checks: add gpio binding properties check

The GPIO binding is different compared to other phandle plus args
properties in that the property name has a variable, optional prefix.
The format of the property name is [<name>-]gpio{s} where <name> can
be any legal property string. Therefore, custom matching of property
names is needed, but the common check_property_phandle_args() function
can still be used.

It's possible that there are property names matching which are not GPIO
binding specifiers. There's only been one case found in testing which is
"[<vendor>,]nr-gpio{s}". This property has been blacklisted and the same
should be done to any others we find. This check will prevent getting
any more of these, too.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

@@ -1065,6 +1065,76 @@ WARNING_PROPERTY_PHANDLE_CELLS(resets, "resets", "#reset-cells");
 WARNING_PROPERTY_PHANDLE_CELLS(sound_dais, "sound-dais", "#sound-dai-cells");
 WARNING_PROPERTY_PHANDLE_CELLS(thermal_sensors, "thermal-sensors", "#thermal-sensor-cells");
 
+static bool prop_is_gpio(struct property *prop)
+{
+	char *str;
+
+	/*
+	 * *-gpios and *-gpio can appear in property names,
+	 * so skip over any false matches (only one known ATM)
+	 */
+	if (strstr(prop->name, "nr-gpio"))
+		return false;
+
+	str = strrchr(prop->name, '-');
+	if (str)
+		str++;
+	else
+		str = prop->name;
+	if (!(streq(str, "gpios") || streq(str, "gpio")))
+		return false;
+
+	return true;
+}
+
+static void check_gpios_property(struct check *c,
+					  struct dt_info *dti,
+				          struct node *node)
+{
+	struct property *prop;
+
+	/* Skip GPIO hog nodes which have 'gpios' property */
+	if (get_property(node, "gpio-hog"))
+		return;
+
+	for_each_property(node, prop) {
+		struct provider provider;
+
+		if (!prop_is_gpio(prop))
+			continue;
+
+		provider.prop_name = prop->name;
+		provider.cell_name = "#gpio-cells";
+		provider.optional = false;
+		check_property_phandle_args(c, dti, node, prop, &provider);
+	}
+
+}
+WARNING(gpios_property, check_gpios_property, NULL, &phandle_references);
+
+static void check_deprecated_gpio_property(struct check *c,
+					   struct dt_info *dti,
+				           struct node *node)
+{
+	struct property *prop;
+
+	for_each_property(node, prop) {
+		char *str;
+
+		if (!prop_is_gpio(prop))
+			continue;
+
+		str = strstr(prop->name, "gpio");
+		if (!streq(str, "gpio"))
+			continue;
+
+		FAIL(c, dti, "'[*-]gpio' is deprecated, use '[*-]gpios' instead for %s:%s",
+		     node->fullpath, prop->name);
+	}
+
+}
+CHECK(deprecated_gpio_property, check_deprecated_gpio_property, NULL);
+
 static struct check *check_table[] = {
 	&duplicate_node_names, &duplicate_property_names,
 	&node_name_chars, &node_name_format, &property_name_chars,
@@ -1113,6 +1183,9 @@ static struct check *check_table[] = {
 	&sound_dais_property,
 	&thermal_sensors_property,
 
+	&deprecated_gpio_property,
+	&gpios_property,
+
 	&always_fail,
 };
 

tests/bad-gpio.dts

@@ -0,0 +1,13 @@
+/dts-v1/;
+
+/ {
+	gpio: gpio-controller {
+		#gpio-cells = <3>;
+	};
+
+	node {
+		nr-gpios = <1>;
+		foo-gpios = <&gpio>;
+		bar-gpio = <&gpio 1 2 3>;
+	};
+};

tests/run_tests.sh

@@ -551,6 +551,8 @@ dtc_tests () {
     check_tests unit-addr-leading-0x.dts unit_address_format
     check_tests unit-addr-leading-0s.dts unit_address_format
     check_tests bad-phandle-cells.dts interrupts_extended_property
+    check_tests bad-gpio.dts gpios_property
+    run_sh_test dtc-checkfails.sh deprecated_gpio_property -- -Wdeprecated_gpio_property -I dts -O dtb bad-gpio.dts
     run_sh_test dtc-checkfails.sh node_name_chars -- -I dtb -O dtb bad_node_char.dtb
     run_sh_test dtc-checkfails.sh node_name_format -- -I dtb -O dtb bad_node_format.dtb
     run_sh_test dtc-checkfails.sh prop_name_chars -- -I dtb -O dtb bad_prop_char.dtb