[PATCH v8 2/2] remoteproc: imx_rpoc: use memory-region-names to avoid hidden ABI

[Frank.Li at oss.nxp.com]

From: Laurentiu Mihalcea <laurentiu.mihalcea at nxp.com>

The driver currently derives the memory region type from the referenced
memory node name, creating a hidden DT ABI. Since memory node names are
not constrained by the binding, incorrect names can silently pass DT
validation, as seen in examples using "vdevbuffer" instead of
"vdev0buffer" ([1] and [2]).

Parse memory-region-names to identify the expected memory regions and avoid
relying on memory node names as ABI.

Link: https://lore.kernel.org/imx/a3602ef8-2b77-4cc3-adef-2c4cba08a5d9@nabladev.com/ [1]
Link: https://lore.kernel.org/imx/alexXTYQHUs76J7v@SMW015318/T/#mb9dc709ff3adc24d9db6d30c973f37b580f6f1f9 [2]

Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea at nxp.com>
Reviewed-by: Peng Fan <peng.fan at nxp.com>
Reviewed-by: Francesco Valla <francesco at valla.it>
Signed-off-by: Frank Li <Frank.Li at nxp.com>
---
 drivers/remoteproc/imx_rproc.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
index 581bb07f5893f..2707040f16d06 100644
--- a/drivers/remoteproc/imx_rproc.c
+++ b/drivers/remoteproc/imx_rproc.c
@@ -635,6 +635,25 @@ static int imx_rproc_sm_lmm_prepare(struct rproc *rproc)
 	return 0;
 }
 
+static int imx_rproc_rmem_to_resource(struct device_node *np,
+				      int index,
+				      struct resource *res)
+{
+	int ret;
+
+	ret = of_reserved_mem_region_to_resource(np, index, res);
+	if (ret)
+		return ret;
+
+	/* "memory-region-names" is optional */
+	ret = of_property_read_string_index(np, "memory-region-names",
+					    index, &res->name);
+	if (ret == -EINVAL)
+		return 0;
+
+	return ret;
+}
+
 static int imx_rproc_prepare(struct rproc *rproc)
 {
 	struct imx_rproc *priv = rproc->priv;
@@ -648,7 +667,7 @@ static int imx_rproc_prepare(struct rproc *rproc)
 		int err;
 		struct resource res;
 
-		err = of_reserved_mem_region_to_resource(np, i++, &res);
+		err = imx_rproc_rmem_to_resource(np, i++, &res);
 		if (err)
 			break;
 
@@ -823,11 +842,17 @@ static int imx_rproc_addr_init(struct imx_rproc *priv,
 	if (nph <= 0)
 		return 0;
 
+	if (of_property_present(np, "memory-region-names") &&
+	    nph != of_property_count_strings(np, "memory-region-names")) {
+		dev_err(dev, "invalid reserved memory name count\n");
+		return -EINVAL;
+	}
+
 	/* remap optional addresses */
 	for (a = 0; a < nph; a++) {
 		struct resource res;
 
-		err = of_reserved_mem_region_to_resource(np, a, &res);
+		err = imx_rproc_rmem_to_resource(np, a, &res);
 		if (err) {
 			dev_err(dev, "unable to resolve memory region\n");
 			return err;

-- 
2.43.0