ramips: add support for TP-Link Archer C20 v4

TP-Link Archer C20 v4 is a router with 5-port FE switch and
non-detachable antennas. It's based on MediaTek MT7628N+MT7610EN.

Specification:
- MediaTek MT7628N/N (580 Mhz)
- 64 MB of RAM
- 8 MB of FLASH
- 2T2R 2.4 GHz and 1T1R 5 GHz
- 5x 10/100 Mbps Ethernet
- 3x external, non-detachable antennas
- UART (J1) header on PCB (115200 8n1)
- 7x LED (GPIO-controlled*), 2x button, power input switch

* WAN LED in this devices is a dual-color, dual-leads type which isn't
  (fully) supported by gpio-leds driver. This type of LED requires both
  GPIOs state change at the same time to select color or turn it off.
  For now, we support/use only the green part of the LED.
* MT7610EN ac chip isn't not supported by LEDE. Therefore 5Ghz won't
  work.

Flash instruction:

The only way to flash LEDE image in ArcherC20v4 is to use
tftp recovery mode in U-Boot:

1. Configure PC with static IP 192.168.0.66/24 and tftp server.
2. Rename "openwrt-ramips-mt7628-ArcherC20v4-squashfs-tftp-recovery.bin"
   to "tp_recovery.bin" and place it in tftp server directory.
3. Connect PC with one of LAN ports, press the reset button, power up
   the router and keep button pressed for around 6-7 seconds, until
   device starts downloading the file.
4. Router will download file from server, write it to flash and reboot.

Signed-off-by: Maxim Anisimov <maxim.anisimov.ua@gmail.com>

target/linux/ramips/base-files/etc/board.d/01_leds

@@ -388,6 +388,11 @@ tplink,c20-v1)
 	set_usb_led "$boardname:blue:usb"
 	ucidef_set_led_netdev "wlan2g" "wlan2g" "$boardname:blue:wlan2g" "wlan0"
 	;;
+tplink,c20-v4)
+	ucidef_set_led_switch "lan" "lan" "$boardname:green:lan" "switch0" "0x1e"
+	ucidef_set_led_switch "wan" "wan" "$boardname:green:wan" "switch0" "0x01"
+	ucidef_set_led_netdev "wlan2g" "wlan2g" "$boardname:green:wlan2g" "wlan0"
+	;;
 tplink,tl-mr3420-v5)
 	set_usb_led "$boardname:green:usb"
 	set_wifi_led "$boardname:green:wlan"

target/linux/ramips/base-files/etc/board.d/02_network

@@ -173,6 +173,7 @@ ramips_setup_interfaces()
 	mzk-wdpr|\
 	rb750gr3|\
 	rt-n14u|\
+	tplink,c20-v4|\
 	tplink,tl-mr3420-v5|\
 	tl-wr840n-v4|\
 	tl-wr840n-v5|\

target/linux/ramips/base-files/etc/diag.sh

@@ -38,6 +38,7 @@ get_status_led() {
 	nbg-419n2|\
 	pwh2004|\
 	r6220|\
+	tplink,c20-v4|\
 	tplink,tl-mr3420-v5|\
 	tl-wr840n-v4|\
 	tl-wr840n-v5|\

target/linux/ramips/base-files/lib/upgrade/platform.sh

@@ -241,6 +241,7 @@ platform_check_image() {
 	c50|\
 	mr200|\
 	tplink,c20-v1|\
+	tplink,c20-v4|\
 	tplink,tl-mr3420-v5|\
 	tl-wr840n-v4|\
 	tl-wr840n-v5|\

target/linux/ramips/dts/ArcherC20v4.dts

@@ -0,0 +1,170 @@
+/dts-v1/;
+
+#include "mt7628an.dtsi"
+
+#include <dt-bindings/input/input.h>
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+	compatible = "tplink,c20-v4", "mediatek,mt7628an-soc";
+	model = "TP-Link Archer C20 v4";
+
+	chosen {
+		bootargs = "console=ttyS0,115200";
+	};
+
+	gpio-leds {
+		compatible = "gpio-leds";
+
+		lan {
+			label = "c20-v4:green:lan";
+			gpios = <&gpio1 10 GPIO_ACTIVE_LOW>;
+		};
+
+		power {
+			label = "c20-v4:green:power";
+			gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;
+		};
+
+		wan {
+			label = "c20-v4:green:wan";
+			gpios = <&gpio1 11 GPIO_ACTIVE_LOW>;
+		};
+
+		wan_orange {
+			label = "c20-v4:orange:wan";
+			gpios = <&gpio0 11 GPIO_ACTIVE_LOW>;
+		};
+		
+		wlan5g {
+			label = "c20-v4:green:wlan5g";
+			gpios = <&gpio1 8 GPIO_ACTIVE_LOW>;
+		};
+
+		wlan2g {
+			label = "c20-v4:green:wlan2g";
+			gpios = <&gpio1 7 GPIO_ACTIVE_LOW>;
+		};
+
+		wps {
+			label = "c20-v4:green:wps";
+			gpios = <&gpio1 9 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	gpio-keys-polled {
+		compatible = "gpio-keys-polled";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		poll-interval = <20>;
+
+		reset {
+			label = "reset";
+			gpios = <&gpio1 6 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+
+		rfkill {
+			label = "rfkill";
+			gpios = <&gpio1 5 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RFKILL>;
+		};
+	};
+
+	memory@0 {
+		device_type = "memory";
+		reg = <0x0 0x4000000>;
+	};
+};
+
+&spi0 {
+	status = "okay";
+
+	m25p80@0 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <10000000>;
+		m25p,chunked-io = <32>;
+
+		partition@0 {
+			label = "u-boot";
+			reg = <0x0 0x20000>;
+			read-only;
+		};
+
+		partition@20000 {
+			label = "firmware";
+			reg = <0x20000 0x7a0000>;
+		};
+
+		partition@7c0000 {
+			label = "config";
+			reg = <0x7c0000 0x10000>;
+			read-only;
+		};
+
+		rom: partition@7d0000 {
+			label = "rom";
+			reg = <0x7d0000 0x10000>;
+			read-only;
+		};
+
+		partition@7e0000 {
+			label = "romfile";
+			reg = <0x7e0000 0x10000>;
+			read-only;
+		};
+
+		radio: partition@7f0000 {
+			label = "radio";
+			reg = <0x7f0000 0x10000>;
+			read-only;
+		};
+	};
+};
+
+&ehci {
+	status = "disabled";
+};
+
+&ohci {
+	status = "disabled";
+};
+
+&wmac {
+	status = "okay";
+	mediatek,mtd-eeprom = <&radio 0x0>;
+	mtd-mac-address = <&rom 0xf100>;
+	mtd-mac-address-increment = <(-2)>;
+};
+
+&ethernet {
+	mtd-mac-address = <&rom 0xf100>;
+	mediatek,portmap = "wllll";
+};
+
+&pinctrl {
+	state_default: pinctrl0 {
+		gpio {
+			ralink,group = "i2s", "refclk", "p0led_an", "p1led_an", "p2led_an", "p3led_an", "p4led_an", "wdt";
+			ralink,function = "gpio";
+		};
+	};
+};
+
+&pcie {
+	status = "okay";
+
+	pcie-bridge {
+		mt76@0,0 {
+			reg = <0x0000 0 0 0 0>;
+			device_type = "pci";
+			mediatek,mtd-eeprom = <&radio 0x8000>;
+			ieee80211-freq-limit = <5000000 6000000>;
+			mtd-mac-address = <&rom 0xf100>;
+			mtd-mac-address-increment = <(-1)>;
+		};
+	};
+};

target/linux/ramips/image/mt76x8.mk

@@ -139,6 +139,19 @@ define Device/tl-wr841n-v13
 endef
 TARGET_DEVICES += tl-wr841n-v13
 
+define Device/tplink_c20-v4
+  $(Device/tplink)
+  DTS := ArcherC20v4
+  IMAGE_SIZE := 7808k
+  DEVICE_TITLE := TP-Link ArcherC20 v4
+  TPLINK_FLASHLAYOUT := 8Mmtk
+  TPLINK_HWID := 0xc200004
+  TPLINK_HWREV := 0x1
+  TPLINK_HWREVADD := 0x4
+  TPLINK_HVERSION := 3
+endef
+TARGET_DEVICES += tplink_c20-v4
+
 define Device/tplink_tl-mr3420-v5
   $(Device/tplink)
   DTS := TL-MR3420V5