We are going to require dma_ops for several common drivers, even for
systems that do have an identity mapping. Lets provide some minimal
no-op dma_ops that can be used for that purpose.
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Reviewed-by: Joerg Roedel <jroedel@xxxxxxx>
---
include/linux/dma-mapping.h | 2 ++
lib/Makefile | 1 +
lib/dma-noop.c | 75 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 78 insertions(+)
create mode 100644 lib/dma-noop.c
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index ac07ff0..7912f54 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -66,6 +66,8 @@ 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
diff --git a/lib/Makefile b/lib/Makefile
index 13a7c6a..92d6135 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -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
diff --git a/lib/dma-noop.c b/lib/dma-noop.c
new file mode 100644
index 0000000..7214564
--- /dev/null
+++ b/lib/dma-noop.c
@@ -0,0 +1,75 @@
+/*
+ * 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);
--
2.4.3
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