On Mon, May 18, 2009 at 00:45, Arnd Bergmann <arnd@xxxxxxxx> wrote:
--- /dev/null
+++ b/include/asm-generic/dma-mapping.h
@@ -0,0 +1,399 @@
+#ifndef _ASM_GENERIC_DMA_MAPPING_H
+#define _ASM_GENERIC_DMA_MAPPING_H
+/*
+ * This provides a no-op variant of the DMA mapping API,
+ * for use by architectures that do not actually support
+ * DMA, or that are fully consistent and linear-mapped
+ * in their DMA implementation.
+ */
+
+#include <asm/scatterlist.h>
+
+/*
+ * If any driver asks for DMA, it's not supported.
+ */
+#ifndef dma_supported
+static inline int
+dma_supported(struct device *dev, u64 mask)
+{
+ return 0;
+}
+#endif
+
+#ifndef dma_set_mask
+static inline int
+dma_set_mask(struct device *dev, u64 dma_mask)
+{
+ if (!dev->dma_mask || !dma_supported(dev, dma_mask))
+ return -EIO;
+
+ *dev->dma_mask = dma_mask;
+ return 0;
+}
+#endif
+
+/**
+ * dma_alloc_coherent - allocate consistent memory for DMA
+ * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
+ * @size: required memory size
+ * @handle: bus-specific DMA address
+ *
+ * Allocate some uncached, unbuffered memory for a device for
+ * performing DMA. This function allocates pages, and will
+ * return the CPU-viewed address, and sets @handle to be the
+ * device-viewed address.
+ */
+#ifndef dma_alloc_coherent
+static inline void *
+dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
+ gfp_t flag)
+{
+ void *virt = kmalloc(size, flag);
kmalloc() may fail.
+ *dma_handle = virt_to_phys(virt);
Not all variants of virt_to_phys() may handle the NULL case very well.
I took a statistically invalid sample: some just cast to unsigned
long, other subtract PAGE_OFFSET.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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