config: enable DFU over USB on Raspberry Pi4 boards

Enable support for DFU over USB. This requires to enable USB gadget,
DWC2 UDC OTG driver and DFU command. DFU entities are defined for the
following firmware objects: u-boot.bin, uboot.env, config.txt, and
zImage/Image.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>

include/configs/rpi.h

@@ -74,6 +74,25 @@
 #define CONFIG_TFTP_TSIZE
 #endif
 
+/* DFU over USB/UDC */
+#ifdef CONFIG_CMD_DFU
+#define CONFIG_SYS_DFU_DATA_BUF_SIZE	SZ_1M
+#define CONFIG_SYS_DFU_MAX_FILE_SIZE	SZ_2M
+
+#ifdef CONFIG_ARM64
+#define KERNEL_FILENAME		"Image"
+#else
+#define KERNEL_FILENAME		"zImage"
+#endif
+
+#define ENV_DFU_SETTINGS \
+	"dfu_alt_info=u-boot.bin fat 0 1;uboot.env fat 0 1;" \
+		      "config.txt fat 0 1;" \
+		      KERNEL_FILENAME " fat 0 1\0"
+#else
+#define ENV_DFU_SETTINGS ""
+#endif
+
 /* Console configuration */
 #define CONFIG_SYS_CBSIZE		1024
 
@@ -188,6 +207,7 @@
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	"dhcpuboot=usb start; dhcp u-boot.uimg; bootm\0" \
 	ENV_DEVICE_SETTINGS \
+	ENV_DFU_SETTINGS \
 	ENV_MEM_LAYOUT_SETTINGS \
 	BOOTENV