functions in struct drm_driver.gem_create_object. If no functions
+ * are set, the new GEM object will use the default functions from GEM VRAM
+ * helpers.
+ *
+ * Returns:
+ * A new instance of &struct drm_gem_vram_object on success, or
+ * an ERR_PTR()-encoded error code otherwise.
+ */
+struct drm_gem_vram_object *drm_gem_vram_create(struct drm_device *dev,
+						size_t size,
+						unsigned long pg_align)
+{
+	struct drm_gem_vram_object *gbo;
+	struct drm_gem_object *gem;
+	struct drm_vram_mm *vmm = dev->vram_mm;
+	struct ttm_device *bdev;
+	int ret;
+
+	if (WARN_ONCE(!vmm, "VRAM MM not initialized"))
+		return ERR_PTR(-EINVAL);
+
+	if (dev->driver->gem_create_object) {
+		gem = dev->driver->gem_create_object(dev, size);
+		if (IS_ERR(gem))
+			return ERR_CAST(gem);
+		gbo = drm_gem_vram_of_gem(gem);
+	} else {
+		gbo = kzalloc(sizeof(*gbo), GFP_KERNEL);
+		if (!gbo)
+			return ERR_PTR(-ENOMEM);
+		gem = &gbo->bo.base;
+	}
+
+	if (!gem->funcs)
+		gem->funcs = &drm_gem_vram_object_funcs;
+
+	ret = drm_gem_object_init(dev, gem, size);
+	if (ret) {
+		kfree(gbo);
+		return ERR_PTR(ret);
+	}
+
+	bdev = &vmm->bdev;
+
+	gbo->bo.bdev = bdev;
+	drm_gem_vram_placement(gbo, DRM_GEM_VRAM_PL_FLAG_SYSTEM);
+
+	/*
+	 * A failing ttm_bo_init will call ttm_buffer_object_destroy
+	 * to release gbo->bo.base and kfree gbo.
+	 */
+	ret = ttm_bo_init_validate(bdev, &gbo->bo, ttm_bo_type_device,
+				   &gbo->placement, pg_align, false, NULL, NULL,
+				   ttm_buffer_object_destroy);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return gbo;
+}
+EXPORT_SYMBOL(drm_gem_vram_create);
+
+/**
+ * drm_gem_vram_put() - Releases a reference to a VRAM-backed GEM object
+ * @gbo:	the GEM VRAM object
+ *
+ * See ttm_bo_put() for more information.
+ */
+void drm_gem_vram_put(struct drm_gem_vram_object *gbo)
+{
+	ttm_bo_put(&gbo->bo);
+}
+EXPORT_SYMBOL(drm_gem_vram_put);
+
+static u64 drm_gem_vram_pg_offset(struct drm_gem_vram_object *gbo)
+{
+	/* Keep TTM behavior for now, remove when drivers are audited */
+	if (WARN_ON_ONCE(!gbo->bo.resource ||
+			 gbo->bo.resource->mem_type == TTM_PL_SYSTEM))
+		return 0;
+
+	return gbo->bo.resource->start;
+}
+
+/**
+ * drm_gem_vram_offset() - \
+	Returns a GEM VRAM object's offset in video memory
+ * @gbo:	the GEM VRAM object
+ *
+ * This function returns the buffer object's offset in the device's video
+ * memory. The buffer object has to be pinned to %TTM_PL_VRAM.
+ *
+ * Returns:
+ * The buffer object's offset in video memory on success, or
+ * a negative errno code otherwise.
+ */
+s64 drm_gem_vram_offset(struct drm_gem_vram_object *gbo)
+{
+	if (WARN_ON_ONCE(!gbo->bo.pin_count))
+		return (s64)-ENODEV;
+	return drm_gem_vram_pg_offset(gbo) << PAGE_SHIFT;
+}
+EXPORT_SYMBOL(drm_gem_vram_offset);
+
+static int drm_gem_vram_pin_locked(struct drm_gem_vram_object *gbo,
+				   unsigned long pl_flag)
+{
+	struct ttm_operation_ctx ctx = { false, false };
+	int ret;
+
+	if (gbo->bo.pin_count)
+		goto out;
+
+	if (pl_flag)
+		drm_gem_vram_placement(gbo, pl_flag);
+
+	ret = ttm_bo_validate(&gbo->bo, &gbo->placement, &ctx);
+	if (ret < 0)
+		return ret;
+
+out:
+	ttm_bo_pin(&gbo->bo);
+
+	return 0;
+}
+
+/**
+ * drm_gem_vram_pin() - Pins a GEM VRAM object in a region.
+ * @gbo:	the GEM VRAM object
+ * @pl_flag:	a bitmask of possible memory regions
+ *
+ * Pinning a buffer object ensures that it is not evicted from
+ * a memory region. A pinned buffer object has to be unpinned before
+ * it can be pinned to another region. If the pl_flag argument is 0,
+ * the buffer is pinned at its current location (video RAM or system
+ * memory).
+ *
+ * Small buffer objects, such as cursor images, can lead to memory
+ * fragmentation if they are pinned in the middle of video RAM. This
+ * is especially a problem on devices with only a small amount of
+ * video RAM. Fragmentation can prevent the primary framebuffer from
+ * fitting in, even though there's enough memory overall. The modifier
+ * DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks the buffer object to be pinned
+ * at the high end of the memory region to avoid fragmentation.
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative error code otherwise.
+ */
+int drm_gem_vram_pin(struct drm_gem_vram_object *gbo, unsigned long pl_flag)
+{
+	int ret;
+
+	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
+	if (ret)
+		return ret;
+	ret = drm_gem_vram_pin_locked(gbo, pl_flag);
+	ttm_bo_unreserve(&gbo->bo);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_vram_pin);
+
+static void drm_gem_vram_unpin_locked(struct drm_gem_vram_object *gbo)
+{
+	ttm_bo_unpin(&gbo->bo);
+}
+
+/**
+ * drm_gem_vram_unpin() - Unpins a GEM VRAM object
+ * @gbo:	the GEM VRAM object
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative error code otherwise.
+ */
+int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo)
+{
+	int ret;
+
+	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
+	if (ret)
+		return ret;
+
+	drm_gem_vram_unpin_locked(gbo);
+	ttm_bo_unreserve(&gbo->bo);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_vram_unpin);
+
+static int drm_gem_vram_kmap_locked(struct drm_gem_vram_object *gbo,
+				    struct iosys_map *map)
+{
+	int ret;
+
+	if (gbo->vmap_use_count > 0)
+		goto out;
+
+	/*
+	 * VRAM helpers unmap the BO only on demand. So the previous
+	 * page mapping might still be around. Only vmap if the there's
+	 * no mapping present.
+	 */
+	if (iosys_map_is_null(&gbo->map)) {
+		ret = ttm_bo_vmap(&gbo->bo, &gbo->map);
+		if (ret)
+			return ret;
+	}
+
+out:
+	++gbo->vmap_use_count;
+	*map = gbo->map;
+
+	return 0;
+}
+
+static void drm_gem_vram_kunmap_locked(struct drm_gem_vram_object *gbo,
+				       struct iosys_map *map)
+{
+	struct drm_device *dev = gbo->bo.base.dev;
+
+	if (drm_WARN_ON_ONCE(dev, !gbo->vmap_use_count))
+		return;
+
+	if (drm_WARN_ON_ONCE(dev, !iosys_map_is_equal(&gbo->map, map)))
+		return; /* BUG: map not mapped from this BO */
+
+	if (--gbo->vmap_use_count > 0)
+		return;
+
+	/*
+	 * Permanently mapping and unmapping buffers adds overhead from
+	 * updating the page tables and creates debugging output. Therefore,
+	 * we delay the actual unmap operation until the BO gets evicted
+	 * from memory. See drm_gem_vram_bo_driver_move_notify().
+	 */
+}
+
+/**
+ * drm_gem_vram_vmap() - Pins and maps a GEM VRAM object into kernel address
+ *                       space
+ * @gbo: The GEM VRAM object to map
+ * @map: Returns the kernel virtual address of the VRAM GEM object's backing
+ *       store.
+ *
+ * The vmap function pins a GEM VRAM object to its current location, either
+ * system or video memory, and maps its buffer into kernel address space.
+ * As pinned object cannot be relocated, you should avoid pinning objects
+ * permanently. Call drm_gem_vram_vunmap() with the returned address to
+ * unmap and unpin the GEM VRAM object.
+ *
+ * Returns:
+ * 0 on success, or a negative error code otherwise.
+ */
+int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct iosys_map *map)
+{
+	int ret;
+
+	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
+	if (ret)
+		return ret;
+
+	ret = drm_gem_vram_pin_locked(gbo, 0);
+	if (ret)
+		goto err_ttm_bo_unreserve;
+	ret = drm_gem_vram_kmap_locked(gbo, map);
+	if (ret)
+		goto err_drm_gem_vram_unpin_locked;
+
+	ttm_bo_unreserve(&gbo->bo);
+
+	return 0;
+
+err_drm_gem_vram_unpin_locked:
+	drm_gem_vram_unpin_locked(gbo);
+err_ttm_bo_unreserve:
+	ttm_bo_unreserve(&gbo->bo);
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_vram_vmap);
+
+/**
+ * drm_gem_vram_vunmap() - Unmaps and unpins a GEM VRAM object
+ * @gbo: The GEM VRAM object to unmap
+ * @map: Kernel virtual address where the VRAM GEM object was mapped
+ *
+ * A call to drm_gem_vram_vunmap() unmaps and unpins a GEM VRAM buffer. See
+ * the documentation for drm_gem_vram_vmap() for more information.
+ */
+void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo,
+			 struct iosys_map *map)
+{
+	int ret;
+
+	ret = ttm_bo_reserve(&gbo->bo, false, false, NULL);
+	if (WARN_ONCE(ret, "ttm_bo_reserve_failed(): ret=%d\n", ret))
+		return;
+
+	drm_gem_vram_kunmap_locked(gbo, map);
+	drm_gem_vram_unpin_locked(gbo);
+
+	ttm_bo_unreserve(&gbo->bo);
+}
+EXPORT_SYMBOL(drm_gem_vram_vunmap);
+
+/**
+ * drm_gem_vram_fill_create_dumb() - \
+	Helper for implementing &struct drm_driver.dumb_create
+ * @file:		the DRM file
+ * @dev:		the DRM device
+ * @pg_align:		the buffer's alignment in multiples of the page size
+ * @pitch_align:	the scanline's alignment in powers of 2
+ * @args:		the arguments as provided to \
+				&struct drm_driver.dumb_create
+ *
+ * This helper function fills &struct drm_mode_create_dumb, which is used
+ * by &struct drm_driver.dumb_create. Implementations of this interface
+ * should forwards their arguments to this helper, plus the driver-specific
+ * parameters.
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative error code otherwise.
+ */
+int drm_gem_vram_fill_create_dumb(struct drm_file *file,
+				  struct drm_device *dev,
+				  unsigned long pg_align,
+				  unsigned long pitch_align,
+				  struct drm_mode_create_dumb *args)
+{
+	size_t pitch, size;
+	struct drm_gem_vram_object *gbo;
+	int ret;
+	u32 handle;
+
+	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
+	if (pitch_align) {
+		if (WARN_ON_ONCE(!is_power_of_2(pitch_align)))
+			return -EINVAL;
+		pitch = ALIGN(pitch, pitch_align);
+	}
+	size = pitch * args->height;
+
+	size = roundup(size, PAGE_SIZE);
+	if (!size)
+		return -EINVAL;
+
+	gbo = drm_gem_vram_create(dev, size, pg_align);
+	if (IS_ERR(gbo))
+		return PTR_ERR(gbo);
+
+	ret = drm_gem_handle_create(file, &gbo->bo.base, &handle);
+	if (ret)
+		goto err_drm_gem_object_put;
+
+	drm_gem_object_put(&gbo->bo.base);
+
+	args->pitch = pitch;
+	args->size = size;
+	args->handle = handle;
+
+	return 0;
+
+err_drm_gem_object_put:
+	drm_gem_object_put(&gbo->bo.base);
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_vram_fill_create_dumb);
+
+/*
+ * Helpers for struct ttm_device_funcs
+ */
+
+static bool drm_is_gem_vram(struct ttm_buffer_object *bo)
+{
+	return (bo->destroy == ttm_buffer_object_destroy);
+}
+
+static void drm_gem_vram_bo_driver_evict_flags(struct drm_gem_vram_object *gbo,
+					       struct ttm_placement *pl)
+{
+	drm_gem_vram_placement(gbo, DRM_GEM_VRAM_PL_FLAG_SYSTEM);
+	*pl = gbo->placement;
+}
+
+static void drm_gem_vram_bo_driver_move_notify(struct drm_gem_vram_object *gbo)
+{
+	struct ttm_buffer_object *bo = &gbo->bo;
+	struct drm_device *dev = bo->base.dev;
+
+	if (drm_WARN_ON_ONCE(dev, gbo->vmap_use_count))
+		return;
+
+	ttm_bo_vunmap(bo, &gbo->map);
+	iosys_map_clear(&gbo->map); /* explicitly clear mapping for next vmap call */
+}
+
+static int drm_gem_vram_bo_driver_move(struct drm_gem_vram_object *gbo,
+				       bool evict,
+				       struct ttm_operation_ctx *ctx,
+				       struct ttm_resource *new_mem)
+{
+	drm_gem_vram_bo_driver_move_notify(gbo);
+	return ttm_bo_move_memcpy(&gbo->bo, ctx, new_mem);
+}
+
+/*
+ * Helpers for struct drm_gem_object_funcs
+ */
+
+/**
+ * drm_gem_vram_object_free() - \
+	Implements &struct drm_gem_object_funcs.free
+ * @gem:       GEM object. Refers to &struct drm_gem_vram_object.gem
+ */
+static void drm_gem_vram_object_free(struct drm_gem_object *gem)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
+
+	drm_gem_vram_put(gbo);
+}
+
+/*
+ * Helpers for dump buffers
+ */
+
+/**
+ * drm_gem_vram_driver_dumb_create() - \
+	Implements &struct drm_driver.dumb_create
+ * @file:		the DRM file
+ * @dev:		the DRM device
+ * @args:		the arguments as provided to \
+				&struct drm_driver.dumb_create
+ *
+ * This function requires the driver to use @drm_device.vram_mm for its
+ * instance of VRAM MM.
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative error code otherwise.
+ */
+int drm_gem_vram_driver_dumb_create(struct drm_file *file,
+				    struct drm_device *dev,
+				    struct drm_mode_create_dumb *args)
+{
+	if (WARN_ONCE(!dev->vram_mm, "VRAM MM not initialized"))
+		return -EINVAL;
+
+	return drm_gem_vram_fill_create_dumb(file, dev, 0, 0, args);
+}
+EXPORT_SYMBOL(drm_gem_vram_driver_dumb_create);
+
+/*
+ * Helpers for struct drm_plane_helper_funcs
+ */
+
+static void __drm_gem_vram_plane_helper_cleanup_fb(struct drm_plane *plane,
+						   struct drm_plane_state *state,
+						   unsigned int num_planes)
+{
+	struct drm_gem_object *obj;
+	struct drm_gem_vram_object *gbo;
+	struct drm_framebuffer *fb = state->fb;
+
+	while (num_planes) {
+		--num_planes;
+		obj = drm_gem_fb_get_obj(fb, num_planes);
+		if (!obj)
+			continue;
+		gbo = drm_gem_vram_of_gem(obj);
+		drm_gem_vram_unpin(gbo);
+	}
+}
+
+/**
+ * drm_gem_vram_plane_helper_prepare_fb() - \
+ *	Implements &struct drm_plane_helper_funcs.prepare_fb
+ * @plane:	a DRM plane
+ * @new_state:	the plane's new state
+ *
+ * During plane updates, this function sets the plane's fence and
+ * pins the GEM VRAM objects of the plane's new framebuffer to VRAM.
+ * Call drm_gem_vram_plane_helper_cleanup_fb() to unpin them.
+ *
+ * Returns:
+ *	0 on success, or
+ *	a negative errno code otherwise.
+ */
+int
+drm_gem_vram_plane_helper_prepare_fb(struct drm_plane *plane,
+				     struct drm_plane_state *new_state)
+{
+	struct drm_framebuffer *fb = new_state->fb;
+	struct drm_gem_vram_object *gbo;
+	struct drm_gem_object *obj;
+	unsigned int i;
+	int ret;
+
+	if (!fb)
+		return 0;
+
+	for (i = 0; i < fb->format->num_planes; ++i) {
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj) {
+			ret = -EINVAL;
+			goto err_drm_gem_vram_unpin;
+		}
+		gbo = drm_gem_vram_of_gem(obj);
+		ret = drm_gem_vram_pin(gbo, DRM_GEM_VRAM_PL_FLAG_VRAM);
+		if (ret)
+			goto err_drm_gem_vram_unpin;
+	}
+
+	ret = drm_gem_plane_helper_prepare_fb(plane, new_state);
+	if (ret)
+		goto err_drm_gem_vram_unpin;
+
+	return 0;
+
+err_drm_gem_vram_unpin:
+	__drm_gem_vram_plane_helper_cleanup_fb(plane, new_state, i);
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_vram_plane_helper_prepare_fb);
+
+/**
+ * drm_gem_vram_plane_helper_cleanup_fb() - \
+ *	Implements &struct drm_plane_helper_funcs.cleanup_fb
+ * @plane:	a DRM plane
+ * @old_state:	the plane's old state
+ *
+ * During plane updates, this function unpins the GEM VRAM
+ * objects of the plane's old framebuffer from VRAM. Complements
+ * drm_gem_vram_plane_helper_prepare_fb().
+ */
+void
+drm_gem_vram_plane_helper_cleanup_fb(struct drm_plane *plane,
+				     struct drm_plane_state *old_state)
+{
+	struct drm_framebuffer *fb = old_state->fb;
+
+	if (!fb)
+		return;
+
+	__drm_gem_vram_plane_helper_cleanup_fb(plane, old_state, fb->format->num_planes);
+}
+EXPORT_SYMBOL(drm_gem_vram_plane_helper_cleanup_fb);
+
+/*
+ * Helpers for struct drm_simple_display_pipe_funcs
+ */
+
+/**
+ * drm_gem_vram_simple_display_pipe_prepare_fb() - \
+ *	Implements &struct drm_simple_display_pipe_funcs.prepare_fb
+ * @pipe:	a simple display pipe
+ * @new_state:	the plane's new state
+ *
+ * During plane updates, this function pins the GEM VRAM
+ * objects of the plane's new framebuffer to VRAM. Call
+ * drm_gem_vram_simple_display_pipe_cleanup_fb() to unpin them.
+ *
+ * Returns:
+ *	0 on success, or
+ *	a negative errno code otherwise.
+ */
+int drm_gem_vram_simple_display_pipe_prepare_fb(
+	struct drm_simple_display_pipe *pipe,
+	struct drm_plane_state *new_state)
+{
+	return drm_gem_vram_plane_helper_prepare_fb(&pipe->plane, new_state);
+}
+EXPORT_SYMBOL(drm_gem_vram_simple_display_pipe_prepare_fb);
+
+/**
+ * drm_gem_vram_simple_display_pipe_cleanup_fb() - \
+ *	Implements &struct drm_simple_display_pipe_funcs.cleanup_fb
+ * @pipe:	a simple display pipe
+ * @old_state:	the plane's old state
+ *
+ * During plane updates, this function unpins the GEM VRAM
+ * objects of the plane's old framebuffer from VRAM. Complements
+ * drm_gem_vram_simple_display_pipe_prepare_fb().
+ */
+void drm_gem_vram_simple_display_pipe_cleanup_fb(
+	struct drm_simple_display_pipe *pipe,
+	struct drm_plane_state *old_state)
+{
+	drm_gem_vram_plane_helper_cleanup_fb(&pipe->plane, old_state);
+}
+EXPORT_SYMBOL(drm_gem_vram_simple_display_pipe_cleanup_fb);
+
+/*
+ * PRIME helpers
+ */
+
+/**
+ * drm_gem_vram_object_pin() - \
+	Implements &struct drm_gem_object_funcs.pin
+ * @gem:	The GEM object to pin
+ *
+ * Returns:
+ * 0 on success, or
+ * a negative errno code otherwise.
+ */
+static int drm_gem_vram_object_pin(struct drm_gem_object *gem)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
+
+	/* Fbdev console emulation is the use case of these PRIME
+	 * helpers. This may involve updating a hardware buffer from
+	 * a shadow FB. We pin the buffer to it's current location
+	 * (either video RAM or system memory) to prevent it from
+	 * being relocated during the update operation. If you require
+	 * the buffer to be pinned to VRAM, implement a callback that
+	 * sets the flags accordingly.
+	 */
+	return drm_gem_vram_pin(gbo, 0);
+}
+
+/**
+ * drm_gem_vram_object_unpin() - \
+	Implements &struct drm_gem_object_funcs.unpin
+ * @gem:	The GEM object to unpin
+ */
+static void drm_gem_vram_object_unpin(struct drm_gem_object *gem)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
+
+	drm_gem_vram_unpin(gbo);
+}
+
+/**
+ * drm_gem_vram_object_vmap() -
+ *	Implements &struct drm_gem_object_funcs.vmap
+ * @gem: The GEM object to map
+ * @map: Returns the kernel virtual address of the VRAM GEM object's backing
+ *       store.
+ *
+ * Returns:
+ * 0 on success, or a negative error code otherwise.
+ */
+static int drm_gem_vram_object_vmap(struct drm_gem_object *gem,
+				    struct iosys_map *map)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
+
+	return drm_gem_vram_vmap(gbo, map);
+}
+
+/**
+ * drm_gem_vram_object_vunmap() -
+ *	Implements &struct drm_gem_object_funcs.vunmap
+ * @gem: The GEM object to unmap
+ * @map: Kernel virtual address where the VRAM GEM object was mapped
+ */
+static void drm_gem_vram_object_vunmap(struct drm_gem_object *gem,
+				       struct iosys_map *map)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
+
+	drm_gem_vram_vunmap(gbo, map);
+}
+
+/*
+ * GEM object funcs
+ */
+
+static const struct drm_gem_object_funcs drm_gem_vram_object_funcs = {
+	.free	= drm_gem_vram_object_free,
+	.pin	= drm_gem_vram_object_pin,
+	.unpin	= drm_gem_vram_object_unpin,
+	.vmap	= drm_gem_vram_object_vmap,
+	.vunmap	= drm_gem_vram_object_vunmap,
+	.mmap   = drm_gem_ttm_mmap,
+	.print_info = drm_gem_ttm_print_info,
+};
+
+/*
+ * VRAM memory manager
+ */
+
+/*
+ * TTM TT
+ */
+
+static void bo_driver_ttm_tt_destroy(struct ttm_device *bdev, struct ttm_tt *tt)
+{
+	ttm_tt_fini(tt);
+	kfree(tt);
+}
+
+/*
+ * TTM BO device
+ */
+
+static struct ttm_tt *bo_driver_ttm_tt_create(struct ttm_buffer_object *bo,
+					      uint32_t page_flags)
+{
+	struct ttm_tt *tt;
+	int ret;
+
+	tt = kzalloc(sizeof(*tt), GFP_KERNEL);
+	if (!tt)
+		return NULL;
+
+	ret = ttm_tt_init(tt, bo, page_flags, ttm_cached, 0);
+	if (ret < 0)
+		goto err_ttm_tt_init;
+
+	return tt;
+
+err_ttm_tt_init:
+	kfree(tt);
+	return NULL;
+}
+
+static void bo_driver_evict_flags(struct ttm_buffer_object *bo,
+				  struct ttm_placement *placement)
+{
+	struct drm_gem_vram_object *gbo;
+
+	/* TTM may pass BOs that are not GEM VRAM BOs. */
+	if (!drm_is_gem_vram(bo))
+		return;
+
+	gbo = drm_gem_vram_of_bo(bo);
+
+	drm_gem_vram_bo_driver_evict_flags(gbo, placement);
+}
+
+static void bo_driver_delete_mem_notify(struct ttm_buffer_object *bo)
+{
+	struct drm_gem_vram_object *gbo;
+
+	/* TTM may pass BOs that are not GEM VRAM BOs. */
+	if (!drm_is_gem_vram(bo))
+		return;
+
+	gbo = drm_gem_vram_of_bo(bo);
+
+	drm_gem_vram_bo_driver_move_notify(gbo);
+}
+
+static int bo_driver_move(struct ttm_buffer_object *bo,
+			  bool evict,
+			  struct ttm_operation_ctx *ctx,
+			  struct ttm_resource *new_mem,
+			  struct ttm_place *hop)
+{
+	struct drm_gem_vram_object *gbo;
+
+	gbo = drm_gem_vram_of_bo(bo);
+
+	return drm_gem_vram_bo_driver_move(gbo, evict, ctx, new_mem);
+}
+
+static int bo_driver_io_mem_reserve(struct ttm_device *bdev,
+				    struct ttm_resource *mem)
+{
+	struct drm_vram_mm *vmm = drm_vram_mm_of_bdev(bdev);
+
+	switch (mem->mem_type) {
+	case TTM_PL_SYSTEM:	/* nothing to do */
+		break;
+	case TTM_PL_VRAM:
+		mem->bus.offset = (mem->start << PAGE_SHIFT) + vmm->vram_base;
+		mem->bus.is_iomem = true;
+		mem->bus.caching = ttm_write_combined;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct ttm_device_funcs bo_driver = {
+	.ttm_tt_create = bo_driver_ttm_tt_create,
+	.ttm_tt_destroy = bo_driver_ttm_tt_destroy,
+	.eviction_valuable = ttm_bo_eviction_valuable,
+	.evict_flags = bo_driver_evict_flags,
+	.move = bo_driver_move,
+	.delete_mem_notify = bo_driver_delete_mem_notify,
+	.io_mem_reserve = bo_driver_io_mem_reserve,
+};
+
+/*
+ * struct drm_vram_mm
+ */
+
+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 ttm_resource_manager *man = ttm_manager_type(&vmm->bdev, TTM_PL_VRAM);
+	struct drm_printer p = drm_seq_file_printer(m);
+
+	ttm_resource_manager_debug(man, &p);
+	return 0;
+}
+
+static const struct drm_info_list drm_vram_mm_debugfs_list[] = {
+	{ "vram-mm", drm_vram_mm_debugfs, 0, NULL },
+};
+
+/**
+ * drm_vram_mm_debugfs_init() - Register VRAM MM debugfs file.
+ *
+ * @minor: drm minor device.
+ *
+ */
+void drm_vram_mm_debugfs_init(struct drm_minor *minor)
+{
+	drm_debugfs_create_files(drm_vram_mm_debugfs_list,
+				 ARRAY_SIZE(drm_vram_mm_debugfs_list),
+				 minor->debugfs_root, minor);
+}
+EXPORT_SYMBOL(drm_vram_mm_debugfs_init);
+
+static int drm_vram_mm_init(struct drm_vram_mm *vmm, struct drm_device *dev,
+			    uint64_t vram_base, size_t vram_size)
+{
+	int ret;
+
+	vmm->vram_base = vram_base;
+	vmm->vram_size = vram_size;
+
+	ret = ttm_device_init(&vmm->bdev, &bo_driver, dev->dev,
+				 dev->anon_inode->i_mapping,
+				 dev->vma_offset_manager,
+				 false, true);
+	if (ret)
+		return ret;
+
+	ret = ttm_range_man_init(&vmm->bdev, TTM_PL_VRAM,
+				 false, vram_size >> PAGE_SHIFT);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void drm_vram_mm_cleanup(struct drm_vram_mm *vmm)
+{
+	ttm_range_man_fini(&vmm->bdev, TTM_PL_VRAM);
+	ttm_device_fini(&vmm->bdev);
+}
+
+/*
+ * Helpers for integration with struct drm_device
+ */
+
+static struct drm_vram_mm *drm_vram_helper_alloc_mm(struct drm_device *dev, uint64_t vram_base,
+						    size_t vram_size)
+{
+	int ret;
+
+	if (WARN_ON(dev->vram_mm))
+		return dev->vram_mm;
+
+	dev->vram_mm = kzalloc(sizeof(*dev->vram_mm), GFP_KERNEL);
+	if (!dev->vram_mm)
+		return ERR_PTR(-ENOMEM);
+
+	ret = drm_vram_mm_init(dev->vram_mm, dev, vram_base, vram_size);
+	if (ret)
+		goto err_kfree;
+
+	return dev->vram_mm;
+
+err_kfree:
+	kfree(dev->vram_mm);
+	dev->vram_mm = NULL;
+	return ERR_PTR(ret);
+}
+
+static void drm_vram_helper_release_mm(struct drm_device *dev)
+{
+	if (!dev->vram_mm)
+		return;
+
+	drm_vram_mm_cleanup(dev->vram_mm);
+	kfree(dev->vram_mm);
+	dev->vram_mm = NULL;
+}
+
+static void drm_vram_mm_release(struct drm_device *dev, void *ptr)
+{
+	drm_vram_helper_release_mm(dev);
+}
+
+/**
+ * drmm_vram_helper_init - Initializes a device's instance of
+ *                         &struct drm_vram_mm
+ * @dev:	the DRM device
+ * @vram_base:	the base address of the video memory
+ * @vram_size:	the size of the video memory in bytes
+ *
+ * Creates a new instance of &struct drm_vram_mm and stores it in
+ * struct &drm_device.vram_mm. The instance is auto-managed and cleaned
+ * up as part of device cleanup. Calling this function multiple times
+ * will generate an error message.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ */
+int drmm_vram_helper_init(struct drm_device *dev, uint64_t vram_base,
+			  size_t vram_size)
+{
+	struct drm_vram_mm *vram_mm;
+
+	if (drm_WARN_ON_ONCE(dev, dev->vram_mm))
+		return 0;
+
+	vram_mm = drm_vram_helper_alloc_mm(dev, vram_base, vram_size);
+	if (IS_ERR(vram_mm))
+		return PTR_ERR(vram_mm);
+	return drmm_add_action_or_reset(dev, drm_vram_mm_release, NULL);
+}
+EXPORT_SYMBOL(drmm_vram_helper_init);
+
+/*
+ * Mode-config helpers
+ */
+
+static enum drm_mode_status
+drm_vram_helper_mode_valid_internal(struct drm_device *dev,
+				    const struct drm_display_mode *mode,
+				    unsigned long max_bpp)
+{
+	struct drm_vram_mm *vmm = dev->vram_mm;
+	unsigned long fbsize, fbpages, max_fbpages;
+
+	if (WARN_ON(!dev->vram_mm))
+		return MODE_BAD;
+
+	max_fbpages = (vmm->vram_size / 2) >> PAGE_SHIFT;
+
+	fbsize = mode->hdisplay * mode->vdisplay * max_bpp;
+	fbpages = DIV_ROUND_UP(fbsize, PAGE_SIZE);
+
+	if (fbpages > max_fbpages)
+		return MODE_MEM;
+
+	return MODE_OK;
+}
+
+/**
+ * drm_vram_helper_mode_valid - Tests if a display mode's
+ *	framebuffer fits into the available video memory.
+ * @dev:	the DRM device
+ * @mode:	the mode to test
+ *
+ * This function tests if enough video memory is available for using the
+ * specified display mode. Atomic modesetting requires importing the
+ * designated framebuffer into video memory before evicting the active
+ * one. Hence, any framebuffer may consume at most half of the available
+ * VRAM. Display modes that require a larger framebuffer can not be used,
+ * even if the CRTC does support them. Each framebuffer is assumed to
+ * have 32-bit color depth.
+ *
+ * Note:
+ * The function can only test if the display mode is supported in
+ * general. If there are too many framebuffers pinned to video memory,
+ * a display mode may still not be usable in practice. The color depth of
+ * 32-bit fits all current use case. A more flexible test can be added
+ * when necessary.
+ *
+ * Returns:
+ * MODE_OK if the display mode is supported, or an error code of type
+ * enum drm_mode_status otherwise.
+ */
+enum drm_mode_status
+drm_vram_helper_mode_valid(struct drm_device *dev,
+			   const struct drm_display_mode *mode)
+{
+	static const unsigned long max_bpp = 4; /* DRM_FORMAT_XRGB8888 */
+
+	return drm_vram_helper_mode_valid_internal(dev, mode, max_bpp);
+}
+EXPORT_SYMBOL(drm_vram_helper_mode_valid);
+
+MODULE_DESCRIPTION("DRM VRAM memory-management helpers");
+MODULE_LICENSE("GPL");