dm: core: support reading a single indexed u32 value

The patch adds helper functions to allow reading a single indexed u32
value from a device-tree property containing multiple u32 values, that
is an array of integers.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Reviewed-by: Simon Glass <sjg@chromium.org>

3 files changed, 75 insertions, 0 deletions

diff --git a/drivers/core/of_access.c b/drivers/core/of_access.c
index 29e705e0b66..8b2ce7a0c21 100644
--- a/drivers/core/of_access.c
+++ b/drivers/core/of_access.c
@@ -485,6 +485,28 @@ int of_read_u32_array(const struct device_node *np, const char *propname,
 	return 0;
 }
 
+int of_read_u32_index(const struct device_node *np, const char *propname,
+		      int index, u32 *outp)
+{
+	const __be32 *val;
+
+	debug("%s: %s: ", __func__, propname);
+	if (!np)
+		return -EINVAL;
+
+	val = of_find_property_value_of_size(np, propname,
+					     sizeof(*outp) * (index + 1));
+	if (IS_ERR(val)) {
+		debug("(not found)\n");
+		return PTR_ERR(val);
+	}
+
+	*outp = be32_to_cpup(val + index);
+	debug("%#x (%d)\n", *outp, *outp);
+
+	return 0;
+}
+
 int of_read_u64(const struct device_node *np, const char *propname, u64 *outp)
 {
 	const __be64 *val;
diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index 96a5dd20bd1..5bc3b02996e 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -48,6 +48,46 @@ u32 ofnode_read_u32_default(ofnode node, const char *propname, u32 def)
 	return def;
 }
 
+int ofnode_read_u32_index(ofnode node, const char *propname, int index,
+			  u32 *outp)
+{
+	const fdt32_t *cell;
+	int len;
+
+	assert(ofnode_valid(node));
+	debug("%s: %s: ", __func__, propname);
+
+	if (ofnode_is_np(node))
+		return of_read_u32_index(ofnode_to_np(node), propname, index,
+					 outp);
+
+	cell = fdt_getprop(gd->fdt_blob, ofnode_to_offset(node), propname,
+			   &len);
+	if (!cell) {
+		debug("(not found)\n");
+		return -EINVAL;
+	}
+
+	if (len < (sizeof(int) * (index + 1))) {
+		debug("(not large enough)\n");
+		return -EOVERFLOW;
+	}
+
+	*outp = fdt32_to_cpu(cell[index]);
+	debug("%#x (%d)\n", *outp, *outp);
+
+	return 0;
+}
+
+u32 ofnode_read_u32_index_default(ofnode node, const char *propname, int index,
+				  u32 def)
+{
+	assert(ofnode_valid(node));
+	ofnode_read_u32_index(node, propname, index, &def);
+
+	return def;
+}
+
 int ofnode_read_s32_default(ofnode node, const char *propname, s32 def)
 {
 	assert(ofnode_valid(node));
diff --git a/drivers/core/read.c b/drivers/core/read.c
index 1f999b1b316..ce78f09d286 100644
--- a/drivers/core/read.c
+++ b/drivers/core/read.c
@@ -22,6 +22,19 @@ int dev_read_u32_default(const struct udevice *dev, const char *propname,
 	return ofnode_read_u32_default(dev_ofnode(dev), propname, def);
 }
 
+int dev_read_u32_index(struct udevice *dev, const char *propname, int index,
+		       u32 *outp)
+{
+	return ofnode_read_u32_index(dev_ofnode(dev), propname, index, outp);
+}
+
+u32 dev_read_u32_index_default(struct udevice *dev, const char *propname,
+			       int index, u32 def)
+{
+	return ofnode_read_u32_index_default(dev_ofnode(dev), propname, index,
+					     def);
+}
+
 int dev_read_s32(const struct udevice *dev, const char *propname, s32 *outp)
 {
 	return ofnode_read_u32(dev_ofnode(dev), propname, (u32 *)outp);