of: address: Add support for the parent DMA bus

Some SoCs have devices that are using a separate bus from the main bus to
perform DMA.

These buses might have some restrictions and/or different mapping than from
the CPU side, so we'd need to express those using the usual dma-ranges, but
using a different DT node than the node's parent.

Now that the generic interconnect bindings are available, we can model an
interconnect with the reserved name "dma-mem" for those use-cases.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 5359a80c4e8cb6095bdc35d4337d5d6017814589..978427a9d5e68faca2c4a0f835e3b8c474113815 100644 (file)
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -677,12 +677,30 @@ u64 of_translate_address(struct device_node *dev, const __be32 *in_addr)
 }
 EXPORT_SYMBOL(of_translate_address);
 
+static struct device_node *__of_get_dma_parent(const struct device_node *np)
+{
+       struct of_phandle_args args;
+       int ret, index;
+
+       index = of_property_match_string(np, "interconnect-names", "dma-mem");
+       if (index < 0)
+               return of_get_parent(np);
+
+       ret = of_parse_phandle_with_args(np, "interconnects",
+                                        "#interconnect-cells",
+                                        index, &args);
+       if (ret < 0)
+               return of_get_parent(np);
+
+       return of_node_get(args.np);
+}
+
 u64 of_translate_dma_address(struct device_node *dev, const __be32 *in_addr)
 {
        struct device_node *host;
        u64 ret;
 
-       ret = __of_translate_address(dev, of_get_parent,
+       ret = __of_translate_address(dev, __of_get_dma_parent,
                                     in_addr, "dma-ranges", &host);
 
        if (host) {
@@ -912,9 +930,15 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
                return -EINVAL;
 
        while (1) {
+               struct device_node *parent;
+
                naddr = of_n_addr_cells(node);
                nsize = of_n_size_cells(node);
-               node = of_get_next_parent(node);
+
+               parent = __of_get_dma_parent(node);
+               of_node_put(node);
+
+               node = parent;
                if (!node)
                        break;