core: Add functions to set properties in live-tree

Implement a set of functions to manipulate properties in a live device
tree:

* ofnode_write_prop() to set generic properties of a node
* ofnode_write_string() to set string properties of a node
* ofnode_set_enabled() to either enable or disable a node

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/core/ofnode.c

@@ -791,3 +791,73 @@ ofnode ofnode_by_prop_value(ofnode from, const char *propname,
 				propname, propval, proplen));
 	}
 }
+
+int ofnode_write_prop(ofnode node, const char *propname, int len,
+		      const void *value)
+{
+	const struct device_node *np = ofnode_to_np(node);
+	struct property *pp;
+	struct property *pp_last = NULL;
+	struct property *new;
+
+	if (!of_live_active())
+		return -ENOSYS;
+
+	if (!np)
+		return -EINVAL;
+
+	for (pp = np->properties; pp; pp = pp->next) {
+		if (strcmp(pp->name, propname) == 0) {
+			/* Property exists -> change value */
+			pp->value = (void *)value;
+			pp->length = len;
+			return 0;
+		}
+		pp_last = pp;
+	}
+
+	if (!pp_last)
+		return -ENOENT;
+
+	/* Property does not exist -> append new property */
+	new = malloc(sizeof(struct property));
+	if (!new)
+		return -ENOMEM;
+
+	new->name = strdup(propname);
+	if (!new->name)
+		return -ENOMEM;
+
+	new->value = (void *)value;
+	new->length = len;
+	new->next = NULL;
+
+	pp_last->next = new;
+
+	return 0;
+}
+
+int ofnode_write_string(ofnode node, const char *propname, const char *value)
+{
+	if (!of_live_active())
+		return -ENOSYS;
+
+	assert(ofnode_valid(node));
+
+	debug("%s: %s = %s", __func__, propname, value);
+
+	return ofnode_write_prop(node, propname, strlen(value) + 1, value);
+}
+
+int ofnode_set_enabled(ofnode node, bool value)
+{
+	if (!of_live_active())
+		return -ENOSYS;
+
+	assert(ofnode_valid(node));
+
+	if (value)
+		return ofnode_write_string(node, "status", "okay");
+	else
+		return ofnode_write_string(node, "status", "disable");
+}