iommu: Add DMA window parser, of_get_dma_window()

This code was based on:
    "arch/microblaze/kernel/prom_parse.c"
    "arch/powerpc/kernel/prom_parse.c"

Can replace "of_parse_dma_window()" in the above. This supports
different formats flexibly. "prefix" can be configured if any. "busno"
and "index" are optionally specified. Set NULL and 0 if not used.

Signed-off-by: Hiroshi DOYU <hdoyu@nvidia.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
new file mode 100644
index 00000000000..51a560f34bc
--- /dev/null
+++ b/include/linux/of_iommu.h
@@ -0,0 +1,21 @@
+#ifndef __OF_IOMMU_H
+#define __OF_IOMMU_H
+
+#ifdef CONFIG_OF_IOMMU
+
+extern int of_get_dma_window(struct device_node *dn, const char *prefix,
+			     int index, unsigned long *busno, dma_addr_t *addr,
+			     size_t *size);
+
+#else
+
+static inline int of_get_dma_window(struct device_node *dn, const char *prefix,
+			    int index, unsigned long *busno, dma_addr_t *addr,
+			    size_t *size)
+{
+	return -EINVAL;
+}
+
+#endif	/* CONFIG_OF_IOMMU */
+
+#endif /* __OF_IOMMU_H */