nuttx/arch/arm/src/stm32/stm32_lowputc.c

/**************************************************************************
 * arch/arm/src/stm32/stm32_lowputc.c
 *
 *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 **************************************************************************/

/**************************************************************************
 * Included Files
 **************************************************************************/

#include <nuttx/config.h>

#include <stdint.h>

#include <arch/board/board.h>

#include "up_internal.h"
#include "up_arch.h"

#include "chip.h"
#include "stm32_rcc.h"
#include "stm32_gpio.h"
#include "stm32_uart.h"
#include "stm32_internal.h"

/**************************************************************************
 * Private Definitions
 **************************************************************************/

/* Configuration **********************************************************/

/* Is there a serial console? */

#if defined(CONFIG_USART1_SERIAL_CONSOLE) && defined(CONFIG_STM32_USART1)
#  undef CONFIG_USART2_SERIAL_CONSOLE
#  undef CONFIG_USART3_SERIAL_CONSOLE
#  define HAVE_CONSOLE 1
#elif defined(CONFIG_USART2_SERIAL_CONSOLE) && defined(CONFIG_STM32_USART2)
#  undef CONFIG_USART1_SERIAL_CONSOLE
#  undef CONFIG_USART3_SERIAL_CONSOLE
#  define HAVE_CONSOLE 1
#elif defined(CONFIG_USART3_SERIAL_CONSOLE) && defined(CONFIG_STM32_USART3)
#  undef CONFIG_USART1_SERIAL_CONSOLE
#  undef CONFIG_USART2_SERIAL_CONSOLE
#  define HAVE_CONSOLE 1
#else
#  undef CONFIG_USART1_SERIAL_CONSOLE
#  undef CONFIG_USART2_SERIAL_CONSOLE
#  undef CONFIG_USART3_SERIAL_CONSOLE
#  undef HAVE_CONSOLE
#endif

/* Select USART parameters for the selected console */

#if defined(CONFIG_USART1_SERIAL_CONSOLE)
#  define STM32_CONSOLE_BASE     STM32_USART1_BASE
#  define STM32_APBCLOCK         STM32_PCLK2_FREQUENCY
#  define STM32_CONSOLE_BAUD     CONFIG_USART1_BAUD
#  define STM32_CONSOLE_BITS     CONFIG_USART1_BITS
#  define STM32_CONSOLE_PARITY   CONFIG_USART1_PARITY
#  define STM32_CONSOLE_2STOP    CONFIG_USART1_2STOP
#elif defined(CONFIG_USART2_SERIAL_CONSOLE)
#  define STM32_CONSOLE_BASE     STM32_USART2_BASE
#  define STM32_APBCLOCK         STM32_PCLK1_FREQUENCY
#  define STM32_CONSOLE_BAUD     CONFIG_USART2_BAUD
#  define STM32_CONSOLE_BITS     CONFIG_USART2_BITS
#  define STM32_CONSOLE_PARITY   CONFIG_USART2_PARITY
#  define STM32_CONSOLE_2STOP    CONFIG_USART2_2STOP
#elif defined(CONFIG_USART3_SERIAL_CONSOLE)
#  define STM32_CONSOLE_BASE     STM32_USART3_BASE
#  define STM32_APBCLOCK         STM32_PCLK1_FREQUENCY
#  define STM32_CONSOLE_BAUD     CONFIG_USART3_BAUD
#  define STM32_CONSOLE_BITS     CONFIG_USART3_BITS
#  define STM32_CONSOLE_PARITY   CONFIG_USART3_PARITY
#  define STM32_CONSOLE_2STOP    CONFIG_USART3_2STOP
#else
#  error "No CONFIG_USARTn_SERIAL_CONSOLE Setting"
#endif

/* CR1 settings */

#if STM32_CONSOLE_BITS == 9
#  define USART_CR1_M_VALUE USART_CR1_M
#else
#  define USART_CR1_M_VALUE 0
#endif

#if STM32_CONSOLE_PARITY == 1
#  define USART_CR1_PARITY_VALUE (USART_CR1_PCE|USART_CR1_PS)
#elif STM32_CONSOLE_PARITY == 2
#  define USART_CR1_PARITY_VALUE USART_CR1_PCE
#else
#  define USART_CR1_PARITY_VALUE 0
#endif

#define USART_CR1_CLRBITS (USART_CR1_M|USART_CR1_PCE|USART_CR1_PS|USART_CR1_TE|USART_CR1_RE|USART_CR1_ALLINTS)
#define USART_CR1_SETBITS (USART_CR1_M_VALUE|USART_CR1_PARITY_VALUE)

/* CR2 settings */

#if STM32_CONSOLE_2STOP != 0
#  define USART_CR2_STOP2_VALUE USART_CR2_STOP2
#else
#  define USART_CR2_STOP2_VALUE 0
#endif

#define USART_CR2_CLRBITS (USART_CR2_STOP_MASK|USART_CR2_CLKEN|USART_CR2_CPOL|USART_CR2_CPHA|USART_CR2_LBCL|USART_CR2_LBDIE)
#define USART_CR2_SETBITS USART_CR2_STOP2_VALUE

/* CR3 settings */

#define USART_CR3_CLRBITS (USART_CR3_CTSIE|USART_CR3_CTSE|USART_CR3_RTSE|USART_CR3_EIE)
#define USART_CR3_SETBITS 0

/* Calculate USART BAUD rate divider
 *
 * The baud rate for the receiver and transmitter (Rx and Tx) are both set to
 * the same value as programmed in the Mantissa and Fraction values of USARTDIV.
 *
 *   baud     = fCK / (16 * usartdiv)
 *   usartdiv = fCK / (16 * baud)
 *
 * Where fCK is the input clock to the peripheral (PCLK1 for USART2, 3, 4, 5
 * or PCLK2 for USART1).  Example, fCK=72MHz baud=115200, usartdiv=39.0625=39 1/16th;
 *
 * First calculate:
 *
 *   usartdiv32 = 32 * usartdiv = fCK / (baud/2)
 *
 * (NOTE: all standard baud values are even so dividing by two does not
 * lose precision).  Eg. (same fCK and buad), usartdiv32 = 1250
 */

#define STM32_USARTDIV32 (STM32_APBCLOCK / (STM32_CONSOLE_BAUD >> 1))

/* The mantissa is then usartdiv32 * 32:
 *
 *   mantissa = 32 * usartdiv32
 *
 * Eg. usartdiv32=1250, mantissa = 39 
 */

#define STM32_MANTISSA   (STM32_USARTDIV32 >> 5)

/* And the fraction:
 *
 *  fraction = (usartdiv32 - mantissa*32 + 1) / 2
 *
 * Eg., (1,250 - 39*32 + 1)/2 = 1 (or 0.0625)
 */
 
#define STM32_FRACTION   ((STM32_USARTDIV32 - (STM32_MANTISSA << 5) + 1) >> 1)

/* And, finally, the BRR value is: */

#define STM32_BRR_VALUE  ((STM32_MANTISSA << USART_BRR_MANT_SHIFT) | (STM32_FRACTION << USART_BRR_FRAC_SHIFT))

/**************************************************************************
 * Private Types
 **************************************************************************/

/**************************************************************************
 * Private Function Prototypes
 **************************************************************************/

/**************************************************************************
 * Global Variables
 **************************************************************************/

/**************************************************************************
 * Private Variables
 **************************************************************************/

/**************************************************************************
 * Private Functions
 **************************************************************************/

/**************************************************************************
 * Public Functions
 **************************************************************************/

/**************************************************************************
 * Name: up_lowputc
 *
 * Description:
 *   Output one byte on the serial console
 *
 **************************************************************************/

void up_lowputc(char ch)
{
#ifdef HAVE_CONSOLE
  /* Wait until the TX data register is empty */

  while ((getreg32(STM32_CONSOLE_BASE + STM32_USART_SR_OFFSET) & USART_SR_TXE) == 0);

  /* Then send the character */

  putreg32((uint32_t)ch, STM32_CONSOLE_BASE + STM32_USART_DR_OFFSET);
#endif
}

/**************************************************************************
 * Name: stm32_lowsetup
 *
 * Description:
 *   This performs basic initialization of the USART used for the serial
 *   console.  Its purpose is to get the console output availabe as soon
 *   as possible.
 *
 **************************************************************************/

void stm32_lowsetup(void)
{
#if defined(CONFIG_STM32_USART1) || defined(CONFIG_STM32_USART2) || defined(CONFIG_STM32_USART3)
  uint32_t mapr;
#if defined(HAVE_CONSOLE) && !defined(CONFIG_SUPPRESS_USART_CONFIG)
  uint32_t cr;
#endif

  /* Enable the selected USARTs and configure GPIO pins need byed the
   * the selected USARTs.  NOTE: The serial driver later depends on
   * this pin configuration -- whether or not a serial console is selected.
   *
   * NOTE: Clocking for USART1, USART2, and/or USART3 was already provided in stm32_rcc.c
   */

  mapr = getreg32(STM32_AFIO_MAPR);

#ifdef CONFIG_STM32_USART1
  /* Assume default pin mapping:
   *
   *   Alternate  USART1_REMAP USART1_REMAP
   *   Function   = 0          = 1
   *   ---------- ------------ ------------
   *   USART1_TX  PA9          PB6
   *   USART1_RX  PA10         PB7
   */

#ifdef CONFIG_STM32_USART1_REMAP
  mapr |= AFIO_MAPR_USART1_REMAP;
#else
  mapr &= ~AFIO_MAPR_USART1_REMAP;
#endif
  putreg32(mapr, STM32_AFIO_MAPR);

  stm32_configgpio(GPIO_USART1_TX);
  stm32_configgpio(GPIO_USART1_RX);
#endif /* CONFIG_STM32_USART1 */

#ifdef CONFIG_STM32_USART2
  /* Assume default pin mapping:
   *
   *   Alternate  USART2_REMAP USART2_REMAP
   *   Function   = 0          = 1
   *   ---------- ------------ ------------
   *   USART2_CTS PA0          PD3
   *   USART2_RTS PA1          PD4
   *   USART2_TX  PA2          PD5
   *   USART2_RX  PA3          PD6
   *   USART3_CK  PA4          PD7
   */

#ifdef CONFIG_STM32_USART2_REMAP
  mapr |= ~AFIO_MAPR_USART2_REMAP;
#else
  mapr &= ~AFIO_MAPR_USART2_REMAP;
#endif
  putreg32(mapr, STM32_AFIO_MAPR);

  stm32_configgpio(GPIO_USART2_TX);
  stm32_configgpio(GPIO_USART2_RX);
  stm32_configgpio(GPIO_USART2_CTS);
  stm32_configgpio(GPIO_USART2_RTS);
#endif /* CONFIG_STM32_USART2 */

#ifdef CONFIG_STM32_USART3
  /* Assume default pin mapping:
   *
   * Alternate  USART3_REMAP[1:0]  USART3_REMAP[1:0]      USART3_REMAP[1:0]
   * Function   = “00” (no remap)  = “01” (partial remap) = “11” (full remap)
   * ---------_ ------------------ ---------------------- --------------------
   * USART3_TX  PB10               PC10                   PD8
   * USART3_RX  PB11               PC11                   PD9
   * USART3_CK  PB12               PC12                   PD10
   * USART3_CTS PB13               PB13                   PD11
   * USART3_RTS PB14               PB14                   PD12
   */

  mapr &= ~AFIO_MAPR_USART3_REMAP_MASK;
#if defined(CONFIG_STM32_USART3_PARTIAL_REMAP)
  mapr |= AFIO_MAPR_USART3_PARTREMAP;
#elif defined(CONFIG_STM32_USART3_FULL_REMAP)
  mapr |= AFIO_MAPR_USART3_FULLREMAP;
#endif
  putreg32(mapr, STM32_AFIO_MAPR);

  stm32_configgpio(GPIO_USART3_TX);
  stm32_configgpio(GPIO_USART3_RX);
  stm32_configgpio(GPIO_USART3_CTS);
  stm32_configgpio(GPIO_USART3_RTS);
#endif /* CONFIG_STM32_USART3 */

  /* Enable and configure the selected console device */

#if defined(HAVE_CONSOLE) && !defined(CONFIG_SUPPRESS_USART_CONFIG)
  /* Configure CR2 */

  cr  = getreg32(STM32_CONSOLE_BASE + STM32_USART_CR2_OFFSET);
  cr &= ~USART_CR2_CLRBITS;
  cr |= USART_CR2_SETBITS;
  putreg32(cr, STM32_CONSOLE_BASE + STM32_USART_CR2_OFFSET);

  /* Configure CR1 */

  cr  = getreg32(STM32_CONSOLE_BASE + STM32_USART_CR1_OFFSET);
  cr &= ~USART_CR1_CLRBITS;
  cr |= USART_CR1_SETBITS;
  putreg32(cr, STM32_CONSOLE_BASE + STM32_USART_CR1_OFFSET);

  /* Configure CR3 */

  cr  = getreg32(STM32_CONSOLE_BASE + STM32_USART_CR3_OFFSET);
  cr &= ~USART_CR3_CLRBITS;
  cr |= USART_CR3_SETBITS;
  putreg32(cr, STM32_CONSOLE_BASE + STM32_USART_CR3_OFFSET);

  /* Configure the USART Baud Rate */

  putreg32(STM32_BRR_VALUE, STM32_CONSOLE_BASE + STM32_USART_BRR_OFFSET);

  /* Enable Rx, Tx, and the USART */

  cr  = getreg32(STM32_CONSOLE_BASE + STM32_USART_CR1_OFFSET);
  cr |= (USART_CR1_UE|USART_CR1_TE|USART_CR1_RE);
  putreg32(cr, STM32_CONSOLE_BASE + STM32_USART_CR1_OFFSET);
#endif
#endif /* CONFIG_STM32_USART1 || CONFIG_STM32_USART2 || CONFIG_STM32_USART3 */
}