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path: root/drivers/of/address.c
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Diffstat (limited to 'drivers/of/address.c')
-rw-r--r--drivers/of/address.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/drivers/of/address.c b/drivers/of/address.c
index 1c3257a2d4e3..73ddf2540f3f 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -1025,6 +1025,48 @@ out:
#endif /* CONFIG_HAS_DMA */
/**
+ * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
+ * @np: The node to start searching from or NULL to start from the root
+ *
+ * Gets the highest CPU physical address that is addressable by all DMA masters
+ * in the sub-tree pointed by np, or the whole tree if NULL is passed. If no
+ * DMA constrained device is found, it returns PHYS_ADDR_MAX.
+ */
+phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
+{
+ phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
+ struct of_range_parser parser;
+ phys_addr_t subtree_max_addr;
+ struct device_node *child;
+ struct of_range range;
+ const __be32 *ranges;
+ u64 cpu_end = 0;
+ int len;
+
+ if (!np)
+ np = of_root;
+
+ ranges = of_get_property(np, "dma-ranges", &len);
+ if (ranges && len) {
+ of_dma_range_parser_init(&parser, np);
+ for_each_of_range(&parser, &range)
+ if (range.cpu_addr + range.size > cpu_end)
+ cpu_end = range.cpu_addr + range.size - 1;
+
+ if (max_cpu_addr > cpu_end)
+ max_cpu_addr = cpu_end;
+ }
+
+ for_each_available_child_of_node(np, child) {
+ subtree_max_addr = of_dma_get_max_cpu_address(child);
+ if (max_cpu_addr > subtree_max_addr)
+ max_cpu_addr = subtree_max_addr;
+ }
+
+ return max_cpu_addr;
+}
+
+/**
* of_dma_is_coherent - Check if device is coherent
* @np: device node
*