add synchronous UART transmission and use it in exceptions

The default ISR (particularly the HardFault handler) print information,
but this information was not displayed on the console because the UART
IRQ is lower than some default blocking IRQ.
Allowing to set synchronous transfer corrects this.

The underlying Atmel exception library had to be modified to use the
synchronous output.

Making UART_PutChar always synchronous when called from an ISR is not
desired because we use TRACE_ macros is some ISR. The synchronous
output must be set explicitly.

Change-Id: I1b4ace5185cf2dc32684934ed12bf6a8682e9bad

firmware/atmel_softpack_libraries/libchip_sam3s/source/exceptions.c

@@ -2,6 +2,7 @@
  *         ATMEL Microcontroller Software Support
  * ----------------------------------------------------------------------------
  * Copyright (c) 2009, Atmel Corporation
+ * Copyright (c) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
  *
  * All rights reserved.
  *
@@ -41,6 +42,7 @@
  *        Headers
  *----------------------------------------------------------------------------*/
 
+#define printf printf_sync
 #include "chip.h"
 
 /*----------------------------------------------------------------------------

firmware/libboard/common/include/uart_console.h

@@ -29,16 +29,15 @@
  */
 #ifndef _UART_CONSOLE_
 #define _UART_CONSOLE_
-
 #include <stdint.h>
 
 extern void UART_Configure( uint32_t dwBaudrate, uint32_t dwMasterClock ) ;
-extern void UART_Exit(void) ;
+extern void UART_Exit( void ) ;
 extern void UART_PutChar( uint8_t uc ) ;
+extern void UART_PutChar_Sync( uint8_t uc ) ;
 extern uint32_t UART_GetChar( void ) ;
 extern uint32_t UART_IsRxReady( void ) ;
 
-
 extern void UART_DumpFrame( uint8_t* pucFrame, uint32_t dwSize ) ;
 extern void UART_DumpMemory( uint8_t* pucBuffer, uint32_t dwSize, uint32_t dwAddress ) ;
 extern uint32_t UART_GetInteger( uint32_t* pdwValue ) ;

firmware/libboard/common/source/uart_console.c

@@ -2,6 +2,7 @@
  *         ATMEL Microcontroller Software Support
  * ----------------------------------------------------------------------------
  * Copyright (c) 2009, Atmel Corporation
+ * Copyright (c) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
  *
  * All rights reserved.
  *
@@ -135,10 +136,10 @@ void CONSOLE_ISR(void)
 /**
  * \brief Outputs a character on the UART line.
  *
- * \note This function is synchronous (i.e. uses polling).
+ * \note This function is asynchronous (i.e. uses a buffer and interrupt to complete the transfer).
  * \param c  Character to send.
  */
-extern void UART_PutChar( uint8_t c )
+void UART_PutChar( uint8_t uc )
 {
 	Uart *pUart = CONSOLE_UART ;
 
@@ -148,9 +149,8 @@ extern void UART_PutChar( uint8_t c )
 		UART_Configure(CONSOLE_BAUDRATE, BOARD_MCK);
 	}
 
-	/* Only store input if buffer is not full, else drop it */
 	if (!rbuf_is_full(&uart_tx_buffer)) {
-		rbuf_write(&uart_tx_buffer, c);
+		rbuf_write(&uart_tx_buffer, uc);
 		if (!(pUart->UART_IMR & UART_IMR_TXRDY)) {
 			pUart->UART_IER = UART_IER_TXRDY;
 			CONSOLE_ISR();
@@ -158,6 +158,28 @@ extern void UART_PutChar( uint8_t c )
 	}
 }
 
+/**
+ * \brief Outputs a character on the UART line.
+ *
+ * \note This function is synchronous (i.e. uses polling and blocks until the transfer is complete).
+ * \param c  Character to send.
+ */
+void UART_PutChar_Sync( uint8_t uc )
+{
+	Uart *pUart = CONSOLE_UART ;
+
+	/* Initialize console is not already done */
+	if ( !_ucIsConsoleInitialized )
+	{
+		UART_Configure(CONSOLE_BAUDRATE, BOARD_MCK);
+	}
+
+	while (!(pUart->UART_SR & UART_SR_TXRDY)); /* Wait for transfer buffer to be empty */
+	pUart->UART_THR = uc; /* Send data to UART peripheral */
+	while (!(pUart->UART_SR & UART_SR_TXRDY)); /* Wait for transfer buffer to transferred to shift register */
+	while (!(pUart->UART_SR & UART_SR_TXEMPTY)); /* Wait for transfer shift register to be empty (i.e. transfer is complete) */
+}
+
 /**
  * \brief Input a character from the UART line.
  *

firmware/libcommon/include/stdio.h

@@ -52,9 +52,14 @@ signed int printf(const char *pFormat, ...);
 signed int sprintf(char *pStr, const char *pFormat, ...);
 signed int puts(const char *pStr);
 
-
 int fputc(int c, FILE *stream);
 int fputs(const char *s, FILE *stream);
 
 #define putc(c, stream) fputc(c, stream)
 #define putchar(c) fputc(c, stdout)
+
+signed int vfprintf_sync(FILE *pStream, const char *pFormat, va_list ap);
+signed int vprintf_sync(const char *pFormat, va_list ap);
+signed int printf_sync(const char *pFormat, ...);
+int fputc_sync(int c, FILE *stream);
+int fputs_sync(const char *s, FILE *stream);

firmware/libcommon/source/fputs.c

@@ -26,6 +26,19 @@ int fputc(int c, FILE *stream)
 int fputs(const char *s, FILE *stream)
 {
 	while (*s != '\0')
-		UART_PutChar(*s++);
+		fputc(*s++, stream);
+	return 0;
+}
+
+int fputc_sync(int c, FILE *stream)
+{
+	UART_PutChar_Sync(c);
+	return c;
+}
+
+int fputs_sync(const char *s, FILE *stream)
+{
+	while (*s != '\0')
+		fputc_sync(*s++, stream);
 	return 0;
 }

firmware/libcommon/source/stdio.c

@@ -2,6 +2,7 @@
  *         ATMEL Microcontroller Software Support 
  * ----------------------------------------------------------------------------
  * Copyright (c) 2008, Atmel Corporation
+ * Copyright (c) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
  *
  * All rights reserved.
  *
@@ -435,6 +436,32 @@ signed int vfprintf(FILE *pStream, const char *pFormat, va_list ap)
 	return fputs(pStr, pStream);
 }
 
+//------------------------------------------------------------------------------
+/// Outputs a formatted string on the given stream. Format arguments are given
+/// in a va_list instance.
+/// \note This function is synchronous (i.e. blocks until the print completes)
+/// \param pStream  Output stream.
+/// \param pFormat  Format string
+/// \param ap  Argument list.
+//------------------------------------------------------------------------------
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
+signed int vfprintf_sync(FILE *pStream, const char *pFormat, va_list ap)
+{
+	char pStr[MAX_STRING_SIZE];
+	char pError[] = "stdio.c: increase MAX_STRING_SIZE\n\r";
+
+	// Write formatted string in buffer
+	if (vsprintf(pStr, pFormat, ap) >= MAX_STRING_SIZE) {
+
+		fputs_sync(pError, stderr);
+	}
+
+	// Display string
+	return fputs_sync(pStr, pStream);
+}
+#pragma GCC diagnostic pop
+
 //------------------------------------------------------------------------------
 /// Outputs a formatted string on the DBGU stream. Format arguments are given
 /// in a va_list instance.
@@ -446,6 +473,18 @@ signed int vprintf(const char *pFormat, va_list ap)
 	return vfprintf(stdout, pFormat, ap);
 }
 
+//------------------------------------------------------------------------------
+/// Outputs a formatted string on the DBGU stream. Format arguments are given
+/// in a va_list instance.
+/// \note This function is synchronous (i.e. blocks until the print completes)
+/// \param pFormat  Format string
+/// \param ap  Argument list.
+//------------------------------------------------------------------------------
+signed int vprintf_sync(const char *pFormat, va_list ap)
+{
+	return vfprintf_sync(stdout, pFormat, ap);
+}
+
 //------------------------------------------------------------------------------
 /// Outputs a formatted string on the given stream, using a variable number of
 /// arguments.
@@ -483,6 +522,25 @@ signed int printf(const char *pFormat, ...)
 	return result;
 }
 
+//------------------------------------------------------------------------------
+/// Outputs a formatted string on the DBGU stream, using a variable number of
+/// arguments.
+/// \note This function is synchronous (i.e. blocks until the print completes)
+/// \param pFormat  Format string.
+//------------------------------------------------------------------------------
+signed int printf_sync(const char *pFormat, ...)
+{
+	va_list ap;
+	signed int result;
+
+	// Forward call to vprintf
+	va_start(ap, pFormat);
+	result = vprintf_sync(pFormat, ap);
+	va_end(ap);
+
+	return result;
+}
+
 //------------------------------------------------------------------------------
 /// Writes a formatted string inside another string.
 /// \param pStr  Storage string.