alistair23-linux/kernel/dma/mapping.c

// SPDX-License-Identifier: GPL-2.0
/*
 * arch-independent dma-mapping routines
 *
 * Copyright (c) 2006  SUSE Linux Products GmbH
 * Copyright (c) 2006  Tejun Heo <teheo@suse.de>
 */
#include <linux/memblock.h> /* for max_pfn */
#include <linux/acpi.h>
#include <linux/dma-direct.h>
#include <linux/dma-noncoherent.h>
#include <linux/export.h>
#include <linux/gfp.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

/*
 * Managed DMA API
 */
struct dma_devres {
	size_t		size;
	void		*vaddr;
	dma_addr_t	dma_handle;
	unsigned long	attrs;
};

static void dmam_release(struct device *dev, void *res)
{
	struct dma_devres *this = res;

	dma_free_attrs(dev, this->size, this->vaddr, this->dma_handle,
			this->attrs);
}

static int dmam_match(struct device *dev, void *res, void *match_data)
{
	struct dma_devres *this = res, *match = match_data;

	if (this->vaddr == match->vaddr) {
		WARN_ON(this->size != match->size ||
			this->dma_handle != match->dma_handle);
		return 1;
	}
	return 0;
}

/**
 * dmam_free_coherent - Managed dma_free_coherent()
 * @dev: Device to free coherent memory for
 * @size: Size of allocation
 * @vaddr: Virtual address of the memory to free
 * @dma_handle: DMA handle of the memory to free
 *
 * Managed dma_free_coherent().
 */
void dmam_free_coherent(struct device *dev, size_t size, void *vaddr,
			dma_addr_t dma_handle)
{
	struct dma_devres match_data = { size, vaddr, dma_handle };

	dma_free_coherent(dev, size, vaddr, dma_handle);
	WARN_ON(devres_destroy(dev, dmam_release, dmam_match, &match_data));
}
EXPORT_SYMBOL(dmam_free_coherent);

/**
 * dmam_alloc_attrs - Managed dma_alloc_attrs()
 * @dev: Device to allocate non_coherent memory for
 * @size: Size of allocation
 * @dma_handle: Out argument for allocated DMA handle
 * @gfp: Allocation flags
 * @attrs: Flags in the DMA_ATTR_* namespace.
 *
 * Managed dma_alloc_attrs().  Memory allocated using this function will be
 * automatically released on driver detach.
 *
 * RETURNS:
 * Pointer to allocated memory on success, NULL on failure.
 */
void *dmam_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
		gfp_t gfp, unsigned long attrs)
{
	struct dma_devres *dr;
	void *vaddr;

	dr = devres_alloc(dmam_release, sizeof(*dr), gfp);
	if (!dr)
		return NULL;

	vaddr = dma_alloc_attrs(dev, size, dma_handle, gfp, attrs);
	if (!vaddr) {
		devres_free(dr);
		return NULL;
	}

	dr->vaddr = vaddr;
	dr->dma_handle = *dma_handle;
	dr->size = size;
	dr->attrs = attrs;

	devres_add(dev, dr);

	return vaddr;
}
EXPORT_SYMBOL(dmam_alloc_attrs);

/*
 * Create scatter-list for the already allocated DMA buffer.
 */
int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
		 void *cpu_addr, dma_addr_t dma_addr, size_t size,
		 unsigned long attrs)
{
	struct page *page = virt_to_page(cpu_addr);
	int ret;

	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
	if (!ret)
		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
	return ret;
}

/*
 * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems
 * that the intention is to allow exporting memory allocated via the
 * coherent DMA APIs through the dma_buf API, which only accepts a
 * scattertable.  This presents a couple of problems:
 * 1. Not all memory allocated via the coherent DMA APIs is backed by
 *    a struct page
 * 2. Passing coherent DMA memory into the streaming APIs is not allowed
 *    as we will try to flush the memory through a different alias to that
 *    actually being used (and the flushes are redundant.)
 */
int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
		void *cpu_addr, dma_addr_t dma_addr, size_t size,
		unsigned long attrs)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	if (dma_is_direct(ops))
		return dma_direct_get_sgtable(dev, sgt, cpu_addr, dma_addr,
				size, attrs);
	if (!ops->get_sgtable)
		return -ENXIO;
	return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size, attrs);
}
EXPORT_SYMBOL(dma_get_sgtable_attrs);

#ifdef CONFIG_MMU
/*
 * Return the page attributes used for mapping dma_alloc_* memory, either in
 * kernel space if remapping is needed, or to userspace through dma_mmap_*.
 */
pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
{
	if (dev_is_dma_coherent(dev) ||
	    (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) &&
             (attrs & DMA_ATTR_NON_CONSISTENT)))
		return prot;
#ifdef CONFIG_ARCH_HAS_DMA_WRITE_COMBINE
	if (attrs & DMA_ATTR_WRITE_COMBINE)
		return pgprot_writecombine(prot);
#endif
	return pgprot_dmacoherent(prot);
}
#endif /* CONFIG_MMU */

/*
 * Create userspace mapping for the DMA-coherent memory.
 */
int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
		void *cpu_addr, dma_addr_t dma_addr, size_t size,
		unsigned long attrs)
{
#ifdef CONFIG_MMU
	unsigned long user_count = vma_pages(vma);
	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
	unsigned long off = vma->vm_pgoff;
	int ret = -ENXIO;

	vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);

	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
		return ret;

	if (off >= count || user_count > count - off)
		return -ENXIO;

	return remap_pfn_range(vma, vma->vm_start,
			page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
			user_count << PAGE_SHIFT, vma->vm_page_prot);
#else
	return -ENXIO;
#endif /* CONFIG_MMU */
}

/**
 * dma_can_mmap - check if a given device supports dma_mmap_*
 * @dev: device to check
 *
 * Returns %true if @dev supports dma_mmap_coherent() and dma_mmap_attrs() to
 * map DMA allocations to userspace.
 */
bool dma_can_mmap(struct device *dev)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	if (dma_is_direct(ops))
		return dma_direct_can_mmap(dev);
	return ops->mmap != NULL;
}
EXPORT_SYMBOL_GPL(dma_can_mmap);

/**
 * dma_mmap_attrs - map a coherent DMA allocation into user space
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @vma: vm_area_struct describing requested user mapping
 * @cpu_addr: kernel CPU-view address returned from dma_alloc_attrs
 * @dma_addr: device-view address returned from dma_alloc_attrs
 * @size: size of memory originally requested in dma_alloc_attrs
 * @attrs: attributes of mapping properties requested in dma_alloc_attrs
 *
 * Map a coherent DMA buffer previously allocated by dma_alloc_attrs into user
 * space.  The coherent DMA buffer must not be freed by the driver until the
 * user space mapping has been released.
 */
int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
		void *cpu_addr, dma_addr_t dma_addr, size_t size,
		unsigned long attrs)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	if (dma_is_direct(ops))
		return dma_direct_mmap(dev, vma, cpu_addr, dma_addr, size,
				attrs);
	if (!ops->mmap)
		return -ENXIO;
	return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
}
EXPORT_SYMBOL(dma_mmap_attrs);

u64 dma_get_required_mask(struct device *dev)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	if (dma_is_direct(ops))
		return dma_direct_get_required_mask(dev);
	if (ops->get_required_mask)
		return ops->get_required_mask(dev);

	/*
	 * We require every DMA ops implementation to at least support a 32-bit
	 * DMA mask (and use bounce buffering if that isn't supported in
	 * hardware).  As the direct mapping code has its own routine to
	 * actually report an optimal mask we default to 32-bit here as that
	 * is the right thing for most IOMMUs, and at least not actively
	 * harmful in general.
	 */
	return DMA_BIT_MASK(32);
}
EXPORT_SYMBOL_GPL(dma_get_required_mask);

void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
		gfp_t flag, unsigned long attrs)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);
	void *cpu_addr;

	WARN_ON_ONCE(!dev->coherent_dma_mask);

	if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr))
		return cpu_addr;

	/* let the implementation decide on the zone to allocate from: */
	flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);

	if (dma_is_direct(ops))
		cpu_addr = dma_direct_alloc(dev, size, dma_handle, flag, attrs);
	else if (ops->alloc)
		cpu_addr = ops->alloc(dev, size, dma_handle, flag, attrs);
	else
		return NULL;

	debug_dma_alloc_coherent(dev, size, *dma_handle, cpu_addr);
	return cpu_addr;
}
EXPORT_SYMBOL(dma_alloc_attrs);

void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
		dma_addr_t dma_handle, unsigned long attrs)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	if (dma_release_from_dev_coherent(dev, get_order(size), cpu_addr))
		return;
	/*
	 * On non-coherent platforms which implement DMA-coherent buffers via
	 * non-cacheable remaps, ops->free() may call vunmap(). Thus getting
	 * this far in IRQ context is a) at risk of a BUG_ON() or trying to
	 * sleep on some machines, and b) an indication that the driver is
	 * probably misusing the coherent API anyway.
	 */
	WARN_ON(irqs_disabled());

	if (!cpu_addr)
		return;

	debug_dma_free_coherent(dev, size, cpu_addr, dma_handle);
	if (dma_is_direct(ops))
		dma_direct_free(dev, size, cpu_addr, dma_handle, attrs);
	else if (ops->free)
		ops->free(dev, size, cpu_addr, dma_handle, attrs);
}
EXPORT_SYMBOL(dma_free_attrs);

int dma_supported(struct device *dev, u64 mask)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	if (dma_is_direct(ops))
		return dma_direct_supported(dev, mask);
	if (!ops->dma_supported)
		return 1;
	return ops->dma_supported(dev, mask);
}
EXPORT_SYMBOL(dma_supported);

#ifdef CONFIG_ARCH_HAS_DMA_SET_MASK
void arch_dma_set_mask(struct device *dev, u64 mask);
#else
#define arch_dma_set_mask(dev, mask)	do { } while (0)
#endif

int dma_set_mask(struct device *dev, u64 mask)
{
	/*
	 * Truncate the mask to the actually supported dma_addr_t width to
	 * avoid generating unsupportable addresses.
	 */
	mask = (dma_addr_t)mask;

	if (!dev->dma_mask || !dma_supported(dev, mask))
		return -EIO;

	arch_dma_set_mask(dev, mask);
	*dev->dma_mask = mask;
	return 0;
}
EXPORT_SYMBOL(dma_set_mask);

#ifndef CONFIG_ARCH_HAS_DMA_SET_COHERENT_MASK
int dma_set_coherent_mask(struct device *dev, u64 mask)
{
	/*
	 * Truncate the mask to the actually supported dma_addr_t width to
	 * avoid generating unsupportable addresses.
	 */
	mask = (dma_addr_t)mask;

	if (!dma_supported(dev, mask))
		return -EIO;

	dev->coherent_dma_mask = mask;
	return 0;
}
EXPORT_SYMBOL(dma_set_coherent_mask);
#endif

void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
		enum dma_data_direction dir)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	BUG_ON(!valid_dma_direction(dir));

	if (dma_is_direct(ops))
		arch_dma_cache_sync(dev, vaddr, size, dir);
	else if (ops->cache_sync)
		ops->cache_sync(dev, vaddr, size, dir);
}
EXPORT_SYMBOL(dma_cache_sync);

size_t dma_max_mapping_size(struct device *dev)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);
	size_t size = SIZE_MAX;

	if (dma_is_direct(ops))
		size = dma_direct_max_mapping_size(dev);
	else if (ops && ops->max_mapping_size)
		size = ops->max_mapping_size(dev);

	return size;
}
EXPORT_SYMBOL_GPL(dma_max_mapping_size);

unsigned long dma_get_merge_boundary(struct device *dev)
{
	const struct dma_map_ops *ops = get_dma_ops(dev);

	if (!ops || !ops->get_merge_boundary)
		return 0;	/* can't merge */

	return ops->get_merge_boundary(dev);
}
EXPORT_SYMBOL_GPL(dma_get_merge_boundary);