[PATCH 27/34] dma-direct: add support for CMA allocation
From: hch@lst.de (Christoph Hellwig)
Date: 2018-01-12 08:44:15
Also in:
linux-alpha, linux-arch, linux-iommu, linux-mips, linux-s390, linux-sh, linuxppc-dev, lkml, sparclinux
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
Try the CMA allocator for coherent allocations if supported. Roughly modelled after the x86 code. Signed-off-by: Christoph Hellwig <hch@lst.de> --- lib/dma-direct.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/lib/dma-direct.c b/lib/dma-direct.c
index 32fd4d9e4c47..a9ae98be7af3 100644
--- a/lib/dma-direct.c
+++ b/lib/dma-direct.c@@ -7,6 +7,7 @@ #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
@@ -29,19 +30,30 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size, static void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) { - void *ret; + unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; + int page_order = get_order(size); + struct page *page = NULL; - ret = (void *)__get_free_pages(gfp, get_order(size)); - if (ret) - *dma_handle = phys_to_dma(dev, virt_to_phys(ret)); + /* 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(gfp, page_order); + if (!page) + return NULL; - return ret; + *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) { - free_pages((unsigned long)cpu_addr, get_order(size)); + 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,
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2.14.2