dtc: Wrap phandle validity check

In several places we check for a returned phandle value to be valid,
for that it must not be 0 or "-1".

Wrap this check in a static inline function in dtc.h, and use ~0U instead
of -1 on the way, to keep everything in the unsigned realm.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Message-Id: <20210618172030.9684-4-andre.przywara@arm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

@@ -520,7 +520,7 @@ static cell_t check_phandle_prop(struct check *c, struct dt_info *dti,
 
 	phandle = propval_cell(prop);
 
-	if ((phandle == 0) || (phandle == -1)) {
+	if (!phandle_is_valid(phandle)) {
 		FAIL_PROP(c, dti, node, prop, "bad value (0x%x) in %s property",
 		     phandle, prop->name);
 		return 0;
@@ -1400,14 +1400,14 @@ static void check_property_phandle_args(struct check *c,
 	for (cell = 0; cell < prop->val.len / sizeof(cell_t); cell += cellsize + 1) {
 		struct node *provider_node;
 		struct property *cellprop;
-		int phandle;
+		cell_t phandle;
 
 		phandle = propval_cell_n(prop, cell);
 		/*
 		 * Some bindings use a cell value 0 or -1 to skip over optional
 		 * entries when each index position has a specific definition.
 		 */
-		if (phandle == 0 || phandle == -1) {
+		if (!phandle_is_valid(phandle)) {
 			/* Give up if this is an overlay with external references */
 			if (dti->dtsflags & DTSF_PLUGIN)
 				break;
@@ -1615,7 +1615,7 @@ static void check_interrupts_property(struct check *c,
 		prop = get_property(parent, "interrupt-parent");
 		if (prop) {
 			phandle = propval_cell(prop);
-			if ((phandle == 0) || (phandle == -1)) {
+			if (!phandle_is_valid(phandle)) {
 				/* Give up if this is an overlay with
 				 * external references */
 				if (dti->dtsflags & DTSF_PLUGIN)
@@ -1772,7 +1772,7 @@ static struct node *get_remote_endpoint(struct check *c, struct dt_info *dti,
 
 	phandle = propval_cell(prop);
 	/* Give up if this is an overlay with external references */
-	if (phandle == 0 || phandle == -1)
+	if (!phandle_is_valid(phandle))
 		return NULL;
 
 	node = get_node_by_phandle(dti->dt, phandle);

dtc.h

@@ -51,6 +51,11 @@ extern int annotate;		/* annotate .dts with input source location */
 
 typedef uint32_t cell_t;
 
+static inline bool phandle_is_valid(cell_t phandle)
+{
+	return phandle != 0 && phandle != ~0U;
+}
+
 static inline uint16_t dtb_ld16(const void *p)
 {
 	const uint8_t *bp = (const uint8_t *)p;

livetree.c

@@ -559,7 +559,7 @@ struct node *get_node_by_phandle(struct node *tree, cell_t phandle)
 {
 	struct node *child, *node;
 
-	if ((phandle == 0) || (phandle == -1)) {
+	if (!phandle_is_valid(phandle)) {
 		assert(generate_fixups);
 		return NULL;
 	}
@@ -594,7 +594,7 @@ cell_t get_node_phandle(struct node *root, struct node *node)
 	static cell_t phandle = 1; /* FIXME: ick, static local */
 	struct data d = empty_data;
 
-	if ((node->phandle != 0) && (node->phandle != -1))
+	if (phandle_is_valid(node->phandle))
 		return node->phandle;
 
 	while (get_node_by_phandle(root, phandle))