// SPDX-License-Identifier: GPL-2.0-or-later
/*
* drm gem DMA 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/module.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_dma_helper.h>
#include <drm/drm_vma_manager.h>
/**
* DOC: dma helpers
*
* The DRM GEM/DMA helpers are a means to provide buffer objects that are
* presented to the device as a contiguous chunk of memory. This is useful
* for devices that do not support scatter-gather DMA (either directly or
* by using an intimately attached IOMMU).
*
* For devices that access the memory bus through an (external) IOMMU then
* the buffer objects are allocated using a traditional page-based
* allocator and may be scattered through physical memory. However they
* are contiguous in the IOVA space so appear contiguous to devices using
* them.
*
* For other devices then the helpers rely on CMA to provide buffer
* objects that are physically contiguous in memory.
*
* For GEM callback helpers in struct &drm_gem_object functions, see likewise
* named functions with an _object_ infix (e.g., drm_gem_dma_object_vmap() wraps
* drm_gem_dma_vmap()). These helpers perform the necessary type conversion.
*/
static const struct drm_gem_object_funcs drm_gem_dma_default_funcs = {
.free = drm_gem_dma_object_free,
.print_info = drm_gem_dma_object_print_info,
.get_sg_table = drm_gem_dma_object_get_sg_table,
.vmap = drm_gem_dma_object_vmap,
.mmap = drm_gem_dma_object_mmap,
.vm_ops = &drm_gem_dma_vm_ops,
};
/**
* __drm_gem_dma_create - Create a GEM DMA object without allocating memory
* @drm: DRM device
* @size: size of the object to allocate
* @private: true if used for internal purposes
*
* This function creates and initializes a GEM DMA object of the given size,
* but doesn't allocate any memory to back the object.
*
* Returns:
* A struct drm_gem_dma_object * on success or an ERR_PTR()-encoded negative
* error code on failure.
*/
static struct drm_gem_dma_object *
__drm_gem_dma_create(struct drm_device *drm, size_t size, bool private)
{
struct drm_gem_dma_object *dma_obj;
struct drm_gem_object *gem_obj;
int ret = 0;
if (drm->driver->gem_create_object) {
gem_obj = drm->driver->gem_create_object(drm, size);
if (IS_ERR(gem_obj))
return ERR_CAST(gem_obj);
dma_obj = to_drm_gem_dma_obj(gem_obj);
} else {
dma_obj = kzalloc(sizeof(*dma_obj), GFP_KERNEL);
if (!dma_obj)
return ERR_PTR(-ENOMEM);
gem_obj = &dma_obj->base;
}
if (!gem_obj->funcs)
gem_obj->funcs = &drm_gem_dma_default_funcs;
if (private) {
drm_gem_private_object_init(drm, gem_obj, size);
/* Always use writecombine for dma-buf mappings */
dma_obj->map_noncoherent = false;
} else {
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 dma_obj;
error:
kfree(dma_obj);
return ERR_PTR(ret);
}
/**
* drm_gem_dma_create - allocate an object with the given size
* @drm: DRM device
* @size: size of the object to allocate
*
* This function creates a DMA GEM object and allocates memory as backing store.
* The allocated memory will occupy a contiguous chunk of bus address space.
*
* For devices that are directly connected to the memory bus then the allocated
* memory will be physically contiguous. For devices that access through an
* IOMMU, then the allocated memory is not expected to be physically contiguous
* because having contiguous IOVAs is sufficient to meet a devices DMA
* requirements.
*
* Returns:
* A struct drm_gem_dma_object * on success or an ERR_PTR()-encoded negative
* error code on failure.
*/
struct drm_gem_dma_object *drm_gem_dma_create(struct drm_device *drm,
size_t size)
{
struct drm_gem_dma_object *dma_obj;
int ret;
size = round_up(size, PAGE_SIZE);
dma_obj = __drm_gem_dma_create(drm, size, false);
if (IS_ERR(dma_obj))
return dma_obj;
if (dma_obj->map_noncoherent) {
dma_obj->vaddr = dma_alloc_noncoherent(drm->dev, size,
&dma_obj->dma_addr,
DMA_TO_DEVICE,
GFP_KERNEL | __GFP_NOWARN);
} else {
dma_obj->vaddr = dma_alloc_wc(drm->dev, size,
&dma_obj->dma_addr,
GFP_KERNEL | __GFP_NOWARN);
}
if (!dma_obj->vaddr) {
drm_dbg(drm, "failed to allocate buffer with size %zu\n",
size);
ret = -ENOMEM;
goto error;
}
return dma_obj;
error:
drm_gem_object_put(&dma_obj->base);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(drm_gem_dma_create);
/**
* drm_gem_dma_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 DMA GEM object, allocating a 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.
*
* The allocated memory will occupy a contiguous chunk of bus address space.
* See drm_gem_dma_create() for more details.
*
* Returns:
* A struct drm_gem_dma_object * on success or an ERR_PTR()-encoded negative
* error code on failure.
*/
static struct drm_gem_dma_object *
drm_gem_dma_create_with_handle(struct drm_file *file_priv,
struct drm_device *drm, size_t size,
uint32_t *handle)
{
struct drm_gem_dma_object *dma_obj;
struct drm_gem_object *gem_obj;
int ret;
dma_obj = drm_gem_dma_create(drm, size);
if (IS_ERR(dma_obj))
return dma_obj;
gem_obj = &dma_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 dma_obj;
}
/**
* drm_gem_dma_free - free resources associated with a DMA GEM object
* @dma_obj: DMA GEM object to free
*
* This function frees the backing memory of the DMA 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.
*/
void drm_gem_dma_free(struct drm_gem_dma_object *dma_obj)
{
struct drm_gem_object *gem_obj = &dma_obj->base;
struct iosys_map map = IOSYS_MAP_INIT_VADDR(dma_obj->vaddr);
if (gem_obj->import_attach) {
if (dma_obj->vaddr)
dma_buf_vunmap_unlocked(gem_obj->import_attach->dmabuf, &map);
drm_prime_gem_destroy(gem_obj, dma_obj->sgt);
} else if (dma_obj->vaddr) {
if (dma_obj->map_noncoherent)
dma_free_noncoherent(gem_obj->dev->dev, dma_obj->base.size,
dma_obj->vaddr, dma_obj->dma_addr,
DMA_TO_DEVICE);
else
dma_free_wc(gem_obj->dev->dev, dma_obj->base.size,
dma_obj->vaddr, dma_obj->dma_addr);
}
drm_gem_object_release(gem_obj);
kfree(dma_obj);
}
EXPORT_SYMBOL_GPL(drm_gem_dma_free);
/**
* drm_gem_dma_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_dma_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_dma_object *dma_obj;
if (args->pitch < min_pitch)
args->pitch = min_pitch;
if (args->size < args->pitch * args->height)
args->size = args->pitch * args->height;
dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
&args->handle);
return PTR_ERR_OR_ZERO(dma_obj);
}
EXPORT_SYMBOL_GPL(drm_gem_dma_dumb_create_internal);
/**
* drm_gem_dma_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_dma_dumb_create_internal() function.
*
* Returns:
* 0 on success or a negative error code on failure.
*/
int drm_gem_dma_dumb_create(struct drm_file *file_priv,
struct drm_device *drm,
struct drm_mode_create_dumb *args)
{
struct drm_gem_dma_object *dma_obj;
args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
args->size = args->pitch * args->height;
dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
&args->handle);
return PTR_ERR_OR_ZERO(dma_obj);
}
EXPORT_SYMBOL_GPL(drm_gem_dma_dumb_create);
const struct vm_operations_struct drm_gem_dma_vm_ops = {
.open = drm_gem_vm_open,
.close = drm_gem_vm_close,
};
EXPORT_SYMBOL_GPL(drm_gem_dma_vm_ops);
#ifndef CONFIG_MMU
/**
* drm_gem_dma_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_dma_get_unmapped_area(struct file *filp,
unsigned long addr,
unsigned long len,
unsigned long pgoff,
unsigned long flags)
{
struct drm_gem_dma_object *dma_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;
}
dma_obj = to_drm_gem_dma_obj(obj);
drm_gem_object_put(obj);
return dma_obj->vaddr ? (unsigned long)dma_obj->vaddr : -EINVAL;
}
EXPORT_SYMBOL_GPL(drm_gem_dma_get_unmapped_area);
#endif
/**
* drm_gem_dma_print_info() - Print &drm_gem_dma_object info for debugfs
* @dma_obj: DMA GEM object
* @p: DRM printer
* @indent: Tab indentation level
*
* This function prints dma_addr and vaddr for use in e.g. debugfs output.
*/
void drm_gem_dma_print_info(const struct drm_gem_dma_object *dma_obj,
struct drm_printer *p, unsigned int indent)
{
drm_printf_indent(p, indent, "dma_addr=%pad\n", &dma_obj->dma_addr);
drm_printf_indent(p, indent, "vaddr=%p\n", dma_obj->vaddr);
}
EXPORT_SYMBOL(drm_gem_dma_print_info);
/**
* drm_gem_dma_get_sg_table - provide a scatter/gather table of pinned
* pages for a DMA GEM object
* @dma_obj: DMA GEM object
*
* This function exports a scatter/gather table by calling the standard
* DMA mapping API.
*
* Returns:
* A pointer to the scatter/gather table of pinned pages or NULL on failure.
*/
struct sg_table *drm_gem_dma_get_sg_table(struct drm_gem_dma_object *dma_obj)
{
struct drm_gem_object *obj = &dma_obj->base;
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, dma_obj->vaddr,
dma_obj->dma_addr, obj->size);
if (ret < 0)
goto out;
return sgt;
out:
kfree(sgt);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(drm_gem_dma_get_sg_table);
/**
* drm_gem_dma_prime_import_sg_table - produce a DMA 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 DMA 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_dma_prime_import_sg_table(struct drm_device *dev,
struct dma_buf_attachment *attach,
struct sg_table *sgt)
{
struct drm_gem_dma_object *dma_obj;
/* check if the entries in the sg_table are contiguous */
if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size)
return ERR_PTR(-EINVAL);
/* Create a DMA GEM buffer. */
dma_obj = __drm_gem_dma_create(dev, attach->dmabuf->size, true);
if (IS_ERR(dma_obj))
return ERR_CAST(dma_obj);
dma_obj->dma_addr = sg_dma_address(sgt->sgl);
dma_obj->sgt = sgt;
drm_dbg_prime(dev, "dma_addr = %pad, size = %zu\n", &dma_obj->dma_addr,
attach->dmabuf->size);
return &dma_obj->base;
}
EXPORT_SYMBOL_GPL(drm_gem_dma_prime_import_sg_table);
/**
* drm_gem_dma_vmap - map a DMA GEM object into the kernel's virtual
* address space
* @dma_obj: DMA GEM object
* @map: Returns the kernel virtual address of the DMA GEM object's backing
* store.
*
* This function maps a buffer into the kernel's virtual address space.
* Since the DMA buffers are already mapped into the kernel virtual address
* space this simply returns the cached virtual address.
*
* Returns:
* 0 on success, or a negative error code otherwise.
*/
int drm_gem_dma_vmap(struct drm_gem_dma_object *dma_obj,
struct iosys_map *map)
{
iosys_map_set_vaddr(map, dma_obj->vaddr);
return 0;
}
EXPORT_SYMBOL_GPL(drm_gem_dma_vmap);
/**
* drm_gem_dma_mmap - memory-map an exported DMA GEM object
* @dma_obj: DMA 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.
*
* Returns:
* 0 on success or a negative error code on failure.
*/
int drm_gem_dma_mmap(struct drm_gem_dma_object *dma_obj, struct vm_area_struct *vma)
{
struct drm_gem_object *obj = &dma_obj->base;
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);
vm_flags_mod(vma, VM_DONTEXPAND, VM_PFNMAP);
if (dma_obj->map_noncoherent) {
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
ret = dma_mmap_pages(dma_obj->base.dev->dev,
vma, vma->vm_end - vma->vm_start,
virt_to_page(dma_obj->vaddr));
} else {
ret = dma_mmap_wc(dma_obj->base.dev->dev, vma, dma_obj->vaddr,
dma_obj->dma_addr,
vma->vm_end - vma->vm_start);
}
if (ret)
drm_gem_vm_close(vma);
return ret;
}
EXPORT_SYMBOL_GPL(drm_gem_dma_mmap);
/**
* drm_gem_dma_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_dma_prime_import_sg_table() and uses dma_buf_vmap() to get the kernel
* virtual address. This ensures that a DMA 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_DMA_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_dma_prime_import_sg_table_vmap(struct drm_device *dev,
struct dma_buf_attachment *attach,
struct sg_table *sgt)
{
struct drm_gem_dma_object *dma_obj;
struct drm_gem_object *obj;
struct iosys_map map;
int ret;
ret = dma_buf_vmap_unlocked(attach->dmabuf, &map);
if (ret) {
DRM_ERROR("Failed to vmap PRIME buffer\n");
return ERR_PTR(ret);
}
obj = drm_gem_dma_prime_import_sg_table(dev, attach, sgt);
if (IS_ERR(obj)) {
dma_buf_vunmap_unlocked(attach->dmabuf, &map);
return obj;
}
dma_obj = to_drm_gem_dma_obj(obj);
dma_obj->vaddr = map.vaddr;
return obj;
}
EXPORT_SYMBOL(drm_gem_dma_prime_import_sg_table_vmap);
MODULE_DESCRIPTION("DRM DMA memory-management helpers");
MODULE_IMPORT_NS(DMA_BUF);
MODULE_LICENSE("GPL");
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