// SPDX-License-Identifier: GPL-2.0 /* * lib/dma-noop.c * * DMA operations that map to physical addresses without flushing memory. */ #include <linux/export.h> #include <linux/mm.h> #include <linux/dma-mapping.h> #include <linux/scatterlist.h> #include <linux/pfn.h> static void *dma_noop_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) { void *ret; ret = (void *)__get_free_pages(gfp, get_order(size)); if (ret) *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset); return ret; } static void dma_noop_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs) { free_pages((unsigned long)cpu_addr, get_order(size)); } static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, unsigned long attrs) { return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset); } static int dma_noop_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) { dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset); void *va; BUG_ON(!sg_page(sg)); va = sg_virt(sg); sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va) - offset; sg_dma_len(sg) = sg->length; } return nents; } const struct dma_map_ops dma_noop_ops = { .alloc = dma_noop_alloc, .free = dma_noop_free, .map_page = dma_noop_map_page, .map_sg = dma_noop_map_sg, }; EXPORT_SYMBOL(dma_noop_ops);