bcma: use chipcommon node from DT for SoC GPIO chip

This will allow us to define GPIO-attached devices (LEDs, buttons) in
the the device tree.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

Documentation/devicetree/bindings/bus/bcma.txt

@@ -9,6 +9,11 @@ Required properties:
 The cores on the AXI bus are automatically detected by bcma with the
 memory ranges they are using and they get registered afterwards.
 
+The top-level axi bus may contain children representing attached cores
+(devices). This is needed since some hardware details can't be auto
+detected (e.g. IRQ numbers). Also some of the cores may be responsible
+for extra things, e.g. ChipCommon providing access to the GPIO chip.
+
 Example:
 
 	axi@18000000 {
@@ -17,4 +22,11 @@ Example:
 		ranges = <0x00000000 0x18000000 0x00100000>;
 		#address-cells = <1>;
 		#size-cells = <1>;
+
+		chipcommon {
+			reg = <0x00000000 0x1000>;
+
+			gpio-controller;
+			#gpio-cells = <2>;
+		};
 	};

drivers/bcma/driver_gpio.c

@@ -217,6 +217,10 @@ int bcma_gpio_init(struct bcma_drv_cc *cc)
 	chip->direction_output	= bcma_gpio_direction_output;
 #if IS_BUILTIN(CONFIG_BCM47XX)
 	chip->to_irq		= bcma_gpio_to_irq;
+#endif
+#if IS_BUILTIN(CONFIG_OF)
+	if (cc->core->bus->hosttype == BCMA_HOSTTYPE_SOC)
+		chip->of_node	= cc->core->dev.of_node;
 #endif
 	switch (cc->core->bus->chipinfo.id) {
 	case BCMA_CHIP_ID_BCM5357: