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Subject[PATCH 7/7] of/address: Support multiple 'dma-ranges' entries
Date
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>
---
drivers/of/address.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index a2c45812a50e..8eea3f6e29a4 100644
--- 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);
--
2.20.1
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