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// SPDX-License-Identifier: GPL-2.0
/*
* DMA operations that map physical memory directly without using an IOMMU or
* flushing caches.
*/
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/dma-direct.h>
#include <linux/scatterlist.h>
#include <linux/dma-contiguous.h>
#include <linux/pfn.h>
#define DIRECT_MAPPING_ERROR 0
/*
* Most architectures use ZONE_DMA for the first 16 Megabytes, but
* some use it for entirely different regions:
*/
#ifndef ARCH_ZONE_DMA_BITS
#define ARCH_ZONE_DMA_BITS 24
#endif
static bool
check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
const char *caller)
{
if (unlikely(dev && !dma_capable(dev, dma_addr, size))) {
if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
dev_err(dev,
"%s: overflow %pad+%zu of device mask %llx\n",
caller, &dma_addr, size, *dev->dma_mask);
}
return false;
}
return true;
}
static void *dma_direct_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
int page_order = get_order(size);
struct page *page = NULL;
/* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */
if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
gfp |= GFP_DMA;
if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))
gfp |= GFP_DMA32;
/* CMA can be used only in the context which permits sleeping */
if (gfpflags_allow_blocking(gfp))
page = dma_alloc_from_contiguous(dev, count, page_order, gfp);
if (!page)
page = alloc_pages_node(dev_to_node(dev), gfp, page_order);
if (!page)
return NULL;
*dma_handle = phys_to_dma(dev, page_to_phys(page));
memset(page_address(page), 0, size);
return page_address(page);
}
static void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_addr, unsigned long attrs)
{
unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
free_pages((unsigned long)cpu_addr, get_order(size));
}
static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size, enum dma_data_direction dir,
unsigned long attrs)
{
dma_addr_t dma_addr = phys_to_dma(dev, page_to_phys(page)) + offset;
if (!check_addr(dev, dma_addr, size, __func__))
return DIRECT_MAPPING_ERROR;
return dma_addr;
}
static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir, unsigned long attrs)
{
int i;
struct scatterlist *sg;
for_each_sg(sgl, sg, nents, i) {
BUG_ON(!sg_page(sg));
sg_dma_address(sg) = phys_to_dma(dev, sg_phys(sg));
if (!check_addr(dev, sg_dma_address(sg), sg->length, __func__))
return 0;
sg_dma_len(sg) = sg->length;
}
return nents;
}
static int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
return dma_addr == DIRECT_MAPPING_ERROR;
}
const struct dma_map_ops dma_direct_ops = {
.alloc = dma_direct_alloc,
.free = dma_direct_free,
.map_page = dma_direct_map_page,
.map_sg = dma_direct_map_sg,
.mapping_error = dma_direct_mapping_error,
};
EXPORT_SYMBOL(dma_direct_ops);
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