266 lines
9.8 KiB
C
266 lines
9.8 KiB
C
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/**************************************************************************
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* arch/arm/src/lm3s/lm3s_lowputc.c
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*
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* Copyright (C) 2009 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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**************************************************************************/
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/**************************************************************************
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* Included Files
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**************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include "up_internal.h"
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#include "up_arch.h"
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#include "chip.h"
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/**************************************************************************
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* Private Definitions
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**************************************************************************/
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/* Configuration **********************************************************/
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/* Is there a serial console? */
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#if defined(CONFIG_UART0_SERIAL_CONSOLE) && !defined(CONFIG_UART0_DISABLE)
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# undef CONFIG_UART1_SERIAL_CONSOLE
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# define HAVE_CONSOLE 1
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#elif defined(CONFIG_UART1_SERIAL_CONSOLE) && !defined(CONFIG_UART1_DISABLE)
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# undef CONFIG_UART0_SERIAL_CONSOLE
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# define HAVE_CONSOLE 1
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#else
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# undef CONFIG_UART0_SERIAL_CONSOLE
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# undef CONFIG_UART1_SERIAL_CONSOLE
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# undef HAVE_CONSOLE
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#endif
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/* Select UART parameters for the selected console */
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#if defined(CONFIG_UART0_SERIAL_CONSOLE)
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# define LM3S_CONSOLE_BASE LM3S_UART0_BASE
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# define LM3S_CONSOLE_BAUD CONFIG_UART0_BAUD
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# define LM3S_CONSOLE_BITS CONFIG_UART0_BITS
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# define LM3S_CONSOLE_PARITY CONFIG_UART0_PARITY
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# define LM3S_CONSOLE_2STOP CONFIG_UART0_2STOP
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#elif defined(CONFIG_UART1_SERIAL_CONSOLE)
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# define LM3S_CONSOLE_BASE LM3S_UART1_BASE
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# define LM3S_CONSOLE_BAUD CONFIG_UART1_BAUD
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# define LM3S_CONSOLE_BITS CONFIG_UART1_BITS
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# define LM3S_CONSOLE_PARITY CONFIG_UART1_PARITY
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# define LM3S_CONSOLE_2STOP CONFIG_UART1_2STOP
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#else
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# error "No CONFIG_UARTn_SERIAL_CONSOLE Setting"
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#endif
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/* Get LCRH settings */
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#if LM3S_CONSOLE_BITS == 5
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# define UART_LCRH_NBITS UART_LCRH_WLEN_5BITS
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#elif LM3S_CONSOLE_BITS == 6
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# define UART_LCRH_NBITS UART_LCRH_WLEN_6BITS
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#elif LM3S_CONSOLE_BITS == 7
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# define UART_LCRH_NBITS UART_LCRH_WLEN_7BITS
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#elif LM3S_CONSOLE_BITS == 8
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# define UART_LCRH_NBITS UART_LCRH_WLEN_8BITS
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#else
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# error "Number of bits not supported"
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#endif
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#if LM3S_CONSOLE_PARITY == 0
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# define UART_LCRH_PARITY (0)
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#elif LM3S_CONSOLE_PARITY == 1
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# define UART_LCRH_PARITY UART_LCRH_PEN
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#elif LM3S_CONSOLE_PARITY == 2
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# define UART_LCRH_PARITY (UART_LCRH_PEN|UART_LCRH_EPS)
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#else
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# error "Invalid parity selection"
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#endif
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#if LM3S_CONSOLE_2STOP != 0
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# define UART_LCRH_NSTOP UART_LCRH_STP2
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#else
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# define UART_LCRH_NSTOP (0)
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#endif
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#define UART_LCRH_VALUE (UART_LCRH_NBITS|UART_LCRH_PARITY|UART_LCRH_NSTOP|UART_LCRH_FEN)
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/* Calculate BAUD rate from PCLK1:
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*
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* "The baud-rate divisor is a 22-bit number consisting of a 16-bit integer and a 6-bit
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* fractional part. The number formed by these two values is used by the baud-rate generator
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* to determine the bit period. Having a fractional baud-rate divider allows the UART to
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* generate all the standard baud rates.
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*
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* "The 16-bit integer is loaded through the UART Integer Baud-Rate Divisor (UARTIBRD)
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* register ... and the 6-bit fractional part is loaded with the UART Fractional Baud-Rate
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* Divisor (UARTFBRD) register... The baud-rate divisor (BRD) has the following relationship
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* to the system clock (where BRDI is the integer part of the BRD and BRDF is the fractional
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* part, separated by a decimal place.):
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*
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* "BRD = BRDI + BRDF = UARTSysClk / (16 * Baud Rate)
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*
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* "where UARTSysClk is the system clock connected to the UART. The 6-bit fractional number
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* (that is to be loaded into the DIVFRAC bit field in the UARTFBRD register) can be calculated
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* by taking the fractional part of the baud-rate divisor, multiplying it by 64, and adding 0.5
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* to account for rounding errors:
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*
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* "UARTFBRD[DIVFRAC] = integer(BRDF * 64 + 0.5)
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*
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* "The UART generates an internal baud-rate reference clock at 16x the baud-rate (referred
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* to as Baud16). This reference clock is divided by 16 to generate the transmit clock, and is
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* used for error detection during receive operations.
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*
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* "Along with the UART Line Control, High Byte (UARTLCRH) register ..., the UARTIBRD and
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* UARTFBRD registers form an internal 30-bit register. This internal register is only
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* updated when a write operation to UARTLCRH is performed, so any changes to the baud-rate
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* divisor must be followed by a write to the UARTLCRH register for the changes to take effect. ..."
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*/
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#define LM3S_BRDDEN (16 * LM3S_CONSOLE_BAUD)
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#define LM3S_BRDI (SYSCLK_FREQUENCY / LM3S_BRDDEN)
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#define LM3S_REMAINDER (SYSCLK_FREQUENCY - LM3S_BRDDEN * LM3S_BRDI)
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#define LM3S_DIVFRAC ((LM3S_REMAINDER * 64 + (LM3S_BRDDEN/2)) / LM3S_BRDDEN)
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/* For example: LM3S_CONSOLE_BAUD = 115,200, SYSCLK_FREQUENCY = 20,000,000:
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*
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* LM3S_BRDDEN = (16 * 115,200) = 1,843,200
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* LM3S_BRDI = 20,000,000 / 1,843,200 = 10
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* LM3S_REMAINDER = 20,000,000 - 1,843,200 * 10 = 1,568,000
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* LM3S_DIVFRAC = (1,568,000 * 64 + 921,600) / 1,843,200 = 54
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*
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* Which should yied BAUD = 20,000,000 / (16 * (10 + 54/64)) = 115273.8
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*/
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/**************************************************************************
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* Private Types
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**************************************************************************/
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/**************************************************************************
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* Private Function Prototypes
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**************************************************************************/
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/**************************************************************************
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* Global Variables
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**************************************************************************/
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/**************************************************************************
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* Private Variables
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**************************************************************************/
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/**************************************************************************
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* Private Functions
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**************************************************************************/
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/**************************************************************************
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* Public Functions
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**************************************************************************/
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/**************************************************************************
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* Name: up_lowputc
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*
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* Description:
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* Output one byte on the serial console
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*
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**************************************************************************/
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void up_lowputc(char ch)
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{
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#ifdef HAVE_CONSOLE
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/* Wait until the TX FIFO is not full */
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while ((getreg32(LM3S_CONSOLE_BASE+LM3S_UART_FR_OFFSET) & UART_FR_TXFF) != 0);
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/* Then send the character */
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putreg32((uint32)ch, LM3S_CONSOLE_BASE+LM3S_UART_DR_OFFSET);
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#endif
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}
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/**************************************************************************
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* Name: up_lowsetup
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*
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* Description:
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* This performs basic initialization of the UART used for the serial
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* console. Its purpose is to get the console output availabe as soon
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* as possible.
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*
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**************************************************************************/
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void up_lowsetup(void)
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{
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#ifdef HAVE_CONSOLE
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uint16 ctl;
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/* Enable the selected console device */
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/* 1. Disable the UART by clearing the UARTEN bit in the UART CTL register */
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ctl = getreg32(LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET);
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ctl &= ~UART_CTL_UARTEN;
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putreg32(ctl, LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET);
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/* 2. Write the integer portion of the BRD to the UART IBRD register */
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putreg32(LM3S_BRDI, LM3S_CONSOLE_BASE+LM3S_UART_IBRD_OFFSET);
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/* 3. Write the fractional portion of the BRD to the UART FBRD register */
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putreg32(LM3S_DIVFRAC, LM3S_CONSOLE_BASE+LM3S_UART_FBRD_OFFSET);
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/* 4. Write the desired serial parameters to the UART LCRH register */
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putreg32(UART_LCRH_VALUE, LM3S_CONSOLE_BASE+LM3S_UART_LCRH_OFFSET);
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/* 5. Enable the UART by setting the UARTEN bit in the UART CTL register */
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ctl |= UART_CTL_UARTEN;
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putreg32(ctl, LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET);
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#endif
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/* Configure GPIO pins to enable all UARTs in the configuration
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* (the serial driver later depends on this configuration)
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*/
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#ifndef CONFIG_UART0_DISABLE
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lm3x_configgpio(GPIO_UART0_RX);
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lm3x_configgpio(GPIO_UART0_TX);
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#endif
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#ifndef CONFIG_UART1_DISABLE
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lm3x_configgpio(GPIO_UART1_RX);
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lm3x_configgpio(GPIO_UART1_TX);
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#endif
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}
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