arch/arm/src/samd2l2: Add RS485 support to SAMD2L2 serial

arch/arm/src/samd2l2/Kconfig

@@ -616,6 +616,27 @@ config SAMD2L2_SERCOM0_ISUSART
 
 endchoice
 
+if USART0_SERIALDRIVER
+
+config USART0_RS485MODE
+	bool "RS-485 on USART0"
+	default n
+	---help---
+		Enable RS-485 interface on USART0. Your board config will have to
+		provide GPIO_USART0_RS485_DIR pin definition. Currently it cannot be
+		used with USART0_RXDMA.
+
+config USART0_RS485_DIR_POLARITY
+	int "USART0 RS-485 DIR pin polarity"
+	default 1
+	range 0 1
+	depends on USART0_RS485MODE
+	---help---
+		Polarity of DIR pin for RS-485 on USART0. Set to state on DIR pin which
+		enables TX (0 - low / nTXEN, 1 - high / TXEN).
+
+endif # USART0_SERIALDRIVER
+
 choice
 	prompt "SERCOM1 mode"
 	default SAMD2L2_SERCOM1_ISUSART
@@ -636,6 +657,27 @@ config SAMD2L2_SERCOM1_ISUSART
 
 endchoice
 
+if USART1_SERIALDRIVER
+
+config USART1_RS485MODE
+	bool "RS-485 on USART1"
+	default n
+	---help---
+		Enable RS-485 interface on USART1. Your board config will have to
+		provide GPIO_USART1_RS485_DIR pin definition. Currently it cannot be
+		used with USART1_RXDMA.
+
+config USART1_RS485_DIR_POLARITY
+	int "USART1 RS-485 DIR pin polarity"
+	default 1
+	range 0 1
+	depends on USART1_RS485MODE
+	---help---
+		Polarity of DIR pin for RS-485 on USART1. Set to state on DIR pin which
+		enables TX (0 - low / nTXEN, 1 - high / TXEN).
+
+endif # USART1_SERIALDRIVER
+
 choice
 	prompt "SERCOM2 mode"
 	default SAMD2L2_SERCOM2_ISUSART
@@ -656,6 +698,27 @@ config SAMD2L2_SERCOM2_ISUSART
 
 endchoice
 
+if USART2_SERIALDRIVER
+
+config USART2_RS485MODE
+	bool "RS-485 on USART2"
+	default n
+	---help---
+		Enable RS-485 interface on USART2. Your board config will have to
+		provide GPIO_USART2_RS485_DIR pin definition. Currently it cannot be
+		used with USART2_RXDMA.
+
+config USART2_RS485_DIR_POLARITY
+	int "USART2 RS-485 DIR pin polarity"
+	default 1
+	range 0 1
+	depends on USART2_RS485MODE
+	---help---
+		Polarity of DIR pin for RS-485 on USART2. Set to state on DIR pin which
+		enables TX (0 - low / nTXEN, 1 - high / TXEN).
+
+endif # USART2_SERIALDRIVER
+
 choice
 	prompt "SERCOM3 mode"
 	default SAMD2L2_SERCOM3_ISUSART
@@ -676,6 +739,27 @@ config SAMD2L2_SERCOM3_ISUSART
 
 endchoice
 
+if USART3_SERIALDRIVER
+
+config USART3_RS485MODE
+	bool "RS-485 on USART3"
+	default n
+	---help---
+		Enable RS-485 interface on USART3. Your board config will have to
+		provide GPIO_USART3_RS485_DIR pin definition. Currently it cannot be
+		used with USART3_RXDMA.
+
+config USART3_RS485_DIR_POLARITY
+	int "USART3 RS-485 DIR pin polarity"
+	default 1
+	range 0 1
+	depends on USART3_RS485MODE
+	---help---
+		Polarity of DIR pin for RS-485 on USART3. Set to state on DIR pin which
+		enables TX (0 - low / nTXEN, 1 - high / TXEN).
+
+endif # USART3_SERIALDRIVER
+
 choice
 	prompt "SERCOM4 mode"
 	default SAMD2L2_SERCOM4_ISUSART
@@ -696,6 +780,27 @@ config SAMD2L2_SERCOM4_ISUSART
 
 endchoice
 
+if USART4_SERIALDRIVER
+
+config USART4_RS485MODE
+	bool "RS-485 on USART4"
+	default n
+	---help---
+		Enable RS-485 interface on USART4. Your board config will have to
+		provide GPIO_USART4_RS485_DIR pin definition. Currently it cannot be
+		used with USART4_RXDMA.
+
+config USART4_RS485_DIR_POLARITY
+	int "USART4 RS-485 DIR pin polarity"
+	default 1
+	range 0 1
+	depends on USART4_RS485MODE
+	---help---
+		Polarity of DIR pin for RS-485 on USART4. Set to state on DIR pin which
+		enables TX (0 - low / nTXEN, 1 - high / TXEN).
+
+endif # USART4_SERIALDRIVER
+
 choice
 	prompt "SERCOM5 mode"
 	default SAMD2L2_SERCOM5_ISUSART
@@ -716,6 +821,27 @@ config SAMD2L2_SERCOM5_ISUSART
 
 endchoice
 
+if USART5_SERIALDRIVER
+
+config USART5_RS485MODE
+	bool "RS-485 on USART5"
+	default n
+	---help---
+		Enable RS-485 interface on USART5. Your board config will have to
+		provide GPIO_USART5_RS485_DIR pin definition. Currently it cannot be
+		used with USART5_RXDMA.
+
+config USART5_RS485_DIR_POLARITY
+	int "USART5 RS-485 DIR pin polarity"
+	default 1
+	range 0 1
+	depends on USART5_RS485MODE
+	---help---
+		Polarity of DIR pin for RS-485 on USART5. Set to state on DIR pin which
+		enables TX (0 - low / nTXEN, 1 - high / TXEN).
+
+endif # USART5_SERIALDRIVER
+
 config SAMD2L2_HAVE_SPI
 	bool
 	select SPI

arch/arm/src/samd2l2/sam_config.h

@@ -1,7 +1,7 @@
 /************************************************************************************
  * arch/arm/src/samd2l2/sam_config.h
  *
- *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014, 2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -135,6 +135,14 @@
 #  undef CONFIG_USART4_SERIAL_CONSOLE
 #  undef CONFIG_USART5_SERIAL_CONSOLE
 #  define HAVE_SERIAL_CONSOLE 1
+#  ifdef CONFIG_USART0_RS485MODE
+#    define SAM_CONSOLE_RS485_DIR GPIO_USART0_RS485_DIR
+#    if (CONFIG_USART0_RS485_DIR_POLARITY == 0)
+#      define SAM_CONSOLE_RS485_DIR_POLARITY false
+#    else
+#      define SAM_CONSOLE_RS485_DIR_POLARITY true
+#    endif
+#  endif
 #elif defined(CONFIG_USART1_SERIAL_CONSOLE)
 #  undef CONFIG_USART0_SERIAL_CONSOLE
 #  undef CONFIG_USART2_SERIAL_CONSOLE
@@ -142,6 +150,14 @@
 #  undef CONFIG_USART4_SERIAL_CONSOLE
 #  undef CONFIG_USART5_SERIAL_CONSOLE
 #  define HAVE_SERIAL_CONSOLE 1
+#  ifdef CONFIG_USART1_RS485MODE
+#    define SAM_CONSOLE_RS485_DIR GPIO_USART1_RS485_DIR
+#    if (CONFIG_USART1_RS485_DIR_POLARITY == 0)
+#      define SAM_CONSOLE_RS485_DIR_POLARITY false
+#    else
+#      define SAM_CONSOLE_RS485_DIR_POLARITY true
+#    endif
+#  endif
 #elif defined(CONFIG_USART2_SERIAL_CONSOLE)
 #  undef CONFIG_USART0_SERIAL_CONSOLE
 #  undef CONFIG_USART1_SERIAL_CONSOLE
@@ -149,6 +165,14 @@
 #  undef CONFIG_USART4_SERIAL_CONSOLE
 #  undef CONFIG_USART5_SERIAL_CONSOLE
 #  define HAVE_SERIAL_CONSOLE 1
+#  ifdef CONFIG_USART2_RS485MODE
+#    define SAM_CONSOLE_RS485_DIR GPIO_USART2_RS485_DIR
+#    if (CONFIG_USART2_RS485_DIR_POLARITY == 0)
+#      define SAM_CONSOLE_RS485_DIR_POLARITY false
+#    else
+#      define SAM_CONSOLE_RS485_DIR_POLARITY true
+#    endif
+#  endif
 #elif defined(CONFIG_USART3_SERIAL_CONSOLE)
 #  undef CONFIG_USART0_SERIAL_CONSOLE
 #  undef CONFIG_USART1_SERIAL_CONSOLE
@@ -156,6 +180,14 @@
 #  undef CONFIG_USART4_SERIAL_CONSOLE
 #  undef CONFIG_USART5_SERIAL_CONSOLE
 #  define HAVE_SERIAL_CONSOLE 1
+#  ifdef CONFIG_USART3_RS485MODE
+#    define SAM_CONSOLE_RS485_DIR GPIO_USART3_RS485_DIR
+#    if (CONFIG_USART3_RS485_DIR_POLARITY == 0)
+#      define SAM_CONSOLE_RS485_DIR_POLARITY false
+#    else
+#      define SAM_CONSOLE_RS485_DIR_POLARITY true
+#    endif
+#  endif
 #elif defined(CONFIG_USART4_SERIAL_CONSOLE)
 #  undef CONFIG_USART0_SERIAL_CONSOLE
 #  undef CONFIG_USART1_SERIAL_CONSOLE
@@ -163,6 +195,14 @@
 #  undef CONFIG_USART3_SERIAL_CONSOLE
 #  undef CONFIG_USART5_SERIAL_CONSOLE
 #  define HAVE_SERIAL_CONSOLE 1
+#  ifdef CONFIG_USART4_RS485MODE
+#    define SAM_CONSOLE_RS485_DIR GPIO_USART4_RS485_DIR
+#    if (CONFIG_USART4_RS485_DIR_POLARITY == 0)
+#      define SAM_CONSOLE_RS485_DIR_POLARITY false
+#    else
+#      define SAM_CONSOLE_RS485_DIR_POLARITY true
+#    endif
+#  endif
 #elif defined(CONFIG_USART5_SERIAL_CONSOLE)
 #  undef CONFIG_USART0_SERIAL_CONSOLE
 #  undef CONFIG_USART1_SERIAL_CONSOLE
@@ -170,6 +210,14 @@
 #  undef CONFIG_USART3_SERIAL_CONSOLE
 #  undef CONFIG_USART4_SERIAL_CONSOLE
 #  define HAVE_SERIAL_CONSOLE 1
+#  ifdef CONFIG_USART5_RS485MODE
+#    define SAM_CONSOLE_RS485_DIR GPIO_USART5_RS485_DIR
+#    if (CONFIG_USART5_RS485_DIR_POLARITY == 0)
+#      define SAM_CONSOLE_RS485_DIR_POLARITY false
+#    else
+#      define SAM_CONSOLE_RS485_DIR_POLARITY true
+#    endif
+#  endif
 #else
 #  undef CONFIG_USART0_SERIAL_CONSOLE
 #  undef CONFIG_USART1_SERIAL_CONSOLE
@@ -178,6 +226,7 @@
 #  undef CONFIG_USART4_SERIAL_CONSOLE
 #  undef CONFIG_USART5_SERIAL_CONSOLE
 #  undef HAVE_SERIAL_CONSOLE
+#  undef SAM_CONSOLE_RS485_DIR
 #endif
 
 /* Are any SERCOM peripherals are configured as SPI peripherals? */

arch/arm/src/samd2l2/sam_lowputc.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/src/samd2l2/sam_lowputc.c
  *
- *   Copyright (C) 2014-2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014-2016, 2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * References:
@@ -467,7 +467,13 @@ void sam_lowputc(uint32_t ch)
 
   /* Wait for the USART to be ready for new TX data */
 
-  while ((getreg8(intflag) & USART_INT_DRE) == 0);
+  while ((getreg8(intflag) & USART_INT_DRE) == 0)
+    {
+    }
+
+#ifdef SAM_CONSOLE_RS485_DIR
+  sam_portwrite(SAM_CONSOLE_RS485_DIR, SAM_CONSOLE_RS485_DIR_POLARITY);
+#endif
 
   /* Wait until synchronization is complete */
 
@@ -479,6 +485,12 @@ void sam_lowputc(uint32_t ch)
 
   /* Wait until data is sent */
 
-  while ((getreg8(intflag) & USART_INT_TXC) == 0);
+  while ((getreg8(intflag) & USART_INT_TXC) == 0)
+    {
+    }
+
+#ifdef SAM_CONSOLE_RS485_DIR
+  sam_portwrite(SAM_CONSOLE_RS485_DIR, !SAM_CONSOLE_RS485_DIR_POLARITY);
+#endif
 }
 #endif

arch/arm/src/samd2l2/sam_serial.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/src/samd2l2/sam_serial.c
  *
- *   Copyright (C) 2014-2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014-2015, 2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -229,6 +229,11 @@ struct sam_dev_s
   const struct sam_usart_config_s * const config;
 
   /* Information unique to the serial driver */
+
+#ifdef HAVE_RS485
+  const uint32_t rs485_dir_gpio;     /* USART RS-485 DIR GPIO pin configuration */
+  const bool     rs485_dir_polarity; /* USART RS-485 DIR pin state for TX enabled */
+#endif
 };
 
 /****************************************************************************
@@ -319,7 +324,15 @@ static char g_usart5txbuffer[CONFIG_USART5_TXBUFSIZE];
 #ifdef SAMD2L2_HAVE_USART0
 static struct sam_dev_s g_usart0priv =
 {
-  .config   = &g_usart0config,
+  .config             = &g_usart0config,
+#ifdef CONFIG_USART0_RS485MODE
+  .rs485_dir_gpio     = GPIO_USART0_RS485_DIR,
+#  if (CONFIG_USART0_RS485_DIR_POLARITY == 0)
+  .rs485_dir_polarity = false,
+#  else
+  .rs485_dir_polarity = true,
+#  endif
+#endif
 };
 
 static uart_dev_t g_usart0port =
@@ -344,7 +357,15 @@ static uart_dev_t g_usart0port =
 #ifdef SAMD2L2_HAVE_USART1
 static struct sam_dev_s g_usart1priv =
 {
-  .config   = &g_usart1config,
+  .config             = &g_usart1config,
+#ifdef CONFIG_USART1_RS485MODE
+  .rs485_dir_gpio     = GPIO_USART1_RS485_DIR,
+#  if (CONFIG_USART1_RS485_DIR_POLARITY == 0)
+  .rs485_dir_polarity = false,
+#  else
+  .rs485_dir_polarity = true,
+#  endif
+#endif
 };
 
 static uart_dev_t g_usart1port =
@@ -369,7 +390,15 @@ static uart_dev_t g_usart1port =
 #ifdef SAMD2L2_HAVE_USART2
 static struct sam_dev_s g_usart2priv =
 {
-  .config   = &g_usart2config,
+  .config             = &g_usart2config,
+#ifdef CONFIG_USART2_RS485MODE
+  .rs485_dir_gpio     = GPIO_USART2_RS485_DIR,
+#  if (CONFIG_USART2_RS485_DIR_POLARITY == 0)
+  .rs485_dir_polarity = false,
+#  else
+  .rs485_dir_polarity = true,
+#  endif
+#endif
 };
 
 static uart_dev_t g_usart2port =
@@ -394,7 +423,15 @@ static uart_dev_t g_usart2port =
 #ifdef SAMD2L2_HAVE_USART3
 static struct sam_dev_s g_usart3priv =
 {
-  .config   = &g_usart3config,
+  .config             = &g_usart3config,
+#ifdef CONFIG_USART3_RS485MODE
+  .rs485_dir_gpio     = GPIO_USART3_RS485_DIR,
+#  if (CONFIG_USART3_RS485_DIR_POLARITY == 0)
+  .rs485_dir_polarity = false,
+#  else
+  .rs485_dir_polarity = true,
+#  endif
+#endif
 };
 
 static uart_dev_t g_usart3port =
@@ -419,7 +456,15 @@ static uart_dev_t g_usart3port =
 #ifdef SAMD2L2_HAVE_USART4
 static struct sam_dev_s g_usart4priv =
 {
-  .config   = &g_usart4config,
+  .config             = &g_usart4config,
+#ifdef CONFIG_USART4_RS485MODE
+  .rs485_dir_gpio     = GPIO_USART4_RS485_DIR,
+#  if (CONFIG_USART4_RS485_DIR_POLARITY == 0)
+  .rs485_dir_polarity = false,
+#  else
+  .rs485_dir_polarity = true,
+#  endif
+#endif
 };
 
 static uart_dev_t g_usart4port =
@@ -444,7 +489,15 @@ static uart_dev_t g_usart4port =
 #ifdef SAMD2L2_HAVE_USART5
 static struct sam_dev_s g_usart5priv =
 {
-  .config   = &g_usart5config,
+  .config             = &g_usart5config,
+#ifdef CONFIG_USART5_RS485MODE
+  .rs485_dir_gpio     = GPIO_USART5_RS485_DIR,
+#  if (CONFIG_USART5_RS485_DIR_POLARITY == 0)
+  .rs485_dir_polarity = false,
+#  else
+  .rs485_dir_polarity = true,
+#  endif
+#endif
 };
 
 static uart_dev_t g_usart5port =
@@ -546,7 +599,21 @@ static int sam_interrupt(int irq, void *context, FAR void *arg)
 
   intflag = sam_serialin8(priv, SAM_USART_INTFLAG_OFFSET);
   inten   = sam_serialin8(priv, SAM_USART_INTENCLR_OFFSET);
-  pending  = intflag & inten;
+  pending = intflag & inten;
+
+#ifdef HAVE_RS485
+  /* Transmission of whole buffer is over - TXC is set.
+   * Note - this should be first, to have the most recent TC bit value from
+   * SR register - sending data affects TXC, but without refresh we will not
+   * know that...
+   */
+
+  if ((pending & USART_INT_TXC) != 0)
+    {
+      sam_portwrite(priv->rs485_dir_gpio, !priv->rs485_dir_polarity);
+      sam_serialout8(priv, SAM_USART_INTENCLR_OFFSET, USART_INT_TXC);
+    }
+#endif
 
   /* Handle an incoming, receive byte.  The RXC flag is set when there is
    * unread data in DATA register.  This flag is cleared by reading the DATA
@@ -602,6 +669,14 @@ static int sam_setup(struct uart_dev_s *dev)
     }
 #endif
 
+#ifdef HAVE_RS485
+  if (priv->rs485_dir_gpio != 0)
+    {
+      (void)sam_configport(priv->rs485_dir_gpio);
+      sam_portwrite(priv->rs485_dir_gpio, !priv->rs485_dir_polarity);
+    }
+#endif
+
   return ret;
 }
 
@@ -831,7 +906,7 @@ static void sam_txint(struct uart_dev_s *dev, bool enable)
        */
 
 #ifndef CONFIG_SUPPRESS_SERIAL_INTS
-      sam_serialout8(priv, SAM_USART_INTENSET_OFFSET, USART_INT_DRE);
+      sam_serialout8(priv, SAM_USART_INTENSET_OFFSET, USART_TX_INTS);
 
       /* Fake a TX interrupt here by just calling uart_xmitchars() with
        * interrupts disabled (note this may recurse).
@@ -843,7 +918,7 @@ static void sam_txint(struct uart_dev_s *dev, bool enable)
     }
   else
     {
-      /* Disable the TX interrupt */
+      /* Disable the TX interrupt. Only disable DRE, TXC will disable itself! */
 
       sam_serialout8(priv, SAM_USART_INTENCLR_OFFSET, USART_INT_DRE);
     }

arch/arm/src/samd2l2/sam_usart.h

@@ -79,6 +79,20 @@
 #  undef  g_consoleconfig
 #endif
 
+/* Is RS-485 used? */
+
+#if defined(CONFIG_USART0_RS485MODE) || defined(CONFIG_USART1_RS485MODE) || \
+    defined(CONFIG_USART2_RS485MODE) || defined(CONFIG_USART3_RS485MODE) || \
+    defined(CONFIG_USART4_RS485MODE) || defined(CONFIG_USART5_RS485MODE)
+#  define HAVE_RS485 1
+#endif
+
+#ifdef HAVE_RS485
+#  define USART_TX_INTS    (USART_INT_DRE | USART_INT_TXC)
+#else
+#  define USART_TX_INTS    (USART_INT_DRE)
+#endif
+
 /************************************************************************************
  * Public Types
  ************************************************************************************/