dma: Provide simple noop dma ops (a8463d4b) · Commits · 戴 / test

include/linux/dma-mapping.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -70,6 +70,8 @@ struct dma_map_ops {
		int is_phys;
		};

		extern struct dma_map_ops dma_noop_ops;

		#define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))

		#define DMA_MASK_NONE 0x0ULL

lib/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
		obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
		lib-$(CONFIG_MMU) += ioremap.o
		lib-$(CONFIG_SMP) += cpumask.o
		lib-$(CONFIG_HAS_DMA) += dma-noop.o

		lib-y += kobject.o klist.o
		obj-y += lockref.o

lib/dma-noop.c

0 → 100644

+75 −0

Original line number	Diff line number	Diff line
		/*
		* lib/dma-noop.c
		*
		* Simple DMA noop-ops that map 1:1 with memory
		*/
		#include <linux/export.h>
		#include <linux/mm.h>
		#include <linux/dma-mapping.h>
		#include <linux/scatterlist.h>

		static void dma_noop_alloc(struct device dev, size_t size,
		dma_addr_t *dma_handle, gfp_t gfp,
		struct dma_attrs *attrs)
		{
		void *ret;

		ret = (void *)__get_free_pages(gfp, get_order(size));
		if (ret)
		*dma_handle = virt_to_phys(ret);
		return ret;
		}

		static void dma_noop_free(struct device *dev, size_t size,
		void *cpu_addr, dma_addr_t dma_addr,
		struct dma_attrs *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,
		struct dma_attrs *attrs)
		{
		return page_to_phys(page) + offset;
		}

		static int dma_noop_map_sg(struct device dev, struct scatterlist sgl, int nents,
		enum dma_data_direction dir, struct dma_attrs *attrs)
		{
		int i;
		struct scatterlist *sg;

		for_each_sg(sgl, sg, nents, i) {
		void *va;

		BUG_ON(!sg_page(sg));
		va = sg_virt(sg);
		sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
		sg_dma_len(sg) = sg->length;
		}

		return nents;
		}

		static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr)
		{
		return 0;
		}

		static int dma_noop_supported(struct device *dev, u64 mask)
		{
		return 1;
		}

		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,
		.mapping_error = dma_noop_mapping_error,
		.dma_supported = dma_noop_supported,
		};

		EXPORT_SYMBOL(dma_noop_ops);

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