/**************************************************************************
* arch/arm/src/lm3s/lm3s_lowputc.c
*
* Copyright (C) 2009-2010 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 "chip.h"
#include "up_arch.h"
#include "up_internal.h"
#include "lm3s_internal.h"
/**************************************************************************
* Pre-processor Definitions
**************************************************************************/
/* Configuration **********************************************************/
#if LM3S_NUARTS < 2
# undef CONFIG_UART1_DISABLE
# undef CONFIG_UART1_SERIAL_CONSOLE
# define CONFIG_UART1_DISABLE 1
#endif
#if LM3S_NUARTS < 3
# undef CONFIG_UART2_DISABLE
# undef CONFIG_UART2_SERIAL_CONSOLE
# define CONFIG_UART2_DISABLE 1
#endif
/* Is there a serial console? */
#if defined(CONFIG_UART0_SERIAL_CONSOLE) && !defined(CONFIG_UART0_DISABLE)
# undef CONFIG_UART1_SERIAL_CONSOLE
# undef CONFIG_UART2_SERIAL_CONSOLE
# define HAVE_CONSOLE 1
#elif defined(CONFIG_UART1_SERIAL_CONSOLE) && !defined(CONFIG_UART1_DISABLE)
# undef CONFIG_UART0_SERIAL_CONSOLE
# undef CONFIG_UART2_SERIAL_CONSOLE
# define HAVE_CONSOLE 1
#elif defined(CONFIG_UART2_SERIAL_CONSOLE) && !defined(CONFIG_UART2_DISABLE)
# undef CONFIG_UART0_SERIAL_CONSOLE
# undef CONFIG_UART1_SERIAL_CONSOLE
# define HAVE_CONSOLE 1
#else
# warning "No valid CONFIG_UARTn_SERIAL_CONSOLE Setting"
# undef CONFIG_UART0_SERIAL_CONSOLE
# undef CONFIG_UART1_SERIAL_CONSOLE
# undef CONFIG_UART2_SERIAL_CONSOLE
# undef HAVE_CONSOLE
#endif
/* Select UART parameters for the selected console */
#if defined(CONFIG_UART0_SERIAL_CONSOLE)
# define LM3S_CONSOLE_BASE LM3S_UART0_BASE
# define LM3S_CONSOLE_BAUD CONFIG_UART0_BAUD
# define LM3S_CONSOLE_BITS CONFIG_UART0_BITS
# define LM3S_CONSOLE_PARITY CONFIG_UART0_PARITY
# define LM3S_CONSOLE_2STOP CONFIG_UART0_2STOP
#elif defined(CONFIG_UART1_SERIAL_CONSOLE)
# define LM3S_CONSOLE_BASE LM3S_UART1_BASE
# define LM3S_CONSOLE_BAUD CONFIG_UART1_BAUD
# define LM3S_CONSOLE_BITS CONFIG_UART1_BITS
# define LM3S_CONSOLE_PARITY CONFIG_UART1_PARITY
# define LM3S_CONSOLE_2STOP CONFIG_UART1_2STOP
#elif defined(CONFIG_UART2_SERIAL_CONSOLE)
# define LM3S_CONSOLE_BASE LM3S_UART2_BASE
# define LM3S_CONSOLE_BAUD CONFIG_UART2_BAUD
# define LM3S_CONSOLE_BITS CONFIG_UART2_BITS
# define LM3S_CONSOLE_PARITY CONFIG_UART2_PARITY
# define LM3S_CONSOLE_2STOP CONFIG_UART2_2STOP
#else
# error "No CONFIG_UARTn_SERIAL_CONSOLE Setting"
#endif
/* Get LCRH settings */
#if LM3S_CONSOLE_BITS == 5
# define UART_LCRH_NBITS UART_LCRH_WLEN_5BITS
#elif LM3S_CONSOLE_BITS == 6
# define UART_LCRH_NBITS UART_LCRH_WLEN_6BITS
#elif LM3S_CONSOLE_BITS == 7
# define UART_LCRH_NBITS UART_LCRH_WLEN_7BITS
#elif LM3S_CONSOLE_BITS == 8
# define UART_LCRH_NBITS UART_LCRH_WLEN_8BITS
#else
# error "Number of bits not supported"
#endif
#if LM3S_CONSOLE_PARITY == 0
# define UART_LCRH_PARITY (0)
#elif LM3S_CONSOLE_PARITY == 1
# define UART_LCRH_PARITY UART_LCRH_PEN
#elif LM3S_CONSOLE_PARITY == 2
# define UART_LCRH_PARITY (UART_LCRH_PEN|UART_LCRH_EPS)
#else
# error "Invalid parity selection"
#endif
#if LM3S_CONSOLE_2STOP != 0
# define UART_LCRH_NSTOP UART_LCRH_STP2
#else
# define UART_LCRH_NSTOP (0)
#endif
#define UART_LCRH_VALUE (UART_LCRH_NBITS|UART_LCRH_PARITY|UART_LCRH_NSTOP|UART_LCRH_FEN)
/* Calculate BAUD rate from the SYS clock:
*
* "The baud-rate divisor is a 22-bit number consisting of a 16-bit integer and a 6-bit
* fractional part. The number formed by these two values is used by the baud-rate generator
* to determine the bit period. Having a fractional baud-rate divider allows the UART to
* generate all the standard baud rates.
*
* "The 16-bit integer is loaded through the UART Integer Baud-Rate Divisor (UARTIBRD)
* register ... and the 6-bit fractional part is loaded with the UART Fractional Baud-Rate
* Divisor (UARTFBRD) register... The baud-rate divisor (BRD) has the following relationship
* to the system clock (where BRDI is the integer part of the BRD and BRDF is the fractional
* part, separated by a decimal place.):
*
* "BRD = BRDI + BRDF = UARTSysClk / (16 * Baud Rate)
*
* "where UARTSysClk is the system clock connected to the UART. The 6-bit fractional number
* (that is to be loaded into the DIVFRAC bit field in the UARTFBRD register) can be calculated
* by taking the fractional part of the baud-rate divisor, multiplying it by 64, and adding 0.5
* to account for rounding errors:
*
* "UARTFBRD[DIVFRAC] = integer(BRDF * 64 + 0.5)
*
* "The UART generates an internal baud-rate reference clock at 16x the baud-rate (referred
* to as Baud16). This reference clock is divided by 16 to generate the transmit clock, and is
* used for error detection during receive operations.
*
* "Along with the UART Line Control, High Byte (UARTLCRH) register ..., the UARTIBRD and
* UARTFBRD registers form an internal 30-bit register. This internal register is only
* updated when a write operation to UARTLCRH is performed, so any changes to the baud-rate
* divisor must be followed by a write to the UARTLCRH register for the changes to take effect. ..."
*/
#define LM3S_BRDDEN (16 * LM3S_CONSOLE_BAUD)
#define LM3S_BRDI (SYSCLK_FREQUENCY / LM3S_BRDDEN)
#define LM3S_REMAINDER (SYSCLK_FREQUENCY - LM3S_BRDDEN * LM3S_BRDI)
#define LM3S_DIVFRAC ((LM3S_REMAINDER * 64 + (LM3S_BRDDEN/2)) / LM3S_BRDDEN)
/* For example: LM3S_CONSOLE_BAUD = 115,200, SYSCLK_FREQUENCY = 50,000,000:
*
* LM3S_BRDDEN = (16 * 115,200) = 1,843,200
* LM3S_BRDI = 50,000,000 / 1,843,200 = 27
* LM3S_REMAINDER = 50,000,000 - 1,843,200 * 27 = 233,600
* LM3S_DIVFRAC = (233,600 * 64 + 921,600) / 1,843,200 = 8
*
* Which should yied BAUD = 50,000,000 / (16 * (27 + 8/64)) = 115207.37
*/
/**************************************************************************
* 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 FIFO is not full */
while ((getreg32(LM3S_CONSOLE_BASE+LM3S_UART_FR_OFFSET) & UART_FR_TXFF) != 0);
/* Then send the character */
putreg32((uint32_t)ch, LM3S_CONSOLE_BASE+LM3S_UART_DR_OFFSET);
#endif
}
/**************************************************************************
* Name: up_lowsetup
*
* Description:
* This performs basic initialization of the UART used for the serial
* console. Its purpose is to get the console output availabe as soon
* as possible.
*
**************************************************************************/
void up_lowsetup(void)
{
uint32_t regval;
#if defined(HAVE_CONSOLE) && !defined(CONFIG_SUPPRESS_UART_CONFIG)
uint32_t ctl;
#endif
/* Enable the selected UARTs and configure GPIO pins to need by the
* the selected UARTs. NOTE: The serial driver later depends on
* this pin configuration -- whether or not a serial console is selected.
*/
#ifndef CONFIG_UART0_DISABLE
regval = getreg32(LM3S_SYSCON_RCGC1);
regval |= SYSCON_RCGC1_UART0;
putreg32(regval, LM3S_SYSCON_RCGC1);
lm3s_configgpio(GPIO_UART0_RX);
lm3s_configgpio(GPIO_UART0_TX);
#endif
#ifndef CONFIG_UART1_DISABLE
regval = getreg32(LM3S_SYSCON_RCGC1);
regval |= SYSCON_RCGC1_UART1;
putreg32(regval, LM3S_SYSCON_RCGC1);
lm3s_configgpio(GPIO_UART1_RX);
lm3s_configgpio(GPIO_UART1_TX);
#endif
/* Enable the selected console device */
#if defined(HAVE_CONSOLE) && !defined(CONFIG_SUPPRESS_UART_CONFIG)
/* Disable the UART by clearing the UARTEN bit in the UART CTL register */
ctl = getreg32(LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET);
ctl &= ~UART_CTL_UARTEN;
putreg32(ctl, LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET);
/* Write the integer portion of the BRD to the UART IBRD register */
putreg32(LM3S_BRDI, LM3S_CONSOLE_BASE+LM3S_UART_IBRD_OFFSET);
/* Write the fractional portion of the BRD to the UART FBRD register */
putreg32(LM3S_DIVFRAC, LM3S_CONSOLE_BASE+LM3S_UART_FBRD_OFFSET);
/* Write the desired serial parameters to the UART LCRH register */
putreg32(UART_LCRH_VALUE, LM3S_CONSOLE_BASE+LM3S_UART_LCRH_OFFSET);
/* Enable the UART by setting the UARTEN bit in the UART CTL register */
ctl |= (UART_CTL_UARTEN|UART_CTL_TXE|UART_CTL_RXE);
putreg32(ctl, LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET);
#endif
}
