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>

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index ab8710888ddffba4c0c3d0bf761e9a9a46908cc0..426c43d4fdbf49fedbc9a0f0ad85fe8d92c6c3d3 100644 (file)
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -128,6 +128,7 @@ struct dma_map_ops {
 };
 
 extern const struct dma_map_ops dma_noop_ops;
+extern const struct dma_map_ops dma_virt_ops;
 
 #define DMA_BIT_MASK(n)        (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
 

diff --git a/lib/Kconfig b/lib/Kconfig
index b6baf0609e8b2b661d1c926f9b9f6b0144765243..97af23b26f3383477e30349f20a47362b1c96e61 100644 (file)
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -400,6 +400,11 @@ config DMA_NOOP_OPS
        depends on HAS_DMA && (!64BIT || ARCH_DMA_ADDR_T_64BIT)
        default n
 
+config DMA_VIRT_OPS
+       bool
+       depends on HAS_DMA && (!64BIT || ARCH_DMA_ADDR_T_64BIT)
+       default n
+
 config CHECK_SIGNATURE
        bool
 

diff --git a/lib/Makefile b/lib/Makefile
index ada06d5652e8ce54c00cde878338ef9989fef320..b97e9a8148549497f6246dea01e3c9590227698f 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -27,6 +27,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 lib-$(CONFIG_MMU) += ioremap.o
 lib-$(CONFIG_SMP) += cpumask.o
 lib-$(CONFIG_DMA_NOOP_OPS) += dma-noop.o
+lib-$(CONFIG_DMA_VIRT_OPS) += dma-virt.o
 
 lib-y  += kobject.o klist.o
 obj-y  += lockref.o

diff --git a/lib/dma-virt.c b/lib/dma-virt.c
new file mode 100644 (file)
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);