linux_kernel/arch/arm64/mm/dma-mapping.c

/*
 * SWIOTLB-based DMA API implementation
 *
 * Copyright (C) 2012 ARM Ltd.
 * Author: Catalin Marinas <catalin.marinas@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/gfp.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include <linux/dma-contiguous.h>
#include <linux/vmalloc.h>
#include <linux/swiotlb.h>

#include <asm/cacheflush.h>

struct dma_map_ops *dma_ops;
EXPORT_SYMBOL(dma_ops);

static void *arm64_swiotlb_alloc_coherent(struct device *dev, size_t size,
					  dma_addr_t *dma_handle, gfp_t flags,
					  struct dma_attrs *attrs)
{
	if (dev == NULL) {
		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
		return NULL;
	}

	if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
	    dev->coherent_dma_mask <= DMA_BIT_MASK(32))
		flags |= GFP_DMA32;
	if (IS_ENABLED(CONFIG_DMA_CMA)) {
		struct page *page;

		size = PAGE_ALIGN(size);
		page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
							get_order(size));
		if (!page)
			return NULL;

		*dma_handle = phys_to_dma(dev, page_to_phys(page));
		return page_address(page);
	} else {
		return swiotlb_alloc_coherent(dev, size, dma_handle, flags);
	}
}

static void arm64_swiotlb_free_coherent(struct device *dev, size_t size,
					void *vaddr, dma_addr_t dma_handle,
					struct dma_attrs *attrs)
{
	if (dev == NULL) {
		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
		return;
	}

	if (IS_ENABLED(CONFIG_DMA_CMA)) {
		phys_addr_t paddr = dma_to_phys(dev, dma_handle);

		dma_release_from_contiguous(dev,
					phys_to_page(paddr),
					size >> PAGE_SHIFT);
	} else {
		swiotlb_free_coherent(dev, size, vaddr, dma_handle);
	}
}

static struct dma_map_ops arm64_swiotlb_dma_ops = {
	.alloc = arm64_swiotlb_alloc_coherent,
	.free = arm64_swiotlb_free_coherent,
	.map_page = swiotlb_map_page,
	.unmap_page = swiotlb_unmap_page,
	.map_sg = swiotlb_map_sg_attrs,
	.unmap_sg = swiotlb_unmap_sg_attrs,
	.sync_single_for_cpu = swiotlb_sync_single_for_cpu,
	.sync_single_for_device = swiotlb_sync_single_for_device,
	.sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
	.sync_sg_for_device = swiotlb_sync_sg_for_device,
	.dma_supported = swiotlb_dma_supported,
	.mapping_error = swiotlb_dma_mapping_error,
};

void __init arm64_swiotlb_init(void)
{
	dma_ops = &arm64_swiotlb_dma_ops;
	swiotlb_init(1);
}

#define PREALLOC_DMA_DEBUG_ENTRIES	4096

static int __init dma_debug_do_init(void)
{
	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
	return 0;
}
fs_initcall(dma_debug_do_init);