// 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 bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) { return phys_to_dma(dev, phys) + size - 1 <= dev->coherent_dma_mask; } 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; again: /* 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 && !dma_coherent_ok(dev, page_to_phys(page), size)) { dma_release_from_contiguous(dev, page, count); page = NULL; } } if (!page) page = alloc_pages_node(dev_to_node(dev), gfp, page_order); if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { __free_pages(page, page_order); page = NULL; if (dev->coherent_dma_mask < DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) { gfp = (gfp & ~GFP_DMA32) | GFP_DMA; goto again; } } if (!page) return NULL; *dma_handle = phys_to_dma(dev, page_to_phys(page)); memset(page_address(page), 0, size); return page_address(page); } /* * NOTE: this function must never look at the dma_addr argument, because we want * to be able to use it as a helper for iommu implementations as well. */ 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; } int dma_direct_supported(struct device *dev, u64 mask) { #ifdef CONFIG_ZONE_DMA if (mask < DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)) return 0; #else /* * Because 32-bit DMA masks are so common we expect every architecture * to be able to satisfy them - either by not supporting more physical * memory, or by providing a ZONE_DMA32. If neither is the case, the * architecture needs to use an IOMMU instead of the direct mapping. */ if (mask < DMA_BIT_MASK(32)) return 0; #endif return 1; } 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, .dma_supported = dma_direct_supported, .mapping_error = dma_direct_mapping_error, .is_phys = 1, }; EXPORT_SYMBOL(dma_direct_ops);