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) {
		drm_dbg(drm, "failed to allocate buffer with size %zu\n",
			 size);
		ret = -ENOMEM;
		goto error;
	}

	return cma_obj;

error:
	drm_gem_object_put(&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(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;

	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
 * @filp: file object
 * @addr: memory address
 * @len: buffer size
 * @pgoff: page offset
 * @flags: memory flags
 *
 * This function is used in noMMU platforms to propose address mapping
 * for a given buffer.
 * It's intended to be used as a direct handler for the struct
 * &file_operations.get_unmapped_area operation.
 *
 * Returns:
 * mapping address on success or a negative error code on failure.
 */
unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
					    unsigned long addr,
					    unsigned long len,
					    unsigned long pgoff,
					    unsigned long flags)
{
	struct drm_gem_cma_object *cma_obj;
	struct drm_gem_object *obj = NULL;
	struct drm_file *priv = filp->private_data;
	struct drm_device *dev = priv->minor->dev;
	struct drm_vma_offset_node *node;

	if (drm_dev_is_unplugged(dev))
		return -ENODEV;

	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
						  pgoff,
						  len >> PAGE_SHIFT);
	if (likely(node)) {
		obj = container_of(node, struct drm_gem_object, vma_node);
		/*
		 * When the object is being freed, after it hits 0-refcnt it
		 * proceeds to tear down the object. In the process it will
		 * attempt to remove the VMA offset and so acquire this
		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
		 * that matches our range, we know it is in the process of being
		 * destroyed and will be freed as soon as we release the lock -
		 * so we have to check for the 0-refcnted object and treat it as
		 * invalid.
		 */
		if (!kref_get_unless_zero(&obj->refcount))
			obj = NULL;
	}

	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);

	if (!obj)
		return -EINVAL;

	if (!drm_vma_node_is_allowed(node, priv)) {
		drm_gem_object_put(obj);
		return -EACCES;
	}

	cma_obj = to_drm_gem_cma_obj(obj);

	drm_gem_object_put(obj);

	return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
}
EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
#endif

/**
 * drm_gem_cma_print_info() - Print &drm_gem_cma_object info for debugfs
 * @p: DRM printer
 * @indent: Tab indentation level
 * @obj: GEM object
 *
 * This function can be used as the &drm_driver->gem_print_info callback.
 * It prints paddr and vaddr for use in e.g. debugfs output.
 */
void drm_gem_cma_print_info(struct drm_printer *p, unsigned int indent,
			    const struct drm_gem_object *obj)
{
	const struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

	drm_printf_indent(p, indent, "paddr=%pad\n", &cma_obj->paddr);
	drm_printf_indent(p, indent, "vaddr=%p\n", cma_obj->vaddr);
}
EXPORT_SYMBOL(drm_gem_cma_print_info);

/**
 * drm_gem_cma_prime_get_sg_table - provide a scatter/gather table of pinned
 *     pages for a CMA GEM object
 * @obj: GEM object
 *
 * This function exports a scatter/gather table suitable for PRIME usage by
 * calling the standard DMA mapping API. Drivers using the CMA helpers should
 * set this as their &drm_driver.gem_prime_get_sg_table callback.
 *
 * Returns:
 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
 */
struct sg_table *drm_gem_cma_prime_get_sg_table(struct drm_gem_object *obj)
{
	struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
	struct sg_table *sgt;
	int ret;

	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
	if (!sgt)
		return ERR_PTR(-ENOMEM);

	ret = dma_get_sgtable(obj->dev->dev, sgt, cma_obj->vaddr,
			      cma_obj->paddr, obj->size);
	if (ret < 0)
		goto out;

	return sgt;

out:
	kfree(sgt);
	return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(drm_gem_cma_prime_get_sg_table);

/**
 * drm_gem_cma_prime_import_sg_table - produce a CMA GEM object from another
 *     driver's scatter/gather table of pinned pages
 * @dev: device to import into
 * @attach: DMA-BUF attachment
 * @sgt: scatter/gather table of pinned pages
 *
 * This function imports a scatter/gather table exported via DMA-BUF by
 * another driver. Imported buffers must be physically contiguous in memory
 * (i.e. the scatter/gather table must contain a single entry). Drivers that
 * use the CMA helpers should set this as their
 * &drm_driver.gem_prime_import_sg_table callback.
 *
 * Returns:
 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
 * error code on failure.
 */
struct drm_gem_object *
drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
				  struct dma_buf_attachment *attach,
				  struct sg_table *sgt)
{
	struct drm_gem_cma_object *cma_obj;

	if (sgt->nents != 1) {
		/* check if the entries in the sg_table are contiguous */
		dma_addr_t next_addr = sg_dma_address(sgt->sgl);
		struct scatterlist *s;
		unsigned int i;

		for_each_sg(sgt->sgl, s, sgt->nents, i) {
			/*
			 * sg_dma_address(s) is only valid for entries
			 * that have sg_dma_len(s) != 0
			 */
			if (!sg_dma_len(s))
				continue;

			if (sg_dma_address(s) != next_addr)
				return ERR_PTR(-EINVAL);

			next_addr = sg_dma_address(s) + sg_dma_len(s);
		}
	}

	/* Create a CMA GEM buffer. */
	cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
	if (IS_ERR(cma_obj))
		return ERR_CAST(cma_obj);

	cma_obj->paddr = sg_dma_address(sgt->sgl);
	cma_obj->sgt = sgt;

	DRM_DEBUG_PRIME("dma_addr = %pad, size = %zu\n", &cma_obj->paddr, attach->dmabuf->size);

	return &cma_obj->base;
}
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_prime_vmap - map a CMA GEM object into the kernel's virtual
 *     address space
 * @obj: GEM object
 *
 * This function maps a buffer exported via DRM PRIME into the kernel's
 * virtual address space. Since the CMA buffers are already mapped into the
 * kernel virtual address space this simply returns the cached virtual
 * address. Drivers using the CMA helpers should set this as their DRM
 * driver's &drm_driver.gem_prime_vmap callback.
 *
 * Returns:
 * The kernel virtual address of the CMA GEM object's backing store.
 */
void *drm_gem_cma_prime_vmap(struct drm_gem_object *obj)
{
	struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

	return cma_obj->vaddr;
}
EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vmap);

/**
 * drm_gem_cma_prime_vunmap - unmap a CMA GEM object from the kernel's virtual
 *     address space
 * @obj: GEM object
 * @vaddr: kernel virtual address where the CMA GEM object was mapped
 *
 * This function removes a buffer exported via DRM PRIME from the kernel's
 * virtual address space. This is a no-op because CMA buffers cannot be
 * unmapped from kernel space. Drivers using the CMA helpers should set this
 * as their &drm_driver.gem_prime_vunmap callback.
 */
void drm_gem_cma_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
{
	/* Nothing to do */
}
EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vunmap);

static const struct drm_gem_object_funcs drm_gem_cma_default_funcs = {
	.free = drm_gem_cma_free_object,
	.print_info = drm_gem_cma_print_info,
	.get_sg_table = drm_gem_cma_prime_get_sg_table,
	.vmap = drm_gem_cma_prime_vmap,
	.vm_ops = &drm_gem_cma_vm_ops,
};

/**
 * drm_gem_cma_create_object_default_funcs - Create a CMA GEM object with a
 *                                           default function table
 * @dev: DRM device
 * @size: Size of the object to allocate
 *
 * This sets the GEM object functions to the default CMA helper functions.
 * This function can be used as the &drm_driver.gem_create_object callback.
 *
 * Returns:
 * A pointer to a allocated GEM object or an error pointer on failure.
 */
struct drm_gem_object *
drm_gem_cma_create_object_default_funcs(struct drm_device *dev, size_t size)
{
	struct drm_gem_cma_object *cma_obj;

	cma_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
	if (!cma_obj)
		return NULL;

	cma_obj->base.funcs = &drm_gem_cma_default_funcs;

	return &cma_obj->base;
}
EXPORT_SYMBOL(drm_gem_cma_create_object_default_funcs);

/**
 * drm_gem_cma_prime_import_sg_table_vmap - PRIME import another driver's
 *	scatter/gather table and get the virtual address of the buffer
 * @dev: DRM device
 * @attach: DMA-BUF attachment
 * @sgt: Scatter/gather table of pinned pages
 *
 * This function imports a scatter/gather table using
 * drm_gem_cma_prime_import_sg_table() and uses dma_buf_vmap() to get the kernel
 * virtual address. This ensures that a CMA GEM object always has its virtual
 * address set. This address is released when the object is freed.
 *
 * This function can be used as the &drm_driver.gem_prime_import_sg_table
 * callback. The &DRM_GEM_CMA_DRIVER_OPS_VMAP macro provides a shortcut to set
 * the necessary DRM driver operations.
 *
 * Returns:
 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
 * error code on failure.
 */
struct drm_gem_object *
drm_gem_cma_prime_import_sg_table_vmap(struct drm_device *dev,
				       struct dma_buf_attachment *attach,
				       struct sg_table *sgt)
{
	struct drm_gem_cma_object *cma_obj;
	struct drm_gem_object *obj;
	struct dma_buf_map map;
	int ret;

	ret = dma_buf_vmap(attach->dmabuf, &map);
	if (ret) {
		DRM_ERROR("Failed to vmap PRIME buffer\n");
		return ERR_PTR(ret);
	}

	obj = drm_gem_cma_prime_import_sg_table(dev, attach, sgt);
	if (IS_ERR(obj)) {
		dma_buf_vunmap(attach->dmabuf, map.vaddr);
		return obj;
	}

	cma_obj = to_drm_gem_cma_obj(obj);
	cma_obj->vaddr = map.vaddr;

	return obj;
}
EXPORT_SYMBOL(drm_gem_cma_prime_import_sg_table_vmap);