// 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 = …; /** * __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) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); const struct vm_operations_struct drm_gem_dma_vm_ops = …; EXPORT_SYMBOL_GPL(…); #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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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) { … } EXPORT_SYMBOL(…); MODULE_DESCRIPTION(…) …; MODULE_IMPORT_NS(…); MODULE_LICENSE(…) …;
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