ar71xx: add support for RB750r2

This patch adds support for the MikroTik RouterBOARD hEX lite
https://routerboard.com/RB750r2

Specifications:
- SoC: Qualcomm QCA9531 (850MHz)
- RAM: 64MB
- Storage: 16MB NOR SPI flash
- Ethernet: 5x100M (1 PoE in)

This ethernet router is based on the same platform as the hEX PoE lite (it
shares the same board identifier), but has no USB and no PoE out.

Signed-off-by: Thibaut VARENE <hacks@slashdirt.org>

target/linux/ar71xx/base-files/etc/board.d/01_leds

@@ -222,6 +222,7 @@ rb-750)
 	ucidef_set_led_switch "port4" "port4" "rb750:green:port4" "switch0" "0x04"
 	ucidef_set_led_switch "port5" "port5" "rb750:green:port5" "switch0" "0x02"
 	;;
+rb-750-r2|\
 rb-750up-r2)
 	ucidef_set_led_timer "user" "USER" "rb:green:user" "1000" "1000"
 	ucidef_set_led_netdev "port1" "port1" "rb:green:port1" "eth0"

target/linux/ar71xx/base-files/etc/board.d/02_network

@@ -136,6 +136,7 @@ ar71xx_setup_interfaces()
 	om2p-hsv4|\
 	pb42|\
 	pb44|\
+	rb-750-r2|\
 	rb-750up-r2|\
 	rb-951ui-2hnd|\
 	rb-951ui-2nd|\

target/linux/ar71xx/base-files/etc/diag.sh

@@ -293,6 +293,7 @@ get_status_led() {
 	rb-750)
 		status_led="rb750:green:act"
 		;;
+	rb-750-r2|\
 	rb-750up-r2|\
 	rb-911g-2hpnd|\
 	rb-911g-5hpacd|\

target/linux/ar71xx/base-files/lib/ar71xx.sh

@@ -838,6 +838,9 @@ ar71xx_board_detect() {
 	*"RouterBOARD 750GL")
 		name="rb-750gl"
 		;;
+	*"RouterBOARD 750 r2")
+		name="rb-750-r2"
+		;;
 	*"RouterBOARD 750UP r2")
 		name="rb-750up-r2"
 		;;

target/linux/ar71xx/base-files/lib/upgrade/platform.sh

@@ -343,6 +343,7 @@ platform_check_image() {
 	ls-sr71|\
 	pb42|\
 	pb44|\
+	rb-750-r2|\
 	rb-750up-r2|\
 	rb-941-2nd|\
 	rb-951ui-2nd|\
@@ -618,6 +619,7 @@ platform_pre_upgrade() {
 	local board=$(ar71xx_board_name)
 
 	case "$board" in
+	rb-750-r2|\
 	rb-750up-r2|\
 	rb-941-2nd|\
 	rb-951ui-2nd|\
@@ -657,6 +659,7 @@ platform_do_upgrade() {
 	local board=$(ar71xx_board_name)
 
 	case "$board" in
+	rb-750-r2|\
 	rb-750up-r2|\
 	rb-941-2nd|\
 	rb-951ui-2nd|\

target/linux/ar71xx/files/arch/mips/ath79/Kconfig.openwrt

@@ -930,6 +930,7 @@ config ATH79_MACH_RBSPI
 	  MikroTik RouterBOARD hAP lite
 	  MikroTik RouterBOARD hAP
 	  MikroTik RouterBOARD hEX PoE lite
+	  MikroTik RouterBOARD hEX lite
 
 config ATH79_MACH_RBSXTLITE
 	bool "MikroTik RouterBOARD SXT Lite"

target/linux/ar71xx/files/arch/mips/ath79/mach-rbspi.c

@@ -5,6 +5,7 @@
  *  - MikroTik RouterBOARD 941L-2nD
  *  - MikroTik RouterBOARD 951Ui-2nD
  *  - MikroTik RouterBOARD 750UP r2
+ *  - MikroTik RouterBOARD 750 r2
  *
  *  Copyright (C) 2017 Thibaut VARENE <varenet@parisc-linux.org>
  *
@@ -472,18 +473,22 @@ static void __init rb952_setup(void)
 }
 
 /*
- * Init the hEX PoE lite hardware.
+ * Init the hEX (PoE) lite hardware.
  * The 750UP r2 (hEX PoE lite) is nearly identical to the hAP, only without
- * WLAN.
+ * WLAN. The 750 r2 (hEX lite) is nearly identical to the 750UP r2, only
+ * without USB and POE. It shares the same bootloader board identifier.
  */
 static void __init rb750upr2_setup(void)
 {
-	u32 flags = RBSPI_HAS_WAN4 | RBSPI_HAS_USB |
-			RBSPI_HAS_SSR | RBSPI_HAS_POE;
+	u32 flags = RBSPI_HAS_WAN4 | RBSPI_HAS_SSR;
 
 	if (rbspi_platform_setup())
 		return;
 
+	/* differentiate the hEX lite from the hEX PoE lite */
+	if (strstr(mips_get_machine_name(), "750UP r2"))
+		flags |= RBSPI_HAS_USB | RBSPI_HAS_POE;
+
 	rbspi_952_750r2_setup(flags);
 }