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authorVineet Gupta <vgupta@synopsys.com>2017-07-18 12:14:09 -0700
committerVineet Gupta <vgupta@synopsys.com>2017-08-04 13:56:33 +0530
commit2e332fec2f2c996f8d5447b0946ca43bb0ae4b42 (patch)
tree74ddb425667bd5d87304dabd6616ccfcb12dc372 /arch/arc/mm/dma.c
parentARCv2: SLC: Make sure busy bit is set properly for region ops (diff)
downloadlinux-dev-2e332fec2f2c996f8d5447b0946ca43bb0ae4b42.tar.xz
linux-dev-2e332fec2f2c996f8d5447b0946ca43bb0ae4b42.zip
ARC: dma: implement dma_unmap_page and sg variant
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to '')
-rw-r--r--arch/arc/mm/dma.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index 2a07e6ecafbd..1d0326d874e7 100644
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -153,6 +153,19 @@ static void _dma_cache_sync(phys_addr_t paddr, size_t size,
}
}
+/*
+ * arc_dma_map_page - map a portion of a page for streaming DMA
+ *
+ * Ensure that any data held in the cache is appropriately discarded
+ * or written back.
+ *
+ * The device owns this memory once this call has completed. The CPU
+ * can regain ownership by calling dma_unmap_page().
+ *
+ * Note: while it takes struct page as arg, caller can "abuse" it to pass
+ * a region larger than PAGE_SIZE, provided it is physically contiguous
+ * and this still works correctly
+ */
static dma_addr_t arc_dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size, enum dma_data_direction dir,
unsigned long attrs)
@@ -165,6 +178,24 @@ static dma_addr_t arc_dma_map_page(struct device *dev, struct page *page,
return plat_phys_to_dma(dev, paddr);
}
+/*
+ * arc_dma_unmap_page - unmap a buffer previously mapped through dma_map_page()
+ *
+ * After this call, reads by the CPU to the buffer are guaranteed to see
+ * whatever the device wrote there.
+ *
+ * Note: historically this routine was not implemented for ARC
+ */
+static void arc_dma_unmap_page(struct device *dev, dma_addr_t handle,
+ size_t size, enum dma_data_direction dir,
+ unsigned long attrs)
+{
+ phys_addr_t paddr = plat_dma_to_phys(dev, handle);
+
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ _dma_cache_sync(paddr, size, dir);
+}
+
static int arc_dma_map_sg(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir, unsigned long attrs)
{
@@ -178,6 +209,18 @@ static int arc_dma_map_sg(struct device *dev, struct scatterlist *sg,
return nents;
}
+static void arc_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
+ int nents, enum dma_data_direction dir,
+ unsigned long attrs)
+{
+ struct scatterlist *s;
+ int i;
+
+ for_each_sg(sg, s, nents, i)
+ arc_dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir,
+ attrs);
+}
+
static void arc_dma_sync_single_for_cpu(struct device *dev,
dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
{
@@ -223,7 +266,9 @@ const struct dma_map_ops arc_dma_ops = {
.free = arc_dma_free,
.mmap = arc_dma_mmap,
.map_page = arc_dma_map_page,
+ .unmap_page = arc_dma_unmap_page,
.map_sg = arc_dma_map_sg,
+ .unmap_sg = arc_dma_unmap_sg,
.sync_single_for_device = arc_dma_sync_single_for_device,
.sync_single_for_cpu = arc_dma_sync_single_for_cpu,
.sync_sg_for_cpu = arc_dma_sync_sg_for_cpu,