dm: core: Support writing a boolean

Add functions to write a boolean property. This involves deleting it if
the value is false.

Add a new ofnode_has_property() as well. Add a comment about the behaviour
of of_read_property() when the property value is empty.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/ofnode.c

@@ -491,12 +491,12 @@ u64 ofnode_read_u64_default(ofnode node, const char *propname, u64 def)
 
 bool ofnode_read_bool(ofnode node, const char *propname)
 {
-	const void *prop;
+	bool prop;
 
 	assert(ofnode_valid(node));
 	debug("%s: %s: ", __func__, propname);
 
-	prop = ofnode_get_property(node, propname, NULL);
+	prop = ofnode_has_property(node, propname);
 
 	debug("%s\n", prop ? "true" : "false");
 
@@ -1168,6 +1168,14 @@ const void *ofnode_get_property(ofnode node, const char *propname, int *lenp)
 				   propname, lenp);
 }
 
+bool ofnode_has_property(ofnode node, const char *propname)
+{
+	if (ofnode_is_np(node))
+		return of_find_property(ofnode_to_np(node), propname, NULL);
+	else
+		return ofnode_get_property(node, propname, NULL);
+}
+
 int ofnode_first_property(ofnode node, struct ofprop *prop)
 {
 	prop->node = node;
@@ -1616,6 +1624,30 @@ int ofnode_write_u32(ofnode node, const char *propname, u32 value)
 	return ofnode_write_prop(node, propname, val, sizeof(value), false);
 }
 
+int ofnode_write_bool(ofnode node, const char *propname, bool value)
+{
+	if (value)
+		return ofnode_write_prop(node, propname, NULL, 0, false);
+	else
+		return ofnode_delete_prop(node, propname);
+}
+
+int ofnode_delete_prop(ofnode node, const char *propname)
+{
+	if (ofnode_is_np(node)) {
+		struct property *prop;
+		int len;
+
+		prop = of_find_property(ofnode_to_np(node), propname, &len);
+		if (prop)
+			return of_remove_property(ofnode_to_np(node), prop);
+		return 0;
+	} else {
+		return fdt_delprop(ofnode_to_fdt(node), ofnode_to_offset(node),
+				   propname);
+	}
+}
+
 int ofnode_set_enabled(ofnode node, bool value)
 {
 	assert(ofnode_valid(node));

include/dm/ofnode.h

@@ -1037,10 +1037,19 @@ int ofnode_decode_panel_timing(ofnode node,
  * @node: node to read
  * @propname: property to read
  * @lenp: place to put length on success
- * Return: pointer to property, or NULL if not found
+ * Return: pointer to property value, or NULL if not found or empty
  */
 const void *ofnode_get_property(ofnode node, const char *propname, int *lenp);
 
+/**
+ * ofnode_has_property() - check if a node has a named property
+ *
+ * @node: node to read
+ * @propname: property to read
+ * Return: true if the property exists in the node, false if not
+ */
+bool ofnode_has_property(ofnode node, const char *propname);
+
 /**
  * ofnode_first_property()- get the reference of the first property
  *
@@ -1452,6 +1461,27 @@ int ofnode_write_string(ofnode node, const char *propname, const char *value);
  */
 int ofnode_write_u32(ofnode node, const char *propname, u32 value);
 
+/**
+ * ofnode_write_bool() - Set a boolean property of an ofnode
+ *
+ * This either adds or deleted a property with a zero-length value
+ *
+ * @node:	The node for whose string property should be set
+ * @propname:	The name of the string property to set
+ * @value:	The new value of the boolean property
+ * Return: 0 if successful, -ve on error
+ */
+int ofnode_write_bool(ofnode node, const char *propname, bool value);
+
+/**
+ * ofnode_delete_prop() - Delete a property
+ *
+ * @node:	Node containing the property to delete
+ * @propname:	Name of property to delete
+ * Return: 0 if successful, -ve on error
+ */
+int ofnode_delete_prop(ofnode node, const char *propname);
+
 /**
  * ofnode_set_enabled() - Enable or disable a device tree node given by its
  *			  ofnode

test/dm/ofnode.c

@@ -1480,3 +1480,28 @@ static int dm_test_oftree_to_fdt(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_oftree_to_fdt, UT_TESTF_SCAN_FDT);
+
+/* test ofnode_read_bool() and ofnode_write_bool() */
+static int dm_test_bool(struct unit_test_state *uts)
+{
+	const char *propname = "missing-bool-value";
+	ofnode node;
+
+	node = ofnode_path("/a-test");
+	ut_assert(ofnode_read_bool(node, "bool-value"));
+	ut_assert(!ofnode_read_bool(node, propname));
+	ut_assert(!ofnode_has_property(node, propname));
+
+	ut_assertok(ofnode_write_bool(node, propname, true));
+	ut_assert(ofnode_read_bool(node, propname));
+	ut_assert(ofnode_has_property(node, propname));
+	ut_assert(ofnode_read_bool(node, "bool-value"));
+
+	ut_assertok(ofnode_write_bool(node, propname, false));
+	ut_assert(!ofnode_read_bool(node, propname));
+	ut_assert(!ofnode_has_property(node, propname));
+	ut_assert(ofnode_read_bool(node, "bool-value"));
+
+	return 0;
+}
+DM_TEST(dm_test_bool, UT_TESTF_SCAN_FDT);