of/address: Support multiple 'dma-ranges' entries

Currently, the DMA offset and mask for a device are set based only on the
first 'dma-ranges' entry. We should really be using all the entries. The
kernel doesn't yet support multiple offsets and sizes, so the best we can
do is to find the biggest size for a single offset. The algorithm is
copied from acpi_dma_get_range().

If there's different offsets from the first entry, then we warn and
continue. It really should be an error, but this will likely break
existing DTs.

Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index a2c4581..8eea3f6 100644 (file)
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -944,6 +944,7 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
        bool found_dma_ranges = false;
        struct of_range_parser parser;
        struct of_range range;
+       u64 dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
 
        while (node) {
                ranges = of_get_property(node, "dma-ranges", &len);
@@ -974,14 +975,33 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
                pr_debug("dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
                         range.bus_addr, range.cpu_addr, range.size);
 
-               *dma_addr = range.bus_addr;
-               *paddr = range.cpu_addr;
-               *size = range.size;
+               if (dma_offset && range.cpu_addr - range.bus_addr != dma_offset) {
+                       pr_warn("Can't handle multiple dma-ranges with different offsets on node(%pOF)\n", node);
+                       /* Don't error out as we'd break some existing DTs */
+                       continue;
+               }
+               dma_offset = range.cpu_addr - range.bus_addr;
+
+               /* Take lower and upper limits */
+               if (range.bus_addr < dma_start)
+                       dma_start = range.bus_addr;
+               if (range.bus_addr + range.size > dma_end)
+                       dma_end = range.bus_addr + range.size;
+       }
 
+       if (dma_start >= dma_end) {
+               ret = -EINVAL;
+               pr_debug("Invalid DMA ranges configuration on node(%pOF)\n",
+                        node);
                goto out;
        }
 
-       pr_err("translation of DMA ranges failed on node(%pOF)\n", np);
+       *dma_addr = dma_start;
+       *size = dma_end - dma_start;
+       *paddr = dma_start + dma_offset;
+
+       pr_debug("final: dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
+                *dma_addr, *paddr, *size);
 
 out:
        of_node_put(node);