From 4bbdb87d6be83386e15f5c38e80a49be9308f2a7 Mon Sep 17 00:00:00 2001
From: Rene Straub <rene.straub@netmodule.com>
Date: Mon, 6 Mar 2023 14:52:58 +0100
Subject: [PATCH] hw21/26: set user serial port to RS485 by default

RS485 keeps the port passive, so that no other devices are disturbed.
---
 board/nm/nmhw21/board.c | 7 +++++++
 board/nm/nmhw21/mux.c   | 6 ++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/board/nm/nmhw21/board.c b/board/nm/nmhw21/board.c
index 44c42effff..d605e5c01c 100644
--- a/board/nm/nmhw21/board.c
+++ b/board/nm/nmhw21/board.c
@@ -49,6 +49,8 @@ DECLARE_GLOBAL_DATA_PTR;
 * CPU GPIOs
 *
 * (C15) GPIO0_6: MB_LED_PWM
+* (V2)  GPIO0_8: RS232_485n_SEL (V3.2)
+* (V3)  GPIO0_9: RS485_DE (V3.2)
 * (J18) GPIO0_16: ETH_SW_RST~ (V2.0)
 * (K15) GPIO0_17: CTRL.INT~
 * (T10) GPIO0_23: CAN_TERM1~ (V1.0)
@@ -111,6 +113,8 @@ DECLARE_GLOBAL_DATA_PTR;
 
 #define GPIO_UART2_RX 		GPIO_TO_PIN(0, 2)	/* UART Rx Pin as GPIO */
 
+#define GPIO_RS232_RS485n_SEL	GPIO_TO_PIN(0, 8)
+#define GPIO_RS485_DE		GPIO_TO_PIN(0, 9)
 
 /*
  * PMIC GPIOs
@@ -806,6 +810,9 @@ void am33xx_spl_board_init(void)
 	if (is_v32_or_newer()) {
 		enable_led_mux_v32();
 		enable_uart4_pin_mux();
+		
+		REQUEST_AND_CLEAR_GPIO(GPIO_RS485_DE);
+		REQUEST_AND_CLEAR_GPIO(GPIO_RS232_RS485n_SEL);
 	}
 	else {
 		enable_led_mux();
diff --git a/board/nm/nmhw21/mux.c b/board/nm/nmhw21/mux.c
index 1c2a97ab70..9a8b101dc9 100644
--- a/board/nm/nmhw21/mux.c
+++ b/board/nm/nmhw21/mux.c
@@ -23,6 +23,8 @@
 
 static struct module_pin_mux gpio_pin_mux[] = {
 	/*
+	* (V2)  GPIO0_8: RS232_485n_SEL (V3.2)
+	* (V3)  GPIO0_9: RS485_DE (V3.2)
 	* (J18) GPIO0_16: ETH_SW_RST~ (V2.0)
 	* (K15) GPIO0_17: CTRL.INT~
 	* (T10) GPIO0_23: CAN_TERM1~ (V1.0)
@@ -221,13 +223,13 @@ static struct module_pin_mux uart3_pin_mux[] = {
 /* UART4: User RS232/485 (V3.2 only) */
 static struct module_pin_mux uart4_pin_mux[] = {
 	/*
-	 * CTSn = SEL_RS232/RS485~: Default = High -> RS232 mode
+	 * CTSn = SEL_RS232/RS485~: Default = Low -> RS485 mode
 	 * RTSn = RS485_DE: Default = Low -> RS485 transmitter disabled
 	 *        Configure as GPIO in U-Boot to keep disabled, Linux will change to RTSn
 	 */
 	{OFFSET(gpmc_wait0), (MODE(6) | PULLUDEN | PULLUP_EN | RXACTIVE)},	/* (T17) UART4_RXD */
 	{OFFSET(gpmc_wpn), (MODE(6) | PULLUDEN | PULLUP_EN | SLEWCTRL)},	/* (U17) UART4_TXD */
-	{OFFSET(lcd_data12), (MODE(7) | PULLUDEN | PULLUP_EN)},			/* (V2) uart4_ctsn */
+	{OFFSET(lcd_data12), (MODE(7) | PULLUDEN | PULLDOWN_EN)},		/* (V2) uart4_ctsn */
 	{OFFSET(lcd_data13), (MODE(7) | PULLUDEN | PULLDOWN_EN)},		/* (V3) uart4_rtsn */
 	{-1}
 };