path: root/drivers/gpu/drm/drm_gem_cma_helper.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * drm gem CMA (contiguous memory allocator) helper functions
 *
 * Copyright (C) 2012 Sascha Hauer, Pengutronix
 *
 * Based on Samsung Exynos code
 *
 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
 */

#include <linux/dma-buf.h>
#include <linux/dma-mapping.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/slab.h>

#include <drm/drm.h>
#include <drm/drm_device.h>
#include <drm/drm_drv.h>
#include <drm/drm_gem_cma_helper.h>
#include <drm/drm_vma_manager.h>

/**
 * DOC: cma helpers
 *
 * The Contiguous Memory Allocator reserves a pool of memory at early boot
 * that is used to service requests for large blocks of contiguous memory.
 *
 * The DRM GEM/CMA helpers use this allocator as a means to provide buffer
 * objects that are physically contiguous in memory. This is useful for
 * display drivers that are unable to map scattered buffers via an IOMMU.
 */

/**
 * __drm_gem_cma_create - Create a GEM CMA object without allocating memory
 * @drm: DRM device
 * @size: size of the object to allocate
 *
 * This function creates and initializes a GEM CMA object of the given size,
 * but doesn't allocate any memory to back the object.
 *
 * Returns:
 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
 * error code on failure.
 */
static struct drm_gem_cma_object *
__drm_gem_cma_create(struct drm_device *drm, size_t size)
{
	struct drm_gem_cma_object *cma_obj;
	struct drm_gem_object *gem_obj;
	int ret;

	if (drm->driver->gem_create_object)
		gem_obj = drm->driver->gem_create_object(drm, size);
	else
		gem_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
	if (!gem_obj)
		return ERR_PTR(-ENOMEM);
	cma_obj = container_of(gem_obj, struct drm_gem_cma_object, base);

	ret = drm_gem_object_init(drm, gem_obj, size);
	if (ret)
		goto error;

	ret = drm_gem_create_mmap_offset(gem_obj);
	if (ret) {
		drm_gem_object_release(gem_obj);
		goto error;
	}

	return cma_obj;

error:
	kfree(cma_obj);
	return ERR_PTR(ret);
}

/**
 * drm_gem_cma_create - allocate an object with the given size
 * @drm: DRM device
 * @size: size of the object to allocate
 *
 * This function creates a CMA GEM object and allocates a contiguous chunk of
 * memory as backing store. The backing memory has the writecombine attribute
 * set.
 *
 * Returns:
 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
 * error code on failure.
 */
struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
					      size_t size)
{
	struct drm_gem_cma_object *cma_obj;
	int ret;

	size = round_up(size, PAGE_SIZE);

	cma_obj = __drm_gem_cma_create(drm, size);
	if (IS_ERR(cma_obj))
		return cma_obj;

	cma_obj->vaddr = dma_alloc_wc(drm->dev, size, &cma_obj->paddr,
				      GFP_KERNEL | __GFP_NOWARN);
	if (!cma_obj->vaddr) {
		dev_dbg(drm->dev, "failed to allocate buffer with size %zu\n",
			size);
		ret = -ENOMEM;
		goto error;
	}

	return cma_obj;

error:
	drm_gem_object_put_unlocked(&cma_obj->base);
	return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(drm_gem_cma_create);

/**
 * drm_gem_cma_create_with_handle - allocate an object with the given size and
 *     return a GEM handle to it
 * @file_priv: DRM file-private structure to register the handle for
 * @drm: DRM device
 * @size: size of the object to allocate
 * @handle: return location for the GEM handle
 *
 * This function creates a CMA GEM object, allocating a physically contiguous
 * chunk of memory as backing store. The GEM object is then added to the list
 * of object associated with the given file and a handle to it is returned.
 *
 * Returns:
 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
 * error code on failure.
 */
static struct drm_gem_cma_object *
drm_gem_cma_create_with_handle(struct drm_file *file_priv,
			       struct drm_device *drm, size_t size,
			       uint32_t *handle)
{
	struct drm_gem_cma_object *cma_obj;
	struct drm_gem_object *gem_obj;
	int ret;

	cma_obj = drm_gem_cma_create(drm, size);
	if (IS_ERR(cma_obj))
		return cma_obj;

	gem_obj = &cma_obj->base;

	/*
	 * allocate a id of idr table where the obj is registered
	 * and handle has the id what user can see.
	 */
	ret = drm_gem_handle_create(file_priv, gem_obj, handle);
	/* drop reference from allocate - handle holds it now. */
	drm_gem_object_put_unlocked(gem_obj);
	if (ret)
		return ERR_PTR(ret);

	return cma_obj;
}

/**
 * drm_gem_cma_free_object - free resources associated with a CMA GEM object
 * @gem_obj: GEM object to free
 *
 * This function frees the backing memory of the CMA GEM object, cleans up the
 * GEM object state and frees the memory used to store the object itself.
 * If the buffer is imported and the virtual address is set, it is released.
 * Drivers using the CMA helpers should set this as their
 * &drm_driver.gem_free_object_unlocked callback.
 */
void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
{
	struct drm_gem_cma_object *cma_obj;

	cma_obj = to_drm_gem_cma_obj(gem_obj);

	if (gem_obj->import_attach) {
		if (cma_obj->vaddr)
			dma_buf_vunmap(gem_obj->import_attach->dmabuf, cma_obj->vaddr);
		drm_prime_gem_destroy(gem_obj, cma_obj->sgt);
	} else if (cma_obj->vaddr) {
		dma_free_wc(gem_obj->dev->dev, cma_obj->base.size,
			    cma_obj->vaddr, cma_obj->paddr);
	}

	drm_gem_object_release(gem_obj);

	kfree(cma_obj);
}
EXPORT_SYMBOL_GPL(drm_gem_cma_free_object);

/**
 * drm_gem_cma_dumb_create_internal - create a dumb buffer object
 * @file_priv: DRM file-private structure to create the dumb buffer for
 * @drm: DRM device
 * @args: IOCTL data
 *
 * This aligns the pitch and size arguments to the minimum required. This is
 * an internal helper that can be wrapped by a driver to account for hardware
 * with more specific alignment requirements. It should not be used directly
 * as their &drm_driver.dumb_create callback.
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 */
int drm_gem_cma_dumb_create_internal(struct drm_file *file_priv,
				     struct drm_device *drm,
				     struct drm_mode_create_dumb *args)
{
	unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
	struct drm_gem_cma_object *cma_obj;

	if (args->pitch < min_pitch)
		args->pitch = min_pitch;

	if (args->size < args->pitch * args->height)
		args->size = args->pitch * args->height;

	cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
						 &args->handle);
	return PTR_ERR_OR_ZERO(cma_obj);
}
EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create_internal);

/**
 * drm_gem_cma_dumb_create - create a dumb buffer object
 * @file_priv: DRM file-private structure to create the dumb buffer for
 * @drm: DRM device
 * @args: IOCTL data
 *
 * This function computes the pitch of the dumb buffer and rounds it up to an
 * integer number of bytes per pixel. Drivers for hardware that doesn't have
 * any additional restrictions on the pitch can directly use this function as
 * their &drm_driver.dumb_create callback.
 *
 * For hardware with additional restrictions, drivers can adjust the fields
 * set up by userspace and pass the IOCTL data along to the
 * drm_gem_cma_dumb_create_internal() function.
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 */
int drm_gem_cma_dumb_create(struct drm_file *file_priv,
			    struct drm_device *drm,
			    struct drm_mode_create_dumb *args)
{
	struct drm_gem_cma_object *cma_obj;

	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
	args->size = args->pitch * args->height;

	cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
						 &args->handle);
	return PTR_ERR_OR_ZERO(cma_obj);
}
EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create);

const struct vm_operations_struct drm_gem_cma_vm_ops = {
	.open = drm_gem_vm_open,
	.close = drm_gem_vm_close,
};
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;