pinctrl: rockchip: support unrouted iomuxes per bank

On the upcoming RK3288 SoC contain some unrouted pins in their banks. So while
for example pin8 of bank5 stays pin8 with all its settings (register offset etc),
pins 0 to 7 are not routed outside the SoC at all.
Therefore add a flag to mark these unrouted iomuxes to prevent people from using
them.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-rockchip.c

@@ -70,6 +70,7 @@ enum rockchip_pinctrl_type {
 #define IOMUX_GPIO_ONLY		BIT(0)
 #define IOMUX_WIDTH_4BIT	BIT(1)
 #define IOMUX_SOURCE_PMU	BIT(2)
+#define IOMUX_UNROUTED		BIT(3)
 
 /**
  * @type: iomux variant using IOMUX_* constants
@@ -386,6 +387,11 @@ static int rockchip_get_mux(struct rockchip_pin_bank *bank, int pin)
 	if (iomux_num > 3)
 		return -EINVAL;
 
+	if (bank->iomux[iomux_num].type & IOMUX_UNROUTED) {
+		dev_err(info->dev, "pin %d is unrouted\n", pin);
+		return -EINVAL;
+	}
+
 	if (bank->iomux[iomux_num].type & IOMUX_GPIO_ONLY)
 		return RK_FUNC_GPIO;
 
@@ -436,6 +442,11 @@ static int rockchip_set_mux(struct rockchip_pin_bank *bank, int pin, int mux)
 	if (iomux_num > 3)
 		return -EINVAL;
 
+	if (bank->iomux[iomux_num].type & IOMUX_UNROUTED) {
+		dev_err(info->dev, "pin %d is unrouted\n", pin);
+		return -EINVAL;
+	}
+
 	if (bank->iomux[iomux_num].type & IOMUX_GPIO_ONLY) {
 		if (mux != RK_FUNC_GPIO) {
 			dev_err(info->dev,