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authorBart Van Assche <bart.vanassche@sandisk.com>2017-01-20 13:04:07 -0800
committerDoug Ledford <dledford@redhat.com>2017-01-24 12:23:35 -0500
commit551199aca1c3102ebed390566d681cc1290284ca (patch)
treea093ec747368b2b0fa7d9e7e1e95032502f89541 /lib/dma-virt.c
parent7844572c633964c864d9f32dc3f2a8ffe5d70371 (diff)
downloadop-kernel-dev-551199aca1c3102ebed390566d681cc1290284ca.zip
op-kernel-dev-551199aca1c3102ebed390566d681cc1290284ca.tar.gz
lib/dma-virt: Add dma_virt_ops
Several RDMA drivers (hfi1, qib and rxe) expect that ib_sge.addr is a virtual address. Provide DMA mapping operations that are suitable for these drivers. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
Diffstat (limited to 'lib/dma-virt.c')
-rw-r--r--lib/dma-virt.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/lib/dma-virt.c b/lib/dma-virt.c
new file mode 100644
index 0000000..dcd4df1
--- /dev/null
+++ b/lib/dma-virt.c
@@ -0,0 +1,72 @@
+/*
+ * lib/dma-virt.c
+ *
+ * DMA operations that map to virtual addresses without flushing memory.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+
+static void *dma_virt_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 = (uintptr_t)ret;
+ return ret;
+}
+
+static void dma_virt_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_virt_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size,
+ enum dma_data_direction dir,
+ unsigned long attrs)
+{
+ return (uintptr_t)(page_address(page) + offset);
+}
+
+static int dma_virt_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) = (uintptr_t)sg_virt(sg);
+ sg_dma_len(sg) = sg->length;
+ }
+
+ return nents;
+}
+
+static int dma_virt_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+ return false;
+}
+
+static int dma_virt_supported(struct device *dev, u64 mask)
+{
+ return true;
+}
+
+const struct dma_map_ops dma_virt_ops = {
+ .alloc = dma_virt_alloc,
+ .free = dma_virt_free,
+ .map_page = dma_virt_map_page,
+ .map_sg = dma_virt_map_sg,
+ .mapping_error = dma_virt_mapping_error,
+ .dma_supported = dma_virt_supported,
+};
+EXPORT_SYMBOL(dma_virt_ops);
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