mips: mtmips: add support for MediaTek MT7621 SoC

This patch adds support for MediaTek MT7621 SoC.
All files are dedicated for u-boot.

The default build target is u-boot-mt7621.bin.

The specification of this chip:
https://www.mediatek.com/products/homenetworking/mt7621

Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/arch/mips/mach-mtmips/mt7621/Kconfig b/arch/mips/mach-mtmips/mt7621/Kconfig
new file mode 100644
index 0000000..37d512c
--- /dev/null
+++ b/arch/mips/mach-mtmips/mt7621/Kconfig
@@ -0,0 +1,95 @@
+
+if SOC_MT7621
+
+menu "CPU & DDR configuration"
+
+config MT7621_CPU_FREQ
+	int "CPU Frequency (MHz)"
+	range 400 1200
+	default 880
+
+choice
+	prompt "DRAM Frequency"
+	default MT7621_DRAM_FREQ_1200
+
+config MT7621_DRAM_FREQ_400
+	bool "400MHz"
+
+config MT7621_DRAM_FREQ_800
+	bool "800MHz"
+
+config MT7621_DRAM_FREQ_1066
+	bool "1066MHz"
+
+config MT7621_DRAM_FREQ_1200
+	bool "1200MHz"
+
+endchoice
+
+choice
+	prompt "DDR2 timing parameters"
+	default MT7621_DRAM_DDR2_1024M
+
+config MT7621_DRAM_DDR2_512M
+	bool "64MB"
+
+config MT7621_DRAM_DDR2_1024M
+	bool "128MB"
+
+config MT7621_DRAM_DDR2_512M_W9751G6KB_A02_1066MHZ
+	bool "W9751G6KB_A02 @ 1066MHz (64MB)"
+
+config MT7621_DRAM_DDR2_1024M_W971GG6KB25_800MHZ
+	bool "W971GG6KB25 @ 800MHz (128MB)"
+
+config MT7621_DRAM_DDR2_1024M_W971GG6KB18_1066MHZ
+	bool "W971GG6KB18 @ 1066MHz (128MB)"
+
+endchoice
+
+choice
+	prompt "DDR3 timing parameters"
+	default MT7621_DRAM_DDR3_2048M
+
+config MT7621_DRAM_DDR3_1024M
+	bool "128MB"
+
+config MT7621_DRAM_DDR3_1024M_KGD
+	bool "128MB KGD (MT7621DA)"
+
+config MT7621_DRAM_DDR3_2048M
+	bool "256MB"
+
+config MT7621_DRAM_DDR3_4096M
+	bool "512MB"
+
+endchoice
+
+endmenu
+
+config DEBUG_UART_BOARD_INIT
+	default y
+
+config MT7621_BOOT_FROM_NAND
+	bool "Boot from NAND"
+	help
+	  Select this if u-boot will boot from NAND flash. When booting from
+	  NAND, SPL will be loaded by bootrom directly and no TPL is needed.
+
+choice
+	prompt "Board select"
+
+endchoice
+
+config SYS_CONFIG_NAME
+	string "Board configuration name"
+	default "mt7621" if  BOARD_MT7621_RFB || BOARD_MT7621_NAND_RFB
+
+config SYS_BOARD
+	string "Board name"
+	default "mt7621" if  BOARD_MT7621_RFB || BOARD_MT7621_NAND_RFB
+
+config SYS_VENDOR
+	default "mediatek" if BOARD_MT7621_RFB || BOARD_MT7621_NAND_RFB
+
+endif